X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=lttng-sessiond%2Fust-app.c;h=73dc770c9391f3fac295d6e16b58fcfefa195ac9;hp=bce76f791315b43b07ff023cd530db130a9b2153;hb=90d97d10e57ba8b2b10481837efb3d2402f41f88;hpb=a220deea2ded01fb30a4ad6dfb074ab5499eaf33

diff --git a/lttng-sessiond/ust-app.c b/lttng-sessiond/ust-app.c
index bce76f791..73dc770c9 100644
--- a/lttng-sessiond/ust-app.c
+++ b/lttng-sessiond/ust-app.c
@@ -22,283 +22,245 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
 #include <unistd.h>
 
+#include <urcu/compiler.h>
 #include <lttngerr.h>
 #include <lttng-share.h>
 
 #include "hashtable.h"
 #include "ust-app.h"
-#include "../hashtable/hash.h"
-#include "ust-ctl.h"
 #include "ust-consumer.h"
+#include "ust-ctl.h"
 
 /*
- * Delete a traceable application structure from the global list.
+ * Delete ust context safely. RCU read lock must be held before calling
+ * this function.
  */
-static void delete_ust_app(struct ust_app *lta)
+static
+void delete_ust_app_ctx(int sock, struct ust_app_ctx *ua_ctx)
 {
-	int ret;
-	struct cds_lfht_node *node;
-	struct cds_lfht_iter iter;
-
-	rcu_read_lock();
-
-	free(lta->sessions);
-	close(lta->key.sock);
-
-	/* Remove from apps hash table */
-	node = hashtable_lookup(ust_app_ht,
-			(void *) ((unsigned long) lta->key.pid), sizeof(void *), &iter);
-	if (node == NULL) {
-		ERR("UST app pid %d not found in hash table", lta->key.pid);
-	} else {
-		ret = hashtable_del(ust_app_ht, &iter);
-		if (ret) {
-			ERR("UST app unable to delete app %d from hash table",
-					lta->key.pid);
-		} else {
-			DBG2("UST app pid %d deleted", lta->key.pid);
-		}
-	}
-
-	/* Remove from key hash table */
-	node = hashtable_lookup(ust_app_sock_key_map,
-			(void *) ((unsigned long) lta->key.sock), sizeof(void *), &iter);
-	if (node == NULL) {
-		ERR("UST app key %d not found in key hash table", lta->key.sock);
-	} else {
-		ret = hashtable_del(ust_app_sock_key_map, &iter);
-		if (ret) {
-			ERR("UST app unable to delete app sock %d from key hash table",
-					lta->key.sock);
-		} else {
-			DBG2("UST app pair sock %d key %d deleted",
-					lta->key.sock, lta->key.pid);
-		}
+	if (ua_ctx->obj) {
+		ustctl_release_object(sock, ua_ctx->obj);
+		free(ua_ctx->obj);
 	}
-
-	free(lta);
-
-	rcu_read_unlock();
-}
-
-/*
- * URCU intermediate call to delete an UST app.
- */
-static void delete_ust_app_rcu(struct rcu_head *head)
-{
-	struct cds_lfht_node *node =
-		caa_container_of(head, struct cds_lfht_node, head);
-	struct ust_app *app =
-		caa_container_of(node, struct ust_app, node);
-
-	delete_ust_app(app);
+	free(ua_ctx);
 }
 
 /*
- * Find an ust_app using the sock and return it.
+ * Delete ust app event safely. RCU read lock must be held before calling
+ * this function.
  */
-static struct ust_app *find_app_by_sock(int sock)
+static
+void delete_ust_app_event(int sock, struct ust_app_event *ua_event)
 {
-	struct cds_lfht_node *node;
-	struct ust_app_key *key;
+	int ret;
 	struct cds_lfht_iter iter;
+	struct ust_app_ctx *ua_ctx;
 
-	rcu_read_lock();
-
-	node = hashtable_lookup(ust_app_sock_key_map,
-			(void *)((unsigned long) sock), sizeof(void *), &iter);
-	if (node == NULL) {
-		DBG2("UST app find by sock %d key not found", sock);
-		rcu_read_unlock();
-		goto error;
+	cds_lfht_for_each_entry(ua_event->ctx, &iter, ua_ctx, node) {
+		ret = hashtable_del(ua_event->ctx, &iter);
+		assert(!ret);
+		delete_ust_app_ctx(sock, ua_ctx);
 	}
+	ret = hashtable_destroy(ua_event->ctx);
+	assert(!ret);
 
-	key = caa_container_of(node, struct ust_app_key, node);
-
-	node = hashtable_lookup(ust_app_ht,
-			(void *)((unsigned long) key->pid), sizeof(void *), &iter);
-	if (node == NULL) {
-		DBG2("UST app find by sock %d not found", sock);
-		rcu_read_unlock();
-		goto error;
+	if (ua_event->obj != NULL) {
+		ustctl_release_object(sock, ua_event->obj);
+		free(ua_event->obj);
 	}
-	rcu_read_unlock();
-
-	return caa_container_of(node, struct ust_app, node);
-
-error:
-	return NULL;
+	free(ua_event);
 }
 
 /*
- * Return pointer to traceable apps list.
+ * Delete ust app stream safely. RCU read lock must be held before calling
+ * this function.
  */
-struct cds_lfht *ust_app_get_ht(void)
+static
+void delete_ust_app_stream(int sock, struct ltt_ust_stream *stream)
 {
-	return ust_app_ht;
+	if (stream->obj) {
+		ustctl_release_object(sock, stream->obj);
+		free(stream->obj);
+	}
+	free(stream);
 }
 
 /*
- * Return ust app pointer or NULL if not found.
+ * Delete ust app channel safely. RCU read lock must be held before calling
+ * this function.
  */
-struct ust_app *ust_app_find_by_pid(pid_t pid)
+static
+void delete_ust_app_channel(int sock, struct ust_app_channel *ua_chan)
 {
-	struct cds_lfht_node *node;
+	int ret;
 	struct cds_lfht_iter iter;
+	struct ust_app_event *ua_event;
+	struct ust_app_ctx *ua_ctx;
+	struct ltt_ust_stream *stream, *stmp;
 
-	rcu_read_lock();
-	node = hashtable_lookup(ust_app_ht,
-			(void *)((unsigned long) pid), sizeof(void *), &iter);
-	if (node == NULL) {
-		rcu_read_unlock();
-		DBG2("UST app no found with pid %d", pid);
-		goto error;
+	/* Wipe stream */
+	cds_list_for_each_entry_safe(stream, stmp, &ua_chan->streams.head, list) {
+		cds_list_del(&stream->list);
+		delete_ust_app_stream(sock, stream);
 	}
-	rcu_read_unlock();
-
-	DBG2("Found UST app by pid %d", pid);
 
-	return caa_container_of(node, struct ust_app, node);
+	/* Wipe context */
+	cds_lfht_for_each_entry(ua_chan->ctx, &iter, ua_ctx, node) {
+		ret = hashtable_del(ua_chan->ctx, &iter);
+		assert(!ret);
+		delete_ust_app_ctx(sock, ua_ctx);
+	}
+	ret = hashtable_destroy(ua_chan->ctx);
+	assert(!ret);
+
+	/* Wipe events */
+	cds_lfht_for_each_entry(ua_chan->events, &iter, ua_event, node) {
+		ret = hashtable_del(ua_chan->events, &iter);
+		assert(!ret);
+		delete_ust_app_event(sock, ua_event);
+	}
+	ret = hashtable_destroy(ua_chan->events);
+	assert(!ret);
 
-error:
-	return NULL;
+	if (ua_chan->obj != NULL) {
+		ustctl_release_object(sock, ua_chan->obj);
+		free(ua_chan->obj);
+	}
+	free(ua_chan);
 }
 
 /*
- * Using pid and uid (of the app), allocate a new ust_app struct and
- * add it to the global traceable app list.
- *
- * On success, return 0, else return malloc ENOMEM.
+ * Delete ust app session safely. RCU read lock must be held before calling
+ * this function.
  */
-int ust_app_register(struct ust_register_msg *msg, int sock)
+static
+void delete_ust_app_session(int sock, struct ust_app_session *ua_sess)
 {
-	struct ust_app *lta;
+	int ret;
+	struct cds_lfht_iter iter;
+	struct ust_app_channel *ua_chan;
 
-	lta = malloc(sizeof(struct ust_app));
-	if (lta == NULL) {
-		PERROR("malloc");
-		return -ENOMEM;
+	if (ua_sess->metadata) {
+		if (ua_sess->metadata->stream_obj) {
+			ustctl_release_object(sock, ua_sess->metadata->stream_obj);
+			free(ua_sess->metadata->stream_obj);
+		}
+		if (ua_sess->metadata->obj) {
+			ustctl_release_object(sock, ua_sess->metadata->obj);
+			free(ua_sess->metadata->obj);
+		}
 	}
 
-	lta->uid = msg->uid;
-	lta->gid = msg->gid;
-	lta->key.pid = msg->pid;
-	lta->ppid = msg->ppid;
-	lta->v_major = msg->major;
-	lta->v_minor = msg->minor;
-	lta->key.sock = sock;
-	strncpy(lta->name, msg->name, sizeof(lta->name));
-	lta->name[16] = '\0';
-	hashtable_node_init(&lta->node, (void *)((unsigned long)lta->key.pid),
-			sizeof(void *));
-
-	/* Session hashtable */
-	lta->sessions = hashtable_new(0);
-
-	/* Set sock key map */
-	hashtable_node_init(&lta->key.node, (void *)((unsigned long)lta->key.sock),
-			sizeof(void *));
-
-	rcu_read_lock();
-	hashtable_add_unique(ust_app_ht, &lta->node);
-	hashtable_add_unique(ust_app_sock_key_map, &lta->key.node);
-	rcu_read_unlock();
-
-	DBG("App registered with pid:%d ppid:%d uid:%d gid:%d sock:%d name:%s"
-			" (version %d.%d)", lta->key.pid, lta->ppid, lta->uid, lta->gid,
-			lta->key.sock, lta->name, lta->v_major, lta->v_minor);
-
-	return 0;
-}
-
-/*
- * Unregister app by removing it from the global traceable app list and freeing
- * the data struct.
- *
- * The socket is already closed at this point so no close to sock.
- */
-void ust_app_unregister(int sock)
-{
-	struct ust_app *lta;
-
-	DBG2("UST app unregistering sock %d", sock);
+	cds_lfht_for_each_entry(ua_sess->channels, &iter, ua_chan, node) {
+		ret = hashtable_del(ua_sess->channels, &iter);
+		assert(!ret);
+		delete_ust_app_channel(sock, ua_chan);
+	}
+	ret = hashtable_destroy(ua_sess->channels);
+	assert(!ret);
 
-	lta = find_app_by_sock(sock);
-	if (lta) {
-		DBG("PID %d unregistering with sock %d", lta->key.pid, sock);
-		/* FIXME: Better use a call_rcu here ? */
-		delete_ust_app(lta);
+	if (ua_sess->handle != -1) {
+		ustctl_release_handle(sock, ua_sess->handle);
 	}
+	free(ua_sess);
 }
 
 /*
- * Return traceable_app_count
+ * Delete a traceable application structure from the global list. Never call
+ * this function outside of a call_rcu call.
  */
-unsigned long ust_app_list_count(void)
+static
+void delete_ust_app(struct ust_app *app)
 {
-	unsigned long count;
+	int ret, sock;
+	struct cds_lfht_node *node;
+	struct cds_lfht_iter iter;
+	struct ust_app_session *ua_sess;
 
 	rcu_read_lock();
-	count = hashtable_get_count(ust_app_ht);
-	rcu_read_unlock();
 
-	return count;
-}
+	/* Remove from key hash table */
+	node = hashtable_lookup(ust_app_sock_key_map,
+			(void *) ((unsigned long) app->key.sock), sizeof(void *), &iter);
+	if (node == NULL) {
+		/* Not suppose to happen */
+		ERR("UST app key %d not found in key hash table", app->key.sock);
+		goto end;
+	}
 
-/*
- * Free and clean all traceable apps of the global list.
- */
-void ust_app_clean_list(void)
-{
-	int ret;
-	struct cds_lfht_node *node;
-	struct cds_lfht_iter iter;
+	ret = hashtable_del(ust_app_sock_key_map, &iter);
+	if (ret) {
+		ERR("UST app unable to delete app sock %d from key hash table",
+				app->key.sock);
+	} else {
+		DBG2("UST app pair sock %d key %d deleted",
+				app->key.sock, app->key.pid);
+	}
 
