From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Thu, 8 Sep 2016 02:11:53 +0000 (-0400)
Subject: Fix: rcutorture: work-around signal issue on mac os x
X-Git-Tag: v0.10.0~19
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=0b9c513b2513c37e3ed0a5ee047b8d40eef482ab;p=userspace-rcu.git

Fix: rcutorture: work-around signal issue on mac os x

Our MacOS X test machine with the following config:

15.6.0 Darwin Kernel Version 15.6.0
root:xnu-3248.60.10~1/RELEASE_X86_64

appears to have issues with liburcu-signal signal being delivered on top
of pthread_cond_wait. It seems to make the thread continue, and
therefore corrupt the rcu_head. Work around this issue by unregistering
the RCU read-side thread immediately after call_rcu (call_rcu needs us
to be registered RCU readers).

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

diff --git a/tests/regression/rcutorture.h b/tests/regression/rcutorture.h
index 053653f..db3dfad 100644
--- a/tests/regression/rcutorture.h
+++ b/tests/regression/rcutorture.h
@@ -368,9 +368,6 @@ void *rcu_update_stress_test(void *arg)
 	struct rcu_stress *p;
 	struct rcu_head rh;
 
-	rcu_register_thread();
-	rcu_thread_offline();
-
 	while (goflag == GOFLAG_INIT)
 		(void) poll(NULL, 0, 1);
 	while (goflag == GOFLAG_RUN) {
@@ -399,7 +396,23 @@ void *rcu_update_stress_test(void *arg)
 					strerror(errno));
 				abort();
 			}
+			rcu_register_thread();
 			call_rcu(&rh, rcu_update_stress_test_rcu);
+			rcu_unregister_thread();
+			/*
+			 * Our MacOS X test machine with the following
+			 * config:
+			 * 15.6.0 Darwin Kernel Version 15.6.0
+			 * root:xnu-3248.60.10~1/RELEASE_X86_64
+			 * appears to have issues with liburcu-signal
+			 * signal being delivered on top of
+			 * pthread_cond_wait. It seems to make the
+			 * thread continue, and therefore corrupt the
+			 * rcu_head. Work around this issue by
+			 * unregistering the RCU read-side thread
+			 * immediately after call_rcu (call_rcu needs
+			 * us to be registered RCU readers).
+			 */
 			ret = pthread_cond_wait(&call_rcu_test_cond,
 					&call_rcu_test_mutex);
 			if (ret) {
@@ -419,8 +432,6 @@ void *rcu_update_stress_test(void *arg)
 		n_updates++;
 	}
 
-	rcu_thread_online();
-	rcu_unregister_thread();
 	return NULL;
 }