+static
+void consumer_timer_signal_thread_qs(unsigned int signr)
+{
+ sigset_t pending_set;
+ int ret;
+
+ /*
+ * We need to be the only thread interacting with the thread
+ * that manages signals for teardown synchronization.
+ */
+ pthread_mutex_lock(&timer_signal.lock);
+
+ /* Ensure we don't have any signal queued for this channel. */
+ for (;;) {
+ ret = sigemptyset(&pending_set);
+ if (ret == -1) {
+ PERROR("sigemptyset");
+ }
+ ret = sigpending(&pending_set);
+ if (ret == -1) {
+ PERROR("sigpending");
+ }
+ if (!sigismember(&pending_set, LTTNG_CONSUMER_SIG_SWITCH)) {
+ break;
+ }
+ caa_cpu_relax();
+ }
+
+ /*
+ * From this point, no new signal handler will be fired that would try to
+ * access "chan". However, we still need to wait for any currently
+ * executing handler to complete.
+ */
+ cmm_smp_mb();
+ CMM_STORE_SHARED(timer_signal.qs_done, 0);
+ cmm_smp_mb();
+
+ /*
+ * Kill with LTTNG_CONSUMER_SIG_TEARDOWN, so signal management thread wakes
+ * up.
+ */
+ kill(getpid(), LTTNG_CONSUMER_SIG_TEARDOWN);
+
+ while (!CMM_LOAD_SHARED(timer_signal.qs_done)) {
+ caa_cpu_relax();
+ }
+ cmm_smp_mb();
+
+ pthread_mutex_unlock(&timer_signal.lock);
+}
+