-	DBG2("UST app clean hash table");
+	/* Socket is already closed at this point */
 
-	rcu_read_lock();
+	/* Delete ust app sessions info */
+	sock = app->key.sock;
+	app->key.sock = -1;
 
-	hashtable_get_first(ust_app_ht, &iter);
-	while ((node = hashtable_iter_get_node(&iter)) != NULL) {
-		ret = hashtable_del(ust_app_ht, &iter);
-		if (!ret) {
-			call_rcu(&node->head, delete_ust_app_rcu);
-		}
-		hashtable_get_next(ust_app_ht, &iter);
+	/* Wipe sessions */
+	cds_lfht_for_each_entry(app->sessions, &iter, ua_sess, node) {
+		ret = hashtable_del(app->sessions, &iter);
+		assert(!ret);
+		delete_ust_app_session(app->key.sock, ua_sess);
 	}
-
+	ret = hashtable_destroy(app->sessions);
+	assert(!ret);
+
+	/*
+	 * Wait until we have removed the key from the sock hash table
+	 * before closing this socket, otherwise an application could
+	 * re-use the socket ID and race with the teardown, using the
+	 * same hash table entry.
+	 */
+	close(sock);
+
+	DBG2("UST app pid %d deleted", app->key.pid);
+	free(app);
+end:
 	rcu_read_unlock();
 }
 
 /*
- * Init UST app hash table.
+ * URCU intermediate call to delete an UST app.
  */
-void ust_app_ht_alloc(void)
+static
+void delete_ust_app_rcu(struct rcu_head *head)
 {
-	ust_app_ht = hashtable_new(0);
-	ust_app_sock_key_map = hashtable_new(0);
+	struct cds_lfht_node *node =
+		caa_container_of(head, struct cds_lfht_node, head);
+	struct ust_app *app =
+		caa_container_of(node, struct ust_app, node);
+
+	delete_ust_app(app);
 }
 
 /*
  * Alloc new UST app session.
  */
-static struct ust_app_session *alloc_app_session(void)
+static
+struct ust_app_session *alloc_ust_app_session(void)
 {
 	struct ust_app_session *ua_sess;
 
+	/* Init most of the default value by allocating and zeroing */
 	ua_sess = zmalloc(sizeof(struct ust_app_session));
 	if (ua_sess == NULL) {
 		PERROR("malloc");
 		goto error;
 	}
 
-	ua_sess->enabled = 0;
 	ua_sess->handle = -1;
 	ua_sess->channels = hashtable_new_str(0);
-	ua_sess->metadata = NULL;
-	ua_sess->obj = NULL;
 
 	return ua_sess;
 
@@ -306,27 +268,40 @@ error:
 	return NULL;
 }
 
-static struct ust_app_channel *alloc_app_channel(char *name)
+/*
+ * Alloc new UST app channel.
+ */
+static
+struct ust_app_channel *alloc_ust_app_channel(char *name,
+		struct lttng_ust_channel *attr)
 {
 	struct ust_app_channel *ua_chan;
 
+	/* Init most of the default value by allocating and zeroing */
 	ua_chan = zmalloc(sizeof(struct ust_app_channel));
 	if (ua_chan == NULL) {
 		PERROR("malloc");
 		goto error;
 	}
 
+	/* Setup channel name */
 	strncpy(ua_chan->name, name, sizeof(ua_chan->name));
 	ua_chan->name[sizeof(ua_chan->name) - 1] = '\0';
-	ua_chan->enabled = 0;
+
+	ua_chan->enabled = 1;
 	ua_chan->handle = -1;
-	ua_chan->obj = NULL;
 	ua_chan->ctx = hashtable_new(0);
-	ua_chan->streams = hashtable_new(0);
 	ua_chan->events = hashtable_new_str(0);
 	hashtable_node_init(&ua_chan->node, (void *) ua_chan->name,
 			strlen(ua_chan->name));
 
+	CDS_INIT_LIST_HEAD(&ua_chan->streams.head);
+
+	/* Copy attributes */
+	if (attr) {
+		memcpy(&ua_chan->attr, attr, sizeof(ua_chan->attr));
+	}
+
 	DBG3("UST app channel %s allocated", ua_chan->name);
 
 	return ua_chan;
@@ -335,22 +310,34 @@ error:
 	return NULL;
 }
 
-static struct ust_app_event *alloc_app_event(char *name)
+/*
+ * Alloc new UST app event.
+ */
+static
+struct ust_app_event *alloc_ust_app_event(char *name,
+		struct lttng_ust_event *attr)
 {
 	struct ust_app_event *ua_event;
 
+	/* Init most of the default value by allocating and zeroing */
 	ua_event = zmalloc(sizeof(struct ust_app_event));
 	if (ua_event == NULL) {
 		PERROR("malloc");
 		goto error;
 	}
 
+	ua_event->enabled = 1;
 	strncpy(ua_event->name, name, sizeof(ua_event->name));
 	ua_event->name[sizeof(ua_event->name) - 1] = '\0';
 	ua_event->ctx = hashtable_new(0);
 	hashtable_node_init(&ua_event->node, (void *) ua_event->name,
 			strlen(ua_event->name));
 
+	/* Copy attributes */
+	if (attr) {
+		memcpy(&ua_event->attr, attr, sizeof(ua_event->attr));
+	}
+
 	DBG3("UST app event %s allocated", ua_event->name);
 
 	return ua_event;
@@ -359,472 +346,2031 @@ error:
 	return NULL;
 }
 
-static void shallow_copy_event(struct ust_app_event *ua_event,
-		struct ltt_ust_event *uevent)
+/*
+ * Alloc new UST app context.
+ */
+static
+struct ust_app_ctx *alloc_ust_app_ctx(struct lttng_ust_context *uctx)
 {
-	strncpy(ua_event->name, uevent->attr.name, sizeof(ua_event->name));
-	ua_event->name[sizeof(ua_event->name) - 1] = '\0';
+	struct ust_app_ctx *ua_ctx;
+
+	ua_ctx = zmalloc(sizeof(struct ust_app_ctx));
+	if (ua_ctx == NULL) {
+		goto error;
+	}
+
+	if (uctx) {
+		memcpy(&ua_ctx->ctx, uctx, sizeof(ua_ctx->ctx));
+	}
 
-	/* TODO: support copy context */
+	DBG3("UST app context %d allocated", ua_ctx->ctx.ctx);
+
+error:
+	return ua_ctx;
 }
 
-static void shallow_copy_channel(struct ust_app_channel *ua_chan,
-		struct ltt_ust_channel *uchan)
+/*
+ * Find an ust_app using the sock and return it. RCU read side lock must be
+ * held before calling this helper function.
+ */
+static
+struct ust_app *find_app_by_sock(int sock)
 {
+	struct cds_lfht_node *node;
+	struct ust_app_key *key;
 	struct cds_lfht_iter iter;
-	struct cds_lfht_node *node, *ua_event_node;
-	struct ltt_ust_event *uevent;
-	struct ust_app_event *ua_event;
-
-	DBG2("Shallow copy of UST app channel %s", ua_chan->name);
 
-	strncpy(ua_chan->name, uchan->name, sizeof(ua_chan->name));
-	ua_chan->name[sizeof(ua_chan->name) - 1] = '\0';
+	node = hashtable_lookup(ust_app_sock_key_map,
+			(void *)((unsigned long) sock), sizeof(void *), &iter);
+	if (node == NULL) {
+		DBG2("UST app find by sock %d key not found", sock);
+		goto error;
+	}
 
-	/* TODO: support copy context */
+	key = caa_container_of(node, struct ust_app_key, node);
 
-	hashtable_get_first(uchan->events, &iter);
-	while ((node = hashtable_iter_get_node(&iter)) != NULL) {
-		uevent = caa_container_of(node, struct ltt_ust_event, node);
+	node = hashtable_lookup(ust_app_ht,
+			(void *)((unsigned long) key->pid), sizeof(void *), &iter);
+	if (node == NULL) {
+		DBG2("UST app find by sock %d not found", sock);
+		goto error;
+	}
+	return caa_container_of(node, struct ust_app, node);
 
-		ua_event_node = hashtable_lookup(ua_chan->events,
-				(void *) uevent->attr.name, strlen(uevent->attr.name), &iter);
-		if (ua_event_node == NULL) {
-			DBG2("UST event %s not found on shallow copy channel",
-					uevent->attr.name);
-			ua_event = alloc_app_event(uevent->attr.name);
-			if (ua_event == NULL) {
-				continue;
-			}
-			hashtable_add_unique(ua_chan->events, &ua_event->node);
-		} else {
-			ua_event = caa_container_of(node, struct ust_app_event, node);
-		}
+error:
+	return NULL;
+}
 
-		shallow_copy_event(ua_event, uevent);
+/*
+ * Create the channel context on the tracer.
+ */
+static
+int create_ust_channel_context(struct ust_app_channel *ua_chan,
+		struct ust_app_ctx *ua_ctx, struct ust_app *app)
+{
+	int ret;
 
-		/* Get next UST events */
-		hashtable_get_next(uchan->events, &iter);
+	ret = ustctl_add_context(app->key.sock, &ua_ctx->ctx,
+			ua_chan->obj, &ua_ctx->obj);
+	if (ret < 0) {
+		goto error;
 	}
 
-	DBG3("Shallow copy channel done");
+	ua_ctx->handle = ua_ctx->obj->handle;
+
+	DBG2("UST app context added to channel %s successfully", ua_chan->name);
+
+error:
+	return ret;
 }
 
-static void shallow_copy_session(struct ust_app_session *ua_sess,
-		struct ltt_ust_session *usess)
+/*
+ * Create the event context on the tracer.
+ */
+static
+int create_ust_event_context(struct ust_app_event *ua_event,
+		struct ust_app_ctx *ua_ctx, struct ust_app *app)
 {
-	struct cds_lfht_node *node, *ua_chan_node;
-	struct cds_lfht_iter iter;
-	struct ltt_ust_channel *uchan;
-	struct ust_app_channel *ua_chan;
+	int ret;
 
-	DBG2("Shallow copy of session handle");
+	ret = ustctl_add_context(app->key.sock, &ua_ctx->ctx,
+			ua_event->obj, &ua_ctx->obj);
+	if (ret < 0) {
+		goto error;
+	}
 
-	ua_sess->uid = usess->uid;
+	ua_ctx->handle = ua_ctx->obj->handle;
 
