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Message-Id: <20170801231203.9829-1-nenolod@dereferenced.org>
Date: Tue, 1 Aug 2017 23:12:03 +0000
From: William Pitcock <nenolod@...eferenced.org>
To: musl@...ts.openwall.com
Cc: William Pitcock <nenolod@...eferenced.org>
Subject: [PATCH] thread: do not attempt to join detached threads in pthread_join()
A thread which is detached releases it's resources and TCB upon thread termination.
Therefore a thread which is detached is not joinable as any underlying futex will not
be incremented, resulting in a deadlock. Accordingly, POSIX defines calling
pthread_join() on a detached thread as undefined behaviour.
We attempt, where possible, to detect attempts to join detached threads and crash
instead, to bring the undefined behaviour to the programmer's attention.
---
src/thread/pthread_join.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/src/thread/pthread_join.c b/src/thread/pthread_join.c
index 52111489..b7175c09 100644
--- a/src/thread/pthread_join.c
+++ b/src/thread/pthread_join.c
@@ -11,6 +11,7 @@ int __pthread_timedjoin_np(pthread_t t, void **res, const struct timespec *at)
__pthread_testcancel();
__pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
if (cs == PTHREAD_CANCEL_ENABLE) __pthread_setcancelstate(cs, 0);
+ if (t->detached) a_crash();
while ((tmp = t->tid) && r != ETIMEDOUT && r != EINVAL)
r = __timedwait_cp(&t->tid, tmp, CLOCK_REALTIME, at, 0);
__pthread_setcancelstate(cs, 0);
--
2.13.3
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