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From: Mateusz Guzik <mjg@FreeBSD.org>
Date: Sat, 11 Nov 2017 09:34:12 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
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Subject: svn commit: r325706 - head/sys/kern
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Author: mjg
Date: Sat Nov 11 09:34:11 2017
New Revision: 325706
URL: https://svnweb.freebsd.org/changeset/base/325706

Log:
  rwlock: use fcmpset for setting RW_LOCK_WRITE_SPINNER

Modified:
  head/sys/kern/kern_rwlock.c

Modified: head/sys/kern/kern_rwlock.c
==============================================================================
--- head/sys/kern/kern_rwlock.c	Sat Nov 11 07:21:49 2017	(r325705)
+++ head/sys/kern/kern_rwlock.c	Sat Nov 11 09:34:11 2017	(r325706)
@@ -929,9 +929,8 @@ __rw_wlock_hard(volatile uintptr_t *c, uintptr_t v, ui
 		if ((v & RW_LOCK_READ) && RW_READERS(v) &&
 		    spintries < rowner_retries) {
 			if (!(v & RW_LOCK_WRITE_SPINNER)) {
-				if (!atomic_cmpset_ptr(&rw->rw_lock, v,
+				if (!atomic_fcmpset_ptr(&rw->rw_lock, &v,
 				    v | RW_LOCK_WRITE_SPINNER)) {
-					v = RW_READ_VALUE(rw);
 					continue;
 				}
 			}