-	/* TODO: support all UST domain */
+	DBG2("UST app context added to event %s successfully", ua_event->name);
+
+error:
+	return ret;
+}
+
+/*
+ * Disable the specified event on to UST tracer for the UST session.
+ */
+static int disable_ust_event(struct ust_app *app,
+		struct ust_app_session *ua_sess, struct ust_app_event *ua_event)
+{
+	int ret;
+
+	ret = ustctl_disable(app->key.sock, ua_event->obj);
+	if (ret < 0) {
+		ERR("UST app event %s disable failed for app (pid: %d) "
+				"and session handle %d with ret %d",
+				ua_event->attr.name, app->key.pid, ua_sess->handle, ret);
+		goto error;
+	}
+
+	DBG2("UST app event %s disabled successfully for app (pid: %d)",
+			ua_event->attr.name, app->key.pid);
+
+error:
+	return ret;
+}
+
+/*
+ * Disable the specified channel on to UST tracer for the UST session.
+ */
+static int disable_ust_channel(struct ust_app *app,
+		struct ust_app_session *ua_sess, struct ust_app_channel *ua_chan)
+{
+	int ret;
+
+	ret = ustctl_disable(app->key.sock, ua_chan->obj);
+	if (ret < 0) {
+		ERR("UST app channel %s disable failed for app (pid: %d) "
+				"and session handle %d with ret %d",
+				ua_chan->name, app->key.pid, ua_sess->handle, ret);
+		goto error;
+	}
+
+	DBG2("UST app channel %s disabled successfully for app (pid: %d)",
+			ua_chan->name, app->key.pid);
+
+error:
+	return ret;
+}
+
+/*
+ * Enable the specified channel on to UST tracer for the UST session.
+ */
+static int enable_ust_channel(struct ust_app *app,
+		struct ust_app_session *ua_sess, struct ust_app_channel *ua_chan)
+{
+	int ret;
+
+	ret = ustctl_enable(app->key.sock, ua_chan->obj);
+	if (ret < 0) {
+		ERR("UST app channel %s enable failed for app (pid: %d) "
+				"and session handle %d with ret %d",
+				ua_chan->name, app->key.pid, ua_sess->handle, ret);
+		goto error;
+	}
+
+	ua_chan->enabled = 1;
+
+	DBG2("UST app channel %s enabled successfully for app (pid: %d)",
+			ua_chan->name, app->key.pid);
+
+error:
+	return ret;
+}
+
+/*
+ * Enable the specified event on to UST tracer for the UST session.
+ */
+static int enable_ust_event(struct ust_app *app,
+		struct ust_app_session *ua_sess, struct ust_app_event *ua_event)
+{
+	int ret;
+
+	ret = ustctl_enable(app->key.sock, ua_event->obj);
+	if (ret < 0) {
+		ERR("UST app event %s enable failed for app (pid: %d) "
+				"and session handle %d with ret %d",
+				ua_event->attr.name, app->key.pid, ua_sess->handle, ret);
+		goto error;
+	}
+
+	DBG2("UST app event %s enabled successfully for app (pid: %d)",
+			ua_event->attr.name, app->key.pid);
+
+error:
+	return ret;
+}
+
+/*
+ * Open metadata onto the UST tracer for a UST session.
+ */
+static int open_ust_metadata(struct ust_app *app,
+		struct ust_app_session *ua_sess)
+{
+	int ret;
+	struct lttng_ust_channel_attr uattr;
+
+	uattr.overwrite = ua_sess->metadata->attr.overwrite;
+	uattr.subbuf_size = ua_sess->metadata->attr.subbuf_size;
+	uattr.num_subbuf = ua_sess->metadata->attr.num_subbuf;
+	uattr.switch_timer_interval =
+		ua_sess->metadata->attr.switch_timer_interval;
+	uattr.read_timer_interval =
+		ua_sess->metadata->attr.read_timer_interval;
+	uattr.output = ua_sess->metadata->attr.output;
+
+	/* UST tracer metadata creation */
+	ret = ustctl_open_metadata(app->key.sock, ua_sess->handle, &uattr,
+			&ua_sess->metadata->obj);
+	if (ret < 0) {
+		ERR("UST app open metadata failed for app pid:%d",
+				app->key.pid);
+		goto error;
+	}
+
+	ua_sess->metadata->handle = ua_sess->metadata->obj->handle;
+
+error:
+	return ret;
+}
+
+/*
+ * Create stream onto the UST tracer for a UST session.
+ */
+static int create_ust_stream(struct ust_app *app,
+		struct ust_app_session *ua_sess)
+{
+	int ret;
+
+	ret = ustctl_create_stream(app->key.sock, ua_sess->metadata->obj,
+			&ua_sess->metadata->stream_obj);
+	if (ret < 0) {
+		ERR("UST create metadata stream failed");
+		goto error;
+	}
+
+error:
+	return ret;
+}
+
+/*
+ * Create the specified channel onto the UST tracer for a UST session.
+ */
+static int create_ust_channel(struct ust_app *app,
+		struct ust_app_session *ua_sess, struct ust_app_channel *ua_chan)
+{
+	int ret;
+
+	/* TODO: remove cast and use lttng-ust-abi.h */
+	ret = ustctl_create_channel(app->key.sock, ua_sess->handle,
+			(struct lttng_ust_channel_attr *)&ua_chan->attr, &ua_chan->obj);
+	if (ret < 0) {
+		DBG("Error creating channel %s for app (pid: %d, sock: %d) "
+				"and session handle %d with ret %d",
+				ua_chan->name, app->key.pid, app->key.sock,
+				ua_sess->handle, ret);
+		goto error;
+	}
+
+	ua_chan->handle = ua_chan->obj->handle;
+	ua_chan->attr.shm_fd = ua_chan->obj->shm_fd;
+	ua_chan->attr.wait_fd = ua_chan->obj->wait_fd;
+	ua_chan->attr.memory_map_size = ua_chan->obj->memory_map_size;
+
+	DBG2("UST app channel %s created successfully for pid:%d and sock:%d",
+			ua_chan->name, app->key.pid, app->key.sock);
+
+	/* If channel is not enabled, disable it on the tracer */
+	if (!ua_chan->enabled) {
+		ret = disable_ust_channel(app, ua_sess, ua_chan);
+		if (ret < 0) {
+			goto error;
+		}
+	}
+
+error:
+	return ret;
+}
+
+/*
+ * Create the specified event onto the UST tracer for a UST session.
+ */
+static
+int create_ust_event(struct ust_app *app, struct ust_app_session *ua_sess,
+		struct ust_app_channel *ua_chan, struct ust_app_event *ua_event)
+{
+	int ret = 0;
+
+	/* Create UST event on tracer */
+	ret = ustctl_create_event(app->key.sock, &ua_event->attr, ua_chan->obj,
+			&ua_event->obj);
+	if (ret < 0) {
+		ERR("Error ustctl create event %s for app pid: %d with ret %d",
+				ua_event->attr.name, app->key.pid, ret);
+		goto error;
+	}
+
+	ua_event->handle = ua_event->obj->handle;
+
+	DBG2("UST app event %s created successfully for pid:%d",
+			ua_event->attr.name, app->key.pid);
+
+	/* If event not enabled, disable it on the tracer */
+	if (!ua_event->enabled) {
+		ret = disable_ust_event(app, ua_sess, ua_event);
+		if (ret < 0) {
+			goto error;
+		}
+	}
+
+error:
+	return ret;
+}
+
+/*
+ * Copy data between an UST app event and a LTT event.
+ */
+static void shadow_copy_event(struct ust_app_event *ua_event,
+		struct ltt_ust_event *uevent)
+{
+	struct cds_lfht_iter iter;
+	struct ltt_ust_context *uctx;
+	struct ust_app_ctx *ua_ctx;
+
+	strncpy(ua_event->name, uevent->attr.name, sizeof(ua_event->name));
+	ua_event->name[sizeof(ua_event->name) - 1] = '\0';
+
+	/* Copy event attributes */
+	memcpy(&ua_event->attr, &uevent->attr, sizeof(ua_event->attr));
+
+	cds_lfht_for_each_entry(uevent->ctx, &iter, uctx, node) {
+		ua_ctx = alloc_ust_app_ctx(&uctx->ctx);
+		if (ua_ctx == NULL) {
+			continue;
+		}
+		hashtable_node_init(&ua_ctx->node,
+				(void *)((unsigned long) ua_ctx->ctx.ctx), sizeof(void *));
+		hashtable_add_unique(ua_event->ctx, &ua_ctx->node);
+	}
+}
+
+/*
+ * Copy data between an UST app channel and a LTT channel.
+ */
+static void shadow_copy_channel(struct ust_app_channel *ua_chan,
+		struct ltt_ust_channel *uchan)
+{
+	struct cds_lfht_iter iter;
+	struct cds_lfht_node *ua_event_node;
+	struct ltt_ust_event *uevent;
+	struct ltt_ust_context *uctx;
+	struct ust_app_event *ua_event;
+	struct ust_app_ctx *ua_ctx;
+
+	DBG2("Shadow copy of UST app channel %s", ua_chan->name);
+
+	strncpy(ua_chan->name, uchan->name, sizeof(ua_chan->name));
+	ua_chan->name[sizeof(ua_chan->name) - 1] = '\0';
+	/* Copy event attributes */
+	memcpy(&ua_chan->attr, &uchan->attr, sizeof(ua_chan->attr));
+
+	cds_lfht_for_each_entry(uchan->ctx, &iter, uctx, node) {
+		ua_ctx = alloc_ust_app_ctx(&uctx->ctx);
+		if (ua_ctx == NULL) {
+			continue;
+		}
+		hashtable_node_init(&ua_ctx->node,
+				(void *)((unsigned long) ua_ctx->ctx.ctx), sizeof(void *));
+		hashtable_add_unique(ua_chan->ctx, &ua_ctx->node);
+	}
+
+	/* Copy all events from ltt ust channel to ust app channel */
+	cds_lfht_for_each_entry(uchan->events, &iter, uevent, node) {
+		struct cds_lfht_iter uiter;
+
+		ua_event_node = hashtable_lookup(ua_chan->events,
+				(void *) uevent->attr.name, strlen(uevent->attr.name),
+				&uiter);
+		if (ua_event_node == NULL) {
+			DBG2("UST event %s not found on shadow copy channel",
+					uevent->attr.name);
+			ua_event = alloc_ust_app_event(uevent->attr.name, &uevent->attr);
+			if (ua_event == NULL) {
+				continue;
+			}
+			shadow_copy_event(ua_event, uevent);
+			hashtable_add_unique(ua_chan->events, &ua_event->node);
+		}
+	}
+
+	DBG3("Shadow copy channel done");
+}
+
+/*
+ * Copy data between a UST app session and a regular LTT session.
+ */
+static void shadow_copy_session(struct ust_app_session *ua_sess,
+		struct ltt_ust_session *usess,
+		struct ust_app *app)
+{
+	struct cds_lfht_node *ua_chan_node;
+	struct cds_lfht_iter iter;
+	struct ltt_ust_channel *uchan;
+	struct ust_app_channel *ua_chan;
+	time_t rawtime;
+	struct tm *timeinfo;
+	char datetime[16];
+	int ret;
+
+	/* Get date and time for unique app path */
+	time(&rawtime);
+	timeinfo = localtime(&rawtime);
+	strftime(datetime, sizeof(datetime), "%Y%m%d-%H%M%S", timeinfo);
+
+	DBG2("Shadow copy of session handle %d", ua_sess->handle);
+
+	ua_sess->uid = usess->uid;
+
+	ret = snprintf(ua_sess->path, PATH_MAX,
+			"%s/%s-%d-%s",
+			usess->pathname, app->name, app->key.pid,
+			datetime);
+	if (ret < 0) {
+		PERROR("asprintf UST shadow copy session");
+		/* TODO: We cannot return an error from here.. */
+		assert(0);
+	}
+
+	/* TODO: support all UST domain */
 
