Cleanup: missing ')'
[lttng-tools.git] / src / bin / lttng-sessiond / ust-app.c
index 38d1d78713e6446dca9b55b001ccfbee376c88b3..d303e8b66ec240f590cda13b621dc0a6918cecf4 100644 (file)
@@ -7,29 +7,35 @@
  */
 
 #define _LGPL_SOURCE
+#include <errno.h>
+#include <fcntl.h>
 #include <inttypes.h>
 #include <pthread.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/mman.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>
 #include <urcu/compiler.h>
 #include <signal.h>
 
+#include <common/bytecode/bytecode.h>
 #include <common/compat/errno.h>
 #include <common/common.h>
 #include <common/hashtable/utils.h>
 #include <lttng/event-rule/event-rule.h>
 #include <lttng/event-rule/event-rule-internal.h>
-#include <lttng/event-rule/tracepoint.h>
+#include <lttng/event-rule/user-tracepoint.h>
 #include <lttng/condition/condition.h>
-#include <lttng/condition/event-rule-internal.h>
-#include <lttng/condition/event-rule.h>
+#include <lttng/condition/event-rule-matches-internal.h>
+#include <lttng/condition/event-rule-matches.h>
+#include <lttng/trigger/trigger-internal.h>
 #include <common/sessiond-comm/sessiond-comm.h>
 
 #include "buffer-registry.h"
+#include "condition-internal.h"
 #include "fd-limit.h"
 #include "health-sessiond.h"
 #include "ust-app.h"
@@ -41,6 +47,9 @@
 #include "lttng-sessiond.h"
 #include "notification-thread-commands.h"
 #include "rotate.h"
+#include "event.h"
+#include "event-notifier-error-accounting.h"
+
 
 struct lttng_ht *ust_app_ht;
 struct lttng_ht *ust_app_ht_by_sock;
@@ -84,8 +93,8 @@ static uint64_t get_next_session_id(void)
 }
 
 static void copy_channel_attr_to_ustctl(
-               struct ustctl_consumer_channel_attr *attr,
-               struct lttng_ust_channel_attr *uattr)
+               struct lttng_ust_ctl_consumer_channel_attr *attr,
+               struct lttng_ust_abi_channel_attr *uattr)
 {
        /* Copy event attributes since the layout is different. */
        attr->subbuf_size = uattr->subbuf_size;
@@ -109,8 +118,8 @@ static int ht_match_ust_app_event(struct cds_lfht_node *node, const void *_key)
        const struct ust_app_ht_key *key;
        int ev_loglevel_value;
 
-       assert(node);
-       assert(_key);
+       LTTNG_ASSERT(node);
+       LTTNG_ASSERT(_key);
 
        event = caa_container_of(node, struct ust_app_event, node.node);
        key = _key;
@@ -125,7 +134,7 @@ static int ht_match_ust_app_event(struct cds_lfht_node *node, const void *_key)
 
        /* Event loglevel. */
        if (ev_loglevel_value != key->loglevel_type) {
-               if (event->attr.loglevel_type == LTTNG_UST_LOGLEVEL_ALL
+               if (event->attr.loglevel_type == LTTNG_UST_ABI_LOGLEVEL_ALL
                                && key->loglevel_type == 0 &&
                                ev_loglevel_value == -1) {
                        /*
@@ -162,7 +171,7 @@ static int ht_match_ust_app_event(struct cds_lfht_node *node, const void *_key)
                /* Both exclusions exists, check count followed by the names. */
                if (event->exclusion->count != key->exclusion->count ||
                                memcmp(event->exclusion->names, key->exclusion->names,
-                                       event->exclusion->count * LTTNG_UST_SYM_NAME_LEN) != 0) {
+                                       event->exclusion->count * LTTNG_UST_ABI_SYM_NAME_LEN) != 0) {
                        goto no_match;
                }
        }
@@ -186,9 +195,9 @@ static void add_unique_ust_app_event(struct ust_app_channel *ua_chan,
        struct ust_app_ht_key key;
        struct lttng_ht *ht;
 
-       assert(ua_chan);
-       assert(ua_chan->events);
-       assert(event);
+       LTTNG_ASSERT(ua_chan);
+       LTTNG_ASSERT(ua_chan->events);
+       LTTNG_ASSERT(event);
 
        ht = ua_chan->events;
        key.name = event->attr.name;
@@ -199,7 +208,7 @@ static void add_unique_ust_app_event(struct ust_app_channel *ua_chan,
        node_ptr = cds_lfht_add_unique(ht->ht,
                        ht->hash_fct(event->node.key, lttng_ht_seed),
                        ht_match_ust_app_event, &key, &event->node.node);
-       assert(node_ptr == &event->node.node);
+       LTTNG_ASSERT(node_ptr == &event->node.node);
 }
 
 /*
@@ -213,7 +222,7 @@ static void close_notify_sock_rcu(struct rcu_head *head)
                caa_container_of(head, struct ust_app_notify_sock_obj, head);
 
        /* Must have a valid fd here. */
-       assert(obj->fd >= 0);
+       LTTNG_ASSERT(obj->fd >= 0);
 
        ret = close(obj->fd);
        if (ret) {
@@ -229,14 +238,14 @@ static void close_notify_sock_rcu(struct rcu_head *head)
  * session.
  *
  * A registry per UID object MUST exists before calling this function or else
- * it assert() if not found. RCU read side lock must be acquired.
+ * it LTTNG_ASSERT() if not found. RCU read side lock must be acquired.
  */
 static struct ust_registry_session *get_session_registry(
                struct ust_app_session *ua_sess)
 {
        struct ust_registry_session *registry = NULL;
 
-       assert(ua_sess);
+       LTTNG_ASSERT(ua_sess);
 
        switch (ua_sess->buffer_type) {
        case LTTNG_BUFFER_PER_PID:
@@ -260,7 +269,7 @@ static struct ust_registry_session *get_session_registry(
                break;
        }
        default:
-               assert(0);
+               abort();
        };
 
 error:
@@ -277,15 +286,24 @@ void delete_ust_app_ctx(int sock, struct ust_app_ctx *ua_ctx,
 {
        int ret;
 
-       assert(ua_ctx);
+       LTTNG_ASSERT(ua_ctx);
 
        if (ua_ctx->obj) {
                pthread_mutex_lock(&app->sock_lock);
-               ret = ustctl_release_object(sock, ua_ctx->obj);
+               ret = lttng_ust_ctl_release_object(sock, ua_ctx->obj);
                pthread_mutex_unlock(&app->sock_lock);
-               if (ret < 0 && ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
-                       ERR("UST app sock %d release ctx obj handle %d failed with ret %d",
-                                       sock, ua_ctx->obj->handle, ret);
+               if (ret < 0) {
+                       if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                               DBG3("UST app release ctx failed. Application is dead: pid = %d, sock = %d",
+                                               app->pid, app->sock);
+                       } else if (ret == -EAGAIN) {
+                               WARN("UST app release ctx failed. Communication time out: pid = %d, sock = %d",
+                                               app->pid, app->sock);
+                       } else {
+                               ERR("UST app release ctx obj handle %d failed with ret %d: pid = %d, sock = %d",
+                                               ua_ctx->obj->handle, ret,
+                                               app->pid, app->sock);
+                       }
                }
                free(ua_ctx->obj);
        }
@@ -302,18 +320,26 @@ void delete_ust_app_event(int sock, struct ust_app_event *ua_event,
 {
        int ret;
 
-       assert(ua_event);
+       LTTNG_ASSERT(ua_event);
 
        free(ua_event->filter);
        if (ua_event->exclusion != NULL)
                free(ua_event->exclusion);
        if (ua_event->obj != NULL) {
                pthread_mutex_lock(&app->sock_lock);
-               ret = ustctl_release_object(sock, ua_event->obj);
+               ret = lttng_ust_ctl_release_object(sock, ua_event->obj);
                pthread_mutex_unlock(&app->sock_lock);
-               if (ret < 0 && ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
-                       ERR("UST app sock %d release event obj failed with ret %d",
-                                       sock, ret);
+               if (ret < 0) {
+                       if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                               DBG3("UST app release event failed. Application is dead: pid = %d, sock = %d",
+                                               app->pid, app->sock);
+                       } else if (ret == -EAGAIN) {
+                               WARN("UST app release event failed. Communication time out: pid = %d, sock = %d",
+                                               app->pid, app->sock);
+                       } else {
+                               ERR("UST app release event obj failed with ret %d: pid = %d, sock = %d",
+                                               ret, app->pid, app->sock);
+                       }
                }
                free(ua_event->obj);
        }
@@ -342,7 +368,7 @@ static void delete_ust_app_event_notifier_rule(int sock,
 {
        int ret;
 
-       assert(ua_event_notifier_rule);
+       LTTNG_ASSERT(ua_event_notifier_rule);
 
        if (ua_event_notifier_rule->exclusion != NULL) {
                free(ua_event_notifier_rule->exclusion);
@@ -350,17 +376,25 @@ static void delete_ust_app_event_notifier_rule(int sock,
 
        if (ua_event_notifier_rule->obj != NULL) {
                pthread_mutex_lock(&app->sock_lock);
-               ret = ustctl_release_object(sock, ua_event_notifier_rule->obj);
+               ret = lttng_ust_ctl_release_object(sock, ua_event_notifier_rule->obj);
                pthread_mutex_unlock(&app->sock_lock);
-               if (ret < 0 && ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
-                       ERR("Failed to release event notifier object: app = '%s' (ppid %d), ret = %d",
-                                       app->name, (int) app->ppid, ret);
+               if (ret < 0) {
+                       if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                               DBG3("UST app release event notifier failed. Application is dead: pid = %d, sock = %d",
+                                               app->pid, app->sock);
+                       } else if (ret == -EAGAIN) {
+                               WARN("UST app release event notifier failed. Communication time out: pid = %d, sock = %d",
+                                               app->pid, app->sock);
+                       } else {
+                               ERR("UST app release event notifier failed with ret %d: pid = %d, sock = %d",
+                                               ret, app->pid, app->sock);
+                       }
                }
 
                free(ua_event_notifier_rule->obj);
        }
 
-       lttng_event_rule_put(ua_event_notifier_rule->event_rule);
+       lttng_trigger_put(ua_event_notifier_rule->trigger);
        call_rcu(&ua_event_notifier_rule->rcu_head,
                        free_ust_app_event_notifier_rule_rcu);
 }
@@ -375,15 +409,23 @@ static int release_ust_app_stream(int sock, struct ust_app_stream *stream,
 {
        int ret = 0;
 
-       assert(stream);
+       LTTNG_ASSERT(stream);
 
        if (stream->obj) {
                pthread_mutex_lock(&app->sock_lock);
-               ret = ustctl_release_object(sock, stream->obj);
+               ret = lttng_ust_ctl_release_object(sock, stream->obj);
                pthread_mutex_unlock(&app->sock_lock);
-               if (ret < 0 && ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
-                       ERR("UST app sock %d release stream obj failed with ret %d",
-                                       sock, ret);
+               if (ret < 0) {
+                       if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                               DBG3("UST app release stream failed. Application is dead: pid = %d, sock = %d",
+                                               app->pid, app->sock);
+                       } else if (ret == -EAGAIN) {
+                               WARN("UST app release stream failed. Communication time out: pid = %d, sock = %d",
+                                               app->pid, app->sock);
+                       } else {
+                               ERR("UST app release stream obj failed with ret %d: pid = %d, sock = %d",
+                                               ret, app->pid, app->sock);
+                       }
                }
                lttng_fd_put(LTTNG_FD_APPS, 2);
                free(stream->obj);
@@ -400,7 +442,7 @@ static
 void delete_ust_app_stream(int sock, struct ust_app_stream *stream,
                struct ust_app *app)
 {
-       assert(stream);
+       LTTNG_ASSERT(stream);
 
        (void) release_ust_app_stream(sock, stream, app);
        free(stream);
@@ -437,7 +479,7 @@ void save_per_pid_lost_discarded_counters(struct ust_app_channel *ua_chan)
        struct ltt_session *session;
        struct ltt_ust_channel *uchan;
 
-       if (ua_chan->attr.type != LTTNG_UST_CHAN_PER_CPU) {
+       if (ua_chan->attr.type != LTTNG_UST_ABI_CHAN_PER_CPU) {
                return;
        }
 
@@ -506,7 +548,7 @@ void delete_ust_app_channel(int sock, struct ust_app_channel *ua_chan,
        struct ust_app_stream *stream, *stmp;
        struct ust_registry_session *registry;
 
-       assert(ua_chan);
+       LTTNG_ASSERT(ua_chan);
 
        DBG3("UST app deleting channel %s", ua_chan->name);
 
@@ -520,7 +562,7 @@ void delete_ust_app_channel(int sock, struct ust_app_channel *ua_chan,
        cds_lfht_for_each_entry(ua_chan->ctx->ht, &iter.iter, ua_ctx, node.node) {
                cds_list_del(&ua_ctx->list);
                ret = lttng_ht_del(ua_chan->ctx, &iter);
-               assert(!ret);
+               LTTNG_ASSERT(!ret);
                delete_ust_app_ctx(sock, ua_ctx, app);
        }
 
@@ -528,7 +570,7 @@ void delete_ust_app_channel(int sock, struct ust_app_channel *ua_chan,
        cds_lfht_for_each_entry(ua_chan->events->ht, &iter.iter, ua_event,
                        node.node) {
                ret = lttng_ht_del(ua_chan->events, &iter);
-               assert(!ret);
+               LTTNG_ASSERT(!ret);
                delete_ust_app_event(sock, ua_event, app);
        }
 
@@ -553,13 +595,24 @@ void delete_ust_app_channel(int sock, struct ust_app_channel *ua_chan,
                /* Remove channel from application UST object descriptor. */
                iter.iter.node = &ua_chan->ust_objd_node.node;
                ret = lttng_ht_del(app->ust_objd, &iter);
-               assert(!ret);
+               LTTNG_ASSERT(!ret);
                pthread_mutex_lock(&app->sock_lock);
-               ret = ustctl_release_object(sock, ua_chan->obj);
+               ret = lttng_ust_ctl_release_object(sock, ua_chan->obj);
                pthread_mutex_unlock(&app->sock_lock);
-               if (ret < 0 && ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
-                       ERR("UST app sock %d release channel obj failed with ret %d",
-                                       sock, ret);
+               if (ret < 0) {
+                       if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                               DBG3("UST app channel %s release failed. Application is dead: pid = %d, sock = %d",
+                                               ua_chan->name, app->pid,
+                                               app->sock);
+                       } else if (ret == -EAGAIN) {
+                               WARN("UST app channel %s release failed. Communication time out: pid = %d, sock = %d",
+                                               ua_chan->name, app->pid,
+                                               app->sock);
+                       } else {
+                               ERR("UST app channel %s release failed with ret %d: pid = %d, sock = %d",
+                                               ua_chan->name, ret, app->pid,
+                                               app->sock);
+                       }
                }
                lttng_fd_put(LTTNG_FD_APPS, 1);
                free(ua_chan->obj);
@@ -572,12 +625,12 @@ int ust_app_register_done(struct ust_app *app)
        int ret;
 
        pthread_mutex_lock(&app->sock_lock);
-       ret = ustctl_register_done(app->sock);
+       ret = lttng_ust_ctl_register_done(app->sock);
        pthread_mutex_unlock(&app->sock_lock);
        return ret;
 }
 
-int ust_app_release_object(struct ust_app *app, struct lttng_ust_object_data *data)
+int ust_app_release_object(struct ust_app *app, struct lttng_ust_abi_object_data *data)
 {
        int ret, sock;
 
@@ -587,7 +640,7 @@ int ust_app_release_object(struct ust_app *app, struct lttng_ust_object_data *da
        } else {
                sock = -1;
        }
-       ret = ustctl_release_object(sock, data);
+       ret = lttng_ust_ctl_release_object(sock, data);
        if (app) {
                pthread_mutex_unlock(&app->sock_lock);
        }
@@ -615,8 +668,8 @@ ssize_t ust_app_push_metadata(struct ust_registry_session *registry,
        ssize_t ret_val;
        uint64_t metadata_key, metadata_version;
 
-       assert(registry);
-       assert(socket);
+       LTTNG_ASSERT(registry);
+       LTTNG_ASSERT(socket);
 
        metadata_key = registry->metadata_key;
 
@@ -751,8 +804,8 @@ static int push_metadata(struct ust_registry_session *registry,
        ssize_t ret;
        struct consumer_socket *socket;
 
-       assert(registry);
-       assert(consumer);
+       LTTNG_ASSERT(registry);
+       LTTNG_ASSERT(consumer);
 
        pthread_mutex_lock(&registry->lock);
        if (registry->metadata_closed) {
@@ -801,8 +854,8 @@ static int close_metadata(struct ust_registry_session *registry,
        uint64_t metadata_key;
        bool registry_was_already_closed;
 
-       assert(registry);
-       assert(consumer);
+       LTTNG_ASSERT(registry);
+       LTTNG_ASSERT(consumer);
 
        rcu_read_lock();
 
@@ -873,11 +926,11 @@ void delete_ust_app_session(int sock, struct ust_app_session *ua_sess,
        struct ust_app_channel *ua_chan;
        struct ust_registry_session *registry;
 
-       assert(ua_sess);
+       LTTNG_ASSERT(ua_sess);
 
        pthread_mutex_lock(&ua_sess->lock);
 
-       assert(!ua_sess->deleted);
+       LTTNG_ASSERT(!ua_sess->deleted);
        ua_sess->deleted = true;
 
        registry = get_session_registry(ua_sess);
@@ -901,7 +954,7 @@ void delete_ust_app_session(int sock, struct ust_app_session *ua_sess,
        cds_lfht_for_each_entry(ua_sess->channels->ht, &iter.iter, ua_chan,
                        node.node) {
                ret = lttng_ht_del(ua_sess->channels, &iter);
-               assert(!ret);
+               LTTNG_ASSERT(!ret);
                delete_ust_app_channel(sock, ua_chan, app);
        }
 
@@ -920,16 +973,25 @@ void delete_ust_app_session(int sock, struct ust_app_session *ua_sess,
 
        if (ua_sess->handle != -1) {
                pthread_mutex_lock(&app->sock_lock);
-               ret = ustctl_release_handle(sock, ua_sess->handle);
+               ret = lttng_ust_ctl_release_handle(sock, ua_sess->handle);
                pthread_mutex_unlock(&app->sock_lock);
-               if (ret < 0 && ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
-                       ERR("UST app sock %d release session handle failed with ret %d",
-                                       sock, ret);
+               if (ret < 0) {
+                       if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                               DBG3("UST app release session handle failed. Application is dead: pid = %d, sock = %d",
+                                               app->pid, app->sock);
+                       } else if (ret == -EAGAIN) {
+                               WARN("UST app release session handle failed. Communication time out: pid = %d, sock = %d",
+                                               app->pid, app->sock);
+                       } else {
+                               ERR("UST app release session handle failed with ret %d: pid = %d, sock = %d",
+                                               ret, app->pid, app->sock);
+                       }
                }
+
                /* Remove session from application UST object descriptor. */
                iter.iter.node = &ua_sess->ust_objd_node.node;
                ret = lttng_ht_del(app->ust_sessions_objd, &iter);
-               assert(!ret);
+               LTTNG_ASSERT(!ret);
        }
 
        pthread_mutex_unlock(&ua_sess->lock);
@@ -952,6 +1014,7 @@ void delete_ust_app(struct ust_app *app)
        struct ust_app_session *ua_sess, *tmp_ua_sess;
        struct lttng_ht_iter iter;
        struct ust_app_event_notifier_rule *event_notifier_rule;
+       bool event_notifier_write_fd_is_open;
 
        /*
         * The session list lock must be held during this function to guarantee
@@ -976,7 +1039,7 @@ void delete_ust_app(struct ust_app *app)
        cds_lfht_for_each_entry (app->token_to_event_notifier_rule_ht->ht,
                        &iter.iter, event_notifier_rule, node.node) {
                ret = lttng_ht_del(app->token_to_event_notifier_rule_ht, &iter);
-               assert(!ret);
+               LTTNG_ASSERT(!ret);
 
                delete_ust_app_event_notifier_rule(
                                app->sock, event_notifier_rule, app);
@@ -995,21 +1058,37 @@ void delete_ust_app(struct ust_app *app)
         */
        if (app->event_notifier_group.object) {
                enum lttng_error_code ret_code;
+               enum event_notifier_error_accounting_status status;
+
                const int event_notifier_read_fd = lttng_pipe_get_readfd(
                                app->event_notifier_group.event_pipe);
 
                ret_code = notification_thread_command_remove_tracer_event_source(
-                               notification_thread_handle,
+                               the_notification_thread_handle,
                                event_notifier_read_fd);
                if (ret_code != LTTNG_OK) {
                        ERR("Failed to remove application tracer event source from notification thread");
                }
 
