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authorad <ad@NetBSD.org>2020-01-25 18:01:28 +0000
committerad <ad@NetBSD.org>2020-01-25 18:01:28 +0000
commit496256f073ef40780955ff0da5ee4d1385c52d11 (patch)
tree92b541881c5fa4c36db9f39c5b41bfea4c1ed767 /lib/libpthread/pthread.c
parent5b40ee73af04033a686b0e956c88865251ed5320 (diff)
pthread_exit(): it looks there there is at least one path through which
a thread can exit with waiters still hanging off it (cancellation when waiting on a condvar) so deal with all/any crappy failure like that and make sure there are never any waiters left before exiting. Maybe of help for: PR: bin/50350: rump/rumpkern/t_sp/stress_{long,short} fail on Core 2
Diffstat (limited to 'lib/libpthread/pthread.c')
-rw-r--r--lib/libpthread/pthread.c28
1 files changed, 25 insertions, 3 deletions
diff --git a/lib/libpthread/pthread.c b/lib/libpthread/pthread.c
index 41c9305572f..90b497cf08d 100644
--- a/lib/libpthread/pthread.c
+++ b/lib/libpthread/pthread.c
@@ -1,4 +1,4 @@
-/* $NetBSD: pthread.c,v 1.155 2020/01/25 15:41:52 ad Exp $ */
+/* $NetBSD: pthread.c,v 1.156 2020/01/25 18:01:28 ad Exp $ */
/*-
* Copyright (c) 2001, 2002, 2003, 2006, 2007, 2008, 2020
@@ -31,7 +31,7 @@
*/
#include <sys/cdefs.h>
-__RCSID("$NetBSD: pthread.c,v 1.155 2020/01/25 15:41:52 ad Exp $");
+__RCSID("$NetBSD: pthread.c,v 1.156 2020/01/25 18:01:28 ad Exp $");
#define __EXPOSE_STACK 1
@@ -621,6 +621,23 @@ pthread_resume_np(pthread_t thread)
return errno;
}
+/*
+ * In case the thread is exiting at an inopportune time leaving waiters not
+ * awoken (because cancelled, for instance) make sure we have no waiters
+ * left.
+ */
+static void
+pthread__clear_waiters(pthread_t self)
+{
+
+ if (self->pt_nwaiters != 0) {
+ (void)_lwp_unpark_all(self->pt_waiters, self->pt_nwaiters,
+ NULL);
+ self->pt_nwaiters = 0;
+ }
+ self->pt_willpark = 0;
+}
+
void
pthread_exit(void *retval)
{
@@ -658,7 +675,10 @@ pthread_exit(void *retval)
/* Perform cleanup of thread-specific data */
pthread__destroy_tsd(self);
- /* Signal our exit. */
+ /*
+ * Signal our exit. Our stack and pthread_t won't be reused until
+ * pthread_create() can see from kernel info that this LWP is gone.
+ */
self->pt_exitval = retval;
if (self->pt_flags & PT_FLAG_DETACHED) {
self->pt_state = PT_STATE_DEAD;
@@ -670,11 +690,13 @@ pthread_exit(void *retval)
pthread_mutex_lock(&pthread__deadqueue_lock);
PTQ_INSERT_TAIL(&pthread__deadqueue, self, pt_deadq);
pthread_mutex_unlock(&pthread__deadqueue_lock);
+ pthread__clear_waiters(self);
_lwp_exit();
} else {
self->pt_state = PT_STATE_ZOMBIE;
pthread_cond_broadcast(&self->pt_joiners);
pthread_mutex_unlock(&self->pt_lock);
+ pthread__clear_waiters(self);
/* Note: name will be freed by the joiner. */
_lwp_exit();
}