Fix: notification: client with uid != trigger uid assert on gid check
[lttng-tools.git] / src / bin / lttng-sessiond / notification-thread-events.c
index 9e9a83888d81dac23e933c686846d0b8572b0e3a..827cf2c1459f5ee4cb683ac3fd5b0699ab5d9b82 100644 (file)
 #include <common/macros.h>
 #include <lttng/condition/condition.h>
 #include <lttng/action/action-internal.h>
+#include <lttng/action/group-internal.h>
+#include <lttng/domain-internal.h>
 #include <lttng/notification/notification-internal.h>
 #include <lttng/condition/condition-internal.h>
 #include <lttng/condition/buffer-usage-internal.h>
 #include <lttng/condition/session-consumed-size-internal.h>
 #include <lttng/condition/session-rotation-internal.h>
+#include <lttng/condition/on-event-internal.h>
+#include <lttng/domain-internal.h>
 #include <lttng/notification/channel-internal.h>
+#include <lttng/trigger/trigger-internal.h>
+#include <lttng/event-rule/event-rule-internal.h>
 
 #include <time.h>
 #include <unistd.h>
@@ -34,6 +40,8 @@
 #include <inttypes.h>
 #include <fcntl.h>
 
+#include "condition-internal.h"
+#include "event-notifier-error-accounting.h"
 #include "notification-thread.h"
 #include "notification-thread-events.h"
 #include "notification-thread-commands.h"
@@ -43,6 +51,9 @@
 #define CLIENT_POLL_MASK_IN (LPOLLIN | LPOLLERR | LPOLLHUP | LPOLLRDHUP)
 #define CLIENT_POLL_MASK_IN_OUT (CLIENT_POLL_MASK_IN | LPOLLOUT)
 
+/* The tracers currently limit the capture size to PIPE_BUF (4kb on linux). */
+#define MAX_CAPTURE_SIZE (PIPE_BUF)
+
 enum lttng_object_type {
        LTTNG_OBJECT_TYPE_UNKNOWN,
        LTTNG_OBJECT_TYPE_NONE,
@@ -110,6 +121,8 @@ struct lttng_session_trigger_list {
 struct lttng_trigger_ht_element {
        struct lttng_trigger *trigger;
        struct cds_lfht_node node;
+       struct cds_lfht_node node_by_name_uid;
+       struct cds_list_head client_list_trigger_node;
        /* call_rcu delayed reclaim. */
        struct rcu_head rcu_node;
 };
@@ -187,6 +200,14 @@ int client_handle_transmission_status(
                enum client_transmission_status transmission_status,
                struct notification_thread_state *state);
 
+static
+int handle_one_event_notifier_notification(
+               struct notification_thread_state *state,
+               int pipe, enum lttng_domain_type domain);
+
+static
+void free_lttng_trigger_ht_element_rcu(struct rcu_head *node);
+
 static
 int match_client_socket(struct cds_lfht_node *node, const void *key)
 {
@@ -261,18 +282,26 @@ int match_channel_info(struct cds_lfht_node *node, const void *key)
 }
 
 static
-int match_condition(struct cds_lfht_node *node, const void *key)
+int match_trigger(struct cds_lfht_node *node, const void *key)
 {
-       struct lttng_condition *condition_key = (struct lttng_condition *) key;
-       struct lttng_trigger_ht_element *trigger;
-       struct lttng_condition *condition;
+       struct lttng_trigger *trigger_key = (struct lttng_trigger *) key;
+       struct lttng_trigger_ht_element *trigger_ht_element;
 
-       trigger = caa_container_of(node, struct lttng_trigger_ht_element,
+       trigger_ht_element = caa_container_of(node, struct lttng_trigger_ht_element,
                        node);
-       condition = lttng_trigger_get_condition(trigger->trigger);
-       assert(condition);
 
-       return !!lttng_condition_is_equal(condition_key, condition);
+       return !!lttng_trigger_is_equal(trigger_key, trigger_ht_element->trigger);
+}
+
+static
+int match_trigger_token(struct cds_lfht_node *node, const void *key)
+{
+       const uint64_t *_key = key;
+       struct notification_trigger_tokens_ht_element *element;
+
+       element = caa_container_of(node,
+                       struct notification_trigger_tokens_ht_element, node);
+       return *_key == element->token;
 }
 
 static
@@ -286,7 +315,7 @@ int match_client_list_condition(struct cds_lfht_node *node, const void *key)
 
        client_list = caa_container_of(node, struct notification_client_list,
                        notification_trigger_clients_ht_node);
-       condition = lttng_trigger_get_const_condition(client_list->trigger);
+       condition = client_list->condition;
 
        return !!lttng_condition_is_equal(condition_key, condition);
 }
@@ -302,102 +331,100 @@ int match_session(struct cds_lfht_node *node, const void *key)
 }
 
 static
-unsigned long lttng_condition_buffer_usage_hash(
-       const struct lttng_condition *_condition)
+const char *notification_command_type_str(
+               enum notification_thread_command_type type)
 {
-       unsigned long hash;
-       unsigned long condition_type;
-       struct lttng_condition_buffer_usage *condition;
-
-       condition = container_of(_condition,
-                       struct lttng_condition_buffer_usage, parent);
-
-       condition_type = (unsigned long) condition->parent.type;
-       hash = hash_key_ulong((void *) condition_type, lttng_ht_seed);
-       if (condition->session_name) {
-               hash ^= hash_key_str(condition->session_name, lttng_ht_seed);
-       }
-       if (condition->channel_name) {
-               hash ^= hash_key_str(condition->channel_name, lttng_ht_seed);
-       }
-       if (condition->domain.set) {
-               hash ^= hash_key_ulong(
-                               (void *) condition->domain.type,
-                               lttng_ht_seed);
-       }
-       if (condition->threshold_ratio.set) {
-               uint64_t val;
-
-               val = condition->threshold_ratio.value * (double) UINT32_MAX;
-               hash ^= hash_key_u64(&val, lttng_ht_seed);
-       } else if (condition->threshold_bytes.set) {
-               uint64_t val;
-
-               val = condition->threshold_bytes.value;
-               hash ^= hash_key_u64(&val, lttng_ht_seed);
+       switch (type) {
+       case NOTIFICATION_COMMAND_TYPE_REGISTER_TRIGGER:
+               return "REGISTER_TRIGGER";
+       case NOTIFICATION_COMMAND_TYPE_UNREGISTER_TRIGGER:
+               return "UNREGISTER_TRIGGER";
+       case NOTIFICATION_COMMAND_TYPE_ADD_CHANNEL:
+               return "ADD_CHANNEL";
+       case NOTIFICATION_COMMAND_TYPE_REMOVE_CHANNEL:
+               return "REMOVE_CHANNEL";
+       case NOTIFICATION_COMMAND_TYPE_SESSION_ROTATION_ONGOING:
+               return "SESSION_ROTATION_ONGOING";
+       case NOTIFICATION_COMMAND_TYPE_SESSION_ROTATION_COMPLETED:
+               return "SESSION_ROTATION_COMPLETED";
+       case NOTIFICATION_COMMAND_TYPE_ADD_TRACER_EVENT_SOURCE:
+               return "ADD_TRACER_EVENT_SOURCE";
+       case NOTIFICATION_COMMAND_TYPE_REMOVE_TRACER_EVENT_SOURCE:
+               return "REMOVE_TRACER_EVENT_SOURCE";
+       case NOTIFICATION_COMMAND_TYPE_LIST_TRIGGERS:
+               return "LIST_TRIGGERS";
+       case NOTIFICATION_COMMAND_TYPE_QUIT:
+               return "QUIT";
+       case NOTIFICATION_COMMAND_TYPE_CLIENT_COMMUNICATION_UPDATE:
+               return "CLIENT_COMMUNICATION_UPDATE";
+       default:
+               abort();
        }
-       return hash;
 }
 
+/*
+ * Match trigger based on name and credentials only.
+ * Name duplication is NOT allowed for the same uid.
+ */
 static
-unsigned long lttng_condition_session_consumed_size_hash(
-       const struct lttng_condition *_condition)
+int match_trigger_by_name_uid(struct cds_lfht_node *node,
+               const void *key)
 {
-       unsigned long hash;
-       unsigned long condition_type =
-                       (unsigned long) LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE;
-       struct lttng_condition_session_consumed_size *condition;
-       uint64_t val;
-
-       condition = container_of(_condition,
-                       struct lttng_condition_session_consumed_size, parent);
-
-       hash = hash_key_ulong((void *) condition_type, lttng_ht_seed);
-       if (condition->session_name) {
-               hash ^= hash_key_str(condition->session_name, lttng_ht_seed);
+       bool match = false;
+       const char *name;
+       const char *key_name;
+       enum lttng_trigger_status status;
+       const struct lttng_credentials *key_creds;
+       const struct lttng_credentials *node_creds;
+       const struct lttng_trigger *trigger_key =
+                       (const struct lttng_trigger *) key;
+       const struct lttng_trigger_ht_element *trigger_ht_element =
+                       caa_container_of(node,
+                               struct lttng_trigger_ht_element,
+                               node_by_name_uid);
+
+       status = lttng_trigger_get_name(trigger_ht_element->trigger, &name);
+       assert(status == LTTNG_TRIGGER_STATUS_OK);
+
+       status = lttng_trigger_get_name(trigger_key, &key_name);
+       assert(status == LTTNG_TRIGGER_STATUS_OK);
+
+       /* Compare the names. */
+       if (strcmp(name, key_name) != 0) {
+               goto end;
        }
-       val = condition->consumed_threshold_bytes.value;
-       hash ^= hash_key_u64(&val, lttng_ht_seed);
-       return hash;
-}
 
