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 8e86896f4b2b7c39904ee5112e42a2488332c33e..7842af795da31e4f59eb800c9c5a58e94517ba85 100644 (file)
--- 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();