+ switch(key->ctx) {
+ case LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER:
+ if (strncmp(key->u.perf_counter.name,
+ ctx->ctx.u.perf_counter.name,
+ sizeof(key->u.perf_counter.name))) {
+ goto no_match;
+ }
+ break;
+ case LTTNG_UST_CONTEXT_APP_CONTEXT:
+ if (strcmp(key->u.app_ctx.provider_name,
+ ctx->ctx.u.app_ctx.provider_name) ||
+ strcmp(key->u.app_ctx.ctx_name,
+ ctx->ctx.u.app_ctx.ctx_name)) {
+ goto no_match;
+ }
+ break;
+ default:
+ break;
+ }
+
+ /* Match. */
+ return 1;
+
+no_match:
+ return 0;
+}
+
+/*
+ * Lookup for an ust app context from an lttng_ust_context.
+ *
+ * Must be called while holding RCU read side lock.
+ * Return an ust_app_ctx object or NULL on error.
+ */
+static
+struct ust_app_ctx *find_ust_app_context(struct lttng_ht *ht,
+ struct lttng_ust_context_attr *uctx)
+{
+ struct lttng_ht_iter iter;
+ struct lttng_ht_node_ulong *node;
+ struct ust_app_ctx *app_ctx = NULL;
+
+ assert(uctx);
+ assert(ht);
+
+ /* Lookup using the lttng_ust_context_type and a custom match fct. */
+ cds_lfht_lookup(ht->ht, ht->hash_fct((void *) uctx->ctx, lttng_ht_seed),
+ ht_match_ust_app_ctx, uctx, &iter.iter);
+ node = lttng_ht_iter_get_node_ulong(&iter);
+ if (!node) {
+ goto end;
+ }
+
+ app_ctx = caa_container_of(node, struct ust_app_ctx, node);
+
+end:
+ return app_ctx;
+}
+
+/*
+ * Create a context for the channel on the tracer.
+ *
+ * Called with UST app session lock held and a RCU read side lock.
+ */
+static
+int create_ust_app_channel_context(struct ust_app_session *ua_sess,
+ struct ust_app_channel *ua_chan,
+ struct lttng_ust_context_attr *uctx,
+ struct ust_app *app)
+{
+ int ret = 0;
+ struct ust_app_ctx *ua_ctx;
+
+ DBG2("UST app adding context to channel %s", ua_chan->name);
+
+ ua_ctx = find_ust_app_context(ua_chan->ctx, uctx);
+ if (ua_ctx) {
+ ret = -EEXIST;
+ goto error;
+ }
+
+ ua_ctx = alloc_ust_app_ctx(uctx);
+ if (ua_ctx == NULL) {
+ /* malloc failed */
+ ret = -1;
+ goto error;
+ }
+
+ lttng_ht_node_init_ulong(&ua_ctx->node, (unsigned long) ua_ctx->ctx.ctx);
+ lttng_ht_add_ulong(ua_chan->ctx, &ua_ctx->node);
+ cds_list_add_tail(&ua_ctx->list, &ua_chan->ctx_list);
+
+ ret = create_ust_channel_context(ua_chan, ua_ctx, app);
+ if (ret < 0) {
+ goto error;