Fix: Synchronization issue for data available command

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

diff --git a/src/common/kernel-consumer/kernel-consumer.c b/src/common/kernel-consumer/kernel-consumer.c
index 4e000fbd167e294c6b9139b6b7bdd2cf0098d6f1..196deee9a153e521447703915d9ee9d2790502a4 100644 (file)
--- a/src/common/kernel-consumer/kernel-consumer.c
+++ b/src/common/kernel-consumer/kernel-consumer.c
@@ -485,7 +485,8 @@ error:
 
 /*
  * Check if data is still being extracted from the buffers for a specific
- * stream. Consumer data lock MUST be acquired before calling this function.
+ * stream. Consumer data lock MUST be acquired before calling this function
+ * and the stream lock.
  *
  * Return 0 if the traced data are still getting read else 1 meaning that the
  * data is available for trace viewer reading.
@@ -496,29 +497,17 @@ int lttng_kconsumer_data_available(struct lttng_consumer_stream *stream)
 
        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 == EBUSY) {
-               goto data_not_available;
-       }
-       /* The stream is now locked so we can do our ustctl calls */
-
        ret = kernctl_get_next_subbuf(stream->wait_fd);
        if (ret == 0) {
                /* There is still data so let's put back this subbuffer. */
                ret = kernctl_put_subbuf(stream->wait_fd);
                assert(ret == 0);
-               pthread_mutex_unlock(&stream->lock);
-               goto data_not_available;
+               goto end;
        }
 
        /* Data is available to be read for this stream. */
-       pthread_mutex_unlock(&stream->lock);
-       return 1;
+       ret = 1;
 
-data_not_available:
-       return 0;
+end:
+       return ret;
 }