 	/* Iterate over all channels in global domain. */
-	hashtable_get_first(usess->domain_global.channels, &iter);
-	while ((node = hashtable_iter_get_node(&iter)) != NULL) {
-		uchan = caa_container_of(node, struct ltt_ust_channel, node);
+	cds_lfht_for_each_entry(usess->domain_global.channels, &iter,
+			uchan, node) {
+		struct cds_lfht_iter uiter;
+
+		ua_chan_node = hashtable_lookup(ua_sess->channels,
+				(void *)uchan->name, strlen(uchan->name),
+				&uiter);
+		if (ua_chan_node != NULL) {
+			continue;
+		}
+
+		DBG2("Channel %s not found on shadow session copy, creating it",
+				uchan->name);
+		ua_chan = alloc_ust_app_channel(uchan->name, &uchan->attr);
+		if (ua_chan == NULL) {
+			/* malloc failed... continuing */
+			continue;
+		}
+
+		shadow_copy_channel(ua_chan, uchan);
+		hashtable_add_unique(ua_sess->channels, &ua_chan->node);
+	}
+}
+
+/*
+ * Lookup sesison wrapper.
+ */
+static
+void __lookup_session_by_app(struct ltt_ust_session *usess,
+			struct ust_app *app, struct cds_lfht_iter *iter)
+{
+	/* Get right UST app session from app */
+	(void) hashtable_lookup(app->sessions,
+			(void *) ((unsigned long) usess->uid), sizeof(void *),
+			iter);
+}
+
+/*
+ * Return ust app session from the app session hashtable using the UST session
+ * uid.
+ */
+static struct ust_app_session *lookup_session_by_app(
+		struct ltt_ust_session *usess, struct ust_app *app)
+{
+	struct cds_lfht_iter iter;
+	struct cds_lfht_node *node;
+
+	__lookup_session_by_app(usess, app, &iter);
+	node = hashtable_iter_get_node(&iter);
+	if (node == NULL) {
+		goto error;
+	}
+
+	return caa_container_of(node, struct ust_app_session, node);
+
+error:
+	return NULL;
+}
+
+/*
+ * Create a UST session onto the tracer of app and add it the session
+ * hashtable.
+ *
+ * Return ust app session or NULL on error.
+ */
+static struct ust_app_session *create_ust_app_session(
+		struct ltt_ust_session *usess, struct ust_app *app)
+{
+	int ret;
+	struct ust_app_session *ua_sess;
+
+	ua_sess = lookup_session_by_app(usess, app);
+	if (ua_sess == NULL) {
+		DBG2("UST app pid: %d session uid %d not found, creating it",
+				app->key.pid, usess->uid);
+		ua_sess = alloc_ust_app_session();
+		if (ua_sess == NULL) {
+			/* Only malloc can failed so something is really wrong */
+			goto error;
+		}
+		shadow_copy_session(ua_sess, usess, app);
+	}
+
+	if (ua_sess->handle == -1) {
+		ret = ustctl_create_session(app->key.sock);
+		if (ret < 0) {
+			ERR("Error creating session for app pid %d, sock %d",
+					app->key.pid, app->key.sock);
+			/* TODO: free() ua_sess */
+			goto error;
+		}
+
+		DBG2("UST app ustctl create session handle %d", ret);
+		ua_sess->handle = ret;
+
+		/* Add ust app session to app's HT */
+		hashtable_node_init(&ua_sess->node,
+				(void *)((unsigned long) ua_sess->uid), sizeof(void *));
+		hashtable_add_unique(app->sessions, &ua_sess->node);
+
+		DBG2("UST app session created successfully with handle %d", ret);
+	}
+
+	return ua_sess;
+
+error:
+	return NULL;
+}
+
+/*
+ * Create a context for the channel on the tracer.
+ */
+static
+int create_ust_app_channel_context(struct ust_app_session *ua_sess,
+		struct ust_app_channel *ua_chan, struct lttng_ust_context *uctx,
+		struct ust_app *app)
+{
+	int ret = 0;
+	struct cds_lfht_iter iter;
+	struct cds_lfht_node *node;
+	struct ust_app_ctx *ua_ctx;
+
+	DBG2("UST app adding context to channel %s", ua_chan->name);
+
+	node = hashtable_lookup(ua_chan->ctx, (void *)((unsigned long)uctx->ctx),
+			sizeof(void *), &iter);
+	if (node != NULL) {
+		ret = -EEXIST;
+		goto error;
+	}
+
+	ua_ctx = alloc_ust_app_ctx(uctx);
+	if (ua_ctx == NULL) {
+		/* malloc failed */
+		ret = -1;
+		goto error;
+	}
+
+	hashtable_node_init(&ua_ctx->node,
+			(void *)((unsigned long) ua_ctx->ctx.ctx), sizeof(void *));
+	hashtable_add_unique(ua_chan->ctx, &ua_ctx->node);
+
+	ret = create_ust_channel_context(ua_chan, ua_ctx, app);
+	if (ret < 0) {
+		goto error;
+	}
+
+error:
+	return ret;
+}
+
+/*
+ * Create an UST context and enable it for the event on the tracer.
+ */
+static
+int create_ust_app_event_context(struct ust_app_session *ua_sess,
+		struct ust_app_event *ua_event, struct lttng_ust_context *uctx,
+		struct ust_app *app)
+{
+	int ret = 0;
+	struct cds_lfht_iter iter;
+	struct cds_lfht_node *node;
+	struct ust_app_ctx *ua_ctx;
+
+	DBG2("UST app adding context to event %s", ua_event->name);
+
+	node = hashtable_lookup(ua_event->ctx, (void *)((unsigned long)uctx->ctx),
+			sizeof(void *), &iter);
+	if (node != NULL) {
+		ret = -EEXIST;
+		goto error;
+	}
+
+	ua_ctx = alloc_ust_app_ctx(uctx);
+	if (ua_ctx == NULL) {
+		/* malloc failed */
+		ret = -1;
+		goto error;
+	}
+
+	hashtable_node_init(&ua_ctx->node,
+			(void *)((unsigned long) ua_ctx->ctx.ctx), sizeof(void *));
+	hashtable_add_unique(ua_event->ctx, &ua_ctx->node);
+
+	ret = create_ust_event_context(ua_event, ua_ctx, app);
+	if (ret < 0) {
+		goto error;
+	}
+
+error:
+	return ret;
+}
+
+/*
+ * Enable on the tracer side a ust app event for the session and channel.
+ */
+static
+int enable_ust_app_event(struct ust_app_session *ua_sess,
+		struct ust_app_event *ua_event, struct ust_app *app)
+{
+	int ret;
+
+	ret = enable_ust_event(app, ua_sess, ua_event);
+	if (ret < 0) {
+		goto error;
+	}
+
+	ua_event->enabled = 1;
+
+error:
+	return ret;
+}
+
+/*
+ * Disable on the tracer side a ust app event for the session and channel.
+ */
+static int disable_ust_app_event(struct ust_app_session *ua_sess,
+		struct ust_app_event *ua_event, struct ust_app *app)
+{
+	int ret;
+
+	ret = disable_ust_event(app, ua_sess, ua_event);
+	if (ret < 0) {
+		goto error;
+	}
+
+	ua_event->enabled = 0;
+
+error:
+	return ret;
+}
+
+/*
+ * Lookup ust app channel for session and disable it on the tracer side.
+ */
+static
+int disable_ust_app_channel(struct ust_app_session *ua_sess,
+		struct ust_app_channel *ua_chan, struct ust_app *app)
+{
+	int ret;
+
+	ret = disable_ust_channel(app, ua_sess, ua_chan);
+	if (ret < 0) {
+		goto error;
+	}
+
+	ua_chan->enabled = 0;
+
+error:
+	return ret;
+}
+
+/*
+ * Lookup ust app channel for session and enable it on the tracer side.
+ */
+static int enable_ust_app_channel(struct ust_app_session *ua_sess,
+		struct ltt_ust_channel *uchan, struct ust_app *app)
+{
+	int ret = 0;
+	struct cds_lfht_iter iter;
+	struct cds_lfht_node *ua_chan_node;
+	struct ust_app_channel *ua_chan;
+
+	ua_chan_node = hashtable_lookup(ua_sess->channels,
+			(void *)uchan->name, strlen(uchan->name), &iter);
+	if (ua_chan_node == NULL) {
+		DBG2("Unable to find channel %s in ust session uid %u",
+				uchan->name, ua_sess->uid);
+		goto error;
+	}
+
+	ua_chan = caa_container_of(ua_chan_node, struct ust_app_channel, node);
+
+	ret = enable_ust_channel(app, ua_sess, ua_chan);
+	if (ret < 0) {
+		goto error;
+	}
+
+error:
+	return ret;
+}
+
+/*
+ * Create UST app channel and create it on the tracer.
+ */
+static struct ust_app_channel *create_ust_app_channel(
+		struct ust_app_session *ua_sess, struct ltt_ust_channel *uchan,
+		struct ust_app *app)
+{
+	int ret = 0;
+	struct cds_lfht_iter iter;
+	struct cds_lfht_node *ua_chan_node;
+	struct ust_app_channel *ua_chan;
+
+	/* Lookup channel in the ust app session */
+	ua_chan_node = hashtable_lookup(ua_sess->channels,
+			(void *)uchan->name, strlen(uchan->name), &iter);
+	if (ua_chan_node == NULL) {
+		DBG2("Unable to find channel %s in ust session uid %u",
+				uchan->name, ua_sess->uid);
+		ua_chan = alloc_ust_app_channel(uchan->name, &uchan->attr);
+		if (ua_chan == NULL) {
+			goto error;
+		}
+		shadow_copy_channel(ua_chan, uchan);
+
+		hashtable_add_unique(ua_sess->channels, &ua_chan->node);
+	} else {
+		ua_chan = caa_container_of(ua_chan_node, struct ust_app_channel, node);
+	}
+
+	ret = create_ust_channel(app, ua_sess, ua_chan);
+	if (ret < 0) {
+		goto error;
+	}
+
+	return ua_chan;
+
+error:
+	return NULL;
+}
+
+/*
+ * Create UST app event and create it on the tracer side.
+ */
+static
+int create_ust_app_event(struct ust_app_session *ua_sess,
+		struct ust_app_channel *ua_chan, struct ltt_ust_event *uevent,
+		struct ust_app *app)
+{
+	int ret = 0;
+	struct cds_lfht_iter iter;
+	struct cds_lfht_node *ua_event_node;
+	struct ust_app_event *ua_event;
+
+	/* Get event node */
+	ua_event_node = hashtable_lookup(ua_chan->events,
+			(void *)uevent->attr.name, strlen(uevent->attr.name), &iter);
+	if (ua_event_node != NULL) {
+		ERR("UST app event %s already exist. Stopping creation.",
+				uevent->attr.name);
+		goto end;
+	}
+
+	/* Does not exist so create one */
+	ua_event = alloc_ust_app_event(uevent->attr.name, &uevent->attr);
+	if (ua_event == NULL) {
+		/* Only malloc can failed so something is really wrong */
+		ret = -ENOMEM;
+		goto error;
+	}
+	shadow_copy_event(ua_event, uevent);
+
+	/* Create it on the tracer side */
+	ret = create_ust_event(app, ua_sess, ua_chan, ua_event);
+	if (ret < 0) {
+		rcu_read_lock();
+		delete_ust_app_event(app->key.sock, ua_event);
+		rcu_read_unlock();
+		goto error;
+	}
+
+	ua_event->enabled = 1;
+
+	hashtable_add_unique(ua_chan->events, &ua_event->node);
+
+	DBG2("UST app create event %s for PID %d completed",
+			ua_event->name, app->key.pid);
+
+end:
+error:
+	return ret;
+}
+
+/*
+ * Create UST metadata and open it on the tracer side.
+ */
+static int create_ust_app_metadata(struct ust_app_session *ua_sess,
+		char *pathname, struct ust_app *app)
+{
+	int ret = 0;
+	mode_t old_umask;
+
+	if (ua_sess->metadata == NULL) {
+		/* Allocate UST metadata */
+		ua_sess->metadata = trace_ust_create_metadata(pathname);
+		if (ua_sess->metadata == NULL) {
+			ERR("UST app session %d creating metadata failed",
+					ua_sess->handle);
+			goto error;
+		}
+
+		ret = open_ust_metadata(app, ua_sess);
+		if (ret < 0) {
+			goto error;
+		}
+
+		DBG2("UST metadata opened for app pid %d", app->key.pid);
+	}
+
+	/* Open UST metadata stream */
+	if (ua_sess->metadata->stream_obj == NULL) {
+		ret = create_ust_stream(app, ua_sess);
+		if (ret < 0) {
+			goto error;
+		}
+
+		old_umask = umask(0);
+		ret = mkdir(ua_sess->path, S_IRWXU | S_IRWXG);
+		if (ret < 0) {
+			PERROR("mkdir UST metadata");
+			goto error;
+		}
+		umask(old_umask);
+
+		ret = snprintf(ua_sess->metadata->pathname, PATH_MAX,
+				"%s/metadata", ua_sess->path);
+		if (ret < 0) {
+			PERROR("asprintf UST create stream");
+			goto error;
+		}
+
+		DBG2("UST metadata stream object created for app pid %d",
+				app->key.pid);
+	} else {
+		ERR("Attempting to create stream without metadata opened");
+		goto error;
+	}
+
+	return 0;
+
+error:
+	return -1;
+}
+
+/*
+ * Return pointer to traceable apps list.
+ */
+struct cds_lfht *ust_app_get_ht(void)
+{
+	return ust_app_ht;
+}
+
+/*
+ * Return ust app pointer or NULL if not found.
+ */
+struct ust_app *ust_app_find_by_pid(pid_t pid)
+{
+	struct cds_lfht_node *node;
+	struct cds_lfht_iter iter;
+
+	rcu_read_lock();
+	node = hashtable_lookup(ust_app_ht,
+			(void *)((unsigned long) pid), sizeof(void *), &iter);
+	if (node == NULL) {
+		DBG2("UST app no found with pid %d", pid);
+		goto error;
+	}
+	rcu_read_unlock();
+
+	DBG2("Found UST app by pid %d", pid);
+
+	return caa_container_of(node, struct ust_app, node);
+
+error:
+	rcu_read_unlock();
+	return NULL;
+}
+
+/*
+ * Using pid and uid (of the app), allocate a new ust_app struct and
+ * add it to the global traceable app list.
+ *
+ * On success, return 0, else return malloc -ENOMEM, or -EINVAL if app
+ * bitness is not supported.
+ */
+int ust_app_register(struct ust_register_msg *msg, int sock)
+{
+	struct ust_app *lta;
+
+	if ((msg->bits_per_long == 64 && ust_consumerd64_fd == -EINVAL)
+			|| (msg->bits_per_long == 32 && ust_consumerd32_fd == -EINVAL)) {
+		ERR("Registration failed: application \"%s\" (pid: %d) has "
+			"%d-bit long, but no consumerd for this long size is available.\n",
+			msg->name, msg->pid, msg->bits_per_long);
+		close(sock);
+		return -EINVAL;
+	}
+	lta = zmalloc(sizeof(struct ust_app));
+	if (lta == NULL) {
+		PERROR("malloc");
+		return -ENOMEM;
+	}
+
+	lta->ppid = msg->ppid;
+	lta->uid = msg->uid;
+	lta->gid = msg->gid;
+	lta->bits_per_long = msg->bits_per_long;
+	lta->v_major = msg->major;
+	lta->v_minor = msg->minor;
+	strncpy(lta->name, msg->name, sizeof(lta->name));
+	lta->name[16] = '\0';
+	lta->sessions = hashtable_new(0);
+
+	/* Set key map */
+	lta->key.pid = msg->pid;
+	hashtable_node_init(&lta->node, (void *)((unsigned long)lta->key.pid),
+			sizeof(void *));
+	lta->key.sock = sock;
+	hashtable_node_init(&lta->key.node, (void *)((unsigned long)lta->key.sock),
+			sizeof(void *));
+
+	rcu_read_lock();
+	hashtable_add_unique(ust_app_sock_key_map, &lta->key.node);
+	hashtable_add_unique(ust_app_ht, &lta->node);
+	rcu_read_unlock();
+
+	DBG("App registered with pid:%d ppid:%d uid:%d gid:%d sock:%d name:%s"
+			" (version %d.%d)", lta->key.pid, lta->ppid, lta->uid, lta->gid,
+			lta->key.sock, lta->name, lta->v_major, lta->v_minor);
+
+	return 0;
+}
+
+/*
+ * Unregister app by removing it from the global traceable app list and freeing
+ * the data struct.
+ *
+ * The socket is already closed at this point so no close to sock.
+ */
+void ust_app_unregister(int sock)
+{
+	struct ust_app *lta;
+	struct cds_lfht_node *node;
+	struct cds_lfht_iter iter;
+	int ret;
+
+	rcu_read_lock();
+	lta = find_app_by_sock(sock);
+	if (lta == NULL) {
+		ERR("Unregister app sock %d not found!", sock);
+		goto error;
+	}
+
+	DBG("PID %d unregistering with sock %d", lta->key.pid, sock);
+
+	/* Get the node reference for a call_rcu */
+	node = hashtable_lookup(ust_app_ht,
+			(void *)((unsigned long) lta->key.pid), sizeof(void *), &iter);
+	if (node == NULL) {
+		ERR("Unable to find app sock %d by pid %d", sock, lta->key.pid);
+		goto error;
+	}
+
+	ret = hashtable_del(ust_app_ht, &iter);
+	assert(!ret);
+	call_rcu(&node->head, delete_ust_app_rcu);
+error:
+	rcu_read_unlock();
+	return;
+}
+
+/*
+ * Return traceable_app_count
+ */
+unsigned long ust_app_list_count(void)
+{
+	unsigned long count;
+
+	rcu_read_lock();
+	count = hashtable_get_count(ust_app_ht);
+	rcu_read_unlock();
+
+	return count;
+}
+
+/*
+ * Fill events array with all events name of all registered apps.
+ */
+int ust_app_list_events(struct lttng_event **events)
+{
+	int ret, handle;
+	size_t nbmem, count = 0;
+	struct cds_lfht_iter iter;
+	struct ust_app *app;
+	struct lttng_event *tmp;
+
+	nbmem = UST_APP_EVENT_LIST_SIZE;
+	tmp = zmalloc(nbmem * sizeof(struct lttng_event));
+	if (tmp == NULL) {
+		PERROR("zmalloc ust app events");
+		ret = -ENOMEM;
+		goto error;
+	}
+
+	rcu_read_lock();
+
+	cds_lfht_for_each_entry(ust_app_ht, &iter, app, node) {
+		struct lttng_ust_tracepoint_iter iter;
+
+		handle = ustctl_tracepoint_list(app->key.sock);
+		if (handle < 0) {
+			ERR("UST app list events getting handle failed for app pid %d",
+					app->key.pid);
+			continue;
+		}
+
+		while ((ret = ustctl_tracepoint_list_get(app->key.sock, handle,
+						&iter)) != -ENOENT) {
+			if (count >= nbmem) {
+				DBG2("Reallocating event list from %zu to %zu entries", nbmem,
+						2 * nbmem);
+				nbmem *= 2;
+				tmp = realloc(tmp, nbmem * sizeof(struct lttng_event));
+				if (tmp == NULL) {
+					PERROR("realloc ust app events");
+					ret = -ENOMEM;
+					goto rcu_error;
+				}
+			}
+			memcpy(tmp[count].name, iter.name, LTTNG_UST_SYM_NAME_LEN);
+			memcpy(tmp[count].loglevel, iter.loglevel, LTTNG_UST_SYM_NAME_LEN);
+			tmp[count].loglevel_value = iter.loglevel_value;
+			tmp[count].type = LTTNG_UST_TRACEPOINT;
+			tmp[count].pid = app->key.pid;
+			tmp[count].enabled = -1;
+			count++;
+		}
+	}
+
+	ret = count;
+	*events = tmp;
+
+	DBG2("UST app list events done (%zu events)", count);
+
+rcu_error:
+	rcu_read_unlock();
+error:
+	return ret;
+}
+
+/*
+ * Free and clean all traceable apps of the global list.
+ */
+void ust_app_clean_list(void)
+{
+	int ret;
+	struct cds_lfht_iter iter;
+	struct ust_app *app;
+
+	DBG2("UST app cleaning registered apps hash table");
+
+	rcu_read_lock();
+
+	cds_lfht_for_each_entry(ust_app_ht, &iter, app, node) {
+		ret = hashtable_del(ust_app_ht, &iter);
+		assert(!ret);
+		call_rcu(&iter.node->head, delete_ust_app_rcu);
+	}
+
+	hashtable_destroy(ust_app_ht);
+	hashtable_destroy(ust_app_sock_key_map);
+
+	rcu_read_unlock();
+}
+
+/*
+ * Init UST app hash table.
+ */
+void ust_app_ht_alloc(void)
+{
+	ust_app_ht = hashtable_new(0);
+	ust_app_sock_key_map = hashtable_new(0);
+}
+
+/*
+ * For a specific UST session, disable the channel for all registered apps.
+ */
+int ust_app_disable_channel_glb(struct ltt_ust_session *usess,
+		struct ltt_ust_channel *uchan)
+{
+	int ret = 0;
+	struct cds_lfht_iter iter;
+	struct cds_lfht_node *ua_chan_node;
+	struct ust_app *app;
+	struct ust_app_session *ua_sess;
+	struct ust_app_channel *ua_chan;
+
+	if (usess == NULL || uchan == NULL) {
+		ERR("Disabling UST global channel with NULL values");
+		ret = -1;
+		goto error;
+	}
+
+	DBG2("UST app disabling channel %s from global domain for session uid %d",
+			uchan->name, usess->uid);
+
+	rcu_read_lock();
+
+	/* For every registered applications */
+	cds_lfht_for_each_entry(ust_app_ht, &iter, app, node) {
+		ua_sess = lookup_session_by_app(usess, app);
+		if (ua_sess == NULL) {
+			continue;
+		}
+
+		/* Get channel */
+		ua_chan_node = hashtable_lookup(ua_sess->channels,
+				(void *)uchan->name, strlen(uchan->name), &iter);
+		/* If the session if found for the app, the channel must be there */
+		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);
+
+		/* Disable channel onto application */
+		ret = disable_ust_app_channel(ua_sess, ua_chan, app);
+		if (ret < 0) {
+			/* XXX: We might want to report this error at some point... */
+			continue;
+		}
+	}
+
+	rcu_read_unlock();
+
+error:
+	return ret;
+}
+
+/*
+ * For a specific UST session, enable the channel for all registered apps.
+ */
+int ust_app_enable_channel_glb(struct ltt_ust_session *usess,
+		struct ltt_ust_channel *uchan)
+{
+	int ret = 0;
+	struct cds_lfht_iter iter;
+	struct ust_app *app;
+	struct ust_app_session *ua_sess;
+
+	if (usess == NULL || uchan == NULL) {
+		ERR("Adding UST global channel to NULL values");
+		ret = -1;
+		goto error;
+	}
+
+	DBG2("UST app enabling channel %s to global domain for session uid %d",
+			uchan->name, usess->uid);
+
+	rcu_read_lock();
+
+	/* For every registered applications */
+	cds_lfht_for_each_entry(ust_app_ht, &iter, app, node) {
+		ua_sess = lookup_session_by_app(usess, app);
+		if (ua_sess == NULL) {
+			continue;
+		}
+
+		/* Enable channel onto application */
+		ret = enable_ust_app_channel(ua_sess, uchan, app);
+		if (ret < 0) {
+			/* XXX: We might want to report this error at some point... */
+			continue;
+		}
+	}
+
+	rcu_read_unlock();
+
+error:
+	return ret;
+}
+
+/*
+ * Disable an event in a channel and for a specific session.
+ */
+int ust_app_disable_event_glb(struct ltt_ust_session *usess,
+		struct ltt_ust_channel *uchan, struct ltt_ust_event *uevent)
+{
+	int ret = 0;
+	struct cds_lfht_iter iter, uiter;
+	struct cds_lfht_node *ua_chan_node, *ua_event_node;
+	struct ust_app *app;
+	struct ust_app_session *ua_sess;
+	struct ust_app_channel *ua_chan;
+	struct ust_app_event *ua_event;
+
+	DBG("UST app disabling event %s for all apps in channel "
+			"%s for session uid %d", uevent->attr.name, uchan->name, usess->uid);
+
+	rcu_read_lock();
+
+	/* For all registered applications */
+	cds_lfht_for_each_entry(ust_app_ht, &iter, app, node) {
+		ua_sess = lookup_session_by_app(usess, app);
+		if (ua_sess == NULL) {
+			/* Next app */
+			continue;
+		}
 