-               ustctl_release_object(sock, app->event_notifier_group.object);
+               status = event_notifier_error_accounting_unregister_app(app);
+               if (status != EVENT_NOTIFIER_ERROR_ACCOUNTING_STATUS_OK) {
+                       ERR("Error unregistering app from event notifier error accounting");
+               }
+
+               lttng_ust_ctl_release_object(sock, app->event_notifier_group.object);
                free(app->event_notifier_group.object);
        }
 
+       event_notifier_write_fd_is_open = lttng_pipe_is_write_open(
+                       app->event_notifier_group.event_pipe);
        lttng_pipe_destroy(app->event_notifier_group.event_pipe);
+       /*
+        * Release the file descriptors reserved for the event notifier pipe.
+        * The app could be destroyed before the write end of the pipe could be
+        * passed to the application (and closed). In that case, both file
+        * descriptors must be released.
+        */
+       lttng_fd_put(LTTNG_FD_APPS, event_notifier_write_fd_is_open ? 2 : 1);
 
        /*
         * Wait until we have deleted the application from the sock hash table
@@ -1062,8 +1141,8 @@ static void destroy_app_session(struct ust_app *app,
        int ret;
        struct lttng_ht_iter iter;
 
-       assert(app);
-       assert(ua_sess);
+       LTTNG_ASSERT(app);
+       LTTNG_ASSERT(ua_sess);
 
        iter.iter.node = &ua_sess->node.node;
        ret = lttng_ht_del(app->sessions, &iter);
@@ -1096,7 +1175,7 @@ struct ust_app_session *alloc_ust_app_session(void)
 
        ua_sess->handle = -1;
        ua_sess->channels = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
-       ua_sess->metadata_attr.type = LTTNG_UST_CHAN_METADATA;
+       ua_sess->metadata_attr.type = LTTNG_UST_ABI_CHAN_METADATA;
        pthread_mutex_init(&ua_sess->lock, NULL);
 
        return ua_sess;
@@ -1111,7 +1190,7 @@ error_free:
 static
 struct ust_app_channel *alloc_ust_app_channel(const char *name,
                struct ust_app_session *ua_sess,
-               struct lttng_ust_channel_attr *attr)
+               struct lttng_ust_abi_channel_attr *attr)
 {
        struct ust_app_channel *ua_chan;
 
@@ -1139,7 +1218,7 @@ struct ust_app_channel *alloc_ust_app_channel(const char *name,
 
        /* Copy attributes */
        if (attr) {
-               /* Translate from lttng_ust_channel to ustctl_consumer_channel_attr. */
+               /* Translate from lttng_ust_channel to lttng_ust_ctl_consumer_channel_attr. */
                ua_chan->attr.subbuf_size = attr->subbuf_size;
                ua_chan->attr.num_subbuf = attr->num_subbuf;
                ua_chan->attr.overwrite = attr->overwrite;
@@ -1149,7 +1228,7 @@ struct ust_app_channel *alloc_ust_app_channel(const char *name,
                ua_chan->attr.blocking_timeout = attr->u.s.blocking_timeout;
        }
        /* By default, the channel is a per cpu channel. */
-       ua_chan->attr.type = LTTNG_UST_CHAN_PER_CPU;
+       ua_chan->attr.type = LTTNG_UST_ABI_CHAN_PER_CPU;
 
        DBG3("UST app channel %s allocated", ua_chan->name);
 
@@ -1186,7 +1265,7 @@ error:
  */
 static
 struct ust_app_event *alloc_ust_app_event(char *name,
-               struct lttng_ust_event *attr)
+               struct lttng_ust_abi_event *attr)
 {
        struct ust_app_event *ua_event;
 
@@ -1219,11 +1298,14 @@ error:
  * Allocate a new UST app event notifier rule.
  */
 static struct ust_app_event_notifier_rule *alloc_ust_app_event_notifier_rule(
-               struct lttng_event_rule *event_rule, uint64_t token)
+               struct lttng_trigger *trigger)
 {
        enum lttng_event_rule_generate_exclusions_status
                        generate_exclusion_status;
+       enum lttng_condition_status cond_status;
        struct ust_app_event_notifier_rule *ua_event_notifier_rule;
+       struct lttng_condition *condition = NULL;
+       const struct lttng_event_rule *event_rule = NULL;
 
        ua_event_notifier_rule = zmalloc(sizeof(struct ust_app_event_notifier_rule));
        if (ua_event_notifier_rule == NULL) {
@@ -1232,15 +1314,26 @@ static struct ust_app_event_notifier_rule *alloc_ust_app_event_notifier_rule(
        }
 
        ua_event_notifier_rule->enabled = 1;
-       ua_event_notifier_rule->token = token;
-       lttng_ht_node_init_u64(&ua_event_notifier_rule->node, token);
+       ua_event_notifier_rule->token = lttng_trigger_get_tracer_token(trigger);
+       lttng_ht_node_init_u64(&ua_event_notifier_rule->node,
+                       ua_event_notifier_rule->token);
 
-       /* Get reference of the event rule. */
-       if (!lttng_event_rule_get(event_rule)) {
-               abort();
-       }
+       condition = lttng_trigger_get_condition(trigger);
+       LTTNG_ASSERT(condition);
+       LTTNG_ASSERT(lttng_condition_get_type(condition) ==
+                       LTTNG_CONDITION_TYPE_EVENT_RULE_MATCHES);
+
+       cond_status = lttng_condition_event_rule_matches_get_rule(
+                       condition, &event_rule);
+       LTTNG_ASSERT(cond_status == LTTNG_CONDITION_STATUS_OK);
+       LTTNG_ASSERT(event_rule);
 
-       ua_event_notifier_rule->event_rule = event_rule;
+       ua_event_notifier_rule->error_counter_index =
+                       lttng_condition_event_rule_matches_get_error_counter_index(condition);
+       /* Acquire the event notifier's reference to the trigger. */
+       lttng_trigger_get(trigger);
+
+       ua_event_notifier_rule->trigger = trigger;
        ua_event_notifier_rule->filter = lttng_event_rule_get_filter_bytecode(event_rule);
        generate_exclusion_status = lttng_event_rule_generate_exclusions(
                        event_rule, &ua_event_notifier_rule->exclusion);
@@ -1249,9 +1342,9 @@ static struct ust_app_event_notifier_rule *alloc_ust_app_event_notifier_rule(
        case LTTNG_EVENT_RULE_GENERATE_EXCLUSIONS_STATUS_NONE:
                break;
        default:
-               /* Error occured. */
-               ERR("Failed to generate exclusions from event rule while allocating an event notifier rule");
-               goto error_put_event_rule;
+               /* Error occurred. */
+               ERR("Failed to generate exclusions from trigger while allocating an event notifier rule");
+               goto error_put_trigger;
        }
 
        DBG3("UST app event notifier rule allocated: token = %" PRIu64,
@@ -1259,8 +1352,8 @@ static struct ust_app_event_notifier_rule *alloc_ust_app_event_notifier_rule(
 
        return ua_event_notifier_rule;
 
-error_put_event_rule:
-       lttng_event_rule_put(event_rule);
+error_put_trigger:
+       lttng_trigger_put(trigger);
 error:
        free(ua_event_notifier_rule);
        return NULL;
@@ -1283,7 +1376,7 @@ struct ust_app_ctx *alloc_ust_app_ctx(struct lttng_ust_context_attr *uctx)
 
        if (uctx) {
                memcpy(&ua_ctx->ctx, uctx, sizeof(ua_ctx->ctx));
-               if (uctx->ctx == LTTNG_UST_CONTEXT_APP_CONTEXT) {
+               if (uctx->ctx == LTTNG_UST_ABI_CONTEXT_APP_CONTEXT) {
                        char *provider_name = NULL, *ctx_name = NULL;
 
                        provider_name = strdup(uctx->u.app_ctx.provider_name);
@@ -1307,50 +1400,51 @@ error:
 }
 
 /*
- * Allocate a filter and copy the given original filter.
+ * Create a liblttng-ust filter bytecode from given bytecode.
  *
  * Return allocated filter or NULL on error.
  */
-static struct lttng_filter_bytecode *copy_filter_bytecode(
-               struct lttng_filter_bytecode *orig_f)
+static struct lttng_ust_abi_filter_bytecode *create_ust_filter_bytecode_from_bytecode(
+               const struct lttng_bytecode *orig_f)
 {
-       struct lttng_filter_bytecode *filter = NULL;
+       struct lttng_ust_abi_filter_bytecode *filter = NULL;
 
-       /* Copy filter bytecode */
+       /* Copy filter bytecode. */
        filter = zmalloc(sizeof(*filter) + orig_f->len);
        if (!filter) {
-               PERROR("zmalloc alloc filter bytecode");
+               PERROR("Failed to allocate lttng_ust_filter_bytecode: bytecode len = %" PRIu32 " bytes", orig_f->len);
                goto error;
        }
 
+       LTTNG_ASSERT(sizeof(struct lttng_bytecode) ==
+                       sizeof(struct lttng_ust_abi_filter_bytecode));
        memcpy(filter, orig_f, sizeof(*filter) + orig_f->len);
-
 error:
        return filter;
 }
 
 /*
- * Create a liblttng-ust filter bytecode from given bytecode.
+ * Create a liblttng-ust capture bytecode from given bytecode.
  *
  * Return allocated filter or NULL on error.
  */
-static struct lttng_ust_filter_bytecode *create_ust_bytecode_from_bytecode(
-               const struct lttng_filter_bytecode *orig_f)
+static struct lttng_ust_abi_capture_bytecode *
+create_ust_capture_bytecode_from_bytecode(const struct lttng_bytecode *orig_f)
 {
-       struct lttng_ust_filter_bytecode *filter = NULL;
+       struct lttng_ust_abi_capture_bytecode *capture = NULL;
 
-       /* Copy filter bytecode */
-       filter = zmalloc(sizeof(*filter) + orig_f->len);
-       if (!filter) {
-               PERROR("zmalloc alloc ust filter bytecode");
+       /* Copy capture bytecode. */
+       capture = zmalloc(sizeof(*capture) + orig_f->len);
+       if (!capture) {
+               PERROR("Failed to allocate lttng_ust_abi_capture_bytecode: bytecode len = %" PRIu32 " bytes", orig_f->len);
                goto error;
        }
 
-       assert(sizeof(struct lttng_filter_bytecode) ==
-                       sizeof(struct lttng_ust_filter_bytecode));
-       memcpy(filter, orig_f, sizeof(*filter) + orig_f->len);
+       LTTNG_ASSERT(sizeof(struct lttng_bytecode) ==
+                       sizeof(struct lttng_ust_abi_capture_bytecode));
+       memcpy(capture, orig_f, sizeof(*capture) + orig_f->len);
 error:
-       return filter;
+       return capture;
 }
 
 /*
@@ -1405,7 +1499,7 @@ error:
  * Return an ust_app_event object or NULL on error.
  */
 static struct ust_app_event *find_ust_app_event(struct lttng_ht *ht,
-               const char *name, const struct lttng_filter_bytecode *filter,
+               const char *name, const struct lttng_bytecode *filter,
                int loglevel_value,
                const struct lttng_event_exclusion *exclusion)
 {
@@ -1414,8 +1508,8 @@ static struct ust_app_event *find_ust_app_event(struct lttng_ht *ht,
        struct ust_app_event *event = NULL;
        struct ust_app_ht_key key;
 
-       assert(name);
-       assert(ht);
+       LTTNG_ASSERT(name);
+       LTTNG_ASSERT(ht);
 
        /* Setup key for event lookup. */
        key.name = name;
@@ -1451,7 +1545,7 @@ static struct ust_app_event_notifier_rule *find_ust_app_event_notifier_rule(
        struct lttng_ht_node_u64 *node;
        struct ust_app_event_notifier_rule *event_notifier_rule = NULL;
 
-       assert(ht);
+       LTTNG_ASSERT(ht);
 
        lttng_ht_lookup(ht, &token, &iter);
        node = lttng_ht_iter_get_node_u64(&iter);
@@ -1481,21 +1575,21 @@ int create_ust_channel_context(struct ust_app_channel *ua_chan,
        health_code_update();
 
        pthread_mutex_lock(&app->sock_lock);
-       ret = ustctl_add_context(app->sock, &ua_ctx->ctx,
+       ret = lttng_ust_ctl_add_context(app->sock, &ua_ctx->ctx,
                        ua_chan->obj, &ua_ctx->obj);
        pthread_mutex_unlock(&app->sock_lock);
        if (ret < 0) {
-               if (ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
-                       ERR("UST app create channel context failed for app (pid: %d) "
-                                       "with ret %d", app->pid, ret);
-               } else {
-                       /*
-                        * This is normal behavior, an application can die during the
-                        * creation process. Don't report an error so the execution can
-                        * continue normally.
-                        */
+               if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                       ret = 0;
+                       DBG3("UST app create channel context failed. Application is dead: pid = %d, sock = %d",
+                                       app->pid, app->sock);
+               } else if (ret == -EAGAIN) {
                        ret = 0;
-                       DBG3("UST app add context failed. Application is dead.");
+                       WARN("UST app create channel context failed. Communication time out: pid = %d, sock = %d",
+                                       app->pid, app->sock);
+               } else {
+                       ERR("UST app create channel context failed with ret %d: pid = %d, sock = %d",
+                                       ret, app->pid, app->sock);
                }
                goto error;
        }
@@ -1514,40 +1608,96 @@ error:
  * Set the filter on the tracer.
  */
 static int set_ust_object_filter(struct ust_app *app,
-               const struct lttng_filter_bytecode *bytecode,
-               struct lttng_ust_object_data *ust_object)
+               const struct lttng_bytecode *bytecode,
+               struct lttng_ust_abi_object_data *ust_object)
 {
        int ret;
-       struct lttng_ust_filter_bytecode *ust_bytecode = NULL;
+       struct lttng_ust_abi_filter_bytecode *ust_bytecode = NULL;
 
        health_code_update();
 
-       ust_bytecode = create_ust_bytecode_from_bytecode(bytecode);
+       ust_bytecode = create_ust_filter_bytecode_from_bytecode(bytecode);
        if (!ust_bytecode) {
                ret = -LTTNG_ERR_NOMEM;
                goto error;
        }
        pthread_mutex_lock(&app->sock_lock);
-       ret = ustctl_set_filter(app->sock, ust_bytecode,
+       ret = lttng_ust_ctl_set_filter(app->sock, ust_bytecode,
                        ust_object);
        pthread_mutex_unlock(&app->sock_lock);
        if (ret < 0) {
-               if (ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
-                       ERR("UST app set object filter failed for object %p of app (pid: %d) "
-                                       "with ret %d", ust_object, app->pid, ret);
+               if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                       ret = 0;
+                       DBG3("UST app  set filter failed. Application is dead: pid = %d, sock = %d",
+                                       app->pid, app->sock);
+               } else if (ret == -EAGAIN) {
+                       ret = 0;
+                       WARN("UST app  set filter failed. Communication time out: pid = %d, sock = %d",
+                                       app->pid, app->sock);
                } else {
-                       /*
-                        * This is normal behavior, an application can die during the
-                        * creation process. Don't report an error so the execution can
-                        * continue normally.
-                        */
+                       ERR("UST app  set filter failed with ret %d: pid = %d, sock = %d, object = %p",
+                                       ret, app->pid, app->sock, ust_object);
+               }
+               goto error;
+       }
+
+       DBG2("UST filter successfully set: object = %p", ust_object);
+
+error:
+       health_code_update();
+       free(ust_bytecode);
+       return ret;
+}
+
+/*
+ * Set a capture bytecode for the passed object.
+ * The sequence number enforces the ordering at runtime and on reception of
+ * the captured payloads.
+ */
+static int set_ust_capture(struct ust_app *app,
+               const struct lttng_bytecode *bytecode,
+               unsigned int capture_seqnum,
+               struct lttng_ust_abi_object_data *ust_object)
+{
+       int ret;
+       struct lttng_ust_abi_capture_bytecode *ust_bytecode = NULL;
+
+       health_code_update();
+
+       ust_bytecode = create_ust_capture_bytecode_from_bytecode(bytecode);
+       if (!ust_bytecode) {
+               ret = -LTTNG_ERR_NOMEM;
+               goto error;
+       }
+
+       /*
+        * Set the sequence number to ensure the capture of fields is ordered.
+        */
+       ust_bytecode->seqnum = capture_seqnum;
+
+       pthread_mutex_lock(&app->sock_lock);
+       ret = lttng_ust_ctl_set_capture(app->sock, ust_bytecode,
+                       ust_object);
+       pthread_mutex_unlock(&app->sock_lock);
+       if (ret < 0) {
+               if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                       ret = 0;
+                       DBG3("UST app set capture failed. Application is dead: pid = %d, sock = %d",
+                                       app->pid, app->sock);
+               } else if (ret == -EAGAIN) {
                        ret = 0;
-                       DBG3("Failed to set UST app object filter. Application is dead.");
+                       DBG3("UST app set capture failed. Communication timeout: pid = %d, sock = %d",
+                                       app->pid, app->sock);
+               } else {
+                       ERR("UST app event set capture failed with ret %d: pid = %d, sock = %d",
+                                       ret, app->pid,
+                                       app->sock);
                }
+
                goto error;
        }
 
-       DBG2("UST filter successfully set for object %p", ust_object);
+       DBG2("UST capture successfully set: object = %p", ust_object);
 
 error:
        health_code_update();
@@ -1556,12 +1706,12 @@ error:
 }
 
 static
-struct lttng_ust_event_exclusion *create_ust_exclusion_from_exclusion(
+struct lttng_ust_abi_event_exclusion *create_ust_exclusion_from_exclusion(
                const struct lttng_event_exclusion *exclusion)
 {
-       struct lttng_ust_event_exclusion *ust_exclusion = NULL;
-       size_t exclusion_alloc_size = sizeof(struct lttng_ust_event_exclusion) +
-               LTTNG_UST_SYM_NAME_LEN * exclusion->count;
+       struct lttng_ust_abi_event_exclusion *ust_exclusion = NULL;
+       size_t exclusion_alloc_size = sizeof(struct lttng_ust_abi_event_exclusion) +
+               LTTNG_UST_ABI_SYM_NAME_LEN * exclusion->count;
 
        ust_exclusion = zmalloc(exclusion_alloc_size);
        if (!ust_exclusion) {
@@ -1569,8 +1719,8 @@ struct lttng_ust_event_exclusion *create_ust_exclusion_from_exclusion(
                goto end;
        }
 
-       assert(sizeof(struct lttng_event_exclusion) ==
-                       sizeof(struct lttng_ust_event_exclusion));
+       LTTNG_ASSERT(sizeof(struct lttng_event_exclusion) ==
+                       sizeof(struct lttng_ust_abi_event_exclusion));
        memcpy(ust_exclusion, exclusion, exclusion_alloc_size);
 end:
        return ust_exclusion;
@@ -1581,12 +1731,12 @@ end:
  */
 static int set_ust_object_exclusions(struct ust_app *app,
                const struct lttng_event_exclusion *exclusions,
-               struct lttng_ust_object_data *ust_object)
+               struct lttng_ust_abi_object_data *ust_object)
 {
        int ret;
-       struct lttng_ust_event_exclusion *ust_exclusions = NULL;
+       struct lttng_ust_abi_event_exclusion *ust_exclusions = NULL;
 
-       assert(exclusions && exclusions->count > 0);
+       LTTNG_ASSERT(exclusions && exclusions->count > 0);
 
        health_code_update();
 
