From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Mon, 7 Sep 2015 14:36:09 +0000 (-0400)
Subject: Fix: unbalanced RCU read-side lock in enable event command
X-Git-Url: http://git.efficios.com/?p=lttng-tools.git;a=commitdiff_plain;h=f5ac4bd72b128dc3e6e5d41d3f76755e6215a02d

Fix: unbalanced RCU read-side lock in enable event command

The event validation fails, an unpaired RCU unlock is performed, thus
underflowing the RCU nesting counter.

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

diff --git a/src/bin/lttng-sessiond/cmd.c b/src/bin/lttng-sessiond/cmd.c
index 26845535c..058dbae4d 100644
--- a/src/bin/lttng-sessiond/cmd.c
+++ b/src/bin/lttng-sessiond/cmd.c
@@ -1535,13 +1535,13 @@ static int _cmd_enable_event(struct ltt_session *session,
 
 	DBG("Enable event command for event \'%s\'", event->name);
 
+	rcu_read_lock();
+
 	ret = validate_event_name(event->name);
 	if (ret) {
 		goto error;
 	}
 
-	rcu_read_lock();
-
 	switch (domain->type) {
 	case LTTNG_DOMAIN_KERNEL:
 	{