+		/* Lookup channel in the ust app session */
 		ua_chan_node = hashtable_lookup(ua_sess->channels,
-				(void *) uchan->name, strlen(uchan->name), &iter);
+				(void *)uchan->name, strlen(uchan->name), &uiter);
 		if (ua_chan_node == NULL) {
-			DBG2("Channel %s not found on shallow session copy, creating it",
-					uchan->name);
-			ua_chan = alloc_app_channel(uchan->name);
-			if (ua_chan == NULL) {
-				/* malloc failed... continuing */
+			DBG2("Channel %s not found in session uid %d for app pid %d."
+					"Skipping", uchan->name, usess->uid, app->key.pid);
+			continue;
+		}
+		ua_chan = caa_container_of(ua_chan_node, struct ust_app_channel, node);
+
+		ua_event_node = hashtable_lookup(ua_chan->events,
+				(void *)uevent->attr.name, strlen(uevent->attr.name), &uiter);
+		if (ua_event_node == NULL) {
+			DBG2("Event %s not found in channel %s for app pid %d."
+					"Skipping", uevent->attr.name, uchan->name, app->key.pid);
+			continue;
+		}
+		ua_event = caa_container_of(ua_event_node, struct ust_app_event, node);
+
+		ret = disable_ust_app_event(ua_sess, ua_event, app);
+		if (ret < 0) {
+			/* XXX: Report error someday... */
+			continue;
+		}
+	}
+
+	rcu_read_unlock();
+
+	return ret;
+}
+
+/*
+ * For a specific UST session and UST channel, the event for all
+ * registered apps.
+ */
+int ust_app_disable_all_event_glb(struct ltt_ust_session *usess,
+		struct ltt_ust_channel *uchan)
+{
+	int ret = 0;
+	struct cds_lfht_iter iter, uiter;
+	struct cds_lfht_node *ua_chan_node;
+	struct ust_app *app;
+	struct ust_app_session *ua_sess;
+	struct ust_app_channel *ua_chan;
+	struct ust_app_event *ua_event;
+
+	DBG("UST app disabling all event for all apps in channel "
+			"%s for session uid %d", uchan->name, usess->uid);
+
+	rcu_read_lock();
+
+	/* For all registered applications */
+	cds_lfht_for_each_entry(ust_app_ht, &iter, app, node) {
+		ua_sess = lookup_session_by_app(usess, app);
+		/* If ua_sess is NULL, there is a code flow error */
+		assert(ua_sess);
+
+		/* Lookup channel in the ust app session */
+		ua_chan_node = hashtable_lookup(ua_sess->channels, (void *)uchan->name,
+				strlen(uchan->name), &uiter);
+		/* If the channel is not found, there is a code flow error */
+		assert(ua_chan_node);
+
+		ua_chan = caa_container_of(ua_chan_node, struct ust_app_channel, node);
+
+		/* Disable each events of channel */
+		cds_lfht_for_each_entry(ua_chan->events, &uiter, ua_event, node) {
+			ret = disable_ust_app_event(ua_sess, ua_event, app);
+			if (ret < 0) {
+				/* XXX: Report error someday... */
+				continue;
+			}
+		}
+	}
+
+	rcu_read_unlock();
+
+	return ret;
+}
+
+/*
+ * For a specific UST session, create the channel for all registered apps.
+ */
+int ust_app_create_channel_glb(struct ltt_ust_session *usess,
+		struct ltt_ust_channel *uchan)
+{
+	int ret = 0;
+	struct cds_lfht_iter iter;
+	struct ust_app *app;
+	struct ust_app_session *ua_sess;
+	struct ust_app_channel *ua_chan;
+
+	if (usess == NULL || uchan == NULL) {
+		ERR("Adding UST global channel to NULL values");
+		ret = -1;
+		goto error;
+	}
+
+	DBG2("UST app adding channel %s to global domain for session uid %d",
+			uchan->name, usess->uid);
+
+	rcu_read_lock();
+
+	/* For every registered applications */
+	cds_lfht_for_each_entry(ust_app_ht, &iter, app, node) {
+		/*
+		 * Create session on the tracer side and add it to app session HT. Note
+		 * that if session exist, it will simply return a pointer to the ust
+		 * app session.
+		 */
+		ua_sess = create_ust_app_session(usess, app);
+		if (ua_sess == NULL) {
+			continue;
+		}
+
+		/* Create channel onto application */
+		ua_chan = create_ust_app_channel(ua_sess, uchan, app);
+		if (ua_chan == NULL) {
+			continue;
+		}
+	}
+
+	rcu_read_unlock();
+
+error:
+	return ret;
+}
+
+/*
+ * Enable event for a specific session and channel on the tracer.
+ */
+int ust_app_enable_event_glb(struct ltt_ust_session *usess,
+		struct ltt_ust_channel *uchan, struct ltt_ust_event *uevent)
+{
+	int ret = 0;
+	struct cds_lfht_iter iter, uiter;
+	struct cds_lfht_node *ua_chan_node, *ua_event_node;
+	struct ust_app *app;
+	struct ust_app_session *ua_sess;
+	struct ust_app_channel *ua_chan;
+	struct ust_app_event *ua_event;
+
+	DBG("UST app enabling event %s for all apps for session uid %d",
+			uevent->attr.name, usess->uid);
+
+	/*
+	 * NOTE: At this point, this function is called only if the session and
+	 * channel passed are already created for all apps. and enabled on the
+	 * tracer also.
+	 */
+
+	rcu_read_lock();
+
+	/* For all registered applications */
+	cds_lfht_for_each_entry(ust_app_ht, &iter, app, node) {
+		ua_sess = lookup_session_by_app(usess, app);
+		/* If ua_sess is NULL, there is a code flow error */
+		assert(ua_sess);
+
+		/* Lookup channel in the ust app session */
+		ua_chan_node = hashtable_lookup(ua_sess->channels, (void *)uchan->name,
+				strlen(uchan->name), &uiter);
+		/* If the channel is not found, there is a code flow error */
+		assert(ua_chan_node);
+
+		ua_chan = caa_container_of(ua_chan_node, struct ust_app_channel, node);
+
+		ua_event_node = hashtable_lookup(ua_chan->events,
+				(void*)uevent->attr.name, strlen(uevent->attr.name), &uiter);
+		if (ua_event_node == NULL) {
+			DBG3("UST app enable event %s not found for app PID %d."
+					"Skipping app", uevent->attr.name, app->key.pid);
+			continue;
+		}
+		ua_event = caa_container_of(ua_event_node, struct ust_app_event, node);
+
+		ret = enable_ust_app_event(ua_sess, ua_event, app);
+		if (ret < 0) {
+			goto error;
+		}
+	}
+
+error:
+	rcu_read_unlock();
+	return ret;
+}
+
+/*
+ * For a specific existing UST session and UST channel, creates the event for
+ * all registered apps.
+ */
+int ust_app_create_event_glb(struct ltt_ust_session *usess,
+		struct ltt_ust_channel *uchan, struct ltt_ust_event *uevent)
+{
+	int ret = 0;
+	struct cds_lfht_iter iter, uiter;
+	struct cds_lfht_node *ua_chan_node;
+	struct ust_app *app;
+	struct ust_app_session *ua_sess;
+	struct ust_app_channel *ua_chan;
+
+	DBG("UST app creating event %s for all apps for session uid %d",
+			uevent->attr.name, usess->uid);
+
+	/*
+	 * NOTE: At this point, this function is called only if the session and
+	 * channel passed are already created for all apps. and enabled on the
+	 * tracer also.
+	 */
+
+	rcu_read_lock();
+
+	/* For all registered applications */
+	cds_lfht_for_each_entry(ust_app_ht, &iter, app, node) {
+		ua_sess = lookup_session_by_app(usess, app);
+		/* If ua_sess is NULL, there is a code flow error */
+		assert(ua_sess);
+
+		/* Lookup channel in the ust app session */
+		ua_chan_node = hashtable_lookup(ua_sess->channels, (void *)uchan->name,
+				strlen(uchan->name), &uiter);
+		/* If the channel is not found, there is a code flow error */
+		assert(ua_chan_node);
+
+		ua_chan = caa_container_of(ua_chan_node, struct ust_app_channel, node);
+
+		ret = create_ust_app_event(ua_sess, ua_chan, uevent, app);
+		if (ret < 0) {
+			continue;
+		}
+	}
+
+	rcu_read_unlock();
+
+	return ret;
+}
+
+/*
+ * Start tracing for a specific UST session and app.
+ */
+int ust_app_start_trace(struct ltt_ust_session *usess, struct ust_app *app)
+{
+	int ret = 0;
+	struct cds_lfht_iter iter;
+	struct ust_app_session *ua_sess;
+	struct ust_app_channel *ua_chan;
+	struct ltt_ust_stream *ustream;
+	int consumerd_fd;
+
+	DBG("Starting tracing for ust app pid %d", app->key.pid);
+
+	rcu_read_lock();
+
+	ua_sess = lookup_session_by_app(usess, app);
+	if (ua_sess == NULL) {
+		goto error_rcu_unlock;
+	}
+
+	/* Upon restart, we skip the setup, already done */
+	if (ua_sess->started) {
+		goto skip_setup;
+	}
+
+	ret = create_ust_app_metadata(ua_sess, usess->pathname, app);
+	if (ret < 0) {
+		goto error_rcu_unlock;
+	}
+
+	/* For each channel */
+	cds_lfht_for_each_entry(ua_sess->channels, &iter, ua_chan, node) {
+		/* Create all streams */
+		while (1) {
+			/* Create UST stream */
+			ustream = zmalloc(sizeof(*ustream));
+			if (ustream == NULL) {
+				PERROR("zmalloc ust stream");
+				goto error_rcu_unlock;
+			}
+
+			ret = ustctl_create_stream(app->key.sock, ua_chan->obj,
+					&ustream->obj);
+			if (ret < 0) {
+				/* Got all streams */
+				break;
+			}
+			ustream->handle = ustream->obj->handle;
+
+			/* Order is important */
+			cds_list_add_tail(&ustream->list, &ua_chan->streams.head);
+			ret = snprintf(ustream->pathname, PATH_MAX, "%s/%s_%u",
+					ua_sess->path, ua_chan->name,
+					ua_chan->streams.count++);
+			if (ret < 0) {
+				PERROR("asprintf UST create stream");
 				continue;
 			}
-			hashtable_add_unique(ua_sess->channels, &ua_chan->node);
-		} else {
-			ua_chan = caa_container_of(node, struct ust_app_channel, node);
+			DBG2("UST stream %d ready at %s", ua_chan->streams.count,
+					ustream->pathname);
 		}
+	}
 
