Author: rstone
Date: Wed Apr 20 14:19:34 2011
New Revision: 220888
URL: http://svn.freebsd.org/changeset/base/220888
Log:
r179417 introduced a bug into pthread_once(). Previously pthread_once()
used a global pthread_mutex_t for synchronization. r179417 replaced that
with an implementation that directly used atomic instructions and thr_*
syscalls to synchronize callers to pthread_once. However, calling
pthread_mutex_lock on the global mutex implicitly ensured that
_thr_check_init() had been called but with r179417 this was no longer
guaranteed. This meant that if you were unlucky enough to have your first
call into libthr be a call to pthread_once(), you would segfault when
trying to access the pointer returned by _get_curthread().
The fix is to explicitly call _thr_check_init() from pthread_once().
Reviewed by: davidxu
Approved by: emaste (mentor)
MFC after: 1 week
Modified:
head/lib/libthr/thread/thr_once.c
Modified: head/lib/libthr/thread/thr_once.c
==============================================================================
--- head/lib/libthr/thread/thr_once.c Wed Apr 20 14:16:22 2011
(r220887)
+++ head/lib/libthr/thread/thr_once.c Wed Apr 20 14:19:34 2011
(r220888)
@@ -64,6 +64,8 @@ _pthread_once(pthread_once_t *once_contr
struct pthread *curthread;
int state;
+ _thr_check_init();
+
for (;;) {
state = once_control->state;
if (state == ONCE_DONE)
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