-static
-unsigned long lttng_condition_session_rotation_hash(
-       const struct lttng_condition *_condition)
-{
-       unsigned long hash, condition_type;
-       struct lttng_condition_session_rotation *condition;
+       /* Compare the owners' UIDs. */
+       key_creds = lttng_trigger_get_credentials(trigger_key);
+       node_creds = lttng_trigger_get_credentials(trigger_ht_element->trigger);
 
-       condition = container_of(_condition,
-                       struct lttng_condition_session_rotation, parent);
-       condition_type = (unsigned long) condition->parent.type;
-       hash = hash_key_ulong((void *) condition_type, lttng_ht_seed);
-       assert(condition->session_name);
-       hash ^= hash_key_str(condition->session_name, lttng_ht_seed);
-       return hash;
+       match = lttng_credentials_is_equal_uid(key_creds, node_creds);
+
+end:
+       return match;
 }
 
 /*
- * The lttng_condition hashing code is kept in this file (rather than
- * condition.c) since it makes use of GPLv2 code (hashtable utils), which we
- * don't want to link in liblttng-ctl.
+ * Hash trigger based on name and credentials only.
  */
 static
-unsigned long lttng_condition_hash(const struct lttng_condition *condition)
+unsigned long hash_trigger_by_name_uid(const struct lttng_trigger *trigger)
 {
-       switch (condition->type) {
-       case LTTNG_CONDITION_TYPE_BUFFER_USAGE_LOW:
-       case LTTNG_CONDITION_TYPE_BUFFER_USAGE_HIGH:
-               return lttng_condition_buffer_usage_hash(condition);
-       case LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE:
-               return lttng_condition_session_consumed_size_hash(condition);
-       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_ONGOING:
-       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_COMPLETED:
-               return lttng_condition_session_rotation_hash(condition);
-       default:
-               ERR("[notification-thread] Unexpected condition type caught");
-               abort();
+       unsigned long hash = 0;
+       const struct lttng_credentials *trigger_creds;
+       const char *trigger_name;
+       enum lttng_trigger_status status;
+
+       status = lttng_trigger_get_name(trigger, &trigger_name);
+       if (status == LTTNG_TRIGGER_STATUS_OK) {
+               hash = hash_key_str(trigger_name, lttng_ht_seed);
        }
+
+       trigger_creds = lttng_trigger_get_credentials(trigger);
+       hash ^= hash_key_ulong((void *) (unsigned long) LTTNG_OPTIONAL_GET(trigger_creds->uid),
+                       lttng_ht_seed);
+
+       return hash;
 }
 
 static
@@ -442,6 +469,8 @@ enum lttng_object_type get_condition_binding_object(
        case LTTNG_CONDITION_TYPE_SESSION_ROTATION_ONGOING:
        case LTTNG_CONDITION_TYPE_SESSION_ROTATION_COMPLETED:
                return LTTNG_OBJECT_TYPE_SESSION;
+       case LTTNG_CONDITION_TYPE_ON_EVENT:
+               return LTTNG_OBJECT_TYPE_NONE;
        default:
                return LTTNG_OBJECT_TYPE_UNKNOWN;
        }
@@ -633,62 +662,121 @@ void notification_client_list_release(struct urcu_ref *list_ref)
                        container_of(list_ref, typeof(*list), ref);
        struct notification_client_list_element *client_list_element, *tmp;
 
+       lttng_condition_put(list->condition);
+
        if (list->notification_trigger_clients_ht) {
                rcu_read_lock();
+
                cds_lfht_del(list->notification_trigger_clients_ht,
                                &list->notification_trigger_clients_ht_node);
                rcu_read_unlock();
                list->notification_trigger_clients_ht = NULL;
        }
        cds_list_for_each_entry_safe(client_list_element, tmp,
-                                    &list->list, node) {
+                                    &list->clients_list, node) {
                free(client_list_element);
        }
+
+       assert(cds_list_empty(&list->triggers_list));
+
        pthread_mutex_destroy(&list->lock);
        call_rcu(&list->rcu_node, free_notification_client_list_rcu);
 }
 
+static
+bool condition_applies_to_client(const struct lttng_condition *condition,
+               struct notification_client *client)
+{
+       bool applies = false;
+       struct lttng_condition_list_element *condition_list_element;
+
+       cds_list_for_each_entry(condition_list_element, &client->condition_list,
+                       node) {
+               applies = lttng_condition_is_equal(
+                               condition_list_element->condition,
+                               condition);
+               if (applies) {
+                       break;
+               }
+       }
+
+       return applies;
+}
+
 static
 struct notification_client_list *notification_client_list_create(
-               const struct lttng_trigger *trigger)
+               struct notification_thread_state *state,
+               const struct lttng_condition *condition)
 {
-       struct notification_client_list *client_list =
-                       zmalloc(sizeof(*client_list));
+       struct notification_client *client;
+       struct cds_lfht_iter iter;
+       struct notification_client_list *client_list;
 
+       client_list = zmalloc(sizeof(*client_list));
        if (!client_list) {
-               goto error;
+               PERROR("Failed to allocate notification client list");
+               goto end;
        }
+
        pthread_mutex_init(&client_list->lock, NULL);
+       /*
+        * The trigger that owns the condition has the first reference to this
+        * client list.
+        */
        urcu_ref_init(&client_list->ref);
        cds_lfht_node_init(&client_list->notification_trigger_clients_ht_node);
-       CDS_INIT_LIST_HEAD(&client_list->list);
-       client_list->trigger = trigger;
-error:
-       return client_list;
-}
+       CDS_INIT_LIST_HEAD(&client_list->clients_list);
+       CDS_INIT_LIST_HEAD(&client_list->triggers_list);
 
-static
-void publish_notification_client_list(
-               struct notification_thread_state *state,
-               struct notification_client_list *list)
-{
-       const struct lttng_condition *condition =
-                       lttng_trigger_get_const_condition(list->trigger);
+       /*
+        * Create a copy of the condition so that it's independent of any
+        * trigger. The client list may outlive the trigger object (which owns
+        * the condition) that is used to create it.
+        */
+       client_list->condition = lttng_condition_copy(condition);
+
+       /* Build a list of clients to which this new condition applies. */
+       cds_lfht_for_each_entry (state->client_socket_ht, &iter, client,
+                       client_socket_ht_node) {
+               struct notification_client_list_element *client_list_element;
+
+               if (!condition_applies_to_client(condition, client)) {
+                       continue;
+               }
+
+               client_list_element = zmalloc(sizeof(*client_list_element));
+               if (!client_list_element) {
+                       goto error_put_client_list;
+               }
 
-       assert(!list->notification_trigger_clients_ht);
-       notification_client_list_get(list);
+               CDS_INIT_LIST_HEAD(&client_list_element->node);
+               client_list_element->client = client;
+               cds_list_add(&client_list_element->node, &client_list->clients_list);
+       }
 
-       list->notification_trigger_clients_ht =
+       client_list->notification_trigger_clients_ht =
                        state->notification_trigger_clients_ht;
 
        rcu_read_lock();
-       cds_lfht_add(state->notification_trigger_clients_ht,
-                       lttng_condition_hash(condition),
-                       &list->notification_trigger_clients_ht_node);
+       /*
+        * Add the client list to the global list of client list.
+        */
+       cds_lfht_add_unique(state->notification_trigger_clients_ht,
+                       lttng_condition_hash(client_list->condition),
+                       match_client_list_condition,
+                       client_list->condition,
+                       &client_list->notification_trigger_clients_ht_node);
        rcu_read_unlock();
+       goto end;
+
+error_put_client_list:
+       notification_client_list_put(client_list);
+       client_list = NULL;
+
+end:
+       return client_list;
 }
 
-LTTNG_HIDDEN
 void notification_client_list_put(struct notification_client_list *list)
 {
        if (!list) {
@@ -952,6 +1040,7 @@ int evaluate_condition_for_client(const struct lttng_trigger *trigger,
                                &evaluation, &object_uid, &object_gid);
                break;
        case LTTNG_OBJECT_TYPE_NONE:
+               DBG("[notification-thread] Newly subscribed-to condition not bound to object, nothing to evaluate");
                ret = 0;
                goto end;
        case LTTNG_OBJECT_TYPE_UNKNOWN:
@@ -975,12 +1064,11 @@ int evaluate_condition_for_client(const struct lttng_trigger *trigger,
         * subscribing.
         */
        cds_lfht_node_init(&client_list.notification_trigger_clients_ht_node);
-       CDS_INIT_LIST_HEAD(&client_list.list);
-       client_list.trigger = trigger;
+       CDS_INIT_LIST_HEAD(&client_list.clients_list);
 
        CDS_INIT_LIST_HEAD(&client_list_element.node);
        client_list_element.client = client;
-       cds_list_add(&client_list_element.node, &client_list.list);
+       cds_list_add(&client_list_element.node, &client_list.clients_list);
 
        /* Send evaluation result to the newly-subscribed client. */
        DBG("[notification-thread] Newly subscribed-to condition evaluated to true, notifying client");
@@ -1001,6 +1089,7 @@ int notification_thread_client_subscribe(struct notification_client *client,
        struct notification_client_list *client_list = NULL;
        struct lttng_condition_list_element *condition_list_element = NULL;
        struct notification_client_list_element *client_list_element = NULL;
+       struct lttng_trigger_ht_element *trigger_ht_element;
        enum lttng_notification_channel_status status =
                        LTTNG_NOTIFICATION_CHANNEL_STATUS_OK;
 