@@ -1597,20 +1747,20 @@ static int set_ust_object_exclusions(struct ust_app *app,
                goto error;
        }
        pthread_mutex_lock(&app->sock_lock);
-       ret = ustctl_set_exclusion(app->sock, ust_exclusions, ust_object);
+       ret = lttng_ust_ctl_set_exclusion(app->sock, ust_exclusions, ust_object);
        pthread_mutex_unlock(&app->sock_lock);
        if (ret < 0) {
-               if (ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
-                       ERR("Failed to set UST app exclusions for object %p of app (pid: %d) "
-                                       "with ret %d", ust_object, app->pid, ret);
-               } else {
-                       /*
-                        * This is normal behavior, an application can die during the
-                        * creation process. Don't report an error so the execution can
-                        * continue normally.
-                        */
+               if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
                        ret = 0;
-                       DBG3("Failed to set UST app object exclusions. Application is dead.");
+                       DBG3("UST app event exclusion failed. Application is dead: pid = %d, sock = %d",
+                                       app->pid, app->sock);
+               } else if (ret == -EAGAIN) {
+                       ret = 0;
+                       WARN("UST app event exclusion failed. Communication time out(pid: %d, sock = %d",
+                                       app->pid, app->sock);
+               } else {
+                       ERR("UST app event exclusions failed with ret %d: pid = %d, sock = %d, object = %p",
+                                       ret, app->pid, app->sock, ust_object);
                }
                goto error;
        }
@@ -1627,32 +1777,32 @@ error:
  * Disable the specified event on to UST tracer for the UST session.
  */
 static int disable_ust_object(struct ust_app *app,
-               struct lttng_ust_object_data *object)
+               struct lttng_ust_abi_object_data *object)
 {
        int ret;
 
        health_code_update();
 
        pthread_mutex_lock(&app->sock_lock);
-       ret = ustctl_disable(app->sock, object);
+       ret = lttng_ust_ctl_disable(app->sock, object);
        pthread_mutex_unlock(&app->sock_lock);
        if (ret < 0) {
-               if (ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
-                       ERR("Failed to disable UST app object %p app (pid: %d) with ret %d",
-                                       object, app->pid, ret);
-               } else {
-                       /*
-                        * This is normal behavior, an application can die during the
-                        * creation process. Don't report an error so the execution can
-                        * continue normally.
-                        */
+               if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                       ret = 0;
+                       DBG3("UST app disable object failed. Application is dead: pid = %d, sock = %d",
+                                       app->pid, app->sock);
+               } else if (ret == -EAGAIN) {
                        ret = 0;
-                       DBG3("Failed to disable UST app object. Application is dead.");
+                       WARN("UST app disable object failed. Communication time out: pid = %d, sock = %d",
+                                       app->pid, app->sock);
+               } else {
+                       ERR("UST app disable object failed with ret %d: pid = %d, sock = %d, object = %p",
+                                       ret, app->pid, app->sock, object);
                }
                goto error;
        }
 
-       DBG2("UST app object %p disabled successfully for app (pid: %d)",
+       DBG2("UST app object %p disabled successfully for app: pid = %d",
                        object, app->pid);
 
 error:
@@ -1671,26 +1821,26 @@ static int disable_ust_channel(struct ust_app *app,
        health_code_update();
 
        pthread_mutex_lock(&app->sock_lock);
-       ret = ustctl_disable(app->sock, ua_chan->obj);
+       ret = lttng_ust_ctl_disable(app->sock, ua_chan->obj);
        pthread_mutex_unlock(&app->sock_lock);
        if (ret < 0) {
-               if (ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
-                       ERR("UST app channel %s disable failed for app (pid: %d) "
-                                       "and session handle %d with ret %d",
-                                       ua_chan->name, app->pid, ua_sess->handle, ret);
-               } else {
-                       /*
-                        * This is normal behavior, an application can die during the
-                        * creation process. Don't report an error so the execution can
-                        * continue normally.
-                        */
+               if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                       ret = 0;
+                       DBG3("UST app disable channel failed. Application is dead: pid = %d, sock = %d",
+                                       app->pid, app->sock);
+               } else if (ret == -EAGAIN) {
                        ret = 0;
-                       DBG3("UST app disable channel failed. Application is dead.");
+                       WARN("UST app disable channel failed. Communication time out: pid = %d, sock = %d",
+                                       app->pid, app->sock);
+               } else {
+                       ERR("UST app channel %s disable failed, session handle %d, with ret %d: pid = %d, sock = %d",
+                                       ua_chan->name, ua_sess->handle, ret,
+                                       app->pid, app->sock);
                }
                goto error;
        }
 
-       DBG2("UST app channel %s disabled successfully for app (pid: %d)",
+       DBG2("UST app channel %s disabled successfully for app: pid = %d",
                        ua_chan->name, app->pid);
 
 error:
@@ -1709,28 +1859,28 @@ static int enable_ust_channel(struct ust_app *app,
        health_code_update();
 
        pthread_mutex_lock(&app->sock_lock);
-       ret = ustctl_enable(app->sock, ua_chan->obj);
+       ret = lttng_ust_ctl_enable(app->sock, ua_chan->obj);
        pthread_mutex_unlock(&app->sock_lock);
        if (ret < 0) {
-               if (ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
-                       ERR("UST app channel %s enable failed for app (pid: %d) "
-                                       "and session handle %d with ret %d",
-                                       ua_chan->name, app->pid, ua_sess->handle, ret);
-               } else {
-                       /*
-                        * This is normal behavior, an application can die during the
-                        * creation process. Don't report an error so the execution can
-                        * continue normally.
-                        */
+               if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                       ret = 0;
+                       DBG3("UST app channel %s enable failed. Application is dead: pid = %d, sock = %d",
+                                       ua_chan->name, app->pid, app->sock);
+               } else if (ret == -EAGAIN) {
                        ret = 0;
-                       DBG3("UST app enable channel failed. Application is dead.");
+                       WARN("UST app channel %s enable failed. Communication time out: pid = %d, sock = %d",
+                                       ua_chan->name, app->pid, app->sock);
+               } else {
+                       ERR("UST app channel %s enable failed, session handle %d, with ret %d: pid = %d, sock = %d",
+                                       ua_chan->name, ua_sess->handle, ret,
+                                       app->pid, app->sock);
                }
                goto error;
        }
 
        ua_chan->enabled = 1;
 
-       DBG2("UST app channel %s enabled successfully for app (pid: %d)",
+       DBG2("UST app channel %s enabled successfully for app: pid = %d",
                        ua_chan->name, app->pid);
 
 error:
@@ -1742,32 +1892,32 @@ error:
  * Enable the specified event on to UST tracer for the UST session.
  */
 static int enable_ust_object(
-               struct ust_app *app, struct lttng_ust_object_data *ust_object)
+               struct ust_app *app, struct lttng_ust_abi_object_data *ust_object)
 {
        int ret;
 
        health_code_update();
 
        pthread_mutex_lock(&app->sock_lock);
-       ret = ustctl_enable(app->sock, ust_object);
+       ret = lttng_ust_ctl_enable(app->sock, ust_object);
        pthread_mutex_unlock(&app->sock_lock);
        if (ret < 0) {
-               if (ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
-                       ERR("UST app enable failed for object %p app (pid: %d) with ret %d",
-                                       ust_object, app->pid, ret);
-               } else {
-                       /*
-                        * This is normal behavior, an application can die during the
-                        * creation process. Don't report an error so the execution can
-                        * continue normally.
-                        */
+               if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                       ret = 0;
+                       DBG3("UST app enable object failed. Application is dead: pid = %d, sock = %d",
+                                       app->pid, app->sock);
+               } else if (ret == -EAGAIN) {
                        ret = 0;
-                       DBG3("Failed to enable UST app object. Application is dead.");
+                       WARN("UST app enable object failed. Communication time out: pid = %d, sock = %d",
+                                       app->pid, app->sock);
+               } else {
+                       ERR("UST app enable object failed with ret %d: pid = %d, sock = %d, object = %p",
+                                       ret, app->pid, app->sock, ust_object);
                }
                goto error;
        }
 
-       DBG2("UST app object %p enabled successfully for app (pid: %d)",
+       DBG2("UST app object %p enabled successfully for app: pid = %d",
                        ust_object, app->pid);
 
 error:
@@ -1786,9 +1936,9 @@ static int send_channel_pid_to_ust(struct ust_app *app,
        int ret;
        struct ust_app_stream *stream, *stmp;
 
-       assert(app);
-       assert(ua_sess);
-       assert(ua_chan);
+       LTTNG_ASSERT(app);
+       LTTNG_ASSERT(ua_sess);
+       LTTNG_ASSERT(ua_chan);
 
        health_code_update();
 
@@ -1800,6 +1950,13 @@ static int send_channel_pid_to_ust(struct ust_app *app,
        if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
                ret = -ENOTCONN;        /* Caused by app exiting. */
                goto error;
+       } else if (ret == -EAGAIN) {
+               /* Caused by timeout. */
+               WARN("Communication with application %d timed out on send_channel for channel \"%s\" of session \"%" PRIu64 "\".",
+                               app->pid, ua_chan->name, ua_sess->tracing_id);
+               /* Treat this the same way as an application that is exiting. */
+               ret = -ENOTCONN;
+               goto error;
        } else if (ret < 0) {
                goto error;
        }
@@ -1810,8 +1967,18 @@ static int send_channel_pid_to_ust(struct ust_app *app,
        cds_list_for_each_entry_safe(stream, stmp, &ua_chan->streams.head, list) {
                ret = ust_consumer_send_stream_to_ust(app, ua_chan, stream);
                if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
-                       ret = -ENOTCONN;        /* Caused by app exiting. */
+                       ret = -ENOTCONN; /* Caused by app exiting. */
                        goto error;
+               } else if (ret == -EAGAIN) {
+                       /* Caused by timeout. */
+                       WARN("Communication with application %d timed out on send_stream for stream \"%s\" of channel \"%s\" of session \"%" PRIu64 "\".",
+                                       app->pid, stream->name, ua_chan->name,
+                                       ua_sess->tracing_id);
+                       /*
+                        * Treat this the same way as an application that is
+                        * exiting.
+                        */
+                       ret = -ENOTCONN;
                } else if (ret < 0) {
                        goto error;
                }
@@ -1842,29 +2009,29 @@ int create_ust_event(struct ust_app *app, struct ust_app_session *ua_sess,
 
        /* Create UST event on tracer */
        pthread_mutex_lock(&app->sock_lock);
-       ret = ustctl_create_event(app->sock, &ua_event->attr, ua_chan->obj,
+       ret = lttng_ust_ctl_create_event(app->sock, &ua_event->attr, ua_chan->obj,
                        &ua_event->obj);
        pthread_mutex_unlock(&app->sock_lock);
        if (ret < 0) {
-               if (ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
-                       abort();
-                       ERR("Error ustctl create event %s for app pid: %d with ret %d",
-                                       ua_event->attr.name, app->pid, ret);
-               } else {
-                       /*
-                        * This is normal behavior, an application can die during the
-                        * creation process. Don't report an error so the execution can
-                        * continue normally.
-                        */
+               if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
                        ret = 0;
-                       DBG3("UST app create event failed. Application is dead.");
+                       DBG3("UST app create event failed. Application is dead: pid = %d, sock = %d",
+                                       app->pid, app->sock);
+               } else if (ret == -EAGAIN) {
+                       ret = 0;
+                       WARN("UST app create event failed. Communication time out: pid = %d, sock = %d",
+                                       app->pid, app->sock);
+               } else {
+                       ERR("UST app create event '%s' failed with ret %d: pid = %d, sock = %d",
+                                       ua_event->attr.name, ret, app->pid,
+                                       app->sock);
                }
                goto error;
        }
 
        ua_event->handle = ua_event->obj->handle;
 
-       DBG2("UST app event %s created successfully for pid:%d object: %p",
+       DBG2("UST app event %s created successfully for pid:%d object = %p",
                        ua_event->attr.name, app->pid, ua_event->obj);
 
        health_code_update();
@@ -1901,7 +2068,7 @@ int create_ust_event(struct ust_app *app, struct ust_app_session *ua_sess,
                        switch (ret) {
                        case -LTTNG_UST_ERR_PERM:
                                /* Code flow problem */
-                               assert(0);
+                               abort();
                        case -LTTNG_UST_ERR_EXIST:
                                /* It's OK for our use case. */
                                ret = 0;
@@ -1920,57 +2087,71 @@ error:
 
 static int init_ust_event_notifier_from_event_rule(
                const struct lttng_event_rule *rule,
-               struct lttng_ust_event_notifier *event_notifier)
+               struct lttng_ust_abi_event_notifier *event_notifier)
 {
        enum lttng_event_rule_status status;
-       enum lttng_loglevel_type loglevel_type;
-       enum lttng_ust_loglevel_type ust_loglevel_type = LTTNG_UST_LOGLEVEL_ALL;
+       enum lttng_ust_abi_loglevel_type ust_loglevel_type = LTTNG_UST_ABI_LOGLEVEL_ALL;
        int loglevel = -1, ret = 0;
        const char *pattern;
 
-       /* For now only LTTNG_EVENT_RULE_TYPE_TRACEPOINT are supported. */
-       assert(lttng_event_rule_get_type(rule) ==
-                       LTTNG_EVENT_RULE_TYPE_TRACEPOINT);
 
        memset(event_notifier, 0, sizeof(*event_notifier));
 
-       status = lttng_event_rule_tracepoint_get_pattern(rule, &pattern);
-       if (status != LTTNG_EVENT_RULE_STATUS_OK) {
-               /* At this point, this is a fatal error. */
-               abort();
-       }
+       if (lttng_event_rule_targets_agent_domain(rule)) {
+               /*
+                * Special event for agents
+                * The actual meat of the event is in the filter that will be
+                * attached later on.
+                * Set the default values for the agent event.
+                */
+               pattern = event_get_default_agent_ust_name(
+                               lttng_event_rule_get_domain_type(rule));
+               loglevel = 0;
+               ust_loglevel_type = LTTNG_UST_ABI_LOGLEVEL_ALL;
+       } else {
+               const struct lttng_log_level_rule *log_level_rule;
 
-       status = lttng_event_rule_tracepoint_get_log_level_type(
-                       rule, &loglevel_type);
-       if (status != LTTNG_EVENT_RULE_STATUS_OK) {
-               /* At this point, this is a fatal error. */
-               abort();
-       }
+               LTTNG_ASSERT(lttng_event_rule_get_type(rule) ==
+                               LTTNG_EVENT_RULE_TYPE_USER_TRACEPOINT);
 
-       switch (loglevel_type) {
-       case LTTNG_EVENT_LOGLEVEL_ALL:
-               ust_loglevel_type = LTTNG_UST_LOGLEVEL_ALL;
-               break;
-       case LTTNG_EVENT_LOGLEVEL_RANGE:
-               ust_loglevel_type = LTTNG_UST_LOGLEVEL_RANGE;
-               break;
-       case LTTNG_EVENT_LOGLEVEL_SINGLE:
-               ust_loglevel_type = LTTNG_UST_LOGLEVEL_SINGLE;
-               break;
-       default:
-               /* Unknown log level specification type. */
-               abort();
-       }
+               status = lttng_event_rule_user_tracepoint_get_name_pattern(rule, &pattern);
+               if (status != LTTNG_EVENT_RULE_STATUS_OK) {
+                       /* At this point, this is a fatal error. */
+                       abort();
+               }
+
+               status = lttng_event_rule_user_tracepoint_get_log_level_rule(
+                               rule, &log_level_rule);
+               if (status == LTTNG_EVENT_RULE_STATUS_UNSET) {
+                       ust_loglevel_type = LTTNG_UST_ABI_LOGLEVEL_ALL;
+               } else if (status == LTTNG_EVENT_RULE_STATUS_OK) {
+                       enum lttng_log_level_rule_status llr_status;
+
+                       switch (lttng_log_level_rule_get_type(log_level_rule)) {
+                       case LTTNG_LOG_LEVEL_RULE_TYPE_EXACTLY:
+                               ust_loglevel_type = LTTNG_UST_ABI_LOGLEVEL_SINGLE;
+                               llr_status = lttng_log_level_rule_exactly_get_level(
+                                               log_level_rule, &loglevel);
+                               break;
+                       case LTTNG_LOG_LEVEL_RULE_TYPE_AT_LEAST_AS_SEVERE_AS:
+                               ust_loglevel_type = LTTNG_UST_ABI_LOGLEVEL_RANGE;
+                               llr_status = lttng_log_level_rule_at_least_as_severe_as_get_level(
+                                               log_level_rule, &loglevel);
+                               break;
+                       default:
+                               abort();
+                       }
 
-       if (loglevel_type != LTTNG_EVENT_LOGLEVEL_ALL) {
-               status = lttng_event_rule_tracepoint_get_log_level(
-                               rule, &loglevel);
-               assert(status == LTTNG_EVENT_RULE_STATUS_OK);
+                       LTTNG_ASSERT(llr_status == LTTNG_LOG_LEVEL_RULE_STATUS_OK);
+               } else {
+                       /* At this point this is a fatal error. */
+                       abort();
+               }
        }
 
-       event_notifier->event.instrumentation = LTTNG_UST_TRACEPOINT;
+       event_notifier->event.instrumentation = LTTNG_UST_ABI_TRACEPOINT;
        ret = lttng_strncpy(event_notifier->event.name, pattern,
-                           LTTNG_UST_SYM_NAME_LEN - 1);
+                       LTTNG_UST_ABI_SYM_NAME_LEN - 1);
        if (ret) {
                ERR("Failed to copy event rule pattern to notifier: pattern = '%s' ",
                                pattern);
@@ -1991,50 +2172,68 @@ static int create_ust_event_notifier(struct ust_app *app,
                struct ust_app_event_notifier_rule *ua_event_notifier_rule)
 {
        int ret = 0;
-       struct lttng_ust_event_notifier event_notifier;
+       enum lttng_condition_status condition_status;
+       const struct lttng_condition *condition = NULL;
+       struct lttng_ust_abi_event_notifier event_notifier;
+       const struct lttng_event_rule *event_rule = NULL;
+       unsigned int capture_bytecode_count = 0, i;
+       enum lttng_condition_status cond_status;
+       enum lttng_event_rule_type event_rule_type;
 
        health_code_update();
-       assert(app->event_notifier_group.object);
+       LTTNG_ASSERT(app->event_notifier_group.object);
 
-       ret = init_ust_event_notifier_from_event_rule(
-                       ua_event_notifier_rule->event_rule, &event_notifier);
-       if (ret) {
-               ERR("Failed to initialize UST event notifier from event rule: app = '%s' (ppid: %d)",
-                               app->name, app->ppid);
-               goto error;
-       }
+       condition = lttng_trigger_get_const_condition(
+                       ua_event_notifier_rule->trigger);
+       LTTNG_ASSERT(condition);
+       LTTNG_ASSERT(lttng_condition_get_type(condition) ==
+                       LTTNG_CONDITION_TYPE_EVENT_RULE_MATCHES);
+
+       condition_status = lttng_condition_event_rule_matches_get_rule(
+                       condition, &event_rule);
+       LTTNG_ASSERT(condition_status == LTTNG_CONDITION_STATUS_OK);
+
+       LTTNG_ASSERT(event_rule);
+
+       event_rule_type = lttng_event_rule_get_type(event_rule);
+       LTTNG_ASSERT(event_rule_type == LTTNG_EVENT_RULE_TYPE_USER_TRACEPOINT ||
+                       event_rule_type == LTTNG_EVENT_RULE_TYPE_JUL_LOGGING ||
+                       event_rule_type ==
+                                       LTTNG_EVENT_RULE_TYPE_LOG4J_LOGGING ||
+                       event_rule_type ==
+                                       LTTNG_EVENT_RULE_TYPE_PYTHON_LOGGING);
 
+       init_ust_event_notifier_from_event_rule(event_rule, &event_notifier);
        event_notifier.event.token = ua_event_notifier_rule->token;
+       event_notifier.error_counter_index = ua_event_notifier_rule->error_counter_index;
 
        /* Create UST event notifier against the tracer. */
        pthread_mutex_lock(&app->sock_lock);
-       ret = ustctl_create_event_notifier(app->sock, &event_notifier,
+       ret = lttng_ust_ctl_create_event_notifier(app->sock, &event_notifier,
                        app->event_notifier_group.object,
                        &ua_event_notifier_rule->obj);
        pthread_mutex_unlock(&app->sock_lock);
        if (ret < 0) {
-               if (ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
-                       ERR("Error ustctl create event notifier: name = '%s', app = '%s' (ppid: %d), ret = %d",
-                                       event_notifier.event.name, app->name,
-                                       app->ppid, ret);
-               } else {
-                       /*
-                        * This is normal behavior, an application can die
-                        * during the creation process. Don't report an error so
-                        * the execution can continue normally.
-                        */
+               if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                       ret = 0;
+                       DBG3("UST app create event notifier failed. Application is dead: pid = %d, sock = %d",
+                                       app->pid, app->sock);
+               } else if (ret == -EAGAIN) {
                        ret = 0;
-                       DBG3("UST app create event notifier failed (application is dead): app = '%s' (ppid = %d)",
-                                       app->name, app->ppid);
+                       WARN("UST app create event notifier failed. Communication time out: pid = %d, sock = %d",
+                                       app->pid, app->sock);
+               } else {
+                       ERR("UST app create event notifier '%s' failed with ret %d: pid = %d, sock = %d",
+                                       event_notifier.event.name, ret, app->pid,
+                                       app->sock);
                }
-
                goto error;
        }
 
        ua_event_notifier_rule->handle = ua_event_notifier_rule->obj->handle;
 
-       DBG2("UST app event notifier %s created successfully: app = '%s' (ppid: %d), object: %p",
-                       event_notifier.event.name, app->name, app->ppid,
+       DBG2("UST app event notifier %s created successfully: app = '%s': pid = %d), object = %p",
+                       event_notifier.event.name, app->name, app->pid,
                        ua_event_notifier_rule->obj);
 
        health_code_update();
@@ -2058,6 +2257,23 @@ static int create_ust_event_notifier(struct ust_app *app,
                }
        }
 