-		shallow_copy_channel(ua_chan, uchan);
+	switch (app->bits_per_long) {
+	case 64:
+		consumerd_fd = ust_consumerd64_fd;
+		break;
+	case 32:
+		consumerd_fd = ust_consumerd32_fd;
+		break;
+	default:
+		ret = -EINVAL;
+		goto error_rcu_unlock;
+	}
 
-		/* Next item in hash table */
-		hashtable_get_next(usess->domain_global.channels, &iter);
+	/* Setup UST consumer socket and send fds to it */
+	ret = ust_consumer_send_session(consumerd_fd, ua_sess);
+	if (ret < 0) {
+		goto error_rcu_unlock;
 	}
+	ua_sess->started = 1;
+
+skip_setup:
+	/* This start the UST tracing */
+	ret = ustctl_start_session(app->key.sock, ua_sess->handle);
+	if (ret < 0) {
+		ERR("Error starting tracing for app pid: %d", app->key.pid);
+		goto error_rcu_unlock;
+	}
+
+	rcu_read_unlock();
+
+	/* Quiescent wait after starting trace */
+	ustctl_wait_quiescent(app->key.sock);
+
+	return 0;
+
+error_rcu_unlock:
+	rcu_read_unlock();
+	return -1;
 }
 
-static struct ust_app_session *lookup_session_by_app(
-		struct ltt_ust_session *usess, struct ust_app *app)
+/*
+ * Stop tracing for a specific UST session and app.
+ */
+int ust_app_stop_trace(struct ltt_ust_session *usess, struct ust_app *app)
+{
+	int ret = 0;
+	struct cds_lfht_iter iter;
+	struct ust_app_session *ua_sess;
+	struct ust_app_channel *ua_chan;
+
+	DBG("Stopping tracing for ust app pid %d", app->key.pid);
+
+	rcu_read_lock();
+
+	ua_sess = lookup_session_by_app(usess, app);
+	if (ua_sess == NULL) {
+		/* Only malloc can failed so something is really wrong */
+		goto error_rcu_unlock;
+	}
+
+	cds_lfht_for_each_entry(ua_sess->channels, &iter, ua_chan, node) {
+		ret = ustctl_sock_flush_buffer(app->key.sock, ua_chan->obj);
+		if (ret < 0) {
+			ERR("UST app PID %d channel %s flush failed",
+					app->key.pid, ua_chan->name);
+			ERR("Ended with ret %d", ret);
+			/* Continuing flushing all buffers */
+			continue;
+		}
+	}
+
+	/* This inhibits UST tracing */
+	ret = ustctl_stop_session(app->key.sock, ua_sess->handle);
+	if (ret < 0) {
+		ERR("Error stopping tracing for app pid: %d", app->key.pid);
+		goto error_rcu_unlock;
+	}
+
+	rcu_read_unlock();
+
+	/* Quiescent wait after stopping trace */
+	ustctl_wait_quiescent(app->key.sock);
+
+	/* Flush all buffers before stopping */
+	ret = ustctl_sock_flush_buffer(app->key.sock, ua_sess->metadata->obj);
+	if (ret < 0) {
+		ERR("UST app PID %d metadata flush failed", app->key.pid);
+		ERR("Ended with ret %d", ret);
+	}
+
+	return 0;
+
+error_rcu_unlock:
+	rcu_read_unlock();
+	return -1;
+}
+
+/*
+ * Destroy a specific UST session in apps.
+ */
+int ust_app_destroy_trace(struct ltt_ust_session *usess, struct ust_app *app)
 {
+	struct ust_app_session *ua_sess;
+	struct lttng_ust_object_data obj;
 	struct cds_lfht_iter iter;
 	struct cds_lfht_node *node;
+	int ret;
 
