+ 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;
+ }