From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Tue, 16 Jul 2013 01:47:21 +0000 (-0400)
Subject: document lttng_ustconsumer_request_metadata locking constraints
X-Git-Tag: v2.3.0-rc1~13
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=f666ae706d924ec91ca8212c402fd514ca572e88;p=lttng-tools.git

document lttng_ustconsumer_request_metadata locking constraints

Reviewed-by: Julien Desfossez <julien.desfossez@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/src/common/ust-consumer/ust-consumer.c b/src/common/ust-consumer/ust-consumer.c
index e933f9227..ae933abc0 100644
--- a/src/common/ust-consumer/ust-consumer.c
+++ b/src/common/ust-consumer/ust-consumer.c
@@ -1804,6 +1804,12 @@ void lttng_ustconsumer_close_stream_wakeup(struct lttng_consumer_stream *stream)
 	}
 }
 
+/*
+ * Please refer to consumer-timer.c before adding any lock within this
+ * function or any of its callees. Timers have a very strict locking
+ * semantic with respect to teardown. Failure to respect this semantic
+ * introduces deadlocks.
+ */
 int lttng_ustconsumer_request_metadata(struct lttng_consumer_local_data *ctx,
 		struct lttng_consumer_channel *channel)
 {