From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Tue, 16 Jul 2013 00:56:51 +0000 (-0400)
Subject: document metadata_switch_timer() locking constraints
X-Git-Tag: v2.2.2~11
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=2755a3c6e93020721bd7c5d82bbb367e3fae9fe4;p=lttng-tools.git

document metadata_switch_timer() locking constraints

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

diff --git a/src/common/consumer-timer.c b/src/common/consumer-timer.c
index f9c41c0eb..f2dff4cd9 100644
--- a/src/common/consumer-timer.c
+++ b/src/common/consumer-timer.c
@@ -56,6 +56,10 @@ static void setmask(sigset_t *mask)
 
 /*
  * Execute action on a timer switch.
+ *
+ * Beware: metadata_switch_timer() should *never* take a mutex also held
+ * while consumer_timer_switch_stop() is called. It would result in
+ * deadlocks.
  */
 static void metadata_switch_timer(struct lttng_consumer_local_data *ctx,
 		int sig, siginfo_t *si, void *uc)