+       /* Set the capture bytecodes. */
+       cond_status = lttng_condition_event_rule_matches_get_capture_descriptor_count(
+                       condition, &capture_bytecode_count);
+       LTTNG_ASSERT(cond_status == LTTNG_CONDITION_STATUS_OK);
+
+       for (i = 0; i < capture_bytecode_count; i++) {
+               const struct lttng_bytecode *capture_bytecode =
+                               lttng_condition_event_rule_matches_get_capture_bytecode_at_index(
+                                               condition, i);
+
+               ret = set_ust_capture(app, capture_bytecode, i,
+                               ua_event_notifier_rule->obj);
+               if (ret < 0) {
+                       goto error;
+               }
+       }
+
        /*
         * We now need to explicitly enable the event, since it
         * is disabled at creation.
@@ -2109,14 +2325,14 @@ static void shadow_copy_event(struct ust_app_event *ua_event,
 
        /* Copy filter bytecode */
        if (uevent->filter) {
-               ua_event->filter = copy_filter_bytecode(uevent->filter);
+               ua_event->filter = lttng_bytecode_copy(uevent->filter);
                /* Filter might be NULL here in case of ENONEM. */
        }
 
        /* Copy exclusion data */
        if (uevent->exclusion) {
                exclusion_alloc_size = sizeof(struct lttng_event_exclusion) +
-                               LTTNG_UST_SYM_NAME_LEN * uevent->exclusion->count;
+                               LTTNG_UST_ABI_SYM_NAME_LEN * uevent->exclusion->count;
                ua_event->exclusion = zmalloc(exclusion_alloc_size);
                if (ua_event->exclusion == NULL) {
                        PERROR("malloc");
@@ -2209,12 +2425,12 @@ static void shadow_copy_session(struct ust_app_session *ua_sess,
                                app->bits_per_long);
                break;
        default:
-               assert(0);
+               abort();
                goto error;
        }
        if (ret < 0) {
                PERROR("asprintf UST shadow copy session");
-               assert(0);
+               abort();
                goto error;
        }
 
@@ -2237,12 +2453,12 @@ static void shadow_copy_session(struct ust_app_session *ua_sess,
                                        app->uid, app->bits_per_long);
                        break;
                default:
-                       assert(0);
+                       abort();
                        goto error;
                }
                if (ret < 0) {
                        PERROR("sprintf UST shadow copy session");
-                       assert(0);
+                       abort();
                        goto error;
                }
                strncat(ua_sess->shm_path, tmp_shm_path,
@@ -2301,8 +2517,8 @@ static int setup_buffer_reg_pid(struct ust_app_session *ua_sess,
        int ret = 0;
        struct buffer_reg_pid *reg_pid;
 
-       assert(ua_sess);
-       assert(app);
+       LTTNG_ASSERT(ua_sess);
+       LTTNG_ASSERT(app);
 
        rcu_read_lock();
 
@@ -2370,8 +2586,8 @@ static int setup_buffer_reg_uid(struct ltt_ust_session *usess,
        int ret = 0;
        struct buffer_reg_uid *reg_uid;
 
-       assert(usess);
-       assert(app);
+       LTTNG_ASSERT(usess);
+       LTTNG_ASSERT(app);
 
        rcu_read_lock();
 
@@ -2434,7 +2650,7 @@ error:
  * be NULL.
  *
  * Returns 0 on success or else a negative code which is either -ENOMEM or
- * -ENOTCONN which is the default code if the ustctl_create_session fails.
+ * -ENOTCONN which is the default code if the lttng_ust_ctl_create_session fails.
  */
 static int find_or_create_ust_app_session(struct ltt_ust_session *usess,
                struct ust_app *app, struct ust_app_session **ua_sess_ptr,
@@ -2443,9 +2659,9 @@ static int find_or_create_ust_app_session(struct ltt_ust_session *usess,
        int ret, created = 0;
        struct ust_app_session *ua_sess;
 
-       assert(usess);
-       assert(app);
-       assert(ua_sess_ptr);
+       LTTNG_ASSERT(usess);
+       LTTNG_ASSERT(app);
+       LTTNG_ASSERT(ua_sess_ptr);
 
        health_code_update();
 
@@ -2481,7 +2697,7 @@ static int find_or_create_ust_app_session(struct ltt_ust_session *usess,
                }
                break;
        default:
-               assert(0);
+               abort();
                ret = -EINVAL;
                goto error;
        }
@@ -2490,21 +2706,20 @@ static int find_or_create_ust_app_session(struct ltt_ust_session *usess,
 
        if (ua_sess->handle == -1) {
                pthread_mutex_lock(&app->sock_lock);
-               ret = ustctl_create_session(app->sock);
+               ret = lttng_ust_ctl_create_session(app->sock);
                pthread_mutex_unlock(&app->sock_lock);
                if (ret < 0) {
-                       if (ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
-                               ERR("Creating session for app pid %d with ret %d",
-                                               app->pid, ret);
-                       } else {
-                               DBG("UST app creating session failed. Application is dead");
-                               /*
-                                * This is normal behavior, an application can die during the
-                                * creation process. Don't report an error so the execution can
-                                * continue normally. This will get flagged ENOTCONN and the
-                                * caller will handle it.
-                                */
+                       if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                               DBG("UST app creating session failed. Application is dead: pid = %d, sock = %d",
+                                               app->pid, app->sock);
+                               ret = 0;
+                       } else if (ret == -EAGAIN) {
+                               DBG("UST app creating session failed. Communication time out: pid = %d, sock = %d",
+                                               app->pid, app->sock);
                                ret = 0;
+                       } else {
+                               ERR("UST app creating session failed with ret %d: pid = %d, sock =%d",
+                                               ret, app->pid, app->sock);
                        }
                        delete_ust_app_session(-1, ua_sess, app);
                        if (ret != -ENOMEM) {
@@ -2554,8 +2769,8 @@ static int ht_match_ust_app_ctx(struct cds_lfht_node *node, const void *_key)
        struct ust_app_ctx *ctx;
        const struct lttng_ust_context_attr *key;
 
-       assert(node);
-       assert(_key);
+       LTTNG_ASSERT(node);
+       LTTNG_ASSERT(_key);
 
        ctx = caa_container_of(node, struct ust_app_ctx, node.node);
        key = _key;
@@ -2566,14 +2781,14 @@ static int ht_match_ust_app_ctx(struct cds_lfht_node *node, const void *_key)
        }
 
        switch(key->ctx) {
-       case LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER:
+       case LTTNG_UST_ABI_CONTEXT_PERF_THREAD_COUNTER:
                if (strncmp(key->u.perf_counter.name,
                                ctx->ctx.u.perf_counter.name,
                                sizeof(key->u.perf_counter.name))) {
                        goto no_match;
                }
                break;
-       case LTTNG_UST_CONTEXT_APP_CONTEXT:
+       case LTTNG_UST_ABI_CONTEXT_APP_CONTEXT:
                if (strcmp(key->u.app_ctx.provider_name,
                                ctx->ctx.u.app_ctx.provider_name) ||
                                strcmp(key->u.app_ctx.ctx_name,
@@ -2606,8 +2821,8 @@ struct ust_app_ctx *find_ust_app_context(struct lttng_ht *ht,
        struct lttng_ht_node_ulong *node;
        struct ust_app_ctx *app_ctx = NULL;
 
-       assert(uctx);
-       assert(ht);
+       LTTNG_ASSERT(uctx);
+       LTTNG_ASSERT(ht);
 
        /* Lookup using the lttng_ust_context_type and a custom match fct. */
        cds_lfht_lookup(ht->ht, ht->hash_fct((void *) uctx->ctx, lttng_ht_seed),
@@ -2772,10 +2987,10 @@ static int do_consumer_create_channel(struct ltt_ust_session *usess,
        unsigned int nb_fd = 0;
        struct consumer_socket *socket;
 
-       assert(usess);
-       assert(ua_sess);
-       assert(ua_chan);
-       assert(registry);
+       LTTNG_ASSERT(usess);
+       LTTNG_ASSERT(ua_sess);
+       LTTNG_ASSERT(ua_chan);
+       LTTNG_ASSERT(registry);
 
        rcu_read_lock();
        health_code_update();
@@ -2822,7 +3037,7 @@ static int do_consumer_create_channel(struct ltt_ust_session *usess,
        health_code_update();
 
        /*
-        * Now get the channel from the consumer. This call wil populate the stream
+        * Now get the channel from the consumer. This call will populate the stream
         * list of that channel and set the ust objects.
         */
        if (usess->consumer->enabled) {
@@ -2864,10 +3079,10 @@ static int duplicate_stream_object(struct buffer_reg_stream *reg_stream,
 {
        int ret;
 
-       assert(reg_stream);
-       assert(stream);
+       LTTNG_ASSERT(reg_stream);
+       LTTNG_ASSERT(stream);
 
-       /* Reserve the amount of file descriptor we need. */
+       /* Duplicating a stream requires 2 new fds. Reserve them. */
        ret = lttng_fd_get(LTTNG_FD_APPS, 2);
        if (ret < 0) {
                ERR("Exhausted number of available FD upon duplicate stream");
@@ -2875,7 +3090,7 @@ static int duplicate_stream_object(struct buffer_reg_stream *reg_stream,
        }
 
        /* Duplicate object for stream once the original is in the registry. */
-       ret = ustctl_duplicate_ust_object_data(&stream->obj,
+       ret = lttng_ust_ctl_duplicate_ust_object_data(&stream->obj,
                        reg_stream->obj.ust);
        if (ret < 0) {
                ERR("Duplicate stream obj from %p to %p failed with ret %d",
@@ -2895,15 +3110,15 @@ error:
  *
  * Return 0 on success or else a negative value.
  */
-static int duplicate_channel_object(struct buffer_reg_channel *reg_chan,
+static int duplicate_channel_object(struct buffer_reg_channel *buf_reg_chan,
                struct ust_app_channel *ua_chan)
 {
        int ret;
 
-       assert(reg_chan);
-       assert(ua_chan);
+       LTTNG_ASSERT(buf_reg_chan);
+       LTTNG_ASSERT(ua_chan);
 
-       /* Need two fds for the channel. */
+       /* Duplicating a channel requires 1 new fd. Reserve it. */
        ret = lttng_fd_get(LTTNG_FD_APPS, 1);
        if (ret < 0) {
                ERR("Exhausted number of available FD upon duplicate channel");
@@ -2911,10 +3126,10 @@ static int duplicate_channel_object(struct buffer_reg_channel *reg_chan,
        }
 
        /* Duplicate object for stream once the original is in the registry. */
-       ret = ustctl_duplicate_ust_object_data(&ua_chan->obj, reg_chan->obj.ust);
+       ret = lttng_ust_ctl_duplicate_ust_object_data(&ua_chan->obj, buf_reg_chan->obj.ust);
        if (ret < 0) {
                ERR("Duplicate channel obj from %p to %p failed with ret: %d",
-                               reg_chan->obj.ust, ua_chan->obj, ret);
+                               buf_reg_chan->obj.ust, ua_chan->obj, ret);
                goto error;
        }
        ua_chan->handle = ua_chan->obj->handle;
@@ -2933,15 +3148,15 @@ error_fd_get:
  *
  * Return 0 on success or else a negative value.
  */
-static int setup_buffer_reg_streams(struct buffer_reg_channel *reg_chan,
+static int setup_buffer_reg_streams(struct buffer_reg_channel *buf_reg_chan,
                struct ust_app_channel *ua_chan,
                struct ust_app *app)
 {
        int ret = 0;
        struct ust_app_stream *stream, *stmp;
 
-       assert(reg_chan);
-       assert(ua_chan);
+       LTTNG_ASSERT(buf_reg_chan);
+       LTTNG_ASSERT(ua_chan);
 
        DBG2("UST app setup buffer registry stream");
 
@@ -2960,7 +3175,7 @@ static int setup_buffer_reg_streams(struct buffer_reg_channel *reg_chan,
                 */
                reg_stream->obj.ust = stream->obj;
                stream->obj = NULL;
-               buffer_reg_stream_add(reg_stream, reg_chan);
+               buffer_reg_stream_add(reg_stream, buf_reg_chan);
 
                /* We don't need the streams anymore. */
                cds_list_del(&stream->list);
@@ -2983,22 +3198,22 @@ static int create_buffer_reg_channel(struct buffer_reg_session *reg_sess,
                struct ust_app_channel *ua_chan, struct buffer_reg_channel **regp)
 {
        int ret;
-       struct buffer_reg_channel *reg_chan = NULL;
+       struct buffer_reg_channel *buf_reg_chan = NULL;
 
-       assert(reg_sess);
-       assert(ua_chan);
+       LTTNG_ASSERT(reg_sess);
+       LTTNG_ASSERT(ua_chan);
 
        DBG2("UST app creating buffer registry channel for %s", ua_chan->name);
 
        /* Create buffer registry channel. */
-       ret = buffer_reg_channel_create(ua_chan->tracing_channel_id, &reg_chan);
+       ret = buffer_reg_channel_create(ua_chan->tracing_channel_id, &buf_reg_chan);
        if (ret < 0) {
                goto error_create;
        }
-       assert(reg_chan);
-       reg_chan->consumer_key = ua_chan->key;
-       reg_chan->subbuf_size = ua_chan->attr.subbuf_size;
-       reg_chan->num_subbuf = ua_chan->attr.num_subbuf;
+       LTTNG_ASSERT(buf_reg_chan);
+       buf_reg_chan->consumer_key = ua_chan->key;
+       buf_reg_chan->subbuf_size = ua_chan->attr.subbuf_size;
+       buf_reg_chan->num_subbuf = ua_chan->attr.num_subbuf;
 
        /* Create and add a channel registry to session. */
        ret = ust_registry_channel_add(reg_sess->reg.ust,
@@ -3006,17 +3221,17 @@ static int create_buffer_reg_channel(struct buffer_reg_session *reg_sess,
        if (ret < 0) {
                goto error;
        }
-       buffer_reg_channel_add(reg_sess, reg_chan);
+       buffer_reg_channel_add(reg_sess, buf_reg_chan);
 
        if (regp) {
-               *regp = reg_chan;
+               *regp = buf_reg_chan;
        }
 
        return 0;
 
 error:
        /* Safe because the registry channel object was not added to any HT. */
-       buffer_reg_channel_destroy(reg_chan, LTTNG_DOMAIN_UST);
+       buffer_reg_channel_destroy(buf_reg_chan, LTTNG_DOMAIN_UST);
 error_create:
        return ret;
 }
@@ -3028,32 +3243,32 @@ error_create:
  * Return 0 on success else a negative value.
  */
 static int setup_buffer_reg_channel(struct buffer_reg_session *reg_sess,
-               struct ust_app_channel *ua_chan, struct buffer_reg_channel *reg_chan,
+               struct ust_app_channel *ua_chan, struct buffer_reg_channel *buf_reg_chan,
                struct ust_app *app)
 {
        int ret;
 
-       assert(reg_sess);
-       assert(reg_chan);
-       assert(ua_chan);
-       assert(ua_chan->obj);
+       LTTNG_ASSERT(reg_sess);
+       LTTNG_ASSERT(buf_reg_chan);
+       LTTNG_ASSERT(ua_chan);
+       LTTNG_ASSERT(ua_chan->obj);
 
        DBG2("UST app setup buffer registry channel for %s", ua_chan->name);
 
        /* Setup all streams for the registry. */
-       ret = setup_buffer_reg_streams(reg_chan, ua_chan, app);
+       ret = setup_buffer_reg_streams(buf_reg_chan, ua_chan, app);
        if (ret < 0) {
                goto error;
        }
 
-       reg_chan->obj.ust = ua_chan->obj;
+       buf_reg_chan->obj.ust = ua_chan->obj;
        ua_chan->obj = NULL;
 
        return 0;
 
 error:
-       buffer_reg_channel_remove(reg_sess, reg_chan);
-       buffer_reg_channel_destroy(reg_chan, LTTNG_DOMAIN_UST);
+       buffer_reg_channel_remove(reg_sess, buf_reg_chan);
+       buffer_reg_channel_destroy(buf_reg_chan, LTTNG_DOMAIN_UST);
        return ret;
 }
 
@@ -3062,21 +3277,21 @@ error:
  *
  * Return 0 on success else a negative value.
  */
-static int send_channel_uid_to_ust(struct buffer_reg_channel *reg_chan,
+static int send_channel_uid_to_ust(struct buffer_reg_channel *buf_reg_chan,
                struct ust_app *app, struct ust_app_session *ua_sess,
                struct ust_app_channel *ua_chan)
 {
        int ret;
        struct buffer_reg_stream *reg_stream;
 
-       assert(reg_chan);
-       assert(app);
-       assert(ua_sess);
-       assert(ua_chan);
+       LTTNG_ASSERT(buf_reg_chan);
+       LTTNG_ASSERT(app);
+       LTTNG_ASSERT(ua_sess);
+       LTTNG_ASSERT(ua_chan);
 
        DBG("UST app sending buffer registry channel to ust sock %d", app->sock);
 
-       ret = duplicate_channel_object(reg_chan, ua_chan);
+       ret = duplicate_channel_object(buf_reg_chan, ua_chan);
        if (ret < 0) {
                goto error;
        }
@@ -3086,6 +3301,13 @@ static int send_channel_uid_to_ust(struct buffer_reg_channel *reg_chan,
        if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
                ret = -ENOTCONN;        /* Caused by app exiting. */
                goto error;
+       } else if (ret == -EAGAIN) {
+               /* Caused by timeout. */
+               WARN("Communication with application %d timed out on send_channel for channel \"%s\" of session \"%" PRIu64 "\".",
+                               app->pid, ua_chan->name, ua_sess->tracing_id);
+               /* Treat this the same way as an application that is exiting. */
+               ret = -ENOTCONN;
+               goto error;
        } else if (ret < 0) {
                goto error;
        }
@@ -3093,8 +3315,8 @@ static int send_channel_uid_to_ust(struct buffer_reg_channel *reg_chan,
        health_code_update();
 
        /* Send all streams to application. */
-       pthread_mutex_lock(&reg_chan->stream_list_lock);
-       cds_list_for_each_entry(reg_stream, &reg_chan->streams, lnode) {
+       pthread_mutex_lock(&buf_reg_chan->stream_list_lock);
+       cds_list_for_each_entry(reg_stream, &buf_reg_chan->streams, lnode) {
                struct ust_app_stream stream;
 
                ret = duplicate_stream_object(reg_stream, &stream);
@@ -3104,10 +3326,21 @@ static int send_channel_uid_to_ust(struct buffer_reg_channel *reg_chan,
 
                ret = ust_consumer_send_stream_to_ust(app, ua_chan, &stream);
                if (ret < 0) {
-                       (void) release_ust_app_stream(-1, &stream, app);
                        if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
                                ret = -ENOTCONN; /* Caused by app exiting. */
+                       } else if (ret == -EAGAIN) {
+                               /*
+                                * Caused by timeout.
+                                * Treat this the same way as an application
+                                * that is exiting.
+                                */
+                               WARN("Communication with application %d timed out on send_stream for stream \"%s\" of channel \"%s\" of session \"%" PRIu64 "\".",
+                                               app->pid, stream.name,
+                                               ua_chan->name,
+                                               ua_sess->tracing_id);
+                               ret = -ENOTCONN;
                        }
+                       (void) release_ust_app_stream(-1, &stream, app);
                        goto error_stream_unlock;
                }
 
@@ -3120,7 +3353,7 @@ static int send_channel_uid_to_ust(struct buffer_reg_channel *reg_chan,
        ua_chan->is_sent = 1;
 
 error_stream_unlock:
-       pthread_mutex_unlock(&reg_chan->stream_list_lock);
+       pthread_mutex_unlock(&buf_reg_chan->stream_list_lock);
 error:
        return ret;
 }
@@ -3139,15 +3372,15 @@ static int create_channel_per_uid(struct ust_app *app,
 {
        int ret;
        struct buffer_reg_uid *reg_uid;
-       struct buffer_reg_channel *reg_chan;
+       struct buffer_reg_channel *buf_reg_chan;
        struct ltt_session *session = NULL;
        enum lttng_error_code notification_ret;
-       struct ust_registry_channel *chan_reg;
+       struct ust_registry_channel *ust_reg_chan;
 
-       assert(app);
-       assert(usess);
-       assert(ua_sess);
-       assert(ua_chan);
+       LTTNG_ASSERT(app);
+       LTTNG_ASSERT(usess);
+       LTTNG_ASSERT(ua_sess);
+       LTTNG_ASSERT(ua_chan);
 
        DBG("UST app creating channel %s with per UID buffers", ua_chan->name);
 
@@ -3157,16 +3390,16 @@ static int create_channel_per_uid(struct ust_app *app,
         * object. If none can be find, there is a code flow problem or a
         * teardown race.
         */
-       assert(reg_uid);
+       LTTNG_ASSERT(reg_uid);
 
