[lttng-dev] [PATCH lttng-tools] Fix: Holding the stream lock does not equate to having data pending

[Jonathan Rajotte]

The live timer can hold the stream lock while sending empty beacon. An empty beacon
does not mean that data is still pending for the stream.

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien at efficios.com>
---
 src/common/consumer/consumer.c | 34 +---------------------------------
 1 file changed, 1 insertion(+), 33 deletions(-)

diff --git a/src/common/consumer/consumer.c b/src/common/consumer/consumer.c
index 0cfbf5c7c..66f10c780 100644
--- a/src/common/consumer/consumer.c
+++ b/src/common/consumer/consumer.c
@@ -3668,34 +3668,6 @@ error_nosignal:
 	}
 }
 
-/*
- * Try to lock the stream mutex.
- *
- * On success, 1 is returned else 0 indicating that the mutex is NOT lock.
- */
-static int stream_try_lock(struct lttng_consumer_stream *stream)
-{
-	int ret;
-
-	assert(stream);
-
-	/*
-	 * Try to lock the stream mutex. On failure, we know that the stream is
-	 * being used else where hence there is data still being extracted.
-	 */
-	ret = pthread_mutex_trylock(&stream->lock);
-	if (ret) {
-		/* For both EBUSY and EINVAL error, the mutex is NOT locked. */
-		ret = 0;
-		goto end;
-	}
-
-	ret = 1;
-
-end:
-	return ret;
-}
-
 /*
  * Search for a relayd associated to the session id and return the reference.
  *
@@ -3779,11 +3751,7 @@ int consumer_data_pending(uint64_t id)
 			ht->hash_fct(&id, lttng_ht_seed),
 			ht->match_fct, &id,
 			&iter.iter, stream, node_session_id.node) {
-		/* If this call fails, the stream is being used hence data pending. */
-		ret = stream_try_lock(stream);
-		if (!ret) {
-			goto data_pending;
-		}
+		pthread_mutex_lock(&stream->lock);
 
 		/*
 		 * A removed node from the hash table indicates that the stream has
-- 
2.17.1