Fix: sessiond vs consumerd push/get metadata deadlock

We need to unlock the registry while we push metadata to break a
circular dependency between the consumerd metadata lock and the sessiond
registry lock. Indeed, pushing metadata to the consumerd awaits that it
gets pushed all the way to relayd, but doing so requires grabbing the
metadata lock. If a concurrent metadata request is being performed by
consumerd, this can try to grab the registry lock on the sessiond while
holding the metadata lock on the consumer daemon. Those push and pull
schemes are performed on two different bidirectionnal communication
sockets.

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

diff --git a/src/common/consumer-timer.h b/src/common/consumer-timer.h
index f877b8ffe364e21bf53dc7b052bd20861b4b7c4d..a9360027eb6dd83e325c458ad2f1f133ded99435 100644 (file)
--- a/src/common/consumer-timer.h
+++ b/src/common/consumer-timer.h
@@ -55,4 +55,7 @@ void consumer_signal_init(void);
 int consumer_flush_kernel_index(struct lttng_consumer_stream *stream);
 int consumer_flush_ust_index(struct lttng_consumer_stream *stream);
 
+int consumer_flush_kernel_index(struct lttng_consumer_stream *stream);
+int consumer_flush_ust_index(struct lttng_consumer_stream *stream);
+
 #endif /* CONSUMER_TIMER_H */