-	/* Get right UST app session from app */
-	node = hashtable_lookup(app->sessions,
-			(void *) ((unsigned long) usess->uid),
-			sizeof(void *), &iter);
+	DBG("Destroy tracing for ust app pid %d", app->key.pid);
+
+	rcu_read_lock();
+
+	__lookup_session_by_app(usess, app, &iter);
+	node = hashtable_iter_get_node(&iter);
 	if (node == NULL) {
-		goto error;
+		/* Only malloc can failed so something is really wrong */
+		goto error_rcu_unlock;
 	}
+	ua_sess = caa_container_of(node, struct ust_app_session, node);
+	ret = hashtable_del(app->sessions, &iter);
+	assert(!ret);
+	delete_ust_app_session(app->key.sock, ua_sess);
+	obj.handle = ua_sess->handle;
+	obj.shm_fd = -1;
+	obj.wait_fd = -1;
+	obj.memory_map_size = 0;
+	ustctl_release_object(app->key.sock, &obj);
 
-	return caa_container_of(node, struct ust_app_session, node);
+	rcu_read_unlock();
 
-error:
-	return NULL;
+	/* Quiescent wait after stopping trace */
+	ustctl_wait_quiescent(app->key.sock);
+
+	return 0;
+
+error_rcu_unlock:
+	rcu_read_unlock();
+	return -1;
 }
 
-int ust_app_add_channel(struct ltt_ust_session *usess,
-		struct ltt_ust_channel *uchan)
+/*
+ * Start tracing for the UST session.
+ */
+int ust_app_start_trace_all(struct ltt_ust_session *usess)
 {
 	int ret = 0;
 	struct cds_lfht_iter iter;
-	struct cds_lfht_node *node, *ua_chan_node;
 	struct ust_app *app;
-	struct ust_app_session *ua_sess;
-	struct ust_app_channel *ua_chan;
 
-	DBG2("UST app adding channel %s to global domain for session uid %d",
-			uchan->name, usess->uid);
+	DBG("Starting all UST traces");
 
 	rcu_read_lock();
-	hashtable_get_first(ust_app_ht, &iter);
-	while ((node = hashtable_iter_get_node(&iter)) != NULL) {
-		app = caa_container_of(node, struct ust_app, node);
 
-		ua_sess = lookup_session_by_app(usess, app);
-		if (ua_sess == NULL) {
-			DBG2("UST app pid: %d session uid %d not found, creating one",
-					app->key.pid, usess->uid);
-			ua_sess = alloc_app_session();
-			if (ua_sess == NULL) {
-				/* Only malloc can failed so something is really wrong */
-				goto next;
-			}
-			shallow_copy_session(ua_sess, usess);
+	cds_lfht_for_each_entry(ust_app_ht, &iter, app, node) {
+		ret = ust_app_start_trace(usess, app);
+		if (ret < 0) {
+			/* Continue to next apps even on error */
+			continue;
 		}
+	}
 
-		if (ua_sess->handle == -1) {
-			ret = ustctl_create_session(app->key.sock);
-			if (ret < 0) {
-				DBG("Error creating session for app pid %d, sock %d",
-						app->key.pid, app->key.sock);
-				/* TODO: free() ua_sess */
-				goto next;
-			}
+	rcu_read_unlock();
 
-			DBG2("UST app ustctl create session handle %d", ret);
-			ua_sess->handle = ret;
+	return 0;
+}
 
-			/* Add ust app session to app's HT */
-			hashtable_node_init(&ua_sess->node,
-					(void *)((unsigned long) ua_sess->uid), sizeof(void *));
-			hashtable_add_unique(app->sessions, &ua_sess->node);
-		}
+/*
+ * Start tracing for the UST session.
+ */
+int ust_app_stop_trace_all(struct ltt_ust_session *usess)
+{
+	int ret = 0;
+	struct cds_lfht_iter iter;
+	struct ust_app *app;
 
-		/* Lookup channel in the ust app session */
-		ua_chan_node = hashtable_lookup(ua_sess->channels,
-				(void *) uchan->name, strlen(uchan->name), &iter);
-		if (ua_chan_node == NULL) {
-			ERR("Channel suppose to be present with the above shallow "
-					"session copy. Continuing...");
-			goto next;
-		}
+	DBG("Stopping all UST traces");
 
-		ua_chan = caa_container_of(ua_chan_node, struct ust_app_channel, node);
+	rcu_read_lock();
 
-		/* TODO: remove cast and use lttng-ust-abi.h */
-		ret = ustctl_create_channel(app->key.sock, ua_sess->handle,
-				(struct lttng_ust_channel_attr *)&uchan->attr, &ua_chan->obj);
+	cds_lfht_for_each_entry(ust_app_ht, &iter, app, node) {
+		ret = ust_app_stop_trace(usess, app);
 		if (ret < 0) {
-			DBG("Error creating channel %s for app (pid: %d, sock: %d) "
-					"and session handle %d with ret %d",
-					uchan->name, app->key.pid, app->key.sock,
-					ua_sess->handle, ret);
-			goto next;
+			/* Continue to next apps even on error */
+			continue;
 		}
+	}
+
+	rcu_read_unlock();
+
+	return 0;
+}
+
+/*
+ * Destroy app UST session.
+ */
+int ust_app_destroy_trace_all(struct ltt_ust_session *usess)
+{
+	int ret = 0;
+	struct cds_lfht_iter iter;
+	struct ust_app *app;
 
-		ua_chan->handle = ua_chan->obj->handle;
-		ua_chan->attr.shm_fd = ua_chan->obj->shm_fd;
-		ua_chan->attr.wait_fd = ua_chan->obj->wait_fd;
-		ua_chan->attr.memory_map_size = ua_chan->obj->memory_map_size;
+	DBG("Destroy all UST traces");
 
-		DBG2("Channel %s UST create successfully for pid:%d and sock:%d",
-				uchan->name, app->key.pid, app->key.sock);
+	rcu_read_lock();
 
-next:
-		/* Next applications */
-		hashtable_get_next(ust_app_ht, &iter);
+	cds_lfht_for_each_entry(ust_app_ht, &iter, app, node) {
+		ret = ust_app_destroy_trace(usess, app);
+		if (ret < 0) {
+			/* Continue to next apps even on error */
+			continue;
+		}
 	}
+
 	rcu_read_unlock();
 
-	return ret;
+	return 0;
 }
 
-int ust_app_add_event(struct ltt_ust_session *usess,
-		struct ltt_ust_channel *uchan, struct ltt_ust_event *uevent)
+/*
+ * Add channels/events from UST global domain to registered apps at sock.
+ */
+void ust_app_global_update(struct ltt_ust_session *usess, int sock)
 {
 	int ret = 0;
 	struct cds_lfht_iter iter;
-	struct cds_lfht_node *node, *ua_chan_node, *ua_event_node;
 	struct ust_app *app;
 	struct ust_app_session *ua_sess;
 	struct ust_app_channel *ua_chan;
 	struct ust_app_event *ua_event;
-	struct lttng_ust_event ltt_uevent;
-	struct lttng_ust_object_data *obj_event;
 
-	DBG2("UST app adding event %s to global domain for session uid %d",
-			uevent->attr.name, usess->uid);
+	if (usess == NULL) {
+		ERR("No UST session on global update. Returning");
+		goto error;
+	}
+
+	DBG2("UST app global update for app sock %d for session uid %d", sock,
+			usess->uid);
 
 	rcu_read_lock();
-	hashtable_get_first(ust_app_ht, &iter);
-	while ((node = hashtable_iter_get_node(&iter)) != NULL) {
-		app = caa_container_of(node, struct ust_app, node);
 
-		ua_sess = lookup_session_by_app(usess, app);
-		if (ua_sess == NULL) {
-			DBG2("UST app (pid: %d, sock: %d) session not found, creating one",
-					app->key.pid, app->key.sock);
-			ua_sess = alloc_app_session();
-			if (ua_sess == NULL) {
-				/* Only malloc can failed so something is really wrong */
-				goto next;
-			}
-			shallow_copy_session(ua_sess, usess);
+	app = find_app_by_sock(sock);
+	if (app == NULL) {
+		ERR("Failed to update app sock %d", sock);
+		goto error;
+	}
+
+	ua_sess = create_ust_app_session(usess, app);
+	if (ua_sess == NULL) {
+		goto error;
+	}
+
+	/*
+	 * We can iterate safely here over all UST app session sicne the create ust
+	 * app session above made a shadow copy of the UST global domain from the
+	 * ltt ust session.
+	 */
+	cds_lfht_for_each_entry(ua_sess->channels, &iter, ua_chan, node) {
+		ret = create_ust_channel(app, ua_sess, ua_chan);
+		if (ret < 0) {
+			/* FIXME: Should we quit here or continue... */
+			continue;
 		}
 
-		if (ua_sess->handle == -1) {
-			ret = ustctl_create_session(app->key.sock);
+		/* For each events */
+		cds_lfht_for_each_entry(ua_chan->events, &iter, ua_event, node) {
+			ret = create_ust_event(app, ua_sess, ua_chan, ua_event);
 			if (ret < 0) {
-				DBG("Error creating session for app pid %d, sock %d",
-						app->key.pid, app->key.sock);
-				/* TODO: free() ua_sess */
-				goto next;
+				/* FIXME: Should we quit here or continue... */
+				continue;
 			}
+		}
+	}
+
+	if (usess->start_trace) {
+		ret = ust_app_start_trace(usess, app);
+		if (ret < 0) {
+			goto error;
+		}
+
+		DBG2("UST trace started for app pid %d", app->key.pid);
+	}
+
+error:
+	rcu_read_unlock();
+	return;
+}
+
+/*
+ * Add context to a specific channel for global UST domain.
+ */
+int ust_app_add_ctx_channel_glb(struct ltt_ust_session *usess,
+		struct ltt_ust_channel *uchan, struct ltt_ust_context *uctx)
+{
+	int ret = 0;
+	struct cds_lfht_node *ua_chan_node;
+	struct cds_lfht_iter iter, uiter;
+	struct ust_app_channel *ua_chan = NULL;
+	struct ust_app_session *ua_sess;
+	struct ust_app *app;
+
+	rcu_read_lock();
 
-			DBG2("UST app ustctl create session handle %d", ret);
-			ua_sess->handle = ret;
-			/* Add ust app session to app's HT */
-			hashtable_node_init(&ua_sess->node,
-					(void *)((unsigned long) ua_sess->uid), sizeof(void *));
-			hashtable_add_unique(app->sessions, &ua_sess->node);
+	cds_lfht_for_each_entry(ust_app_ht, &iter, app, node) {
+		ua_sess = lookup_session_by_app(usess, app);
+		if (ua_sess == NULL) {
+			continue;
 		}
 
 		/* Lookup channel in the ust app session */
 		ua_chan_node = hashtable_lookup(ua_sess->channels,
-				(void *) uchan->name, strlen(uchan->name), &iter);
+				(void *)uchan->name, strlen(uchan->name), &uiter);
 		if (ua_chan_node == NULL) {
-			ERR("Channel suppose to be present with the above shallow "
-					"session copy. Continuing...");
-			goto next;
+			continue;
 		}
+		ua_chan = caa_container_of(ua_chan_node, struct ust_app_channel,
+				node);
 
-		ua_chan = caa_container_of(ua_chan_node, struct ust_app_channel, node);
+		ret = create_ust_app_channel_context(ua_sess, ua_chan, &uctx->ctx, app);
+		if (ret < 0) {
+			continue;
+		}
+	}
 
-		/* Prepare lttng ust event */
-		strncpy(ltt_uevent.name, uevent->attr.name, sizeof(ltt_uevent.name));
-		ltt_uevent.name[sizeof(ltt_uevent.name) - 1] = '\0';
-		/* TODO: adjust to other instrumentation types */
-		ltt_uevent.instrumentation = LTTNG_UST_TRACEPOINT;
+	rcu_read_unlock();
+	return ret;
+}
 