@@ -1050,17 +1139,24 @@ int notification_thread_client_subscribe(struct notification_client *client,
         * at this point so that conditions that are already TRUE result
         * in a notification being sent out.
         *
-        * The client_list's trigger is used without locking the list itself.
-        * This is correct since the list doesn't own the trigger and the
-        * object is immutable.
+        * Note the iteration on all triggers which share an identical
+        * `condition` than the one to which the client is registering. This is
+        * done to ensure that the client receives a distinct notification for
+        * all triggers that have a `notify` action that have this condition.
         */
-       if (evaluate_condition_for_client(client_list->trigger, condition,
-                       client, state)) {
-               WARN("[notification-thread] Evaluation of a condition on client subscription failed, aborting.");
-               ret = -1;
-               free(client_list_element);
-               goto end;
+       pthread_mutex_lock(&client_list->lock);
+       cds_list_for_each_entry(trigger_ht_element,
+                       &client_list->triggers_list, client_list_trigger_node) {
+               if (evaluate_condition_for_client(trigger_ht_element->trigger, condition,
+                               client, state)) {
+                       WARN("[notification-thread] Evaluation of a condition on client subscription failed, aborting.");
+                       ret = -1;
+                       free(client_list_element);
+                       pthread_mutex_unlock(&client_list->lock);
+                       goto end;
+               }
        }
+       pthread_mutex_unlock(&client_list->lock);
 
        /*
         * Add the client to the list of clients interested in a given trigger
@@ -1071,7 +1167,7 @@ int notification_thread_client_subscribe(struct notification_client *client,
        CDS_INIT_LIST_HEAD(&client_list_element->node);
 
        pthread_mutex_lock(&client_list->lock);
-       cds_list_add(&client_list_element->node, &client_list->list);
+       cds_list_add(&client_list_element->node, &client_list->clients_list);
        pthread_mutex_unlock(&client_list->lock);
 end:
        if (_status) {
@@ -1142,7 +1238,7 @@ int notification_thread_client_unsubscribe(
 
        pthread_mutex_lock(&client_list->lock);
        cds_list_for_each_entry_safe(client_list_element, client_tmp,
-                       &client_list->list, node) {
+                       &client_list->clients_list, node) {
                if (client_list_element->client->id != client->id) {
                        continue;
                }
@@ -1335,25 +1431,6 @@ fail:
        return false;
 }
 
-static
-bool trigger_applies_to_client(struct lttng_trigger *trigger,
-               struct notification_client *client)
-{
-       bool applies = false;
-       struct lttng_condition_list_element *condition_list_element;
-
-       cds_list_for_each_entry(condition_list_element, &client->condition_list,
-                       node) {
-               applies = lttng_condition_is_equal(
-                               condition_list_element->condition,
-                               lttng_trigger_get_condition(trigger));
-               if (applies) {
-                       break;
-               }
-       }
-       return applies;
-}
-
 /* Must be called with RCU read lock held. */
 static
 struct lttng_session_trigger_list *get_session_trigger_list(
@@ -1623,7 +1700,7 @@ int handle_notification_thread_command_add_channel(
 
        DBG("[notification-thread] Adding channel %s from session %s, channel key = %" PRIu64 " in %s domain",
                        channel_name, session_name, channel_key_int,
-                       channel_domain == LTTNG_DOMAIN_KERNEL ? "kernel" : "user space");
+                       lttng_domain_type_str(channel_domain));
 
        CDS_INIT_LIST_HEAD(&trigger_list);
 
@@ -1724,7 +1801,7 @@ int handle_notification_thread_command_remove_channel(
        struct channel_info *channel_info;
 
        DBG("[notification-thread] Removing channel key = %" PRIu64 " in %s domain",
-                       channel_key, domain == LTTNG_DOMAIN_KERNEL ? "kernel" : "user space");
+                       channel_key, lttng_domain_type_str(domain));
 
        rcu_read_lock();
 
@@ -1918,93 +1995,405 @@ end:
 }
 
 static
-int condition_is_supported(struct lttng_condition *condition)
+int handle_notification_thread_command_add_tracer_event_source(
+               struct notification_thread_state *state,
+               int tracer_event_source_fd,
+               enum lttng_domain_type domain_type,
+               enum lttng_error_code *_cmd_result)
+{
+       int ret = 0;
+       enum lttng_error_code cmd_result = LTTNG_OK;
+       struct notification_event_tracer_event_source_element *element = NULL;
+
+       element = zmalloc(sizeof(*element));
+       if (!element) {
+               cmd_result = LTTNG_ERR_NOMEM;
+               ret = -1;
+               goto end;
+       }
+
+       element->fd = tracer_event_source_fd;
+       element->domain = domain_type;
+
+       cds_list_add(&element->node, &state->tracer_event_sources_list);
+
+       DBG3("[notification-thread] Adding tracer event source fd to poll set: tracer_event_source_fd = %d, domain = '%s'",
+                       tracer_event_source_fd,
+                       lttng_domain_type_str(domain_type));
+
+       /* Adding the read side pipe to the event poll. */
+       ret = lttng_poll_add(&state->events, tracer_event_source_fd, LPOLLIN | LPOLLERR);
+       if (ret < 0) {
+               ERR("[notification-thread] Failed to add tracer event source to poll set: tracer_event_source_fd = %d, domain = '%s'",
+                               tracer_event_source_fd,
+                               lttng_domain_type_str(element->domain));
+               cds_list_del(&element->node);
+               free(element);
+               goto end;
+       }
+
+       element->is_fd_in_poll_set = true;
+
+end:
+       *_cmd_result = cmd_result;
+       return ret;
+}
+
+static
+int drain_event_notifier_notification_pipe(
+               struct notification_thread_state *state,
+               int pipe, enum lttng_domain_type domain)
 {
+       struct lttng_poll_event events = {0};
        int ret;
 
-       switch (lttng_condition_get_type(condition)) {
-       case LTTNG_CONDITION_TYPE_BUFFER_USAGE_LOW:
-       case LTTNG_CONDITION_TYPE_BUFFER_USAGE_HIGH:
-       {
-               enum lttng_domain_type domain;
+       ret = lttng_poll_create(&events, 1, LTTNG_CLOEXEC);
+       if (ret < 0) {
+               ERR("[notification-thread] Error creating lttng_poll_event");
+               goto end;
+       }
 
-               ret = lttng_condition_buffer_usage_get_domain_type(condition,
-                               &domain);
-               if (ret) {
+       ret = lttng_poll_add(&events, pipe, LPOLLIN);
+       if (ret < 0) {
+               ERR("[notification-thread] Error adding fd event notifier notification pipe to lttng_poll_event: fd = %d",
+                               pipe);
+               goto end;
+       }
+
+       while (true) {
+               /*
+                * Continue to consume notifications as long as there are new
+                * ones coming in. The tracer has been asked to stop producing
+                * them.
+                *
+                * LPOLLIN is explicitly checked since LPOLLHUP is implicitly
+                * monitored (on Linux, at least) and will be returned when
+                * the pipe is closed but empty.
+                */
+               ret = lttng_poll_wait_interruptible(&events, 0);
+               if (ret == 0 || (LTTNG_POLL_GETEV(&events, 0) & LPOLLIN) == 0) {
+                       /* No more notification to be read on this pipe. */
+                       ret = 0;
+                       goto end;
+               } else if (ret < 0) {
+                       PERROR("Failed on lttng_poll_wait_interruptible() call");
                        ret = -1;
                        goto end;
                }
 
-               if (domain != LTTNG_DOMAIN_KERNEL) {
-                       ret = 1;
-                       goto end;
+               ret = handle_one_event_notifier_notification(state, pipe, domain);
+               if (ret) {
+                       ERR("[notification-thread] Error consuming an event notifier notification from pipe: fd = %d",
+                                       pipe);
                }
-
-               /*
-                * Older kernel tracers don't expose the API to monitor their
-                * buffers. Therefore, we reject triggers that require that
-                * mechanism to be available to be evaluated.
-                */
-               ret = kernel_supports_ring_buffer_snapshot_sample_positions();
-               break;
-       }
-       default:
-               ret = 1;
        }
 end:
+       lttng_poll_clean(&events);
        return ret;
 }
 
-/* Must be called with RCU read lock held. */
 static
-int bind_trigger_to_matching_session(struct lttng_trigger *trigger,
-               struct notification_thread_state *state)
+int handle_notification_thread_command_remove_tracer_event_source(
+               struct notification_thread_state *state,
+               int tracer_event_source_fd,
+               enum lttng_error_code *_cmd_result)
 {
        int ret = 0;
-       const struct lttng_condition *condition;
-       const char *session_name;
-       struct lttng_session_trigger_list *trigger_list;
-
-       condition = lttng_trigger_get_const_condition(trigger);
-       switch (lttng_condition_get_type(condition)) {
-       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_ONGOING:
-       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_COMPLETED:
-       {
-               enum lttng_condition_status status;
+       bool found = false;
+       enum lttng_error_code cmd_result = LTTNG_OK;
+       struct notification_event_tracer_event_source_element *source_element = NULL, *tmp;
 