-       reg_chan = buffer_reg_channel_find(ua_chan->tracing_channel_id,
+       buf_reg_chan = buffer_reg_channel_find(ua_chan->tracing_channel_id,
                        reg_uid);
-       if (reg_chan) {
+       if (buf_reg_chan) {
                goto send_channel;
        }
 
        /* Create the buffer registry channel object. */
-       ret = create_buffer_reg_channel(reg_uid->registry, ua_chan, &reg_chan);
+       ret = create_buffer_reg_channel(reg_uid->registry, ua_chan, &buf_reg_chan);
        if (ret < 0) {
                ERR("Error creating the UST channel \"%s\" registry instance",
                                ua_chan->name);
@@ -3174,9 +3407,9 @@ static int create_channel_per_uid(struct ust_app *app,
        }
 
        session = session_find_by_id(ua_sess->tracing_id);
-       assert(session);
-       assert(pthread_mutex_trylock(&session->lock));
-       assert(session_trylock_list());
+       LTTNG_ASSERT(session);
+       LTTNG_ASSERT(pthread_mutex_trylock(&session->lock));
+       LTTNG_ASSERT(session_trylock_list());
 
        /*
         * Create the buffers on the consumer side. This call populates the
@@ -3195,8 +3428,8 @@ static int create_channel_per_uid(struct ust_app *app,
                 */
                ust_registry_channel_del_free(reg_uid->registry->reg.ust,
                                ua_chan->tracing_channel_id, false);
-               buffer_reg_channel_remove(reg_uid->registry, reg_chan);
-               buffer_reg_channel_destroy(reg_chan, LTTNG_DOMAIN_UST);
+               buffer_reg_channel_remove(reg_uid->registry, buf_reg_chan);
+               buffer_reg_channel_destroy(buf_reg_chan, LTTNG_DOMAIN_UST);
                goto error;
        }
 
@@ -3204,7 +3437,7 @@ static int create_channel_per_uid(struct ust_app *app,
         * Setup the streams and add it to the session registry.
         */
        ret = setup_buffer_reg_channel(reg_uid->registry,
-                       ua_chan, reg_chan, app);
+                       ua_chan, buf_reg_chan, app);
        if (ret < 0) {
                ERR("Error setting up UST channel \"%s\"", ua_chan->name);
                goto error;
@@ -3212,19 +3445,20 @@ static int create_channel_per_uid(struct ust_app *app,
 
        /* Notify the notification subsystem of the channel's creation. */
        pthread_mutex_lock(&reg_uid->registry->reg.ust->lock);
-       chan_reg = ust_registry_channel_find(reg_uid->registry->reg.ust,
+       ust_reg_chan = ust_registry_channel_find(reg_uid->registry->reg.ust,
                        ua_chan->tracing_channel_id);
-       assert(chan_reg);
-       chan_reg->consumer_key = ua_chan->key;
-       chan_reg = NULL;
+       LTTNG_ASSERT(ust_reg_chan);
+       ust_reg_chan->consumer_key = ua_chan->key;
+       ust_reg_chan = NULL;
        pthread_mutex_unlock(&reg_uid->registry->reg.ust->lock);
 
        notification_ret = notification_thread_command_add_channel(
-                       notification_thread_handle, session->name,
-                       lttng_credentials_get_uid(&ua_sess->effective_credentials),
-                       lttng_credentials_get_gid(&ua_sess->effective_credentials),
-                       ua_chan->name,
-                       ua_chan->key, LTTNG_DOMAIN_UST,
+                       the_notification_thread_handle, session->name,
+                       lttng_credentials_get_uid(
+                                       &ua_sess->effective_credentials),
+                       lttng_credentials_get_gid(
+                                       &ua_sess->effective_credentials),
+                       ua_chan->name, ua_chan->key, LTTNG_DOMAIN_UST,
                        ua_chan->attr.subbuf_size * ua_chan->attr.num_subbuf);
        if (notification_ret != LTTNG_OK) {
                ret = - (int) notification_ret;
@@ -3234,7 +3468,7 @@ static int create_channel_per_uid(struct ust_app *app,
 
 send_channel:
        /* Send buffers to the application. */
-       ret = send_channel_uid_to_ust(reg_chan, app, ua_sess, ua_chan);
+       ret = send_channel_uid_to_ust(buf_reg_chan, app, ua_sess, ua_chan);
        if (ret < 0) {
                if (ret != -ENOTCONN) {
                        ERR("Error sending channel to application");
@@ -3266,12 +3500,12 @@ static int create_channel_per_pid(struct ust_app *app,
        enum lttng_error_code cmd_ret;
        struct ltt_session *session = NULL;
        uint64_t chan_reg_key;
-       struct ust_registry_channel *chan_reg;
+       struct ust_registry_channel *ust_reg_chan;
 
-       assert(app);
-       assert(usess);
-       assert(ua_sess);
-       assert(ua_chan);
+       LTTNG_ASSERT(app);
+       LTTNG_ASSERT(usess);
+       LTTNG_ASSERT(ua_sess);
+       LTTNG_ASSERT(ua_chan);
 
        DBG("UST app creating channel %s with per PID buffers", ua_chan->name);
 
@@ -3279,7 +3513,7 @@ static int create_channel_per_pid(struct ust_app *app,
 
        registry = get_session_registry(ua_sess);
        /* The UST app session lock is held, registry shall not be null. */
-       assert(registry);
+       LTTNG_ASSERT(registry);
 
        /* Create and add a new channel registry to session. */
        ret = ust_registry_channel_add(registry, ua_chan->key);
@@ -3290,10 +3524,10 @@ static int create_channel_per_pid(struct ust_app *app,
        }
 
        session = session_find_by_id(ua_sess->tracing_id);
-       assert(session);
+       LTTNG_ASSERT(session);
 
-       assert(pthread_mutex_trylock(&session->lock));
-       assert(session_trylock_list());
+       LTTNG_ASSERT(pthread_mutex_trylock(&session->lock));
+       LTTNG_ASSERT(session_trylock_list());
 
        /* Create and get channel on the consumer side. */
        ret = do_consumer_create_channel(usess, ua_sess, ua_chan,
@@ -3315,17 +3549,18 @@ static int create_channel_per_pid(struct ust_app *app,
 
        chan_reg_key = ua_chan->key;
        pthread_mutex_lock(&registry->lock);
-       chan_reg = ust_registry_channel_find(registry, chan_reg_key);
-       assert(chan_reg);
-       chan_reg->consumer_key = ua_chan->key;
+       ust_reg_chan = ust_registry_channel_find(registry, chan_reg_key);
+       LTTNG_ASSERT(ust_reg_chan);
+       ust_reg_chan->consumer_key = ua_chan->key;
        pthread_mutex_unlock(&registry->lock);
 
        cmd_ret = notification_thread_command_add_channel(
-                       notification_thread_handle, session->name,
-                       lttng_credentials_get_uid(&ua_sess->effective_credentials),
-                       lttng_credentials_get_gid(&ua_sess->effective_credentials),
-                       ua_chan->name,
-                       ua_chan->key, LTTNG_DOMAIN_UST,
+                       the_notification_thread_handle, session->name,
+                       lttng_credentials_get_uid(
+                                       &ua_sess->effective_credentials),
+                       lttng_credentials_get_gid(
+                                       &ua_sess->effective_credentials),
+                       ua_chan->name, ua_chan->key, LTTNG_DOMAIN_UST,
                        ua_chan->attr.subbuf_size * ua_chan->attr.num_subbuf);
        if (cmd_ret != LTTNG_OK) {
                ret = - (int) cmd_ret;
@@ -3361,11 +3596,11 @@ static int ust_app_channel_send(struct ust_app *app,
 {
        int ret;
 
-       assert(app);
-       assert(usess);
-       assert(usess->active);
-       assert(ua_sess);
-       assert(ua_chan);
+       LTTNG_ASSERT(app);
+       LTTNG_ASSERT(usess);
+       LTTNG_ASSERT(usess->active);
+       LTTNG_ASSERT(ua_sess);
+       LTTNG_ASSERT(ua_chan);
 
        /* Handle buffer type before sending the channel to the application. */
        switch (usess->buffer_type) {
@@ -3386,7 +3621,7 @@ static int ust_app_channel_send(struct ust_app *app,
                break;
        }
        default:
-               assert(0);
+               abort();
                ret = -EINVAL;
                goto error;
        }
@@ -3416,7 +3651,7 @@ error:
  */
 static int ust_app_channel_allocate(struct ust_app_session *ua_sess,
                struct ltt_ust_channel *uchan,
-               enum lttng_ust_chan_type type, struct ltt_ust_session *usess,
+               enum lttng_ust_abi_chan_type type, struct ltt_ust_session *usess,
                struct ust_app_channel **ua_chanp)
 {
        int ret = 0;
@@ -3500,8 +3735,8 @@ int create_ust_app_event(struct ust_app_session *ua_sess,
 
        add_unique_ust_app_event(ua_chan, ua_event);
 
-       DBG2("UST app create event completed: app = '%s' (ppid: %d)",
-                       app->name, app->ppid);
+       DBG2("UST app create event completed: app = '%s' pid = %d",
+                       app->name, app->pid);
 
 end:
        return ret;
@@ -3519,13 +3754,13 @@ error:
  * Called with ust app session mutex held.
  */
 static
-int create_ust_app_event_notifier_rule(struct lttng_event_rule *rule,
-               struct ust_app *app, uint64_t token)
+int create_ust_app_event_notifier_rule(struct lttng_trigger *trigger,
+               struct ust_app *app)
 {
        int ret = 0;
        struct ust_app_event_notifier_rule *ua_event_notifier_rule;
 
-       ua_event_notifier_rule = alloc_ust_app_event_notifier_rule(rule, token);
+       ua_event_notifier_rule = alloc_ust_app_event_notifier_rule(trigger);
        if (ua_event_notifier_rule == NULL) {
                ret = -ENOMEM;
                goto end;
@@ -3543,7 +3778,7 @@ int create_ust_app_event_notifier_rule(struct lttng_event_rule *rule,
                if (ret == -LTTNG_UST_ERR_EXIST) {
                        ERR("Tracer for application reported that an event notifier being created already exists: "
                                        "token = \"%" PRIu64 "\", pid = %d, ppid = %d, uid = %d, gid = %d",
-                                       token,
+                                       lttng_trigger_get_tracer_token(trigger),
                                        app->pid, app->ppid, app->uid,
                                        app->gid);
                }
@@ -3553,15 +3788,15 @@ int create_ust_app_event_notifier_rule(struct lttng_event_rule *rule,
        lttng_ht_add_unique_u64(app->token_to_event_notifier_rule_ht,
                        &ua_event_notifier_rule->node);
 
-       DBG2("UST app create token event rule completed: app = '%s' (ppid: %d), token = %" PRIu64,
-                       app->name, app->ppid, token);
+       DBG2("UST app create token event rule completed: app = '%s', pid = %d), token = %" PRIu64,
+                       app->name, app->pid, lttng_trigger_get_tracer_token(trigger));
 
-end:
-       return ret;
+       goto end;
 
 error:
        /* The RCU read side lock is already being held by the caller. */
        delete_ust_app_event_notifier_rule(-1, ua_event_notifier_rule, app);
+end:
        return ret;
 }
 
@@ -3579,13 +3814,13 @@ static int create_ust_app_metadata(struct ust_app_session *ua_sess,
        struct ust_registry_session *registry;
        struct ltt_session *session = NULL;
 
-       assert(ua_sess);
-       assert(app);
-       assert(consumer);
+       LTTNG_ASSERT(ua_sess);
+       LTTNG_ASSERT(app);
+       LTTNG_ASSERT(consumer);
 
        registry = get_session_registry(ua_sess);
        /* The UST app session is held registry shall not be null. */
-       assert(registry);
+       LTTNG_ASSERT(registry);
 
        pthread_mutex_lock(&registry->lock);
 
@@ -3628,10 +3863,10 @@ static int create_ust_app_metadata(struct ust_app_session *ua_sess,
        registry->metadata_key = metadata->key;
 
        session = session_find_by_id(ua_sess->tracing_id);
-       assert(session);
+       LTTNG_ASSERT(session);
 
-       assert(pthread_mutex_trylock(&session->lock));
-       assert(session_trylock_list());
+       LTTNG_ASSERT(pthread_mutex_trylock(&session->lock));
+       LTTNG_ASSERT(session_trylock_list());
 
        /*
         * Ask the metadata channel creation to the consumer. The metadata object
@@ -3708,28 +3943,43 @@ error:
  */
 struct ust_app *ust_app_create(struct ust_register_msg *msg, int sock)
 {
+       int ret;
        struct ust_app *lta = NULL;
        struct lttng_pipe *event_notifier_event_source_pipe = NULL;
 
-       assert(msg);
-       assert(sock >= 0);
+       LTTNG_ASSERT(msg);
+       LTTNG_ASSERT(sock >= 0);
 
        DBG3("UST app creating application for socket %d", sock);
 
        if ((msg->bits_per_long == 64 &&
-                               (uatomic_read(&ust_consumerd64_fd) == -EINVAL))
-                       || (msg->bits_per_long == 32 &&
-                               (uatomic_read(&ust_consumerd32_fd) == -EINVAL))) {
+                           (uatomic_read(&the_ust_consumerd64_fd) ==
+                                           -EINVAL)) ||
+                       (msg->bits_per_long == 32 &&
+                                       (uatomic_read(&the_ust_consumerd32_fd) ==
+                                                       -EINVAL))) {
                ERR("Registration failed: application \"%s\" (pid: %d) has "
                                "%d-bit long, but no consumerd for this size is available.\n",
                                msg->name, msg->pid, msg->bits_per_long);
                goto error;
        }
 
+       /*
+        * Reserve the two file descriptors of the event source pipe. The write
+        * end will be closed once it is passed to the application, at which
+        * point a single 'put' will be performed.
+        */
+       ret = lttng_fd_get(LTTNG_FD_APPS, 2);
+       if (ret) {
+               ERR("Failed to reserve two file descriptors for the event source pipe while creating a new application instance: app = '%s', pid = %d",
+                               msg->name, (int) msg->pid);
+               goto error;
+       }
+
        event_notifier_event_source_pipe = lttng_pipe_open(FD_CLOEXEC);
        if (!event_notifier_event_source_pipe) {
-               PERROR("Failed to open application event source pipe: '%s' (ppid = %d)",
-                               msg->name, msg->ppid);
+               PERROR("Failed to open application event source pipe: '%s' (pid = %d)",
+                               msg->name, msg->pid);
                goto error;
        }
 
@@ -3783,6 +4033,7 @@ struct ust_app *ust_app_create(struct ust_register_msg *msg, int sock)
 
 error_free_pipe:
        lttng_pipe_destroy(event_notifier_event_source_pipe);
+       lttng_fd_put(LTTNG_FD_APPS, 2);
 error:
        return NULL;
 }
@@ -3792,8 +4043,8 @@ error:
  */
 void ust_app_add(struct ust_app *app)
 {
-       assert(app);
-       assert(app->notify_sock >= 0);
+       LTTNG_ASSERT(app);
+       LTTNG_ASSERT(app->notify_sock >= 0);
 
        app->registration_time = time(NULL);
 
@@ -3816,8 +4067,8 @@ void ust_app_add(struct ust_app *app)
        lttng_ht_node_init_ulong(&app->notify_sock_n, app->notify_sock);
        lttng_ht_add_unique_ulong(ust_app_ht_by_notify_sock, &app->notify_sock_n);
 
-       DBG("App registered with pid:%d ppid:%d uid:%d gid:%d sock:%d name:%s "
-                       "notify_sock:%d (version %d.%d)", app->pid, app->ppid, app->uid,
+       DBG("App registered with pid:%d ppid:%d uid:%d gid:%d sock =%d name:%s "
+                       "notify_sock =%d (version %d.%d)", app->pid, app->ppid, app->uid,
                        app->gid, app->sock, app->name, app->notify_sock, app->v_major,
                        app->v_minor);
 
@@ -3834,22 +4085,37 @@ int ust_app_version(struct ust_app *app)
 {
        int ret;
 
-       assert(app);
+       LTTNG_ASSERT(app);
 
        pthread_mutex_lock(&app->sock_lock);
-       ret = ustctl_tracer_version(app->sock, &app->version);
+       ret = lttng_ust_ctl_tracer_version(app->sock, &app->version);
        pthread_mutex_unlock(&app->sock_lock);
        if (ret < 0) {
-               if (ret != -LTTNG_UST_ERR_EXITING && ret != -EPIPE) {
-                       ERR("UST app %d version failed with ret %d", app->sock, ret);
+               if (ret == -LTTNG_UST_ERR_EXITING || ret == -EPIPE) {
+                       DBG3("UST app version failed. Application is dead: pid = %d, sock = %d",
+                                       app->pid, app->sock);
+               } else if (ret == -EAGAIN) {
+                       WARN("UST app version failed. Communication time out: pid = %d, sock = %d",
+                                       app->pid, app->sock);
                } else {
-                       DBG3("UST app %d version failed. Application is dead", app->sock);
+                       ERR("UST app version failed with ret %d: pid = %d, sock = %d",
+                                       ret, app->pid, app->sock);
                }
        }
 
        return ret;
 }
 
+bool ust_app_supports_notifiers(const struct ust_app *app)
+{
+       return app->v_major >= 9;
+}
+
+bool ust_app_supports_counters(const struct ust_app *app)
+{
+       return app->v_major >= 9;
+}
+
 /*
  * Setup the base event notifier group.
  *
@@ -3860,41 +4126,58 @@ int ust_app_setup_event_notifier_group(struct ust_app *app)
 {
        int ret;
        int event_pipe_write_fd;
-       struct lttng_ust_object_data *event_notifier_group = NULL;
+       struct lttng_ust_abi_object_data *event_notifier_group = NULL;
        enum lttng_error_code lttng_ret;
+       enum event_notifier_error_accounting_status event_notifier_error_accounting_status;
 
-       assert(app);
+       LTTNG_ASSERT(app);
+
+       if (!ust_app_supports_notifiers(app)) {
+               ret = -ENOSYS;
+               goto error;
+       }
 
        /* Get the write side of the pipe. */
        event_pipe_write_fd = lttng_pipe_get_writefd(
                        app->event_notifier_group.event_pipe);
 
        pthread_mutex_lock(&app->sock_lock);
-       ret = ustctl_create_event_notifier_group(app->sock,
+       ret = lttng_ust_ctl_create_event_notifier_group(app->sock,
                        event_pipe_write_fd, &event_notifier_group);
        pthread_mutex_unlock(&app->sock_lock);
        if (ret < 0) {
-               if (ret != -LTTNG_UST_ERR_EXITING && ret != -EPIPE) {
-                       ERR("Failed to create application event notifier group: ret = %d, app socket fd = %d, event_pipe_write_fd = %d",
-                                       ret, app->sock, event_pipe_write_fd);
+               if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                       ret = 0;
+                       DBG3("UST app create event notifier group failed. Application is dead: pid = %d, sock = %d",
+                                       app->pid, app->sock);
+               } else if (ret == -EAGAIN) {
+                       ret = 0;
+                       WARN("UST app create event notifier group failed. Communication time out: pid = %d, sock = %d",
+                                       app->pid, app->sock);
                } else {
-                       DBG("Failed to create application event notifier group (application is dead): app socket fd = %d",
-                                       app->sock);
+                       ERR("UST app create event notifier group failed with ret %d: pid = %d, sock = %d, event_pipe_write_fd: %d",
+                                       ret, app->pid, app->sock, event_pipe_write_fd);
                }
-
                goto error;
        }
 
        ret = lttng_pipe_write_close(app->event_notifier_group.event_pipe);
        if (ret) {
-               ERR("Failed to close write end of the application's event source pipe: app = '%s' (ppid = %d)",
-                               app->name, app->ppid);
+               ERR("Failed to close write end of the application's event source pipe: app = '%s' (pid = %d)",
+                               app->name, app->pid);
                goto error;
        }
 
+       /*
+        * Release the file descriptor that was reserved for the write-end of
+        * the pipe.
+        */
+       lttng_fd_put(LTTNG_FD_APPS, 1);
+
        lttng_ret = notification_thread_command_add_tracer_event_source(
-                       notification_thread_handle,
-                       lttng_pipe_get_readfd(app->event_notifier_group.event_pipe),
+                       the_notification_thread_handle,
+                       lttng_pipe_get_readfd(
+                                       app->event_notifier_group.event_pipe),
                        LTTNG_DOMAIN_UST);
        if (lttng_ret != LTTNG_OK) {
                ERR("Failed to add tracer event source to notification thread");
@@ -3904,11 +4187,43 @@ int ust_app_setup_event_notifier_group(struct ust_app *app)
 
