Date: Mon, 14 Dec 2009 01:26:01 +0000 (UTC) From: Marcel Moolenaar <marcel@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r200498 - head/lib/libthr/thread Message-ID: <200912140126.nBE1Q1Zv003701@svn.freebsd.org>
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Author: marcel Date: Mon Dec 14 01:26:01 2009 New Revision: 200498 URL: http://svn.freebsd.org/changeset/base/200498 Log: Work-around a race condition on ia64 while unlocking a contested lock. The race condition is believed to be in UMTX_OP_MUTEX_WAKE. On ia64, we simply go to the kernel to unlock. The big question is why this is only a race condition on ia64... MFC after: 3 days Modified: head/lib/libthr/thread/thr_umtx.c Modified: head/lib/libthr/thread/thr_umtx.c ============================================================================== --- head/lib/libthr/thread/thr_umtx.c Mon Dec 14 01:10:05 2009 (r200497) +++ head/lib/libthr/thread/thr_umtx.c Mon Dec 14 01:26:01 2009 (r200498) @@ -112,10 +112,13 @@ __thr_umutex_timedlock(struct umutex *mt int __thr_umutex_unlock(struct umutex *mtx, uint32_t id) { +#ifndef __ia64__ + /* XXX this logic has a race-condition on ia64. */ if ((mtx->m_flags & (UMUTEX_PRIO_PROTECT | UMUTEX_PRIO_INHERIT)) == 0) { atomic_cmpset_rel_32(&mtx->m_owner, id | UMUTEX_CONTESTED, UMUTEX_CONTESTED); return _umtx_op_err(mtx, UMTX_OP_MUTEX_WAKE, 0, 0, 0); } +#endif /* __ia64__ */ return _umtx_op_err(mtx, UMTX_OP_MUTEX_UNLOCK, 0, 0, 0); }
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