-               status = lttng_condition_session_rotation_get_session_name(
-                               condition, &session_name);
-               if (status != LTTNG_CONDITION_STATUS_OK) {
-                       ERR("[notification-thread] Failed to bind trigger to session: unable to get 'session_rotation' condition's session name");
-                       ret = -1;
-                       goto end;
+       cds_list_for_each_entry_safe(source_element, tmp,
+                       &state->tracer_event_sources_list, node) {
+               if (source_element->fd != tracer_event_source_fd) {
+                       continue;
                }
+
+               DBG("[notification-thread] Removed tracer event source from poll set: tracer_event_source_fd = %d, domain = '%s'",
+                               tracer_event_source_fd,
+                               lttng_domain_type_str(source_element->domain));
+               cds_list_del(&source_element->node);
+               found = true;
                break;
        }
-       default:
-               ret = -1;
+
+       if (!found) {
+               /*
+                * This is temporarily allowed since the poll activity set is
+                * not properly cleaned-up for the moment. This is adressed in
+                * an upcoming fix.
+                */
+               source_element = NULL;
                goto end;
        }
 
-       trigger_list = get_session_trigger_list(state, session_name);
-       if (!trigger_list) {
-               DBG("[notification-thread] Unable to bind trigger applying to session \"%s\" as it is not yet known to the notification system",
-                               session_name);
+       if (!source_element->is_fd_in_poll_set) {
+               /* Skip the poll set removal. */
+               goto end;
+       }
+
+       DBG3("[notification-thread] Removing tracer event source from poll set: tracer_event_source_fd = %d, domain = '%s'",
+                       tracer_event_source_fd,
+                       lttng_domain_type_str(source_element->domain));
+
+       /* Removing the fd from the event poll set. */
+       ret = lttng_poll_del(&state->events, tracer_event_source_fd);
+       if (ret < 0) {
+               ERR("[notification-thread] Failed to remove tracer event source from poll set: tracer_event_source_fd = %d, domain = '%s'",
+                               tracer_event_source_fd,
+                               lttng_domain_type_str(source_element->domain));
+               cmd_result = LTTNG_ERR_FATAL;
                goto end;
+       }
+
+       source_element->is_fd_in_poll_set = false;
 
+       ret = drain_event_notifier_notification_pipe(state, tracer_event_source_fd,
+                       source_element->domain);
+       if (ret) {
+               ERR("[notification-thread] Error draining event notifier notification: tracer_event_source_fd = %d, domain = %s",
+                               tracer_event_source_fd,
+                               lttng_domain_type_str(source_element->domain));
+               cmd_result = LTTNG_ERR_FATAL;
+               goto end;
        }
 
-       DBG("[notification-thread] Newly registered trigger bound to session \"%s\"",
-                       session_name);
-       ret = lttng_session_trigger_list_add(trigger_list, trigger);
+       /*
+        * The drain_event_notifier_notification_pipe() call might have read
+        * data from an fd that we received in event in the latest _poll_wait()
+        * call. Make sure the thread call poll_wait() again to ensure we have
+        * a clean state.
+        */
+       state->restart_poll = true;
+
 end:
+       free(source_element);
+       *_cmd_result = cmd_result;
        return ret;
 }
 
-/* Must be called with RCU read lock held. */
 static
-int bind_trigger_to_matching_channels(struct lttng_trigger *trigger,
-               struct notification_thread_state *state)
+int condition_on_event_update_error_count(struct lttng_trigger *trigger)
+{
+       int ret = 0;
+       uint64_t error_count = 0;
+       struct lttng_condition *condition;
+       enum event_notifier_error_accounting_status status;
+
+       condition = lttng_trigger_get_condition(trigger);
+       assert(lttng_condition_get_type(condition) ==
+                       LTTNG_CONDITION_TYPE_ON_EVENT);
+
+       status = event_notifier_error_accounting_get_count(trigger, &error_count);
+       if (status != EVENT_NOTIFIER_ERROR_ACCOUNTING_STATUS_OK) {
+               uid_t trigger_owner_uid;
+               const char *trigger_name;
+               const enum lttng_trigger_status trigger_status =
+                               lttng_trigger_get_owner_uid(
+                                               trigger, &trigger_owner_uid);
+
+               assert(trigger_status == LTTNG_TRIGGER_STATUS_OK);
+               if (lttng_trigger_get_name(trigger, &trigger_name) != LTTNG_TRIGGER_STATUS_OK) {
+                       trigger_name = "(unnamed)";
+               }
+
+               ERR("Failed to get event notifier error count of trigger for update: trigger owner = %d, trigger name = '%s'",
+                               trigger_owner_uid, trigger_name);
+               ret = -1;
+       }
+
+       lttng_condition_on_event_set_error_count(condition, error_count);
+       return ret;
+}
+
+int handle_notification_thread_remove_tracer_event_source_no_result(
+               struct notification_thread_state *state,
+               int tracer_event_source_fd)
+{
+       int ret;
+       enum lttng_error_code cmd_result;
+
+       ret = handle_notification_thread_command_remove_tracer_event_source(
+                       state, tracer_event_source_fd, &cmd_result);
+       (void) cmd_result;
+       return ret;
+}
+
+static int handle_notification_thread_command_list_triggers(
+               struct notification_thread_handle *handle,
+               struct notification_thread_state *state,
+               uid_t client_uid,
+               struct lttng_triggers **triggers,
+               enum lttng_error_code *_cmd_result)
+{
+       int ret = 0;
+       enum lttng_error_code cmd_result = LTTNG_OK;
+       struct cds_lfht_iter iter;
+       struct lttng_trigger_ht_element *trigger_ht_element;
+       struct lttng_triggers *local_triggers = NULL;
+       const struct lttng_credentials *creds;
+
+       rcu_read_lock();
+
+       local_triggers = lttng_triggers_create();
+       if (!local_triggers) {
+               /* Not a fatal error. */
+               cmd_result = LTTNG_ERR_NOMEM;
+               goto end;
+       }
+
+       cds_lfht_for_each_entry(state->triggers_ht, &iter,
+                       trigger_ht_element, node) {
+               /*
+                * Only return the triggers to which the client has access.
+                * The root user has visibility over all triggers.
+                */
+               creds = lttng_trigger_get_credentials(trigger_ht_element->trigger);
+               if (client_uid != lttng_credentials_get_uid(creds) && client_uid != 0) {
+                       continue;
+               }
+
+               if (lttng_trigger_needs_tracer_notifier(trigger_ht_element->trigger)) {
+                       ret = condition_on_event_update_error_count(
+                                       trigger_ht_element->trigger);
+                       assert(!ret);
+               }
+
+               ret = lttng_triggers_add(local_triggers,
+                               trigger_ht_element->trigger);
+               if (ret < 0) {
+                       /* Not a fatal error. */
+                       ret = 0;
+                       cmd_result = LTTNG_ERR_NOMEM;
+                       goto end;
+               }
+       }
+
+       /* Transferring ownership to the caller. */
+       *triggers = local_triggers;
+       local_triggers = NULL;
+
+end:
+       rcu_read_unlock();
+       lttng_triggers_destroy(local_triggers);
+       *_cmd_result = cmd_result;
+       return ret;
+}
+
+static
+bool condition_is_supported(struct lttng_condition *condition)
+{
+       bool is_supported;
+
+       switch (lttng_condition_get_type(condition)) {
+       case LTTNG_CONDITION_TYPE_BUFFER_USAGE_LOW:
+       case LTTNG_CONDITION_TYPE_BUFFER_USAGE_HIGH:
+       {
+               int ret;
+               enum lttng_domain_type domain;
+
+               ret = lttng_condition_buffer_usage_get_domain_type(condition,
+                               &domain);
+               assert(ret == 0);
+
+               if (domain != LTTNG_DOMAIN_KERNEL) {
+                       is_supported = true;
+                       goto end;
+               }
+
+               /*
+                * Older kernel tracers don't expose the API to monitor their
+                * buffers. Therefore, we reject triggers that require that
+                * mechanism to be available to be evaluated.
+                *
+                * Assume unsupported on error.
+                */
+               is_supported = kernel_supports_ring_buffer_snapshot_sample_positions() == 1;
+               break;
+       }
+       case LTTNG_CONDITION_TYPE_ON_EVENT:
+       {
+               const struct lttng_event_rule *event_rule;
+               enum lttng_domain_type domain;
+               const enum lttng_condition_status status =
+                               lttng_condition_on_event_get_rule(
+                                               condition, &event_rule);
+
+               assert(status == LTTNG_CONDITION_STATUS_OK);
+
+               domain = lttng_event_rule_get_domain_type(event_rule);
+               if (domain != LTTNG_DOMAIN_KERNEL) {
+                       is_supported = true;
+                       goto end;
+               }
+
+               /*
+                * Older kernel tracers can't emit notification. Therefore, we
+                * reject triggers that require that mechanism to be available
+                * to be evaluated.
+                *
+                * Assume unsupported on error.
+                */
+               is_supported = kernel_supports_event_notifiers() == 1;
+               break;
+       }
+       default:
+               is_supported = true;
+       }
+end:
+       return is_supported;
+}
+
+/* Must be called with RCU read lock held. */
+static
+int bind_trigger_to_matching_session(struct lttng_trigger *trigger,
+               struct notification_thread_state *state)
+{
+       int ret = 0;
+       const struct lttng_condition *condition;
+       const char *session_name;
+       struct lttng_session_trigger_list *trigger_list;
+
+       condition = lttng_trigger_get_const_condition(trigger);
+       switch (lttng_condition_get_type(condition)) {
+       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_ONGOING:
+       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_COMPLETED:
+       {
+               enum lttng_condition_status status;
+
+               status = lttng_condition_session_rotation_get_session_name(
+                               condition, &session_name);
+               if (status != LTTNG_CONDITION_STATUS_OK) {
+                       ERR("[notification-thread] Failed to bind trigger to session: unable to get 'session_rotation' condition's session name");
+                       ret = -1;
+                       goto end;
+               }
+               break;
+       }
+       default:
+               ret = -1;
+               goto end;
+       }
+
+       trigger_list = get_session_trigger_list(state, session_name);
+       if (!trigger_list) {
+               DBG("[notification-thread] Unable to bind trigger applying to session \"%s\" as it is not yet known to the notification system",
+                               session_name);
+               goto end;
+
+       }
+
+       DBG("[notification-thread] Newly registered trigger bound to session \"%s\"",
+                       session_name);
+       ret = lttng_session_trigger_list_add(trigger_list, trigger);
+end:
+       return ret;
+}
+
+/* Must be called with RCU read lock held. */
+static
+int bind_trigger_to_matching_channels(struct lttng_trigger *trigger,
+               struct notification_thread_state *state)
 {
        int ret = 0;
        struct cds_lfht_node *node;
@@ -2085,6 +2474,123 @@ end:
        return is_notify;
 }
 
