Date: Fri, 11 Nov 2011 02:10:24 +0000 (UTC) From: Ryan Stone <rstone@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-8@freebsd.org Subject: svn commit: r227438 - stable/8/lib/libthr/thread Message-ID: <201111110210.pAB2AOod066088@svn.freebsd.org>
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Author: rstone Date: Fri Nov 11 02:10:24 2011 New Revision: 227438 URL: http://svn.freebsd.org/changeset/base/227438 Log: 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(). Modified: stable/8/lib/libthr/thread/thr_once.c 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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