rcu_read_unlock();
}
- call_rcu(&channel->node.head, free_channel_rcu);
+ channel->is_deleted = true;
+ call_rcu(&channel->node.head, free_channel_rcu);
end:
pthread_mutex_unlock(&channel->lock);
pthread_mutex_unlock(&consumer_data.lock);
unsigned long channel_hash;
pthread_mutex_lock(&channel->lock);
+ if (channel->is_deleted) {
+ /*
+ * The channel has been logically deleted and should no longer
+ * be used. It has released its reference to its current trace
+ * chunk and should not acquire a new one.
+ *
+ * Return success as there is nothing for the caller to do.
+ */
+ goto end;
+ }
/*
* A stream can transition to a state where it and its channel
* no longer belong to a trace chunk. For instance, this happens when
{
struct lttng_ht_iter iter;
struct lttng_consumer_channel *channel;
+ unsigned int trace_chunks_left;
rcu_read_lock();
*/
lttng_ht_destroy(consumer_data.stream_list_ht);
+ /*
+ * Trace chunks in the registry may still exist if the session
+ * daemon has encountered an internal error and could not
+ * tear down its sessions and/or trace chunks properly.
+ *
+ * Release the session daemon's implicit reference to any remaining
+ * trace chunk and print an error if any trace chunk was found. Note
+ * that there are _no_ legitimate cases for trace chunks to be left,
+ * it is a leak. However, it can happen following a crash of the
+ * session daemon and not emptying the registry would cause an assertion
+ * to hit.
+ */
+ trace_chunks_left = lttng_trace_chunk_registry_put_each_chunk(
+ consumer_data.chunk_registry);
+ if (trace_chunks_left) {
+ ERR("%u trace chunks are leaked by lttng-consumerd. "
+ "This can be caused by an internal error of the session daemon.",
+ trace_chunks_left);
+ }
+ /* Run all callbacks freeing each chunk. */
+ rcu_barrier();
lttng_trace_chunk_registry_destroy(consumer_data.chunk_registry);
}
void consumer_del_metadata_stream(struct lttng_consumer_stream *stream,
struct lttng_ht *ht)
{
- struct lttng_consumer_channel *free_chan = NULL;
+ struct lttng_consumer_channel *channel = NULL;
+ bool free_channel = false;
assert(stream);
/*
DBG3("Consumer delete metadata stream %d", stream->wait_fd);
pthread_mutex_lock(&consumer_data.lock);
- pthread_mutex_lock(&stream->chan->lock);
+ /*
+ * Note that this assumes that a stream's channel is never changed and
+ * that the stream's lock doesn't need to be taken to sample its
+ * channel.
+ */
+ channel = stream->chan;
+ pthread_mutex_lock(&channel->lock);
pthread_mutex_lock(&stream->lock);
- if (stream->chan->metadata_cache) {
+ if (channel->metadata_cache) {
/* Only applicable to userspace consumers. */
- pthread_mutex_lock(&stream->chan->metadata_cache->lock);
+ pthread_mutex_lock(&channel->metadata_cache->lock);
}
/* Remove any reference to that stream. */
consumer_stream_destroy_buffers(stream);
/* Atomically decrement channel refcount since other threads can use it. */
- if (!uatomic_sub_return(&stream->chan->refcount, 1)
- && !uatomic_read(&stream->chan->nb_init_stream_left)) {
+ if (!uatomic_sub_return(&channel->refcount, 1)
+ && !uatomic_read(&channel->nb_init_stream_left)) {
/* Go for channel deletion! */
- free_chan = stream->chan;
+ free_channel = true;
}
+ stream->chan = NULL;
/*
* Nullify the stream reference so it is not used after deletion. The
* channel lock MUST be acquired before being able to check for a NULL
* pointer value.
*/
- stream->chan->metadata_stream = NULL;
+ channel->metadata_stream = NULL;
- if (stream->chan->metadata_cache) {
- pthread_mutex_unlock(&stream->chan->metadata_cache->lock);
+ if (channel->metadata_cache) {
+ pthread_mutex_unlock(&channel->metadata_cache->lock);
}
pthread_mutex_unlock(&stream->lock);
- pthread_mutex_unlock(&stream->chan->lock);
+ pthread_mutex_unlock(&channel->lock);
pthread_mutex_unlock(&consumer_data.lock);
- if (free_chan) {
- consumer_del_channel(free_chan);
+ if (free_channel) {
+ consumer_del_channel(channel);
}
lttng_trace_chunk_put(stream->trace_chunk);