svn commit: r227438 - stable/8/lib/libthr/thread

Ryan Stone rstone at
Fri Nov 11 02:10:24 UTC 2011

Author: rstone
Date: Fri Nov 11 02:10:24 2011
New Revision: 227438

  MFC 220888
   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().

Directory Properties:
  stable/8/lib/libthr/   (props changed)

Modified: stable/8/lib/libthr/thread/thr_once.c
--- stable/8/lib/libthr/thread/thr_once.c	Fri Nov 11 02:02:55 2011	(r227437)
+++ stable/8/lib/libthr/thread/thr_once.c	Fri Nov 11 02:10:24 2011	(r227438)
@@ -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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