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Message-Id: <1443477525-24743-1-git-send-email-koorogi@koorogi.info>
Date: Mon, 28 Sep 2015 16:58:44 -0500
From: Bobby Bingham <koorogi@...rogi.info>
To: musl@...ts.openwall.com
Subject: [PATCH 1/2] pthread: add missing memory barrier

posix requires pthread_join to synchronize memory on success. in the
case that we call __timedwait_cp, we can rely on its futex_wake call
to synchronize memory, but we need a memory barrier for the case where
we don't call it.
---
 src/thread/pthread_join.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/thread/pthread_join.c b/src/thread/pthread_join.c
index 966b4ab..eb78e2f 100644
--- a/src/thread/pthread_join.c
+++ b/src/thread/pthread_join.c
@@ -11,7 +11,9 @@ int __pthread_join(pthread_t t, void **res)
 	__pthread_testcancel();
 	__pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
 	if (cs == PTHREAD_CANCEL_ENABLE) __pthread_setcancelstate(cs, 0);
-	while ((tmp = t->tid)) __timedwait_cp(&t->tid, tmp, 0, 0, 0);
+	if (!(tmp = t->tid)) a_barrier();
+	else do __timedwait_cp(&t->tid, tmp, 0, 0, 0);
+	while ((tmp = t->tid));
 	__pthread_setcancelstate(cs, 0);
 	if (res) *res = t->result;
 	if (t->map_base) __munmap(t->map_base, t->map_size);
-- 
2.5.3

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