+static bool trigger_name_taken(struct notification_thread_state *state,
+               const struct lttng_trigger *trigger)
+{
+       struct cds_lfht_iter iter;
+
+       /*
+        * No duplicata is allowed in the triggers_by_name_uid_ht.
+        * The match is done against the trigger name and uid.
+        */
+       cds_lfht_lookup(state->triggers_by_name_uid_ht,
+                       hash_trigger_by_name_uid(trigger),
+                       match_trigger_by_name_uid,
+                       trigger,
+                       &iter);
+       return !!cds_lfht_iter_get_node(&iter);
+}
+
+static
+enum lttng_error_code generate_trigger_name(
+               struct notification_thread_state *state,
+               struct lttng_trigger *trigger, const char **name)
+{
+       enum lttng_error_code ret_code = LTTNG_OK;
+       bool taken = false;
+       enum lttng_trigger_status status;
+
+       do {
+               const int ret = lttng_trigger_generate_name(trigger,
+                               state->trigger_id.name_offset++);
+               if (ret) {
+                       /* The only reason this can fail right now. */
+                       ret_code = LTTNG_ERR_NOMEM;
+                       break;
+               }
+
+               status = lttng_trigger_get_name(trigger, name);
+               assert(status == LTTNG_TRIGGER_STATUS_OK);
+
+               taken = trigger_name_taken(state, trigger);
+       } while (taken || state->trigger_id.name_offset == UINT64_MAX);
+
+       return ret_code;
+}
+
+static inline
+void notif_thread_state_remove_trigger_ht_elem(
+               struct notification_thread_state *state,
+               struct lttng_trigger_ht_element *trigger_ht_element)
+{
+       assert(state);
+       assert(trigger_ht_element);
+
+       cds_lfht_del(state->triggers_ht, &trigger_ht_element->node);
+       cds_lfht_del(state->triggers_by_name_uid_ht, &trigger_ht_element->node_by_name_uid);
+}
+
+static
+enum lttng_error_code setup_tracer_notifier(
+               struct notification_thread_state *state,
+               struct lttng_trigger *trigger)
+{
+       enum lttng_error_code ret;
+       enum event_notifier_error_accounting_status error_accounting_status;
+       struct cds_lfht_node *node;
+       uint64_t error_counter_index = 0;
+       struct lttng_condition *condition = lttng_trigger_get_condition(trigger);
+       struct notification_trigger_tokens_ht_element *trigger_tokens_ht_element = NULL;
+
+       trigger_tokens_ht_element = zmalloc(sizeof(*trigger_tokens_ht_element));
+       if (!trigger_tokens_ht_element) {
+               ret = LTTNG_ERR_NOMEM;
+               goto end;
+       }
+
+       /* Add trigger token to the trigger_tokens_ht. */
+       cds_lfht_node_init(&trigger_tokens_ht_element->node);
+       trigger_tokens_ht_element->token = LTTNG_OPTIONAL_GET(trigger->tracer_token);
+       trigger_tokens_ht_element->trigger = trigger;
+
+       node = cds_lfht_add_unique(state->trigger_tokens_ht,
+                       hash_key_u64(&trigger_tokens_ht_element->token, lttng_ht_seed),
+                       match_trigger_token,
+                       &trigger_tokens_ht_element->token,
+                       &trigger_tokens_ht_element->node);
+       if (node != &trigger_tokens_ht_element->node) {
+               ret = LTTNG_ERR_TRIGGER_EXISTS;
+               goto error_free_ht_element;
+       }
+
+       error_accounting_status = event_notifier_error_accounting_register_event_notifier(
+                       trigger, &error_counter_index);
+       if (error_accounting_status != EVENT_NOTIFIER_ERROR_ACCOUNTING_STATUS_OK) {
+               if (error_accounting_status == EVENT_NOTIFIER_ERROR_ACCOUNTING_STATUS_NO_INDEX_AVAILABLE) {
+                       DBG("Trigger group error accounting counter full.");
+                       ret = LTTNG_ERR_EVENT_NOTIFIER_ERROR_ACCOUNTING_FULL;
+               } else {
+                       ERR("Error registering trigger for error accounting");
+                       ret = LTTNG_ERR_EVENT_NOTIFIER_REGISTRATION;
+               }
+
+               goto error_remove_ht_element;
+       }
+
+       lttng_condition_on_event_set_error_counter_index(
+                       condition, error_counter_index);
+
+       ret = LTTNG_OK;
+       goto end;
+
+error_remove_ht_element:
+       cds_lfht_del(state->trigger_tokens_ht, &trigger_tokens_ht_element->node);
+error_free_ht_element:
+       free(trigger_tokens_ht_element);
+end:
+       return ret;
+}
+
 /*
  * FIXME A client's credentials are not checked when registering a trigger.
  *
@@ -2108,33 +2614,49 @@ int handle_notification_thread_command_register_trigger(
 {
        int ret = 0;
        struct lttng_condition *condition;
-       struct notification_client *client;
        struct notification_client_list *client_list = NULL;
        struct lttng_trigger_ht_element *trigger_ht_element = NULL;
-       struct notification_client_list_element *client_list_element;
        struct cds_lfht_node *node;
-       struct cds_lfht_iter iter;
+       const char* trigger_name;
        bool free_trigger = true;
        struct lttng_evaluation *evaluation = NULL;
        struct lttng_credentials object_creds;
        uid_t object_uid;
        gid_t object_gid;
        enum action_executor_status executor_status;
+       const uint64_t trigger_tracer_token =
+                       state->trigger_id.next_tracer_token++;
 
        rcu_read_lock();
 
+       /* Set the trigger's tracer token. */
+       lttng_trigger_set_tracer_token(trigger, trigger_tracer_token);
+
+       if (lttng_trigger_get_name(trigger, &trigger_name) ==
+                       LTTNG_TRIGGER_STATUS_UNSET) {
+               const enum lttng_error_code ret_code = generate_trigger_name(
+                               state, trigger, &trigger_name);
+
+               if (ret_code != LTTNG_OK) {
+                       /* Fatal error. */
+                       ret = -1;
+                       *cmd_result = ret_code;
+                       goto error;
+               }
+       } else if (trigger_name_taken(state, trigger)) {
+               /* Not a fatal error. */
+               *cmd_result = LTTNG_ERR_TRIGGER_EXISTS;
+               ret = 0;
+               goto error;
+       }
+
        condition = lttng_trigger_get_condition(trigger);
        assert(condition);
 
-       ret = condition_is_supported(condition);
-       if (ret < 0) {
-               goto error;
-       } else if (ret == 0) {
+       /* Some conditions require tracers to implement a minimal ABI version. */
+       if (!condition_is_supported(condition)) {
                *cmd_result = LTTNG_ERR_NOT_SUPPORTED;
                goto error;
-       } else {
-               /* Feature is supported, continue. */
-               ret = 0;
        }
 
        trigger_ht_element = zmalloc(sizeof(*trigger_ht_element));
@@ -2145,12 +2667,13 @@ int handle_notification_thread_command_register_trigger(
 
        /* Add trigger to the trigger_ht. */
        cds_lfht_node_init(&trigger_ht_element->node);
+       cds_lfht_node_init(&trigger_ht_element->node_by_name_uid);
        trigger_ht_element->trigger = trigger;
 
        node = cds_lfht_add_unique(state->triggers_ht,
                        lttng_condition_hash(condition),
-                       match_condition,
-                       condition,
+                       match_trigger,
+                       trigger,
                        &trigger_ht_element->node);
        if (node != &trigger_ht_element->node) {
                /* Not a fatal error, simply report it to the client. */
@@ -2158,12 +2681,39 @@ int handle_notification_thread_command_register_trigger(
                goto error_free_ht_element;
        }
 
+       node = cds_lfht_add_unique(state->triggers_by_name_uid_ht,
+                       hash_trigger_by_name_uid(trigger),
+                       match_trigger_by_name_uid,
+                       trigger,
+                       &trigger_ht_element->node_by_name_uid);
+       if (node != &trigger_ht_element->node_by_name_uid) {
+               /* Not a fatal error, simply report it to the client. */
+               cds_lfht_del(state->triggers_ht, &trigger_ht_element->node);
+               *cmd_result = LTTNG_ERR_TRIGGER_EXISTS;
+               goto error_free_ht_element;
+       }
+
        /*
-        * Ownership of the trigger and of its wrapper was transfered to
-        * the triggers_ht.
+        * Some triggers might need a tracer notifier depending on its
+        * condition and actions.
         */
-       trigger_ht_element = NULL;
-       free_trigger = false;
+       if (lttng_trigger_needs_tracer_notifier(trigger)) {
+               enum lttng_error_code error_code;
+
+               error_code = setup_tracer_notifier(state, trigger);
+               if (error_code != LTTNG_OK) {
+                       notif_thread_state_remove_trigger_ht_elem(state,
+                                       trigger_ht_element);
+                       if (error_code == LTTNG_ERR_NOMEM) {
+                               ret = -1;
+                       } else {
+                               *cmd_result = error_code;
+                               ret = 0;
+                       }
+
+                       goto error_free_ht_element;
+               }
+       }
 
