From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Thu, 14 Jul 2016 21:47:08 +0000 (-0400)
Subject: Fix: reset vtid cache before releasing urcu locks
X-Git-Tag: v2.7.5~12
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=9f85f64c20e9edede18c37cbed7f011c09bd0be5;p=lttng-ust.git

Fix: reset vtid cache before releasing urcu locks

When tracing pthread mutex lock/unlock, we need to reset the vtid
context cache before unlocking the urcu lock, else we have vtid/vpid
discrepancies.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/liblttng-ust/lttng-ust-comm.c b/liblttng-ust/lttng-ust-comm.c
index 8e86896f..7842af79 100644
--- a/liblttng-ust/lttng-ust-comm.c
+++ b/liblttng-ust/lttng-ust-comm.c
@@ -1771,11 +1771,11 @@ void ust_after_fork_child(sigset_t *restore_sigset)
 {
 	if (URCU_TLS(lttng_ust_nest_count))
 		return;
+	lttng_context_vtid_reset();
 	DBG("process %d", getpid());
 	/* Release urcu mutexes */
 	rcu_bp_after_fork_child();
 	lttng_ust_cleanup(0);
-	lttng_context_vtid_reset();
 	/* Release mutexes and reenable signals */
 	ust_after_fork_common(restore_sigset);
 	lttng_ust_init();