Fix: relayd: put chunk reference when closing stream

If a stream is closed by an application exiting (per-pid buffers), it
needs to put its reference on the stream trace chunk right away, because
otherwise still holding the reference on the trace chunk could allow a
viewer stream (which holds a reference to the stream) to postpone
destroy waiting for the chunk to cease to exist endlessly until the
viewer is detached.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

diff --git a/src/bin/lttng-relayd/stream.c b/src/bin/lttng-relayd/stream.c
index 4d3d37a2bc91d745b8e6ee83935aa623f27b3db9..9d753bd0a7037c042c6218487d0bda0a4d95a0b4 100644 (file)
--- a/src/bin/lttng-relayd/stream.c
+++ b/src/bin/lttng-relayd/stream.c
@@ -923,6 +923,27 @@ void try_stream_close(struct relay_stream *stream)
        stream->closed = true;
        /* Relay indexes are only used by the "consumer/sessiond" end. */
        relay_index_close_all(stream);
+
+       /*
+        * If we are closed by an application exiting (per-pid buffers),
+        * we need to put our reference on the stream trace chunk right
+        * away, because otherwise still holding the reference on the
+        * trace chunk could allow a viewer stream (which holds a reference
+        * to the stream) to postpone destroy waiting for the chunk to cease
+        * to exist endlessly until the viewer is detached.
+        */
+
+       /* Put stream fd before put chunk. */
+       if (stream->stream_fd) {
+               stream_fd_put(stream->stream_fd);
+               stream->stream_fd = NULL;
+       }
+       if (stream->index_file) {
+               lttng_index_file_put(stream->index_file);
+               stream->index_file = NULL;
+       }
+       lttng_trace_chunk_put(stream->trace_chunk);
+       stream->trace_chunk = NULL;
        pthread_mutex_unlock(&stream->lock);
        DBG("Succeeded in closing stream %" PRIu64, stream->stream_handle);
        stream_put(stream);