        /*
         * The rest only applies to triggers that have a "notify" action.
@@ -2171,45 +2721,44 @@ int handle_notification_thread_command_register_trigger(
         * supported.
         */
        if (is_trigger_action_notify(trigger)) {
-               client_list = notification_client_list_create(trigger);
+               /*
+                * Find or create the client list of this condition. It may
+                * already be present if another trigger is already registered
+                * with the same condition.
+                */
+               client_list = get_client_list_from_condition(state, condition);
                if (!client_list) {
-                       ret = -1;
-                       goto error_free_ht_element;
-               }
-
-               /* Build a list of clients to which this new trigger applies. */
-               cds_lfht_for_each_entry (state->client_socket_ht, &iter, client,
-                               client_socket_ht_node) {
-                       if (!trigger_applies_to_client(trigger, client)) {
-                               continue;
-                       }
-
-                       client_list_element =
-                                       zmalloc(sizeof(*client_list_element));
-                       if (!client_list_element) {
-                               ret = -1;
-                               goto error_put_client_list;
+                       /*
+                        * No client list for this condition yet. We create new
+                        * one and build it up.
+                        */
+                       client_list = notification_client_list_create(state, condition);
+                       if (!client_list) {
+                               ERR("Error creating notification client list for trigger %s", trigger->name);
+                               goto error_free_ht_element;
                        }
-
-                       CDS_INIT_LIST_HEAD(&client_list_element->node);
-                       client_list_element->client = client;
-                       cds_list_add(&client_list_element->node,
-                                       &client_list->list);
                }
 
-               /*
-                * Client list ownership transferred to the
-                * notification_trigger_clients_ht.
-                */
-               publish_notification_client_list(state, client_list);
+               CDS_INIT_LIST_HEAD(&trigger_ht_element->client_list_trigger_node);
+
+               pthread_mutex_lock(&client_list->lock);
+               cds_list_add(&trigger_ht_element->client_list_trigger_node, &client_list->triggers_list);
+               pthread_mutex_unlock(&client_list->lock);
        }
 
+       /*
+        * Ownership of the trigger and of its wrapper was transfered to
+        * the triggers_ht. Same for token ht element if necessary.
+        */
+       trigger_ht_element = NULL;
+       free_trigger = false;
+
        switch (get_condition_binding_object(condition)) {
        case LTTNG_OBJECT_TYPE_SESSION:
                /* Add the trigger to the list if it matches a known session. */
                ret = bind_trigger_to_matching_session(trigger, state);
                if (ret) {
-                       goto error_put_client_list;
+                       goto error_free_ht_element;
                }
                break;
        case LTTNG_OBJECT_TYPE_CHANNEL:
@@ -2219,7 +2768,7 @@ int handle_notification_thread_command_register_trigger(
                 */
                ret = bind_trigger_to_matching_channels(trigger, state);
                if (ret) {
-                       goto error_put_client_list;
+                       goto error_free_ht_element;
                }
                break;
        case LTTNG_OBJECT_TYPE_NONE:
@@ -2227,7 +2776,7 @@ int handle_notification_thread_command_register_trigger(
        default:
                ERR("Unknown object type on which to bind a newly registered trigger was encountered");
                ret = -1;
-               goto error_put_client_list;
+               goto error_free_ht_element;
        }
 
        /*
@@ -2264,35 +2813,36 @@ int handle_notification_thread_command_register_trigger(
                ret = evaluate_session_condition_for_client(condition, state,
                                &evaluation, &object_uid,
                                &object_gid);
+               LTTNG_OPTIONAL_SET(&object_creds.uid, object_uid);
+               LTTNG_OPTIONAL_SET(&object_creds.gid, object_gid);
                break;
        case LTTNG_OBJECT_TYPE_CHANNEL:
                ret = evaluate_channel_condition_for_client(condition, state,
                                &evaluation, &object_uid,
                                &object_gid);
+               LTTNG_OPTIONAL_SET(&object_creds.uid, object_uid);
+               LTTNG_OPTIONAL_SET(&object_creds.gid, object_gid);
                break;
        case LTTNG_OBJECT_TYPE_NONE:
                ret = 0;
-               goto error_put_client_list;
+               break;
        case LTTNG_OBJECT_TYPE_UNKNOWN:
        default:
                ret = -1;
-               goto error_put_client_list;
+               break;
        }
 
        if (ret) {
                /* Fatal error. */
-               goto error_put_client_list;
+               goto error_free_ht_element;
        }
 
-       LTTNG_OPTIONAL_SET(&object_creds.uid, object_uid);
-       LTTNG_OPTIONAL_SET(&object_creds.gid, object_gid);
-
        DBG("Newly registered trigger's condition evaluated to %s",
                        evaluation ? "true" : "false");
        if (!evaluation) {
                /* Evaluation yielded nothing. Normal exit. */
                ret = 0;
-               goto error_put_client_list;
+               goto success;
        }
 
        /*
@@ -2313,7 +2863,7 @@ int handle_notification_thread_command_register_trigger(
                 */
                ERR("Fatal error occurred while enqueuing action associated to newly registered trigger");
                ret = -1;
-               goto error_put_client_list;
+               goto error_free_ht_element;
        case ACTION_EXECUTOR_STATUS_OVERFLOW:
                /*
                 * TODO Add trigger identification (name/id) when
@@ -2323,22 +2873,28 @@ int handle_notification_thread_command_register_trigger(
                 */
                WARN("No space left when enqueuing action associated to newly registered trigger");
                ret = 0;
-               goto error_put_client_list;
+               goto success;
        default:
                abort();
        }
 
+success:
        *cmd_result = LTTNG_OK;
-
-error_put_client_list:
-       notification_client_list_put(client_list);
+       DBG("Registered trigger: name = `%s`, tracer token = %" PRIu64,
+                       trigger_name, trigger_tracer_token);
+       goto end;
 
 error_free_ht_element:
-       free(trigger_ht_element);
+       if (trigger_ht_element) {
+               /* Delayed removal due to RCU constraint on delete. */
+               call_rcu(&trigger_ht_element->rcu_node,
+                               free_lttng_trigger_ht_element_rcu);
+       }
 error:
        if (free_trigger) {
                lttng_trigger_destroy(trigger);
        }
+end:
        rcu_read_unlock();
        return ret;
 }
@@ -2350,10 +2906,47 @@ void free_lttng_trigger_ht_element_rcu(struct rcu_head *node)
                        rcu_node));
 }
 
+static
+void free_notification_trigger_tokens_ht_element_rcu(struct rcu_head *node)
+{
+       free(caa_container_of(node, struct notification_trigger_tokens_ht_element,
+                       rcu_node));
+}
+
+static
+void teardown_tracer_notifier(struct notification_thread_state *state,
+               const struct lttng_trigger *trigger)
+{
+       struct cds_lfht_iter iter;
+       struct notification_trigger_tokens_ht_element *trigger_tokens_ht_element;
+
+       cds_lfht_for_each_entry(state->trigger_tokens_ht, &iter,
+                       trigger_tokens_ht_element, node) {
+
+               if (!lttng_trigger_is_equal(trigger,
+                                       trigger_tokens_ht_element->trigger)) {
+                       continue;
+               }
+
+               event_notifier_error_accounting_unregister_event_notifier(
+                               trigger_tokens_ht_element->trigger);
+
+               /* TODO talk to all app and remove it */
+               DBG("[notification-thread] Removed trigger from tokens_ht");
+               cds_lfht_del(state->trigger_tokens_ht,
+                               &trigger_tokens_ht_element->node);
+
+               call_rcu(&trigger_tokens_ht_element->rcu_node,
+                               free_notification_trigger_tokens_ht_element_rcu);
+
+               break;
+       }
+}
+
 static
 int handle_notification_thread_command_unregister_trigger(
                struct notification_thread_state *state,
-               struct lttng_trigger *trigger,
+               const struct lttng_trigger *trigger,
                enum lttng_error_code *_cmd_reply)
 {
        struct cds_lfht_iter iter;
@@ -2361,7 +2954,7 @@ int handle_notification_thread_command_unregister_trigger(
        struct lttng_channel_trigger_list *trigger_list;
        struct notification_client_list *client_list;
        struct lttng_trigger_ht_element *trigger_ht_element = NULL;
-       struct lttng_condition *condition = lttng_trigger_get_condition(
+       const struct lttng_condition *condition = lttng_trigger_get_const_condition(
                        trigger);
        enum lttng_error_code cmd_reply;
 
