Fix deadlock: don't take channel lock in timer

[lttng-tools.git] / src / common / consumer-timer.c

diff --git a/src/common/consumer-timer.c b/src/common/consumer-timer.c
index a32dbf64d2d229e730f6e87a4add490c75567a39..37c9861b906a0a81c6b08a302c73e486e6c6d3dd 100644 (file)
--- a/src/common/consumer-timer.c
+++ b/src/common/consumer-timer.c
@@ -82,19 +82,17 @@ static void metadata_switch_timer(struct lttng_consumer_local_data *ctx,
                 * Locks taken by lttng_ustconsumer_request_metadata():
                 * - metadata_socket_lock
                 *   - Calling lttng_ustconsumer_recv_metadata():
-                *     - consumer_data.lock
-                *       - channel->lock
-                *         - channel->metadata_cache->lock
+                *     - channel->metadata_cache->lock
                 *     - Calling consumer_metadata_cache_flushed():
-                *       - consumer_data.lock
-                *         - channel->lock
-                *           - channel->metadata_cache->lock
+                *       - channel->timer_lock
+                *         - channel->metadata_cache->lock
                 *
-                * Both consumer_data.lock and channel->lock currently
-                * cause a deadlock, since they are held while
-                * consumer_timer_switch_stop() is called.
+                * Ensure that neither consumer_data.lock nor
+                * channel->lock are taken within this function, since
+                * they are held while consumer_timer_switch_stop() is
+                * called.
                 */
-               ret = lttng_ustconsumer_request_metadata(ctx, channel);
+               ret = lttng_ustconsumer_request_metadata(ctx, channel, 1);
                if (ret < 0) {
                        channel->switch_timer_error = 1;
                }