        /* Assign handle only when the complete setup is valid. */
        app->event_notifier_group.object = event_notifier_group;
+
+       event_notifier_error_accounting_status =
+                       event_notifier_error_accounting_register_app(app);
+       switch (event_notifier_error_accounting_status) {
+       case EVENT_NOTIFIER_ERROR_ACCOUNTING_STATUS_OK:
+               break;
+       case EVENT_NOTIFIER_ERROR_ACCOUNTING_STATUS_UNSUPPORTED:
+               DBG3("Failed to setup event notifier error accounting (application does not support notifier error accounting): app socket fd = %d, app name = '%s', app pid = %d",
+                               app->sock, app->name, (int) app->pid);
+               ret = 0;
+               goto error_accounting;
+       case EVENT_NOTIFIER_ERROR_ACCOUNTING_STATUS_APP_DEAD:
+               DBG3("Failed to setup event notifier error accounting (application is dead): app socket fd = %d, app name = '%s', app pid = %d",
+                               app->sock, app->name, (int) app->pid);
+               ret = 0;
+               goto error_accounting;
+       default:
+               ERR("Failed to setup event notifier error accounting for app");
+               ret = -1;
+               goto error_accounting;
+       }
+
        return ret;
 
+error_accounting:
+       lttng_ret = notification_thread_command_remove_tracer_event_source(
+                       the_notification_thread_handle,
+                       lttng_pipe_get_readfd(
+                                       app->event_notifier_group.event_pipe));
+       if (lttng_ret != LTTNG_OK) {
+               ERR("Failed to remove application tracer event source from notification thread");
+       }
+
 error:
-       ustctl_release_object(app->sock, app->event_notifier_group.object);
+       lttng_ust_ctl_release_object(app->sock, app->event_notifier_group.object);
        free(app->event_notifier_group.object);
+       app->event_notifier_group.object = NULL;
        return ret;
 }
 
@@ -3932,7 +4247,7 @@ void ust_app_unregister(int sock)
        /* Get the node reference for a call_rcu */
        lttng_ht_lookup(ust_app_ht_by_sock, (void *)((unsigned long) sock), &ust_app_sock_iter);
        node = lttng_ht_iter_get_node_ulong(&ust_app_sock_iter);
-       assert(node);
+       LTTNG_ASSERT(node);
 
        lta = caa_container_of(node, struct ust_app, sock_n);
        DBG("PID %d unregistering with sock %d", lta->pid, sock);
@@ -4002,7 +4317,7 @@ void ust_app_unregister(int sock)
 
        /* Remove application from PID hash table */
        ret = lttng_ht_del(ust_app_ht_by_sock, &ust_app_sock_iter);
-       assert(!ret);
+       LTTNG_ASSERT(!ret);
 
        /*
         * Remove application from notify hash table. The thread handling the
@@ -4054,7 +4369,7 @@ int ust_app_list_events(struct lttng_event **events)
        rcu_read_lock();
 
        cds_lfht_for_each_entry(ust_app_ht->ht, &iter.iter, app, pid_n.node) {
-               struct lttng_ust_tracepoint_iter uiter;
+               struct lttng_ust_abi_tracepoint_iter uiter;
 
                health_code_update();
 
@@ -4066,7 +4381,7 @@ int ust_app_list_events(struct lttng_event **events)
                        continue;
                }
                pthread_mutex_lock(&app->sock_lock);
-               handle = ustctl_tracepoint_list(app->sock);
+               handle = lttng_ust_ctl_tracepoint_list(app->sock);
                if (handle < 0) {
                        if (handle != -EPIPE && handle != -LTTNG_UST_ERR_EXITING) {
                                ERR("UST app list events getting handle failed for app pid %d",
@@ -4076,7 +4391,7 @@ int ust_app_list_events(struct lttng_event **events)
                        continue;
                }
 
-               while ((ret = ustctl_tracepoint_list_get(app->sock, handle,
+               while ((ret = lttng_ust_ctl_tracepoint_list_get(app->sock, handle,
                                        &uiter)) != -LTTNG_UST_ERR_NOENT) {
                        /* Handle ustctl error. */
                        if (ret < 0) {
@@ -4087,15 +4402,10 @@ int ust_app_list_events(struct lttng_event **events)
                                                        app->sock, ret);
                                } else {
                                        DBG3("UST app tp list get failed. Application is dead");
-                                       /*
-                                        * This is normal behavior, an application can die during the
-                                        * creation process. Don't report an error so the execution can
-                                        * continue normally. Continue normal execution.
-                                        */
                                        break;
                                }
                                free(tmp_event);
-                               release_ret = ustctl_release_handle(app->sock, handle);
+                               release_ret = lttng_ust_ctl_release_handle(app->sock, handle);
                                if (release_ret < 0 &&
                                                release_ret != -LTTNG_UST_ERR_EXITING &&
                                                release_ret != -EPIPE) {
@@ -4122,7 +4432,7 @@ int ust_app_list_events(struct lttng_event **events)
                                        PERROR("realloc ust app events");
                                        free(tmp_event);
                                        ret = -ENOMEM;
-                                       release_ret = ustctl_release_handle(app->sock, handle);
+                                       release_ret = lttng_ust_ctl_release_handle(app->sock, handle);
                                        if (release_ret < 0 &&
                                                        release_ret != -LTTNG_UST_ERR_EXITING &&
                                                        release_ret != -EPIPE) {
@@ -4137,17 +4447,26 @@ int ust_app_list_events(struct lttng_event **events)
                                nbmem = new_nbmem;
                                tmp_event = new_tmp_event;
                        }
-                       memcpy(tmp_event[count].name, uiter.name, LTTNG_UST_SYM_NAME_LEN);
+                       memcpy(tmp_event[count].name, uiter.name, LTTNG_UST_ABI_SYM_NAME_LEN);
                        tmp_event[count].loglevel = uiter.loglevel;
-                       tmp_event[count].type = (enum lttng_event_type) LTTNG_UST_TRACEPOINT;
+                       tmp_event[count].type = (enum lttng_event_type) LTTNG_UST_ABI_TRACEPOINT;
                        tmp_event[count].pid = app->pid;
                        tmp_event[count].enabled = -1;
                        count++;
                }
-               ret = ustctl_release_handle(app->sock, handle);
+               ret = lttng_ust_ctl_release_handle(app->sock, handle);
                pthread_mutex_unlock(&app->sock_lock);
-               if (ret < 0 && ret != -LTTNG_UST_ERR_EXITING && ret != -EPIPE) {
-                       ERR("Error releasing app handle for app %d with ret %d", app->sock, ret);
+               if (ret < 0) {
+                       if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                               DBG3("Error releasing app handle. Application died: pid = %d, sock = %d",
+                                               app->pid, app->sock);
+                       } else if (ret == -EAGAIN) {
+                               WARN("Error releasing app handle. Communication time out: pid = %d, sock = %d",
+                                               app->pid, app->sock);
+                       } else {
+                               ERR("Error releasing app handle with ret %d: pid = %d, sock = %d",
+                                               ret, app->pid, app->sock);
+                       }
                }
        }
 
@@ -4185,7 +4504,7 @@ int ust_app_list_event_fields(struct lttng_event_field **fields)
        rcu_read_lock();
 
        cds_lfht_for_each_entry(ust_app_ht->ht, &iter.iter, app, pid_n.node) {
-               struct lttng_ust_field_iter uiter;
+               struct lttng_ust_abi_field_iter uiter;
 
                health_code_update();
 
@@ -4197,7 +4516,7 @@ int ust_app_list_event_fields(struct lttng_event_field **fields)
                        continue;
                }
                pthread_mutex_lock(&app->sock_lock);
-               handle = ustctl_tracepoint_field_list(app->sock);
+               handle = lttng_ust_ctl_tracepoint_field_list(app->sock);
                if (handle < 0) {
                        if (handle != -EPIPE && handle != -LTTNG_UST_ERR_EXITING) {
                                ERR("UST app list field getting handle failed for app pid %d",
@@ -4207,7 +4526,7 @@ int ust_app_list_event_fields(struct lttng_event_field **fields)
                        continue;
                }
 
-               while ((ret = ustctl_tracepoint_field_list_get(app->sock, handle,
+               while ((ret = lttng_ust_ctl_tracepoint_field_list_get(app->sock, handle,
                                        &uiter)) != -LTTNG_UST_ERR_NOENT) {
                        /* Handle ustctl error. */
                        if (ret < 0) {
@@ -4218,15 +4537,10 @@ int ust_app_list_event_fields(struct lttng_event_field **fields)
                                                        app->sock, ret);
                                } else {
                                        DBG3("UST app tp list field failed. Application is dead");
-                                       /*
-                                        * This is normal behavior, an application can die during the
-                                        * creation process. Don't report an error so the execution can
-                                        * continue normally. Reset list and count for next app.
-                                        */
                                        break;
                                }
                                free(tmp_event);
-                               release_ret = ustctl_release_handle(app->sock, handle);
+                               release_ret = lttng_ust_ctl_release_handle(app->sock, handle);
                                pthread_mutex_unlock(&app->sock_lock);
                                if (release_ret < 0 &&
                                                release_ret != -LTTNG_UST_ERR_EXITING &&
@@ -4253,7 +4567,7 @@ int ust_app_list_event_fields(struct lttng_event_field **fields)
                                        PERROR("realloc ust app event fields");
                                        free(tmp_event);
                                        ret = -ENOMEM;
-                                       release_ret = ustctl_release_handle(app->sock, handle);
+                                       release_ret = lttng_ust_ctl_release_handle(app->sock, handle);
                                        pthread_mutex_unlock(&app->sock_lock);
                                        if (release_ret &&
                                                        release_ret != -LTTNG_UST_ERR_EXITING &&
@@ -4269,19 +4583,19 @@ int ust_app_list_event_fields(struct lttng_event_field **fields)
                                tmp_event = new_tmp_event;
                        }
 
-                       memcpy(tmp_event[count].field_name, uiter.field_name, LTTNG_UST_SYM_NAME_LEN);
+                       memcpy(tmp_event[count].field_name, uiter.field_name, LTTNG_UST_ABI_SYM_NAME_LEN);
                        /* Mapping between these enums matches 1 to 1. */
                        tmp_event[count].type = (enum lttng_event_field_type) uiter.type;
                        tmp_event[count].nowrite = uiter.nowrite;
 
-                       memcpy(tmp_event[count].event.name, uiter.event_name, LTTNG_UST_SYM_NAME_LEN);
+                       memcpy(tmp_event[count].event.name, uiter.event_name, LTTNG_UST_ABI_SYM_NAME_LEN);
                        tmp_event[count].event.loglevel = uiter.loglevel;
                        tmp_event[count].event.type = LTTNG_EVENT_TRACEPOINT;
                        tmp_event[count].event.pid = app->pid;
                        tmp_event[count].event.enabled = -1;
                        count++;
                }
-               ret = ustctl_release_handle(app->sock, handle);
+               ret = lttng_ust_ctl_release_handle(app->sock, handle);
                pthread_mutex_unlock(&app->sock_lock);
                if (ret < 0 &&
                                ret != -LTTNG_UST_ERR_EXITING &&
@@ -4325,7 +4639,7 @@ void ust_app_clean_list(void)
                         * Assert that all notifiers are gone as all triggers
                         * are unregistered prior to this clean-up.
                         */
-                       assert(lttng_ht_get_count(app->token_to_event_notifier_rule_ht) == 0);
+                       LTTNG_ASSERT(lttng_ht_get_count(app->token_to_event_notifier_rule_ht) == 0);
 
                        ust_app_notify_sock_unregister(app->notify_sock);
                }
@@ -4334,7 +4648,7 @@ void ust_app_clean_list(void)
        if (ust_app_ht) {
                cds_lfht_for_each_entry(ust_app_ht->ht, &iter.iter, app, pid_n.node) {
                        ret = lttng_ht_del(ust_app_ht, &iter);
-                       assert(!ret);
+                       LTTNG_ASSERT(!ret);
                        call_rcu(&app->pid_n.head, delete_ust_app_rcu);
                }
        }
@@ -4344,7 +4658,7 @@ void ust_app_clean_list(void)
                cds_lfht_for_each_entry(ust_app_ht_by_sock->ht, &iter.iter, app,
                                sock_n.node) {
                        ret = lttng_ht_del(ust_app_ht_by_sock, &iter);
-                       assert(!ret);
+                       LTTNG_ASSERT(!ret);
                }
        }
 
@@ -4395,7 +4709,7 @@ int ust_app_disable_channel_glb(struct ltt_ust_session *usess,
        struct ust_app_session *ua_sess;
        struct ust_app_channel *ua_chan;
 
-       assert(usess->active);
+       LTTNG_ASSERT(usess->active);
        DBG2("UST app disabling channel %s from global domain for session id %" PRIu64,
                        uchan->name, usess->id);
 
@@ -4420,11 +4734,11 @@ int ust_app_disable_channel_glb(struct ltt_ust_session *usess,
                lttng_ht_lookup(ua_sess->channels, (void *)uchan->name, &uiter);
                ua_chan_node = lttng_ht_iter_get_node_str(&uiter);
                /* If the session if found for the app, the channel must be there */
-               assert(ua_chan_node);
+               LTTNG_ASSERT(ua_chan_node);
 
                ua_chan = caa_container_of(ua_chan_node, struct ust_app_channel, node);
                /* The channel must not be already disabled */
-               assert(ua_chan->enabled == 1);
+               LTTNG_ASSERT(ua_chan->enabled == 1);
 
                /* Disable channel onto application */
                ret = disable_ust_app_channel(ua_sess, ua_chan, app);
@@ -4449,7 +4763,7 @@ int ust_app_enable_channel_glb(struct ltt_ust_session *usess,
        struct ust_app *app;
        struct ust_app_session *ua_sess;
 
-       assert(usess->active);
+       LTTNG_ASSERT(usess->active);
        DBG2("UST app enabling channel %s to global domain for session id %" PRIu64,
                        uchan->name, usess->id);
 
@@ -4495,7 +4809,7 @@ int ust_app_disable_event_glb(struct ltt_ust_session *usess,
        struct ust_app_channel *ua_chan;
        struct ust_app_event *ua_event;
 
-       assert(usess->active);
+       LTTNG_ASSERT(usess->active);
        DBG("UST app disabling event %s for all apps in channel "
                        "%s for session id %" PRIu64,
                        uevent->attr.name, uchan->name, usess->id);
@@ -4557,7 +4871,7 @@ int ust_app_channel_create(struct ltt_ust_session *usess,
        int ret = 0;
        struct ust_app_channel *ua_chan = NULL;
 
-       assert(ua_sess);
+       LTTNG_ASSERT(ua_sess);
        ASSERT_LOCKED(ua_sess->lock);
 
        if (!strncmp(uchan->name, DEFAULT_METADATA_NAME,
@@ -4573,7 +4887,7 @@ int ust_app_channel_create(struct ltt_ust_session *usess,
                 * configuration.
                 */
                ret = ust_app_channel_allocate(ua_sess, uchan,
-                       LTTNG_UST_CHAN_PER_CPU, usess,
+                       LTTNG_UST_ABI_CHAN_PER_CPU, usess,
                        &ua_chan);
                if (ret < 0) {
                        goto error;
@@ -4637,7 +4951,7 @@ int ust_app_enable_event_glb(struct ltt_ust_session *usess,
        struct ust_app_channel *ua_chan;
        struct ust_app_event *ua_event;
 
-       assert(usess->active);
+       LTTNG_ASSERT(usess->active);
        DBG("UST app enabling event %s for all apps for session id %" PRIu64,
                        uevent->attr.name, usess->id);
 
@@ -4723,7 +5037,7 @@ int ust_app_create_event_glb(struct ltt_ust_session *usess,
        struct ust_app_session *ua_sess;
        struct ust_app_channel *ua_chan;
 
-       assert(usess->active);
+       LTTNG_ASSERT(usess->active);
        DBG("UST app creating event %s for all apps for session id %" PRIu64,
                        uevent->attr.name, usess->id);
 
@@ -4755,7 +5069,7 @@ int ust_app_create_event_glb(struct ltt_ust_session *usess,
                lttng_ht_lookup(ua_sess->channels, (void *)uchan->name, &uiter);
                ua_chan_node = lttng_ht_iter_get_node_str(&uiter);
                /* If the channel is not found, there is a code flow error */
-               assert(ua_chan_node);
+               LTTNG_ASSERT(ua_chan_node);
 
                ua_chan = caa_container_of(ua_chan_node, struct ust_app_channel, node);
 
@@ -4824,21 +5138,23 @@ int ust_app_start_trace(struct ltt_ust_session *usess, struct ust_app *app)
 skip_setup:
        /* This starts the UST tracing */
        pthread_mutex_lock(&app->sock_lock);
-       ret = ustctl_start_session(app->sock, ua_sess->handle);
+       ret = lttng_ust_ctl_start_session(app->sock, ua_sess->handle);
        pthread_mutex_unlock(&app->sock_lock);
        if (ret < 0) {
-               if (ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
-                       ERR("Error starting tracing for app pid: %d (ret: %d)",
-                                       app->pid, ret);
-               } else {
-                       DBG("UST app start session failed. Application is dead.");
-                       /*
-                        * This is normal behavior, an application can die during the
-                        * creation process. Don't report an error so the execution can
-                        * continue normally.
-                        */
+               if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                       DBG3("UST app start session failed. Application is dead: pid = %d, sock = %d",
+                                       app->pid, app->sock);
                        pthread_mutex_unlock(&ua_sess->lock);
                        goto end;
+               } else if (ret == -EAGAIN) {
+                       WARN("UST app start session failed. Communication time out: pid = %d, sock = %d",
+                                       app->pid, app->sock);
+                       pthread_mutex_unlock(&ua_sess->lock);
+                       goto end;
+
+               } else {
+                       ERR("UST app start session failed with ret %d: pid = %d, sock = %d",
+                                       ret, app->pid, app->sock);
                }
                goto error_unlock;
        }
@@ -4853,11 +5169,19 @@ skip_setup:
 
        /* Quiescent wait after starting trace */
        pthread_mutex_lock(&app->sock_lock);
-       ret = ustctl_wait_quiescent(app->sock);
+       ret = lttng_ust_ctl_wait_quiescent(app->sock);
        pthread_mutex_unlock(&app->sock_lock);
-       if (ret < 0 && ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
-               ERR("UST app wait quiescent failed for app pid %d ret %d",
-                               app->pid, ret);
+       if (ret < 0) {
+               if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                       DBG3("UST app wait quiescent failed. Application is dead: pid = %d, sock = %d",
+                                       app->pid, app->sock);
+               } else if (ret == -EAGAIN) {
+                       WARN("UST app wait quiescent failed. Communication time out: pid =  %d, sock = %d",
+                                       app->pid, app->sock);
+               } else {
+                       ERR("UST app wait quiescent failed with ret %d: pid %d, sock = %d",
+                                       ret, app->pid, app->sock);
+               }
        }
 
 end:
@@ -4916,20 +5240,21 @@ int ust_app_stop_trace(struct ltt_ust_session *usess, struct ust_app *app)
 
        /* This inhibits UST tracing */
        pthread_mutex_lock(&app->sock_lock);
-       ret = ustctl_stop_session(app->sock, ua_sess->handle);
+       ret = lttng_ust_ctl_stop_session(app->sock, ua_sess->handle);
        pthread_mutex_unlock(&app->sock_lock);
        if (ret < 0) {
-               if (ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
-                       ERR("Error stopping tracing for app pid: %d (ret: %d)",
-                                       app->pid, ret);
-               } else {
-                       DBG("UST app stop session failed. Application is dead.");
-                       /*
-                        * This is normal behavior, an application can die during the
-                        * creation process. Don't report an error so the execution can
-                        * continue normally.
-                        */
+               if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                       DBG3("UST app stop session failed. Application is dead: pid = %d, sock = %d",
+                                       app->pid, app->sock);
                        goto end_unlock;
+               } else if (ret == -EAGAIN) {
+                       WARN("UST app stop session failed. Communication time out: pid = %d, sock = %d",
+                                       app->pid, app->sock);
+                       goto end_unlock;
+
+               } else {
+                       ERR("UST app stop session failed with ret %d: pid = %d, sock = %d",
+                                       ret, app->pid, app->sock);
                }
                goto error_rcu_unlock;
        }
@@ -4939,11 +5264,19 @@ int ust_app_stop_trace(struct ltt_ust_session *usess, struct ust_app *app)
 
