Date: Sun, 19 Jul 2015 22:26:03 +0000 (UTC) From: Mark Johnston <markj@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r285706 - head/sys/kern Message-ID: <201507192226.t6JMQ3ZR006228@repo.freebsd.org>
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Author: markj Date: Sun Jul 19 22:26:02 2015 New Revision: 285706 URL: https://svnweb.freebsd.org/changeset/base/285706 Log: Don't increment the spin count until after the first attempt to acquire a rwlock read lock. Otherwise the lockstat:::rw-spin probe will fire spuriously. MFC after: 1 week Modified: head/sys/kern/kern_rwlock.c Modified: head/sys/kern/kern_rwlock.c ============================================================================== --- head/sys/kern/kern_rwlock.c Sun Jul 19 22:25:16 2015 (r285705) +++ head/sys/kern/kern_rwlock.c Sun Jul 19 22:26:02 2015 (r285706) @@ -382,9 +382,6 @@ __rw_rlock(volatile uintptr_t *c, const state = rw->rw_lock; #endif for (;;) { -#ifdef KDTRACE_HOOKS - spin_cnt++; -#endif /* * Handle the easy case. If no other thread has a write * lock, then try to bump up the count of read locks. Note @@ -413,6 +410,9 @@ __rw_rlock(volatile uintptr_t *c, const } continue; } +#ifdef KDTRACE_HOOKS + spin_cnt++; +#endif #ifdef HWPMC_HOOKS PMC_SOFT_CALL( , , lock, failed); #endif
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