Author: mjg
Date: Thu Feb 9 13:32:19 2017
New Revision: 313472
URL: https://svnweb.freebsd.org/changeset/base/313472
Log:
rwlock: fix r313454
The runlock slow path would update wrong variable before restarting the
loop, in effect corrupting the state.
Reported by: pho
Modified:
head/sys/kern/kern_rwlock.c
Modified: head/sys/kern/kern_rwlock.c
==============================================================================
--- head/sys/kern/kern_rwlock.c Thu Feb 9 09:02:45 2017 (r313471)
+++ head/sys/kern/kern_rwlock.c Thu Feb 9 13:32:19 2017 (r313472)
@@ -755,7 +755,7 @@ __rw_runlock_hard(volatile uintptr_t *c,
if (!atomic_cmpset_rel_ptr(&rw->rw_lock, RW_READERS_LOCK(1) | v,
x)) {
turnstile_chain_unlock(&rw->lock_object);
- x = RW_READ_VALUE(rw);
+ v = RW_READ_VALUE(rw);
continue;
}
if (LOCK_LOG_TEST(&rw->lock_object, 0))
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