        /* Quiescent wait after stopping trace */
        pthread_mutex_lock(&app->sock_lock);
-       ret = ustctl_wait_quiescent(app->sock);
+       ret = lttng_ust_ctl_wait_quiescent(app->sock);
        pthread_mutex_unlock(&app->sock_lock);
-       if (ret < 0 && ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
-               ERR("UST app wait quiescent failed for app pid %d ret %d",
-                               app->pid, ret);
+       if (ret < 0) {
+               if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                       DBG3("UST app wait quiescent failed. Application is dead: pid= %d, sock = %d)",
+                                       app->pid, app->sock);
+               } else if (ret == -EAGAIN) {
+                       WARN("UST app wait quiescent failed. Communication time out: pid= %d, sock = %d)",
+                                       app->pid, app->sock);
+               } else {
+                       ERR("UST app wait quiescent failed with ret %d: pid= %d, sock = %d)",
+                                       ret, app->pid, app->sock);
+               }
        }
 
        health_code_update();
@@ -4951,7 +5284,7 @@ int ust_app_stop_trace(struct ltt_ust_session *usess, struct ust_app *app)
        registry = get_session_registry(ua_sess);
 
        /* The UST app session is held registry shall not be null. */
-       assert(registry);
+       LTTNG_ASSERT(registry);
 
        /* Push metadata for application before freeing the application. */
        (void) push_metadata(registry, ua_sess->consumer);
@@ -5015,7 +5348,7 @@ int ust_app_flush_app_session(struct ust_app *app,
                break;
        case LTTNG_BUFFER_PER_UID:
        default:
-               assert(0);
+               abort();
                break;
        }
 
@@ -5054,7 +5387,7 @@ int ust_app_flush_session(struct ltt_ust_session *usess)
                /* Flush all per UID buffers associated to that session. */
                cds_list_for_each_entry(reg, &usess->buffer_reg_uid_list, lnode) {
                        struct ust_registry_session *ust_session_reg;
-                       struct buffer_reg_channel *reg_chan;
+                       struct buffer_reg_channel *buf_reg_chan;
                        struct consumer_socket *socket;
 
                        /* Get consumer socket to use to push the metadata.*/
@@ -5066,13 +5399,13 @@ int ust_app_flush_session(struct ltt_ust_session *usess)
                        }
 
                        cds_lfht_for_each_entry(reg->registry->channels->ht, &iter.iter,
-                                       reg_chan, node.node) {
+                                       buf_reg_chan, node.node) {
                                /*
                                 * The following call will print error values so the return
                                 * code is of little importance because whatever happens, we
                                 * have to try them all.
                                 */
-                               (void) consumer_flush_channel(socket, reg_chan->consumer_key);
+                               (void) consumer_flush_channel(socket, buf_reg_chan->consumer_key);
                        }
 
                        ust_session_reg = reg->registry->reg.ust;
@@ -5098,7 +5431,7 @@ int ust_app_flush_session(struct ltt_ust_session *usess)
        }
        default:
                ret = -1;
-               assert(0);
+               abort();
                break;
        }
 
@@ -5158,7 +5491,7 @@ int ust_app_clear_quiescent_app_session(struct ust_app *app,
                break;
        case LTTNG_BUFFER_PER_UID:
        default:
-               assert(0);
+               abort();
                ret = -1;
                break;
        }
@@ -5201,7 +5534,7 @@ int ust_app_clear_quiescent_session(struct ltt_ust_session *usess)
                 */
                cds_list_for_each_entry(reg, &usess->buffer_reg_uid_list, lnode) {
                        struct consumer_socket *socket;
-                       struct buffer_reg_channel *reg_chan;
+                       struct buffer_reg_channel *buf_reg_chan;
 
                        /* Get associated consumer socket.*/
                        socket = consumer_find_socket_by_bitness(
@@ -5215,7 +5548,7 @@ int ust_app_clear_quiescent_session(struct ltt_ust_session *usess)
                        }
 
                        cds_lfht_for_each_entry(reg->registry->channels->ht,
-                                       &iter.iter, reg_chan, node.node) {
+                                       &iter.iter, buf_reg_chan, node.node) {
                                /*
                                 * The following call will print error values so
                                 * the return code is of little importance
@@ -5223,7 +5556,7 @@ int ust_app_clear_quiescent_session(struct ltt_ust_session *usess)
                                 * all.
                                 */
                                (void) consumer_clear_quiescent_channel(socket,
-                                               reg_chan->consumer_key);
+                                               buf_reg_chan->consumer_key);
                        }
                }
                break;
@@ -5247,7 +5580,7 @@ int ust_app_clear_quiescent_session(struct ltt_ust_session *usess)
        }
        default:
                ret = -1;
-               assert(0);
+               abort();
                break;
        }
 
@@ -5289,11 +5622,19 @@ static int destroy_trace(struct ltt_ust_session *usess, struct ust_app *app)
 
        /* Quiescent wait after stopping trace */
        pthread_mutex_lock(&app->sock_lock);
-       ret = ustctl_wait_quiescent(app->sock);
+       ret = lttng_ust_ctl_wait_quiescent(app->sock);
        pthread_mutex_unlock(&app->sock_lock);
-       if (ret < 0 && ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
-               ERR("UST app wait quiescent failed for app pid %d ret %d",
-                               app->pid, ret);
+       if (ret < 0) {
+               if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                       DBG3("UST app wait quiescent failed. Application is dead: pid= %d, sock = %d)",
+                                       app->pid, app->sock);
+               } else if (ret == -EAGAIN) {
+                       WARN("UST app wait quiescent failed. Communication time out: pid= %d, sock = %d)",
+                                       app->pid, app->sock);
+               } else {
+                       ERR("UST app wait quiescent failed with ret %d: pid= %d, sock = %d)",
+                                       ret, app->pid, app->sock);
+               }
        }
 end:
        rcu_read_unlock();
@@ -5465,6 +5806,10 @@ void ust_app_synchronize_event_notifier_rules(struct ust_app *app)
        struct ust_app_event_notifier_rule *event_notifier_rule;
        unsigned int count, i;
 
+       if (!ust_app_supports_notifiers(app)) {
+               goto end;
+       }
+
        /*
         * Currrently, registering or unregistering a trigger with an
         * event rule condition causes a full synchronization of the event
@@ -5484,17 +5829,15 @@ void ust_app_synchronize_event_notifier_rules(struct ust_app *app)
 
        /* Get all triggers using uid 0 (root) */
        ret_code = notification_thread_command_list_triggers(
-                       notification_thread_handle, 0, &triggers);
+                       the_notification_thread_handle, 0, &triggers);
        if (ret_code != LTTNG_OK) {
-               ret = -1;
                goto end;
        }
 
-       assert(triggers);
+       LTTNG_ASSERT(triggers);
 
        t_status = lttng_triggers_get_count(triggers, &count);
        if (t_status != LTTNG_TRIGGER_STATUS_OK) {
-               ret = -1;
                goto end;
        }
 
@@ -5507,18 +5850,21 @@ void ust_app_synchronize_event_notifier_rules(struct ust_app *app)
                uint64_t token;
 
                trigger = lttng_triggers_borrow_mutable_at_index(triggers, i);
-               assert(trigger);
+               LTTNG_ASSERT(trigger);
 
                token = lttng_trigger_get_tracer_token(trigger);
                condition = lttng_trigger_get_condition(trigger);
 
-               if (lttng_condition_get_type(condition) != LTTNG_CONDITION_TYPE_EVENT_RULE_HIT) {
+               if (lttng_condition_get_type(condition) !=
+                               LTTNG_CONDITION_TYPE_EVENT_RULE_MATCHES) {
                        /* Does not apply */
                        continue;
                }
 
-               condition_status = lttng_condition_event_rule_borrow_rule_mutable(condition, &event_rule);
-               assert(condition_status == LTTNG_CONDITION_STATUS_OK);
+               condition_status =
+                               lttng_condition_event_rule_matches_borrow_rule_mutable(
+                                               condition, &event_rule);
+               LTTNG_ASSERT(condition_status == LTTNG_CONDITION_STATUS_OK);
 
                if (lttng_event_rule_get_domain_type(event_rule) == LTTNG_DOMAIN_KERNEL) {
                        /* Skip kernel related triggers. */
@@ -5533,7 +5879,7 @@ void ust_app_synchronize_event_notifier_rules(struct ust_app *app)
                looked_up_event_notifier_rule = find_ust_app_event_notifier_rule(
                                app->token_to_event_notifier_rule_ht, token);
                if (!looked_up_event_notifier_rule) {
-                       ret = create_ust_app_event_notifier_rule(event_rule, app, token);
+                       ret = create_ust_app_event_notifier_rule(trigger, app);
                        if (ret < 0) {
                                goto end;
                        }
@@ -5558,7 +5904,7 @@ void ust_app_synchronize_event_notifier_rules(struct ust_app *app)
                                        lttng_triggers_get_at_index(
                                                        triggers, i);
 
-                       assert(trigger);
+                       LTTNG_ASSERT(trigger);
 
                        notification_thread_token =
                                        lttng_trigger_get_tracer_token(trigger);
@@ -5580,7 +5926,7 @@ void ust_app_synchronize_event_notifier_rules(struct ust_app *app)
                 */
                ret = lttng_ht_del(app->token_to_event_notifier_rule_ht,
                                &app_trigger_iter);
-               assert(ret == 0);
+               LTTNG_ASSERT(ret == 0);
 
                /* Callee logs errors. */
                (void) disable_ust_object(app, event_notifier_rule->obj);
@@ -5597,38 +5943,20 @@ end:
 }
 
 /*
- * The caller must ensure that the application is compatible and is tracked
- * by the process attribute trackers.
+ * RCU read lock must be held by the caller.
  */
 static
-void ust_app_synchronize(struct ltt_ust_session *usess,
+void ust_app_synchronize_all_channels(struct ltt_ust_session *usess,
+               struct ust_app_session *ua_sess,
                struct ust_app *app)
 {
        int ret = 0;
        struct cds_lfht_iter uchan_iter;
        struct ltt_ust_channel *uchan;
-       struct ust_app_session *ua_sess = NULL;
 
-       /*
-        * The application's configuration should only be synchronized for
-        * active sessions.
-        */
-       assert(usess->active);
-
-       ret = find_or_create_ust_app_session(usess, app, &ua_sess, NULL);
-       if (ret < 0) {
-               /* Tracer is probably gone or ENOMEM. */
-               goto error;
-       }
-       assert(ua_sess);
-
-       pthread_mutex_lock(&ua_sess->lock);
-       if (ua_sess->deleted) {
-               pthread_mutex_unlock(&ua_sess->lock);
-               goto end;
-       }
-
-       rcu_read_lock();
+       LTTNG_ASSERT(usess);
+       LTTNG_ASSERT(ua_sess);
+       LTTNG_ASSERT(app);
 
        cds_lfht_for_each_entry(usess->domain_global.channels->ht, &uchan_iter,
                        uchan, node.node) {
@@ -5647,7 +5975,7 @@ void ust_app_synchronize(struct ltt_ust_session *usess,
                        app, uchan, &ua_chan);
                if (ret) {
                        /* Tracer is probably gone or ENOMEM. */
-                       goto error_unlock;
+                       goto end;
                }
 
                if (!ua_chan) {
@@ -5660,7 +5988,7 @@ void ust_app_synchronize(struct ltt_ust_session *usess,
                        ret = ust_app_channel_synchronize_event(ua_chan,
                                uevent, ua_sess, app);
                        if (ret) {
-                               goto error_unlock;
+                               goto end;
                        }
                }
 
@@ -5669,10 +5997,49 @@ void ust_app_synchronize(struct ltt_ust_session *usess,
                                enable_ust_app_channel(ua_sess, uchan, app) :
                                disable_ust_app_channel(ua_sess, ua_chan, app);
                        if (ret) {
-                               goto error_unlock;
+                               goto end;
                        }
                }
        }
+end:
+       return;
+}
+
+/*
+ * The caller must ensure that the application is compatible and is tracked
+ * by the process attribute trackers.
+ */
+static
+void ust_app_synchronize(struct ltt_ust_session *usess,
+               struct ust_app *app)
+{
+       int ret = 0;
+       struct ust_app_session *ua_sess = NULL;
+
+       /*
+        * The application's configuration should only be synchronized for
+        * active sessions.
+        */
+       LTTNG_ASSERT(usess->active);
+
+       ret = find_or_create_ust_app_session(usess, app, &ua_sess, NULL);
+       if (ret < 0) {
+               /* Tracer is probably gone or ENOMEM. */
+               if (ua_sess) {
+                       destroy_app_session(app, ua_sess);
+               }
+               goto end;
+       }
+       LTTNG_ASSERT(ua_sess);
+
+       pthread_mutex_lock(&ua_sess->lock);
+       if (ua_sess->deleted) {
+               goto deleted_session;
+       }
+
+       rcu_read_lock();
+
+       ust_app_synchronize_all_channels(usess, ua_sess, app);
 
        /*
         * Create the metadata for the application. This returns gracefully if a
@@ -5685,23 +6052,15 @@ void ust_app_synchronize(struct ltt_ust_session *usess,
         */
        ret = create_ust_app_metadata(ua_sess, app, usess->consumer);
        if (ret < 0) {
-               goto error_unlock;
+               ERR("Metadata creation failed for app sock %d for session id %" PRIu64,
+                               app->sock, usess->id);
        }
 
        rcu_read_unlock();
 
-end:
-       pthread_mutex_unlock(&ua_sess->lock);
-       /* Everything went well at this point. */
-       return;
-
-error_unlock:
-       rcu_read_unlock();
+deleted_session:
        pthread_mutex_unlock(&ua_sess->lock);
-error:
-       if (ua_sess) {
-               destroy_app_session(app, ua_sess);
-       }
+end:
        return;
 }
 
@@ -5725,8 +6084,8 @@ void ust_app_global_destroy(struct ltt_ust_session *usess, struct ust_app *app)
  */
 void ust_app_global_update(struct ltt_ust_session *usess, struct ust_app *app)
 {
-       assert(usess);
-       assert(usess->active);
+       LTTNG_ASSERT(usess);
+       LTTNG_ASSERT(usess->active);
 
        DBG2("UST app global update for app sock %d for session id %" PRIu64,
                        app->sock, usess->id);
@@ -5761,16 +6120,16 @@ void ust_app_global_update(struct ltt_ust_session *usess, struct ust_app *app)
  */
 void ust_app_global_update_event_notifier_rules(struct ust_app *app)
 {
-       DBG2("UST application global event notifier rules update: app = '%s' (ppid: %d)",
-                       app->name, app->ppid);
+       DBG2("UST application global event notifier rules update: app = '%s', pid = %d)",
+                       app->name, app->pid);
 
-       if (!app->compatible) {
+       if (!app->compatible || !ust_app_supports_notifiers(app)) {
                return;
        }
 
        if (app->event_notifier_group.object == NULL) {
-               WARN("UST app global update of event notifiers for app skipped since communication handle is null: app = '%s' (ppid: %d)",
-                               app->name, app->ppid);
+               WARN("UST app global update of event notifiers for app skipped since communication handle is null: app = '%s' pid = %d)",
+                               app->name, app->pid);
                return;
        }
 
@@ -5818,7 +6177,7 @@ int ust_app_add_ctx_channel_glb(struct ltt_ust_session *usess,
        struct ust_app_session *ua_sess;
        struct ust_app *app;
 
-       assert(usess->active);
+       LTTNG_ASSERT(usess->active);
 
        rcu_read_lock();
        cds_lfht_for_each_entry(ust_app_ht->ht, &iter.iter, app, pid_n.node) {
@@ -5871,9 +6230,9 @@ int ust_app_recv_registration(int sock, struct ust_register_msg *msg)
        int ret;
        uint32_t pid, ppid, uid, gid;
 
-       assert(msg);
+       LTTNG_ASSERT(msg);
 
-       ret = ustctl_recv_reg_msg(sock, &msg->type, &msg->major, &msg->minor,
+       ret = lttng_ust_ctl_recv_reg_msg(sock, &msg->type, &msg->major, &msg->minor,
                        &pid, &ppid, &uid, &gid,
                        &msg->bits_per_long,
                        &msg->uint8_t_alignment,
@@ -5922,7 +6281,7 @@ static struct ust_app_session *find_session_by_objd(struct ust_app *app,
        struct lttng_ht_iter iter;
        struct ust_app_session *ua_sess = NULL;
 
-       assert(app);
+       LTTNG_ASSERT(app);
 
        lttng_ht_lookup(app->ust_sessions_objd, (void *)((unsigned long) objd), &iter);
        node = lttng_ht_iter_get_node_ulong(&iter);
@@ -5949,7 +6308,7 @@ static struct ust_app_channel *find_channel_by_objd(struct ust_app *app,
        struct lttng_ht_iter iter;
        struct ust_app_channel *ua_chan = NULL;
 
-       assert(app);
+       LTTNG_ASSERT(app);
 
        lttng_ht_lookup(app->ust_objd, (void *)((unsigned long) objd), &iter);
        node = lttng_ht_iter_get_node_ulong(&iter);
@@ -5973,17 +6332,17 @@ error:
  * On success 0 is returned else a negative value.
  */
 static int reply_ust_register_channel(int sock, int cobjd,
-               size_t nr_fields, struct ustctl_field *fields)
+               size_t nr_fields, struct lttng_ust_ctl_field *fields)
 {
        int ret, ret_code = 0;
        uint32_t chan_id;
        uint64_t chan_reg_key;
-       enum ustctl_channel_header type;
+       enum lttng_ust_ctl_channel_header type;
        struct ust_app *app;
        struct ust_app_channel *ua_chan;
        struct ust_app_session *ua_sess;
        struct ust_registry_session *registry;
-       struct ust_registry_channel *chan_reg;
+       struct ust_registry_channel *ust_reg_chan;
 
        rcu_read_lock();
 
@@ -5992,7 +6351,7 @@ static int reply_ust_register_channel(int sock, int cobjd,
        if (!app) {
                DBG("Application socket %d is being torn down. Abort event notify",
                                sock);
-               ret = 0;
+               ret = -1;
                goto error_rcu_unlock;
        }
 
@@ -6004,7 +6363,7 @@ static int reply_ust_register_channel(int sock, int cobjd,
                goto error_rcu_unlock;
        }
 
-       assert(ua_chan->session);
+       LTTNG_ASSERT(ua_chan->session);
        ua_sess = ua_chan->session;
 
        /* Get right session registry depending on the session buffer type. */
@@ -6024,30 +6383,30 @@ static int reply_ust_register_channel(int sock, int cobjd,
 
        pthread_mutex_lock(&registry->lock);
 
-       chan_reg = ust_registry_channel_find(registry, chan_reg_key);
-       assert(chan_reg);
+       ust_reg_chan = ust_registry_channel_find(registry, chan_reg_key);
+       LTTNG_ASSERT(ust_reg_chan);
 
-       if (!chan_reg->register_done) {
+       if (!ust_reg_chan->register_done) {
                /*
                 * TODO: eventually use the registry event count for
                 * this channel to better guess header type for per-pid
                 * buffers.
                 */
-               type = USTCTL_CHANNEL_HEADER_LARGE;
-               chan_reg->nr_ctx_fields = nr_fields;
-               chan_reg->ctx_fields = fields;
+               type = LTTNG_UST_CTL_CHANNEL_HEADER_LARGE;
+               ust_reg_chan->nr_ctx_fields = nr_fields;
+               ust_reg_chan->ctx_fields = fields;
                fields = NULL;
-               chan_reg->header_type = type;
+               ust_reg_chan->header_type = type;
        } else {
                /* Get current already assigned values. */
-               type = chan_reg->header_type;
+               type = ust_reg_chan->header_type;
        }
        /* Channel id is set during the object creation. */
-       chan_id = chan_reg->chan_id;
+       chan_id = ust_reg_chan->chan_id;
 
        /* Append to metadata */
-       if (!chan_reg->metadata_dumped) {
-               ret_code = ust_metadata_channel_statedump(registry, chan_reg);
+       if (!ust_reg_chan->metadata_dumped) {
+               ret_code = ust_metadata_channel_statedump(registry, ust_reg_chan);
                if (ret_code) {
                        ERR("Error appending channel metadata (errno = %d)", ret_code);
                        goto reply;
@@ -6056,21 +6415,26 @@ static int reply_ust_register_channel(int sock, int cobjd,
 
 reply:
        DBG3("UST app replying to register channel key %" PRIu64
-                       " with id %u, type: %d, ret: %d", chan_reg_key, chan_id, type,
+                       " with id %u, type = %d, ret = %d", chan_reg_key, chan_id, type,
                        ret_code);
 
-       ret = ustctl_reply_register_channel(sock, chan_id, type, ret_code);
+       ret = lttng_ust_ctl_reply_register_channel(sock, chan_id, type, ret_code);
        if (ret < 0) {
-               if (ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
-                       ERR("UST app reply channel failed with ret %d", ret);
+               if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                       DBG3("UST app reply channel failed. Application died: pid = %d, sock = %d",
+                                       app->pid, app->sock);
+               } else if (ret == -EAGAIN) {
+                       WARN("UST app reply channel failed. Communication time out: pid = %d, sock = %d",
+                                       app->pid, app->sock);
                } else {
-                       DBG3("UST app reply channel failed. Application died");
+                       ERR("UST app reply channel failed with ret %d: pid = %d, sock = %d",
+                                       ret, app->pid, app->sock);
                }
                goto error;
        }
 