@@ -2369,8 +2962,8 @@ int handle_notification_thread_command_unregister_trigger(
 
        cds_lfht_lookup(state->triggers_ht,
                        lttng_condition_hash(condition),
-                       match_condition,
-                       condition,
+                       match_trigger,
+                       trigger,
                        &iter);
        triggers_ht_node = cds_lfht_iter_get_node(&iter);
        if (!triggers_ht_node) {
@@ -2387,13 +2980,7 @@ int handle_notification_thread_command_unregister_trigger(
 
                cds_list_for_each_entry_safe(trigger_element, tmp,
                                &trigger_list->list, node) {
-                       const struct lttng_condition *current_condition =
-                                       lttng_trigger_get_const_condition(
-                                               trigger_element->trigger);
-
-                       assert(current_condition);
-                       if (!lttng_condition_is_equal(condition,
-                                       current_condition)) {
+                       if (!lttng_trigger_is_equal(trigger, trigger_element->trigger)) {
                                continue;
                        }
 
@@ -2404,22 +2991,33 @@ int handle_notification_thread_command_unregister_trigger(
                }
        }
 
-       /*
-        * Remove and release the client list from
-        * notification_trigger_clients_ht.
-        */
-       client_list = get_client_list_from_condition(state, condition);
-       assert(client_list);
-
-       /* Put new reference and the hashtable's reference. */
-       notification_client_list_put(client_list);
-       notification_client_list_put(client_list);
-       client_list = NULL;
+       if (lttng_trigger_needs_tracer_notifier(trigger)) {
+               teardown_tracer_notifier(state, trigger);
+       }
 
-       /* Remove trigger from triggers_ht. */
        trigger_ht_element = caa_container_of(triggers_ht_node,
                        struct lttng_trigger_ht_element, node);
-       cds_lfht_del(state->triggers_ht, triggers_ht_node);
+
+       if (is_trigger_action_notify(trigger)) {
+               /*
+                * Remove and release the client list from
+                * notification_trigger_clients_ht.
+                */
+               client_list = get_client_list_from_condition(state, condition);
+               assert(client_list);
+
+               pthread_mutex_lock(&client_list->lock);
+               cds_list_del(&trigger_ht_element->client_list_trigger_node);
+               pthread_mutex_unlock(&client_list->lock);
+
+               /* Put new reference and the hashtable's reference. */
+               notification_client_list_put(client_list);
+               notification_client_list_put(client_list);
+               client_list = NULL;
+       }
+
+       /* Remove trigger from triggers_ht. */
+       notif_thread_state_remove_trigger_ht_elem(state, trigger_ht_element);
 
        /* Release the ownership of the trigger. */
        lttng_trigger_destroy(trigger_ht_element->trigger);
@@ -2453,21 +3051,22 @@ int handle_notification_thread_command(
                        struct notification_thread_command, cmd_list_node);
        cds_list_del(&cmd->cmd_list_node);
        pthread_mutex_unlock(&handle->cmd_queue.lock);
+
+       DBG("[notification-thread] Received `%s` command",
+                       notification_command_type_str(cmd->type));
        switch (cmd->type) {
        case NOTIFICATION_COMMAND_TYPE_REGISTER_TRIGGER:
-               DBG("[notification-thread] Received register trigger command");
-               ret = handle_notification_thread_command_register_trigger(
-                               state, cmd->parameters.trigger,
+               ret = handle_notification_thread_command_register_trigger(state,
+                               cmd->parameters.register_trigger.trigger,
                                &cmd->reply_code);
                break;
        case NOTIFICATION_COMMAND_TYPE_UNREGISTER_TRIGGER:
-               DBG("[notification-thread] Received unregister trigger command");
                ret = handle_notification_thread_command_unregister_trigger(
-                               state, cmd->parameters.trigger,
+                               state,
+                               cmd->parameters.unregister_trigger.trigger,
                                &cmd->reply_code);
                break;
        case NOTIFICATION_COMMAND_TYPE_ADD_CHANNEL:
-               DBG("[notification-thread] Received add channel command");
                ret = handle_notification_thread_command_add_channel(
                                state,
                                cmd->parameters.add_channel.session.name,
@@ -2480,7 +3079,6 @@ int handle_notification_thread_command(
                                &cmd->reply_code);
                break;
        case NOTIFICATION_COMMAND_TYPE_REMOVE_CHANNEL:
-               DBG("[notification-thread] Received remove channel command");
                ret = handle_notification_thread_command_remove_channel(
                                state, cmd->parameters.remove_channel.key,
                                cmd->parameters.remove_channel.domain,
@@ -2488,9 +3086,6 @@ int handle_notification_thread_command(
                break;
        case NOTIFICATION_COMMAND_TYPE_SESSION_ROTATION_ONGOING:
        case NOTIFICATION_COMMAND_TYPE_SESSION_ROTATION_COMPLETED:
-               DBG("[notification-thread] Received session rotation %s command",
-                               cmd->type == NOTIFICATION_COMMAND_TYPE_SESSION_ROTATION_ONGOING ?
-                               "ongoing" : "completed");
                ret = handle_notification_thread_command_session_rotation(
                                state,
                                cmd->type,
@@ -2501,8 +3096,34 @@ int handle_notification_thread_command(
                                cmd->parameters.session_rotation.location,
                                &cmd->reply_code);
                break;
+       case NOTIFICATION_COMMAND_TYPE_ADD_TRACER_EVENT_SOURCE:
+               ret = handle_notification_thread_command_add_tracer_event_source(
+                               state,
+                               cmd->parameters.tracer_event_source.tracer_event_source_fd,
+                               cmd->parameters.tracer_event_source.domain,
+                               &cmd->reply_code);
+               break;
+       case NOTIFICATION_COMMAND_TYPE_REMOVE_TRACER_EVENT_SOURCE:
+               ret = handle_notification_thread_command_remove_tracer_event_source(
+                               state,
+                               cmd->parameters.tracer_event_source.tracer_event_source_fd,
+                               &cmd->reply_code);
+               break;
+       case NOTIFICATION_COMMAND_TYPE_LIST_TRIGGERS:
+       {
+               struct lttng_triggers *triggers = NULL;
+
+               ret = handle_notification_thread_command_list_triggers(
+                               handle,
+                               state,
+                               cmd->parameters.list_triggers.uid,
+                               &triggers,
+                               &cmd->reply_code);
+               cmd->reply.list_triggers.triggers = triggers;
+               ret = 0;
+               break;
+       }
        case NOTIFICATION_COMMAND_TYPE_QUIT:
-               DBG("[notification-thread] Received quit command");
                cmd->reply_code = LTTNG_OK;
                ret = 1;
                goto end;
@@ -3593,8 +4214,7 @@ int send_evaluation_to_clients(const struct lttng_trigger *trigger,
        };
 
        return notification_client_list_send_evaluation(client_list,
-                       lttng_trigger_get_const_condition(trigger), evaluation,
-                       lttng_trigger_get_credentials(trigger),
+                       trigger, evaluation,
                        &creds,
                        client_handle_transmission_status_wrapper, state);
 }
@@ -3635,9 +4255,8 @@ int send_evaluation_to_clients(const struct lttng_trigger *trigger,
 LTTNG_HIDDEN
 int notification_client_list_send_evaluation(
                struct notification_client_list *client_list,
-               const struct lttng_condition *condition,
+               const struct lttng_trigger *trigger,
                const struct lttng_evaluation *evaluation,
-               const struct lttng_credentials *trigger_creds,
                const struct lttng_credentials *source_object_creds,
                report_client_transmission_result_cb client_report,
                void *user_data)
@@ -3646,12 +4265,14 @@ int notification_client_list_send_evaluation(
        struct lttng_payload msg_payload;
        struct notification_client_list_element *client_list_element, *tmp;
        const struct lttng_notification notification = {
-               .condition = (struct lttng_condition *) condition,
+               .trigger = (struct lttng_trigger *) trigger,
                .evaluation = (struct lttng_evaluation *) evaluation,
        };
        struct lttng_notification_channel_message msg_header = {
                .type = (int8_t) LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION,
        };
+       const struct lttng_credentials *trigger_creds =
+                       lttng_trigger_get_credentials(trigger);
 
        lttng_payload_init(&msg_payload);
 
@@ -3685,7 +4306,7 @@ int notification_client_list_send_evaluation(
 
        pthread_mutex_lock(&client_list->lock);
        cds_list_for_each_entry_safe(client_list_element, tmp,
-                       &client_list->list, node) {
+                       &client_list->clients_list, node) {
                enum client_transmission_status transmission_status;
                struct notification_client *client =
                                client_list_element->client;
@@ -3714,7 +4335,7 @@ int notification_client_list_send_evaluation(
                        }
                }
 
-               if (client->uid != lttng_credentials_get_uid(trigger_creds) && client->gid != lttng_credentials_get_gid(trigger_creds)) {
+               if (client->uid != lttng_credentials_get_uid(trigger_creds)) {
                        DBG("[notification-thread] Skipping client at it does not have the permission to receive notification for this trigger");
                        goto skip_client;
                }
@@ -3769,6 +4390,285 @@ end:
        return ret;
 }
 
