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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