        /* This channel registry registration is completed. */
-       chan_reg->register_done = 1;
+       ust_reg_chan->register_done = 1;
 
 error:
        pthread_mutex_unlock(&registry->lock);
@@ -6090,7 +6454,7 @@ error_rcu_unlock:
  * On success 0 is returned else a negative value.
  */
 static int add_event_ust_registry(int sock, int sobjd, int cobjd, char *name,
-               char *sig, size_t nr_fields, struct ustctl_field *fields,
+               char *sig, size_t nr_fields, struct lttng_ust_ctl_field *fields,
                int loglevel_value, char *model_emf_uri)
 {
        int ret, ret_code;
@@ -6108,7 +6472,7 @@ static int add_event_ust_registry(int sock, int sobjd, int cobjd, char *name,
        if (!app) {
                DBG("Application socket %d is being torn down. Abort event notify",
                                sock);
-               ret = 0;
+               ret = -1;
                goto error_rcu_unlock;
        }
 
@@ -6120,7 +6484,7 @@ static int add_event_ust_registry(int sock, int sobjd, int cobjd, char *name,
                goto error_rcu_unlock;
        }
 
-       assert(ua_chan->session);
+       LTTNG_ASSERT(ua_chan->session);
        ua_sess = ua_chan->session;
 
        registry = get_session_registry(ua_sess);
@@ -6156,12 +6520,17 @@ static int add_event_ust_registry(int sock, int sobjd, int cobjd, char *name,
         * application can be notified. In case of an error, it's important not to
         * return a negative error or else the application will get closed.
         */
-       ret = ustctl_reply_register_event(sock, event_id, ret_code);
+       ret = lttng_ust_ctl_reply_register_event(sock, event_id, ret_code);
        if (ret < 0) {
-               if (ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
-                       ERR("UST app reply event failed with ret %d", ret);
+               if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                       DBG3("UST app reply event failed. Application died: pid = %d, sock = %d.",
+                                       app->pid, app->sock);
+               } else if (ret == -EAGAIN) {
+                       WARN("UST app reply event failed. Communication time out: pid = %d, sock = %d",
+                                       app->pid, app->sock);
                } else {
-                       DBG3("UST app reply event failed. Application died");
+                       ERR("UST app reply event failed with ret %d: pid = %d, sock = %d",
+                                       ret, app->pid, app->sock);
                }
                /*
                 * No need to wipe the create event since the application socket will
@@ -6192,7 +6561,7 @@ error_rcu_unlock:
  * On success 0 is returned else a negative value.
  */
 static int add_enum_ust_registry(int sock, int sobjd, char *name,
-               struct ustctl_enum_entry *entries, size_t nr_entries)
+               struct lttng_ust_ctl_enum_entry *entries, size_t nr_entries)
 {
        int ret = 0, ret_code;
        struct ust_app *app;
@@ -6209,6 +6578,7 @@ static int add_enum_ust_registry(int sock, int sobjd, char *name,
                DBG("Application socket %d is being torn down. Aborting enum registration",
                                sock);
                free(entries);
+               ret = -1;
                goto error_rcu_unlock;
        }
 
@@ -6244,12 +6614,17 @@ static int add_enum_ust_registry(int sock, int sobjd, char *name,
         * application can be notified. In case of an error, it's important not to
         * return a negative error or else the application will get closed.
         */
-       ret = ustctl_reply_register_enum(sock, enum_id, ret_code);
+       ret = lttng_ust_ctl_reply_register_enum(sock, enum_id, ret_code);
        if (ret < 0) {
-               if (ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
-                       ERR("UST app reply enum failed with ret %d", ret);
+               if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                       DBG3("UST app reply enum failed. Application died: pid = %d, sock = %d",
+                                       app->pid, app->sock);
+               } else if (ret == -EAGAIN) {
+                       WARN("UST app reply enum failed. Communication time out: pid = %d, sock = %d",
+                                       app->pid, app->sock);
                } else {
-                       DBG3("UST app reply enum failed. Application died");
+                       ERR("UST app reply enum failed with ret %d: pid = %d, sock = %d",
+                                       ret, app->pid, app->sock);
                }
                /*
                 * No need to wipe the create enum since the application socket will
@@ -6275,38 +6650,48 @@ error_rcu_unlock:
 int ust_app_recv_notify(int sock)
 {
        int ret;
-       enum ustctl_notify_cmd cmd;
+       enum lttng_ust_ctl_notify_cmd cmd;
 
        DBG3("UST app receiving notify from sock %d", sock);
 
-       ret = ustctl_recv_notify(sock, &cmd);
+       ret = lttng_ust_ctl_recv_notify(sock, &cmd);
        if (ret < 0) {
-               if (ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
-                       ERR("UST app recv notify failed with ret %d", ret);
+               if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                       DBG3("UST app recv notify failed. Application died: sock = %d",
+                                       sock);
+               } else if (ret == -EAGAIN) {
+                       WARN("UST app recv notify failed. Communication time out: sock = %d",
+                                       sock);
                } else {
-                       DBG3("UST app recv notify failed. Application died");
+                       ERR("UST app recv notify failed with ret %d: sock = %d",
+                                       ret, sock);
                }
                goto error;
        }
 
        switch (cmd) {
-       case USTCTL_NOTIFY_CMD_EVENT:
+       case LTTNG_UST_CTL_NOTIFY_CMD_EVENT:
        {
                int sobjd, cobjd, loglevel_value;
-               char name[LTTNG_UST_SYM_NAME_LEN], *sig, *model_emf_uri;
+               char name[LTTNG_UST_ABI_SYM_NAME_LEN], *sig, *model_emf_uri;
                size_t nr_fields;
-               struct ustctl_field *fields;
+               struct lttng_ust_ctl_field *fields;
 
                DBG2("UST app ustctl register event received");
 
-               ret = ustctl_recv_register_event(sock, &sobjd, &cobjd, name,
+               ret = lttng_ust_ctl_recv_register_event(sock, &sobjd, &cobjd, name,
                                &loglevel_value, &sig, &nr_fields, &fields,
                                &model_emf_uri);
                if (ret < 0) {
-                       if (ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
-                               ERR("UST app recv event failed with ret %d", ret);
+                       if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                               DBG3("UST app recv event failed. Application died: sock = %d",
+                                               sock);
+                       } else if (ret == -EAGAIN) {
+                               WARN("UST app recv event failed. Communication time out: sock = %d",
+                                               sock);
                        } else {
-                               DBG3("UST app recv event failed. Application died");
+                               ERR("UST app recv event failed with ret %d: sock = %d",
+                                               ret, sock);
                        }
                        goto error;
                }
@@ -6325,21 +6710,26 @@ int ust_app_recv_notify(int sock)
 
                break;
        }
-       case USTCTL_NOTIFY_CMD_CHANNEL:
+       case LTTNG_UST_CTL_NOTIFY_CMD_CHANNEL:
        {
                int sobjd, cobjd;
                size_t nr_fields;
-               struct ustctl_field *fields;
+               struct lttng_ust_ctl_field *fields;
 
                DBG2("UST app ustctl register channel received");
 
-               ret = ustctl_recv_register_channel(sock, &sobjd, &cobjd, &nr_fields,
+               ret = lttng_ust_ctl_recv_register_channel(sock, &sobjd, &cobjd, &nr_fields,
                                &fields);
                if (ret < 0) {
-                       if (ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
-                               ERR("UST app recv channel failed with ret %d", ret);
+                       if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                               DBG3("UST app recv channel failed. Application died: sock = %d",
+                                               sock);
+                       } else if (ret == -EAGAIN) {
+                               WARN("UST app recv channel failed. Communication time out: sock = %d",
+                                               sock);
                        } else {
-                               DBG3("UST app recv channel failed. Application died");
+                               ERR("UST app recv channel failed with ret %d: sock = %d)",
+                                               ret, sock);
                        }
                        goto error;
                }
@@ -6357,22 +6747,27 @@ int ust_app_recv_notify(int sock)
 
                break;
        }
-       case USTCTL_NOTIFY_CMD_ENUM:
+       case LTTNG_UST_CTL_NOTIFY_CMD_ENUM:
        {
                int sobjd;
-               char name[LTTNG_UST_SYM_NAME_LEN];
+               char name[LTTNG_UST_ABI_SYM_NAME_LEN];
                size_t nr_entries;
-               struct ustctl_enum_entry *entries;
+               struct lttng_ust_ctl_enum_entry *entries;
 
                DBG2("UST app ustctl register enum received");
 
-               ret = ustctl_recv_register_enum(sock, &sobjd, name,
+               ret = lttng_ust_ctl_recv_register_enum(sock, &sobjd, name,
                                &entries, &nr_entries);
                if (ret < 0) {
-                       if (ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
-                               ERR("UST app recv enum failed with ret %d", ret);
+                       if (ret == -EPIPE || ret == -LTTNG_UST_ERR_EXITING) {
+                               DBG3("UST app recv enum failed. Application died: sock = %d",
+                                               sock);
+                       } else if (ret == -EAGAIN) {
+                               WARN("UST app recv enum failed. Communication time out: sock = %d",
+                                               sock);
                        } else {
-                               DBG3("UST app recv enum failed. Application died");
+                               ERR("UST app recv enum failed with ret %d: sock = %d",
+                                               ret, sock);
                        }
                        goto error;
                }
@@ -6388,7 +6783,7 @@ int ust_app_recv_notify(int sock)
        }
        default:
                /* Should NEVER happen. */
-               assert(0);
+               abort();
        }
 
 error:
@@ -6411,7 +6806,7 @@ void ust_app_notify_sock_unregister(int sock)
        struct ust_app *app;
        struct ust_app_notify_sock_obj *obj;
 
-       assert(sock >= 0);
+       LTTNG_ASSERT(sock >= 0);
 
        rcu_read_lock();
 
@@ -6501,8 +6896,8 @@ enum lttng_error_code ust_app_snapshot_record(
        struct ust_app *app;
        char *trace_path = NULL;
 
-       assert(usess);
-       assert(output);
+       LTTNG_ASSERT(usess);
+       LTTNG_ASSERT(output);
 
        rcu_read_lock();
 
@@ -6512,7 +6907,7 @@ enum lttng_error_code ust_app_snapshot_record(
                struct buffer_reg_uid *reg;
 
                cds_list_for_each_entry(reg, &usess->buffer_reg_uid_list, lnode) {
-                       struct buffer_reg_channel *reg_chan;
+                       struct buffer_reg_channel *buf_reg_chan;
                        struct consumer_socket *socket;
                        char pathname[PATH_MAX];
                        size_t consumer_path_offset = 0;
@@ -6532,7 +6927,7 @@ enum lttng_error_code ust_app_snapshot_record(
 
                        memset(pathname, 0, sizeof(pathname));
                        ret = snprintf(pathname, sizeof(pathname),
-                                       DEFAULT_UST_TRACE_DIR "/" DEFAULT_UST_TRACE_UID_PATH,
+                                       DEFAULT_UST_TRACE_UID_PATH,
                                        reg->uid, reg->bits_per_long);
                        if (ret < 0) {
                                PERROR("snprintf snapshot path");
@@ -6549,9 +6944,9 @@ enum lttng_error_code ust_app_snapshot_record(
                        }
                        /* Add the UST default trace dir to path. */
                        cds_lfht_for_each_entry(reg->registry->channels->ht, &iter.iter,
-                                       reg_chan, node.node) {
+                                       buf_reg_chan, node.node) {
                                status = consumer_snapshot_channel(socket,
-                                               reg_chan->consumer_key,
+                                               buf_reg_chan->consumer_key,
                                                output, 0, usess->uid,
                                                usess->gid, &trace_path[consumer_path_offset], wait,
                                                nb_packets_per_stream);
@@ -6596,7 +6991,7 @@ enum lttng_error_code ust_app_snapshot_record(
 
                        /* Add the UST default trace dir to path. */
                        memset(pathname, 0, sizeof(pathname));
-                       ret = snprintf(pathname, sizeof(pathname), DEFAULT_UST_TRACE_DIR "/%s",
+                       ret = snprintf(pathname, sizeof(pathname), "%s",
                                        ua_sess->path);
                        if (ret < 0) {
                                status = LTTNG_ERR_INVALID;
@@ -6651,7 +7046,7 @@ enum lttng_error_code ust_app_snapshot_record(
                break;
        }
        default:
-               assert(0);
+               abort();
                break;
        }
 
@@ -6671,7 +7066,7 @@ uint64_t ust_app_get_size_one_more_packet_per_stream(
        struct ust_app *app;
        struct lttng_ht_iter iter;
 
-       assert(usess);
+       LTTNG_ASSERT(usess);
 
        switch (usess->buffer_type) {
        case LTTNG_BUFFER_PER_UID:
@@ -6679,19 +7074,19 @@ uint64_t ust_app_get_size_one_more_packet_per_stream(
                struct buffer_reg_uid *reg;
 
                cds_list_for_each_entry(reg, &usess->buffer_reg_uid_list, lnode) {
-                       struct buffer_reg_channel *reg_chan;
+                       struct buffer_reg_channel *buf_reg_chan;
 
                        rcu_read_lock();
                        cds_lfht_for_each_entry(reg->registry->channels->ht, &iter.iter,
-                                       reg_chan, node.node) {
-                               if (cur_nr_packets >= reg_chan->num_subbuf) {
+                                       buf_reg_chan, node.node) {
+                               if (cur_nr_packets >= buf_reg_chan->num_subbuf) {
                                        /*
                                         * Don't take channel into account if we
                                         * already grab all its packets.
                                         */
                                        continue;
                                }
-                               tot_size += reg_chan->subbuf_size * reg_chan->stream_count;
+                               tot_size += buf_reg_chan->subbuf_size * buf_reg_chan->stream_count;
                        }
                        rcu_read_unlock();
                }
@@ -6727,7 +7122,7 @@ uint64_t ust_app_get_size_one_more_packet_per_stream(
                break;
        }
        default:
-               assert(0);
+               abort();
                break;
        }
 
@@ -6797,7 +7192,7 @@ int ust_app_pid_get_channel_runtime_stats(struct ltt_ust_session *usess,
                lttng_ht_lookup(ua_sess->channels, (void *) uchan->name, &uiter);
                ua_chan_node = lttng_ht_iter_get_node_str(&uiter);
                /* If the session is found for the app, the channel must be there */
-               assert(ua_chan_node);
+               LTTNG_ASSERT(ua_chan_node);
 
                ua_chan = caa_container_of(ua_chan_node, struct ust_app_channel, node);
 
@@ -6850,7 +7245,7 @@ int ust_app_regenerate_statedump(struct ltt_ust_session *usess,
        }
 
        pthread_mutex_lock(&app->sock_lock);
-       ret = ustctl_regenerate_statedump(app->sock, ua_sess->handle);
+       ret = lttng_ust_ctl_regenerate_statedump(app->sock, ua_sess->handle);
        pthread_mutex_unlock(&app->sock_lock);
 
 end_unlock:
@@ -6905,7 +7300,7 @@ enum lttng_error_code ust_app_rotate_session(struct ltt_session *session)
        struct ust_app *app;
        struct ltt_ust_session *usess = session->ust_session;
 
-       assert(usess);
+       LTTNG_ASSERT(usess);
 
        rcu_read_lock();
 
@@ -6915,14 +7310,9 @@ enum lttng_error_code ust_app_rotate_session(struct ltt_session *session)
                struct buffer_reg_uid *reg;
 
                cds_list_for_each_entry(reg, &usess->buffer_reg_uid_list, lnode) {
-                       struct buffer_reg_channel *reg_chan;
+                       struct buffer_reg_channel *buf_reg_chan;
                        struct consumer_socket *socket;
 
-                       if (!reg->registry->reg.ust->metadata_key) {
-                               /* Skip since no metadata is present */
-                               continue;
-                       }
-
                        /* Get consumer socket to use to push the metadata.*/
                        socket = consumer_find_socket_by_bitness(reg->bits_per_long,
                                        usess->consumer);
@@ -6933,9 +7323,9 @@ enum lttng_error_code ust_app_rotate_session(struct ltt_session *session)
 
                        /* Rotate the data channels. */
                        cds_lfht_for_each_entry(reg->registry->channels->ht, &iter.iter,
-                                       reg_chan, node.node) {
+                                       buf_reg_chan, node.node) {
                                ret = consumer_rotate_channel(socket,
-                                               reg_chan->consumer_key,
+                                               buf_reg_chan->consumer_key,
                                                usess->uid, usess->gid,
                                                usess->consumer,
                                                /* is_metadata_channel */ false);
@@ -6945,6 +7335,19 @@ enum lttng_error_code ust_app_rotate_session(struct ltt_session *session)
                                }
                        }
 
+                       /*
+                        * The metadata channel might not be present.
+                        *
+                        * Consumer stream allocation can be done
+                        * asynchronously and can fail on intermediary
+                        * operations (i.e add context) and lead to data
+                        * channels created with no metadata channel.
+                        */
+                       if (!reg->registry->reg.ust->metadata_key) {
+                               /* Skip since no metadata is present. */
+                               continue;
+                       }
+
                        (void) push_metadata(reg->registry->reg.ust, usess->consumer);
 
                        ret = consumer_rotate_channel(socket,
@@ -7025,7 +7428,7 @@ enum lttng_error_code ust_app_rotate_session(struct ltt_session *session)
                break;
        }
        default:
-               assert(0);
+               abort();
                break;
        }
 
@@ -7045,7 +7448,7 @@ enum lttng_error_code ust_app_create_channel_subdirectories(
        char *pathname_index;
        int fmt_ret;
 
-       assert(usess->current_trace_chunk);
+       LTTNG_ASSERT(usess->current_trace_chunk);
        rcu_read_lock();
 
        switch (usess->buffer_type) {
@@ -7156,7 +7559,7 @@ enum lttng_error_code ust_app_clear_session(struct ltt_session *session)
        struct ust_app *app;
        struct ltt_ust_session *usess = session->ust_session;
 
-       assert(usess);
+       LTTNG_ASSERT(usess);
 
        rcu_read_lock();
 
@@ -7172,7 +7575,7 @@ enum lttng_error_code ust_app_clear_session(struct ltt_session *session)
                struct buffer_reg_uid *reg;
 
                cds_list_for_each_entry(reg, &usess->buffer_reg_uid_list, lnode) {
-                       struct buffer_reg_channel *reg_chan;
+                       struct buffer_reg_channel *buf_reg_chan;
                        struct consumer_socket *socket;
 
                        /* Get consumer socket to use to push the metadata.*/
@@ -7185,9 +7588,9 @@ enum lttng_error_code ust_app_clear_session(struct ltt_session *session)
 
                        /* Clear the data channels. */
                        cds_lfht_for_each_entry(reg->registry->channels->ht, &iter.iter,
-                                       reg_chan, node.node) {
+                                       buf_reg_chan, node.node) {
                                ret = consumer_clear_channel(socket,
-                                               reg_chan->consumer_key);
+                                               buf_reg_chan->consumer_key);
                                if (ret < 0) {
                                        goto error;
                                }
@@ -7269,7 +7672,7 @@ enum lttng_error_code ust_app_clear_session(struct ltt_session *session)
                break;
        }
        default:
-               assert(0);
+               abort();
                break;
        }
 
@@ -7313,7 +7716,7 @@ enum lttng_error_code ust_app_open_packets(struct ltt_session *session)
        struct lttng_ht_iter iter;
        struct ltt_ust_session *usess = session->ust_session;
 
-       assert(usess);
+       LTTNG_ASSERT(usess);
 
        rcu_read_lock();
 
@@ -7324,7 +7727,7 @@ enum lttng_error_code ust_app_open_packets(struct ltt_session *session)
 
                cds_list_for_each_entry (
                                reg, &usess->buffer_reg_uid_list, lnode) {
-                       struct buffer_reg_channel *reg_chan;
+                       struct buffer_reg_channel *buf_reg_chan;
                        struct consumer_socket *socket;
 
                        socket = consumer_find_socket_by_bitness(
@@ -7335,11 +7738,11 @@ enum lttng_error_code ust_app_open_packets(struct ltt_session *session)
                        }
 
                        cds_lfht_for_each_entry(reg->registry->channels->ht,
-                                       &iter.iter, reg_chan, node.node) {
+                                       &iter.iter, buf_reg_chan, node.node) {
                                const int open_ret =
                                                consumer_open_channel_packets(
                                                        socket,
-                                                       reg_chan->consumer_key);
+                                                       buf_reg_chan->consumer_key);
 
                                if (open_ret < 0) {
                                        ret = LTTNG_ERR_UNK;
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