+static
+struct lttng_event_notifier_notification *recv_one_event_notifier_notification(
+               int notification_pipe_read_fd, enum lttng_domain_type domain)
+{
+       int ret;
+       uint64_t token;
+       struct lttng_event_notifier_notification *notification = NULL;
+       char *capture_buffer = NULL;
+       size_t capture_buffer_size;
+       void *reception_buffer;
+       size_t reception_size;
+
+       struct lttng_ust_abi_event_notifier_notification ust_notification;
+       struct lttng_kernel_event_notifier_notification kernel_notification;
+
+       /* Init lttng_event_notifier_notification */
+       switch(domain) {
+       case LTTNG_DOMAIN_UST:
+               reception_buffer = (void *) &ust_notification;
+               reception_size = sizeof(ust_notification);
+               break;
+       case LTTNG_DOMAIN_KERNEL:
+               reception_buffer = (void *) &kernel_notification;
+               reception_size = sizeof(kernel_notification);
+               break;
+       default:
+               abort();
+       }
+
+       /*
+        * The monitoring pipe only holds messages smaller than PIPE_BUF,
+        * ensuring that read/write of tracer notifications are atomic.
+        */
+       ret = lttng_read(notification_pipe_read_fd, reception_buffer,
+                       reception_size);
+       if (ret != reception_size) {
+               PERROR("Failed to read from event source notification pipe: fd = %d, size to read = %zu, ret = %d",
+                               notification_pipe_read_fd, reception_size, ret);
+               ret = -1;
+               goto end;
+       }
+
+       switch(domain) {
+       case LTTNG_DOMAIN_UST:
+               token = ust_notification.token;
+               capture_buffer_size = ust_notification.capture_buf_size;
+               break;
+       case LTTNG_DOMAIN_KERNEL:
+               token = kernel_notification.token;
+               capture_buffer_size = kernel_notification.capture_buf_size;
+               break;
+       default:
+               abort();
+       }
+
+       if (capture_buffer_size == 0) {
+               capture_buffer = NULL;
+               goto skip_capture;
+       }
+
+       if (capture_buffer_size > MAX_CAPTURE_SIZE) {
+               ERR("[notification-thread] Event notifier has a capture payload size which exceeds the maximum allowed size: capture_payload_size = %zu bytes, max allowed size = %d bytes",
+                               capture_buffer_size, MAX_CAPTURE_SIZE);
+               goto end;
+       }
+
+       capture_buffer = zmalloc(capture_buffer_size);
+       if (!capture_buffer) {
+               ERR("[notification-thread] Failed to allocate capture buffer");
+               goto end;
+       }
+
+       /* Fetch additional payload (capture). */
+       ret = lttng_read(notification_pipe_read_fd, capture_buffer, capture_buffer_size);
+       if (ret != capture_buffer_size) {
+               ERR("[notification-thread] Failed to read from event source pipe (fd = %i)",
+                               notification_pipe_read_fd);
+               goto end;
+       }
+
+skip_capture:
+       notification = lttng_event_notifier_notification_create(token, domain,
+                       capture_buffer, capture_buffer_size);
+       if (notification == NULL) {
+               goto end;
+       }
+
+       /*
+        * Ownership transfered to the lttng_event_notifier_notification object.
+        */
+       capture_buffer = NULL;
+
+end:
+       free(capture_buffer);
+       return notification;
+}
+
+static
+int dispatch_one_event_notifier_notification(struct notification_thread_state *state,
+               struct lttng_event_notifier_notification *notification)
+{
+       struct cds_lfht_node *node;
+       struct cds_lfht_iter iter;
+       struct notification_trigger_tokens_ht_element *element;
+       enum lttng_trigger_status trigger_status;
+       struct lttng_evaluation *evaluation = NULL;
+       enum action_executor_status executor_status;
+       struct notification_client_list *client_list = NULL;
+       const char *trigger_name;
+       int ret;
+       unsigned int capture_count = 0;
+
+       /* Find triggers associated with this token. */
+       rcu_read_lock();
+       cds_lfht_lookup(state->trigger_tokens_ht,
+                       hash_key_u64(&notification->tracer_token, lttng_ht_seed),
+                       match_trigger_token, &notification->tracer_token, &iter);
+       node = cds_lfht_iter_get_node(&iter);
+       if (caa_unlikely(!node)) {
+               /*
+                * This is not an error, slow consumption of the tracer
+                * notifications can lead to situations where a trigger is
+                * removed but we still get tracer notifications matching a
+                * trigger that no longer exists.
+                */
+               ret = 0;
+               goto end_unlock;
+       }
+
+       element = caa_container_of(node,
+                       struct notification_trigger_tokens_ht_element,
+                       node);
+
+       if (!lttng_trigger_should_fire(element->trigger)) {
+               ret = 0;
+               goto end_unlock;
+       }
+
+       lttng_trigger_fire(element->trigger);
+
+       trigger_status = lttng_trigger_get_name(element->trigger, &trigger_name);
+       assert(trigger_status == LTTNG_TRIGGER_STATUS_OK);
+
+       if (lttng_condition_on_event_get_capture_descriptor_count(
+                           lttng_trigger_get_const_condition(element->trigger),
+                           &capture_count) != LTTNG_CONDITION_STATUS_OK) {
+               ERR("Failed to get capture count");
+               ret = -1;
+               goto end;
+       }
+
+       if (!notification->capture_buffer && capture_count != 0) {
+               ERR("Expected capture but capture buffer is null");
+               ret = -1;
+               goto end;
+       }
+
+       evaluation = lttng_evaluation_on_event_create(
+                       container_of(lttng_trigger_get_const_condition(
+                                                    element->trigger),
+                                       struct lttng_condition_on_event,
+                                       parent),
+                       notification->capture_buffer,
+                       notification->capture_buf_size, false);
+
+       if (evaluation == NULL) {
+               ERR("[notification-thread] Failed to create event rule hit evaluation while creating and enqueuing action executor job");
+               ret = -1;
+               goto end_unlock;
+       }
+       client_list = get_client_list_from_condition(state,
+                       lttng_trigger_get_const_condition(element->trigger));
+       executor_status = action_executor_enqueue(state->executor,
+                       element->trigger, evaluation, NULL, client_list);
+       switch (executor_status) {
+       case ACTION_EXECUTOR_STATUS_OK:
+               ret = 0;
+               break;
+       case ACTION_EXECUTOR_STATUS_OVERFLOW:
+       {
+               struct notification_client_list_element *client_list_element,
+                               *tmp;
+
+               /*
+                * Not a fatal error; this is expected and simply means the
+                * executor has too much work queued already.
+                */
+               ret = 0;
+
+               /* No clients subscribed to notifications for this trigger. */
+               if (!client_list) {
+                       break;
+               }
+
+               /* Warn clients that a notification (or more) was dropped. */
+               pthread_mutex_lock(&client_list->lock);
+               cds_list_for_each_entry_safe(client_list_element, tmp,
+                               &client_list->clients_list, node) {
+                       enum client_transmission_status transmission_status;
+                       struct notification_client *client =
+                                       client_list_element->client;
+
+                       pthread_mutex_lock(&client->lock);
+                       ret = client_notification_overflow(client);
+                       if (ret) {
+                               /* Fatal error. */
+                               goto next_client;
+                       }
+
+                       transmission_status =
+                                       client_flush_outgoing_queue(client);
+                       ret = client_handle_transmission_status(
+                                       client, transmission_status, state);
+                       if (ret) {
+                               /* Fatal error. */
+                               goto next_client;
+                       }
+next_client:
+                       pthread_mutex_unlock(&client->lock);
+                       if (ret) {
+                               break;
+                       }
+               }
+
+               pthread_mutex_unlock(&client_list->lock);
+               break;
+       }
+       case ACTION_EXECUTOR_STATUS_INVALID:
+       case ACTION_EXECUTOR_STATUS_ERROR:
+               /* Fatal error, shut down everything. */
+               ERR("Fatal error encoutered while enqueuing action to the action executor");
+               ret = -1;
+               goto end_unlock;
+       default:
+               /* Unhandled error. */
+               abort();
+       }
+
+end_unlock:
+       notification_client_list_put(client_list);
+       rcu_read_unlock();
+end:
+       return ret;
+}
+
+static
+int handle_one_event_notifier_notification(
+               struct notification_thread_state *state,
+               int pipe, enum lttng_domain_type domain)
+{
+       int ret = 0;
+       struct lttng_event_notifier_notification *notification = NULL;
+
+       notification = recv_one_event_notifier_notification(pipe, domain);
+       if (notification == NULL) {
+               /* Reception failed, don't consider it fatal. */
+               ERR("[notification-thread] Error receiving an event notifier notification from tracer: fd = %i, domain = %s",
+                               pipe, lttng_domain_type_str(domain));
+               goto end;
+       }
+
+       ret = dispatch_one_event_notifier_notification(state, notification);
+       if (ret) {
+               ERR("[notification-thread] Error dispatching an event notifier notification from tracer: fd = %i, domain = %s",
+                               pipe, lttng_domain_type_str(domain));
+               goto end;
+       }
+
+end:
+       lttng_event_notifier_notification_destroy(notification);
+       return ret;
+}
+
+int handle_notification_thread_event_notification(struct notification_thread_state *state,
+               int pipe, enum lttng_domain_type domain)
+{
+       return handle_one_event_notifier_notification(state, pipe, domain);
+}
+
 int handle_notification_thread_channel_sample(
                struct notification_thread_state *state, int pipe,
                enum lttng_domain_type domain)
@@ -3822,8 +4722,7 @@ int handle_notification_thread_channel_sample(
                 */
                DBG("[notification-thread] Received a sample for an unknown channel from consumerd, key = %" PRIu64 " in %s domain",
                                latest_sample.key.key,
-                               domain == LTTNG_DOMAIN_KERNEL ? "kernel" :
-                                       "user space");
+                               lttng_domain_type_str(domain));
                goto end_unlock;
        }
        channel_info = caa_container_of(node, struct channel_info,
@@ -3942,6 +4841,12 @@ int handle_notification_thread_channel_sample(
                        goto put_list;
                }
 
+               if (!lttng_trigger_should_fire(trigger)) {
+                       goto put_list;
+               }
+
+               lttng_trigger_fire(trigger);
+
                /*
                 * Ownership of `evaluation` transferred to the action executor
                 * no matter the result.
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