Date: Thu, 23 Nov 2017 03:40:51 +0000 (UTC) From: Mateusz Guzik <mjg@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r326112 - head/sys/kern Message-ID: <201711230340.vAN3ep39064988@repo.freebsd.org>
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Author: mjg Date: Thu Nov 23 03:40:51 2017 New Revision: 326112 URL: https://svnweb.freebsd.org/changeset/base/326112 Log: sx: unbreak debug after r326107 An assertion was modified to use the found value, but it was not updated to handle a race where blocked threads appear after the entrance to the func. Move the assertion down to the area protected with sleepq lock where the lock is read anyway. This does not affect coverage of the assertion and is consistent with what rw locks are doing. Reported by: Shawn Webb Modified: head/sys/kern/kern_sx.c Modified: head/sys/kern/kern_sx.c ============================================================================== --- head/sys/kern/kern_sx.c Thu Nov 23 03:20:12 2017 (r326111) +++ head/sys/kern/kern_sx.c Thu Nov 23 03:40:51 2017 (r326112) @@ -828,12 +828,12 @@ _sx_xunlock_hard(struct sx *sx, uintptr_t x LOCK_FILE_ atomic_cmpset_rel_ptr(&sx->sx_lock, tid, SX_LOCK_UNLOCKED)) return; - MPASS(x & (SX_LOCK_SHARED_WAITERS | SX_LOCK_EXCLUSIVE_WAITERS)); if (LOCK_LOG_TEST(&sx->lock_object, 0)) CTR2(KTR_LOCK, "%s: %p contested", __func__, sx); sleepq_lock(&sx->lock_object); x = SX_READ_VALUE(sx); + MPASS(x & (SX_LOCK_SHARED_WAITERS | SX_LOCK_EXCLUSIVE_WAITERS)); /* * The wake up algorithm here is quite simple and probably not
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