document lttng_ustconsumer_request_metadata locking constraints

Reviewed-by: Julien Desfossez <julien.desfossez@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/src/common/ust-consumer/ust-consumer.c b/src/common/ust-consumer/ust-consumer.c
index 21100dc648747ac132227cb4ea1438969e67a016..8926c1c1604e79968fa0364462c2529315b98857 100644 (file)
--- a/src/common/ust-consumer/ust-consumer.c
+++ b/src/common/ust-consumer/ust-consumer.c
@@ -1486,6 +1486,12 @@ void lttng_ustconsumer_close_stream_wakeup(struct lttng_consumer_stream *stream)
        }
 }
 
+/*
+ * Please refer to consumer-timer.c before adding any lock within this
+ * function or any of its callees. Timers have a very strict locking
+ * semantic with respect to teardown. Failure to respect this semantic
+ * introduces deadlocks.
+ */
 int lttng_ustconsumer_request_metadata(struct lttng_consumer_local_data *ctx,
                struct lttng_consumer_channel *channel)
 {