Fix: Mutex and RCU lock nesting in consumer

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

diff --git a/src/common/consumer.c b/src/common/consumer.c
index 8d897e5df1e20e20c67ddbc6ed8f99af7e7de2aa..295e7be5dab1b533143e4ce2fa6a5be16ddb1c5d 100644 (file)
--- a/src/common/consumer.c
+++ b/src/common/consumer.c
@@ -56,7 +56,7 @@ int consumer_poll_timeout = -1;
  * Also updated by the signal handler (consumer_should_exit()). Read by the
  * polling threads.
  */
-volatile int consumer_quit = 0;
+volatile int consumer_quit;
 
 /*
  * The following two hash tables are visible by all threads which are separated
@@ -66,8 +66,8 @@ volatile int consumer_quit = 0;
  * stream element in this ht should only be updated by the metadata poll thread
  * for the metadata and the data poll thread for the data.
  */
-struct lttng_ht *metadata_ht = NULL;
-struct lttng_ht *data_ht = NULL;
+struct lttng_ht *metadata_ht;
+struct lttng_ht *data_ht;
 
 /*
  * Find a stream. The consumer_data.lock must be locked during this
@@ -1266,11 +1266,11 @@ ssize_t lttng_consumer_on_read_subbuffer_mmap(
        lttng_consumer_sync_trace_file(stream, orig_offset);
 
 end:
-       pthread_mutex_unlock(&stream->lock);
        /* Unlock only if ctrl socket used */
        if (relayd && stream->metadata_flag) {
                pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
        }
+       pthread_mutex_unlock(&stream->lock);
 
        rcu_read_unlock();
        return written;
@@ -1451,10 +1451,10 @@ splice_error:
        }
 
 end:
-       pthread_mutex_unlock(&stream->lock);
        if (relayd && stream->metadata_flag) {
                pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
        }
+       pthread_mutex_unlock(&stream->lock);
 
        rcu_read_unlock();
        return written;
@@ -2462,6 +2462,7 @@ int consumer_data_available(uint64_t id)
 
        DBG("Consumer data available command on session id %" PRIu64, id);
 
+       rcu_read_lock();
        pthread_mutex_lock(&consumer_data.lock);
 
        switch (consumer_data.type) {
@@ -2477,8 +2478,6 @@ int consumer_data_available(uint64_t id)
                assert(0);
        }
 
-       rcu_read_lock();
-
        /* Ease our life a bit */
        ht = consumer_data.stream_list_ht;