-		/* Get event node */
-		ua_event_node = hashtable_lookup(ua_chan->events,
-				(void *) uevent->attr.name, strlen(uevent->attr.name), &iter);
-		if (ua_event_node == NULL) {
-			DBG2("UST app event %s not found, creating one", uevent->attr.name);
-			/* Does not exist so create one */
-			ua_event = alloc_app_event(uevent->attr.name);
-			if (ua_event == NULL) {
-				/* Only malloc can failed so something is really wrong */
-				goto next;
-			}
+/*
+ * Add context to a specific event in a channel for global UST domain.
+ */
+int ust_app_add_ctx_event_glb(struct ltt_ust_session *usess,
+		struct ltt_ust_channel *uchan, struct ltt_ust_event *uevent,
+		struct ltt_ust_context *uctx)
+{
+	int ret = 0;
+	struct cds_lfht_node *ua_chan_node, *ua_event_node;
+	struct cds_lfht_iter iter, uiter;
+	struct ust_app_session *ua_sess;
+	struct ust_app_event *ua_event;
+	struct ust_app_channel *ua_chan = NULL;
+	struct ust_app *app;
 
-			shallow_copy_event(ua_event, uevent);
+	rcu_read_lock();
 
-			/* Create UST event on tracer */
-			ret = ustctl_create_event(app->key.sock, &ltt_uevent, ua_chan->obj,
-					&obj_event);
-			if (ret < 0) {
-				ERR("Error ustctl create event %s for app pid: %d with ret %d",
-						uevent->attr.name, app->key.pid, ret);
-				/* TODO: free() ua_event and obj_event */
-				goto next;
-			}
-			ua_event->obj = obj_event;
-			ua_event->handle = obj_event->handle;
-			ua_event->enabled = 1;
-		} else {
-			ua_event = caa_container_of(ua_event_node,
-					struct ust_app_event, node);
-
-			if (ua_event->enabled == 0) {
-				ret = ustctl_enable(app->key.sock, ua_event->obj);
-				if (ret < 0) {
-					ERR("Error ustctl enable event %s for app "
-							"pid: %d with ret %d", uevent->attr.name,
-							app->key.pid, ret);
-					goto next;
-				}
-				ua_event->enabled = 1;
-			}
+	cds_lfht_for_each_entry(ust_app_ht, &iter, app, node) {
+		ua_sess = lookup_session_by_app(usess, app);
+		if (ua_sess == NULL) {
+			continue;
 		}
 
-		hashtable_add_unique(ua_chan->events, &ua_event->node);
+		/* Lookup channel in the ust app session */
+		ua_chan_node = hashtable_lookup(ua_sess->channels,
+				(void *)uchan->name, strlen(uchan->name), &uiter);
+		if (ua_chan_node == NULL) {
+			continue;
+		}
+		ua_chan = caa_container_of(ua_chan_node, struct ust_app_channel,
+				node);
 
-		DBG2("Event %s UST create successfully for pid:%d", uevent->attr.name,
-				app->key.pid);
+		ua_event_node = hashtable_lookup(ua_chan->events,
+				(void *)uevent->attr.name, strlen(uevent->attr.name), &uiter);
+		if (ua_event_node == NULL) {
+			continue;
+		}
+		ua_event = caa_container_of(ua_event_node, struct ust_app_event,
+				node);
 
-next:
-		/* Next applications */
-		hashtable_get_next(ust_app_ht, &iter);
+		ret = create_ust_app_event_context(ua_sess, ua_event, &uctx->ctx, app);
+		if (ret < 0) {
+			continue;
+		}
 	}
-	rcu_read_unlock();
 
+	rcu_read_unlock();
 	return ret;
 }
 
-int ust_app_start_trace(struct ltt_ust_session *usess)
+/*
+ * Enable event for a channel from a UST session for a specific PID.
+ */
+int ust_app_enable_event_pid(struct ltt_ust_session *usess,
+		struct ltt_ust_channel *uchan, struct ltt_ust_event *uevent, pid_t pid)
 {
 	int ret = 0;
 	struct cds_lfht_iter iter;
-	struct cds_lfht_node *node, *ua_chan_node;
+	struct cds_lfht_node *ua_chan_node, *ua_event_node;
 	struct ust_app *app;
 	struct ust_app_session *ua_sess;
 	struct ust_app_channel *ua_chan;
-	struct lttng_ust_channel_attr uattr;
-	struct ltt_ust_channel *uchan;
-
-	rcu_read_lock();
-	hashtable_get_first(ust_app_ht, &iter);
-	while ((node = hashtable_iter_get_node(&iter)) != NULL) {
-		app = caa_container_of(node, struct ust_app, node);
+	struct ust_app_event *ua_event;
 
-		ua_sess = lookup_session_by_app(usess, app);
-		if (ua_sess == NULL) {
-			/* Only malloc can failed so something is really wrong */
-			goto next;
-		}
+	DBG("UST app enabling event %s for PID %d", uevent->attr.name, pid);
 
-		if (ua_sess->metadata == NULL) {
-			/* Allocate UST metadata */
-			ua_sess->metadata = trace_ust_create_metadata(usess->pathname);
-			if (ua_sess->metadata == NULL) {
-				ERR("UST app session %d creating metadata failed",
-						ua_sess->handle);
-				goto next;
-			}
+	rcu_read_lock();
 
-			uattr.overwrite = ua_sess->metadata->attr.overwrite;
-			uattr.subbuf_size = ua_sess->metadata->attr.subbuf_size;
-			uattr.num_subbuf = ua_sess->metadata->attr.num_subbuf;
-			uattr.switch_timer_interval =
-				ua_sess->metadata->attr.switch_timer_interval;
-			uattr.read_timer_interval =
-				ua_sess->metadata->attr.read_timer_interval;
-			uattr.output = ua_sess->metadata->attr.output;
-
-			/* UST tracer metadata creation */
-			ret = ustctl_open_metadata(app->key.sock, ua_sess->handle, &uattr,
-					&ua_sess->metadata->obj);
-			if (ret < 0) {
-				ERR("UST app open metadata failed for app pid:%d",
-						app->key.pid);
-				goto next;
-			}
+	app = ust_app_find_by_pid(pid);
+	if (app == NULL) {
+		ERR("UST app enable event per PID %d not found", pid);
+		ret = -1;
+		goto error;
+	}
 
-			DBG2("UST metadata opened for app pid %d", app->key.pid);
-		}
+	ua_sess = lookup_session_by_app(usess, app);
+	/* If ua_sess is NULL, there is a code flow error */
+	assert(ua_sess);
 
-		/* Open UST metadata stream */
-		if (ua_sess->metadata->stream_obj == NULL) {
-			ret = ustctl_create_stream(app->key.sock, ua_sess->metadata->obj,
-					&ua_sess->metadata->stream_obj);
-			if (ret < 0) {
-				ERR("UST create metadata stream failed");
-				goto next;
-			}
+	/* Lookup channel in the ust app session */
+	ua_chan_node = hashtable_lookup(ua_sess->channels, (void *)uchan->name,
+			strlen(uchan->name), &iter);
+	/* If the channel is not found, there is a code flow error */
+	assert(ua_chan_node);
 
-			ret = snprintf(ua_sess->metadata->pathname, PATH_MAX, "%s/%s",
-					usess->pathname, "metadata");
-			if (ret < 0) {
-				PERROR("asprintf UST create stream");
-				goto next;
-			}
+	ua_chan = caa_container_of(ua_chan_node, struct ust_app_channel, node);
 
-			DBG2("UST metadata stream object created for app pid %d",
-					app->key.pid);
+	ua_event_node = hashtable_lookup(ua_chan->events,
+			(void*)uevent->attr.name, strlen(uevent->attr.name), &iter);
+	if (ua_event_node == NULL) {
+		ret = create_ust_app_event(ua_sess, ua_chan, uevent, app);
+		if (ret < 0) {
+			goto error;
 		}
+	} else {
+		ua_event = caa_container_of(ua_event_node, struct ust_app_event, node);
 
-		/* For each channel */
-		hashtable_get_first(usess->domain_global.channels, &iter);
-		while ((node = hashtable_iter_get_node(&iter)) != NULL) {
-			uchan = caa_container_of(node, struct ltt_ust_channel, node);
+		ret = enable_ust_app_event(ua_sess, ua_event, app);
+		if (ret < 0) {
+			goto error;
+		}
+	}
 
-			/* Lookup channel in the ust app session */
-			ua_chan_node = hashtable_lookup(ua_sess->channels,
-					(void *) uchan->name, strlen(uchan->name), &iter);
-			if (ua_chan_node == NULL) {
-				ERR("Channel suppose to be present with the above shallow "
-						"session copy. Continuing...");
-				goto next;
-			}
+error:
+	rcu_read_unlock();
+	return ret;
+}
 
-			ua_chan = caa_container_of(ua_chan_node,
-					struct ust_app_channel, node);
+/*
+ * Disable event for a channel from a UST session for a specific PID.
+ */
+int ust_app_disable_event_pid(struct ltt_ust_session *usess,
+		struct ltt_ust_channel *uchan, struct ltt_ust_event *uevent, pid_t pid)
+{
+	int ret = 0;
+	struct cds_lfht_iter iter;
+	struct cds_lfht_node *ua_chan_node, *ua_event_node;
+	struct ust_app *app;
+	struct ust_app_session *ua_sess;
+	struct ust_app_channel *ua_chan;
+	struct ust_app_event *ua_event;
 
-			for (;;) {
-				struct lttng_ust_object_data *obj;
-				struct ltt_ust_stream *ustream;
+	DBG("UST app disabling event %s for PID %d", uevent->attr.name, pid);
 
-				ret = ustctl_create_stream(app->key.sock, ua_chan->obj,
-						&obj);
-				if (ret < 0) {
-					/* Got all streams */
-					goto next_chan;
-				}
+	rcu_read_lock();
 
-				ustream = malloc(sizeof(*ustream));
-				if (ustream == NULL) {
-					goto next_chan;
-				}
-				memset(ustream, 0, sizeof(struct ltt_ust_stream));
-				ustream->obj = obj;
-				ustream->handle = ustream->obj->handle;
-				hashtable_node_init(&ustream->node,
-					(void *)((unsigned long) ustream->handle), sizeof(void *));
-				hashtable_add_unique(ua_chan->streams, &ustream->node);
-				ret = snprintf(ustream->pathname, PATH_MAX, "%s/%s_%lu",
-						uchan->pathname, uchan->name,
-						hashtable_get_count(ua_chan->streams) - 1);
-				if (ret < 0) {
-					PERROR("asprintf UST create stream");
-					goto next_chan;
-				}
-			}
+	app = ust_app_find_by_pid(pid);
+	if (app == NULL) {
+		ERR("UST app disable event per PID %d not found", pid);
+		ret = -1;
+		goto error;
+	}
 
-next_chan:
-			/* Next applications */
-			hashtable_get_next(ua_sess->channels, &iter);
-		}
+	ua_sess = lookup_session_by_app(usess, app);
+	/* If ua_sess is NULL, there is a code flow error */
+	assert(ua_sess);
 
-		/* Setup UST consumer socket and send fds to it */
-		ret = ust_consumer_send_session(usess->consumer_fd, ua_sess);
-		if (ret < 0) {
-			goto next;
-		}
+	/* Lookup channel in the ust app session */
+	ua_chan_node = hashtable_lookup(ua_sess->channels, (void *)uchan->name,
+			strlen(uchan->name), &iter);
+	if (ua_chan_node == NULL) {
+		/* Channel does not exist, skip disabling */
+		goto error;
+	}
+	ua_chan = caa_container_of(ua_chan_node, struct ust_app_channel, node);
 
-		/* This start the UST tracing */
-		ret = ustctl_start_session(app->key.sock, ua_sess->handle);
-		if (ret < 0) {
-			ERR("Error starting tracing for app pid: %d", app->key.pid);
-			goto next;
-		}
+	ua_event_node = hashtable_lookup(ua_chan->events,
+			(void*)uevent->attr.name, strlen(uevent->attr.name), &iter);
+	if (ua_event_node == NULL) {
+		/* Event does not exist, skip disabling */
+		goto error;
+	}
+	ua_event = caa_container_of(ua_event_node, struct ust_app_event, node);
 
-		/* Quiescent wait after starting trace */
-		ustctl_wait_quiescent(app->key.sock);
-next:
-		/* Next applications */
-		hashtable_get_next(ust_app_ht, &iter);
+	ret = disable_ust_app_event(ua_sess, ua_event, app);
+	if (ret < 0) {
+		goto error;
 	}
-	rcu_read_unlock();
 
-	return 0;
+error:
+	rcu_read_unlock();
+	return ret;
 }