[ltt-dev] [PATCH 2/7] urcu, defer_rcu: fix missing respond to a cancellation request

[Lai Jiangshan]

thread1:				thread2
					thr_defer()
						pthread_testcancel();
stop_defer_thread()				.
	pthread_cancel(tid_defer);		.
	wake_up_defer();			.
						wait_defer();
	pthread_join(tid_defer)

thread2 missing respond to the cancellation request from thread1
and wait callback forever.

thread1 wait thread2 forver by pthread_join():

Signed-off-by: Lai Jiangshan <laijs at cn.fujitsu.com>
---
 urcu-defer-impl.h |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/urcu-defer-impl.h b/urcu-defer-impl.h
index d1ab046..6339747 100644
--- a/urcu-defer-impl.h
+++ b/urcu-defer-impl.h
@@ -187,6 +187,7 @@ static void wait_defer(void)
 {
 	uatomic_dec(&defer_thread_futex);
 	cmm_smp_mb();	/* Write futex before read queue */
+	pthread_testcancel();
 	if (rcu_defer_num_callbacks()) {
 		cmm_smp_mb();	/* Read queue before write futex */
 		/* Callbacks are queued, don't wait. */
@@ -359,7 +360,6 @@ void _defer_rcu(void (*fct)(void *p), void *p)
 void *thr_defer(void *args)
 {
 	for (;;) {
-		pthread_testcancel();
 		/*
 		 * "Be green". Don't wake up the CPU if there is no RCU work
 		 * to perform whatsoever. Aims at saving laptop battery life by
@@ -387,6 +387,7 @@ static void start_defer_thread(void)
 {
 	int ret;
 
+	uatomic_set(&defer_thread_futex, 0);
 	ret = pthread_create(&tid_defer, NULL, thr_defer, NULL);
 	assert(!ret);
 }
-- 
1.7.4.4