From 6b79b52cf3d5b3d0f02f0ac185d7feebdd7308cb Mon Sep 17 00:00:00 2001
From: Franco Fichtner <franco@opnsense.org>
Date: Thu, 16 Feb 2017 20:29:01 +0100
Subject: [PATCH] Revert "Microoptimize locking primitives by avoiding
 unnecessary atomic ops."

This reverts commit 25669dd1d9562b9b1717d5ef59b15e1716c81634.
---
 sys/kern/kern_rwlock.c | 4 +---
 sys/sys/rwlock.h       | 4 ++--
 2 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/sys/kern/kern_rwlock.c b/sys/kern/kern_rwlock.c
index ea2f969a8ba..84283327e8c 100644
--- a/sys/kern/kern_rwlock.c
+++ b/sys/kern/kern_rwlock.c
@@ -809,9 +809,7 @@ __rw_wlock_hard(volatile uintptr_t *c, uintptr_t tid, const char *file,
 	all_time -= lockstat_nsecs(&rw->lock_object);
 	state = rw->rw_lock;
 #endif
-	for (;;) {
-		if (rw->rw_lock == RW_UNLOCKED && _rw_write_lock(rw, tid))
-			break;
+	while (!_rw_write_lock(rw, tid)) {
 #ifdef KDTRACE_HOOKS
 		lda.spin_cnt++;
 #endif
diff --git a/sys/sys/rwlock.h b/sys/sys/rwlock.h
index 6b4f505e0d0..f8947c55617 100644
--- a/sys/sys/rwlock.h
+++ b/sys/sys/rwlock.h
@@ -96,7 +96,7 @@
 #define	__rw_wlock(rw, tid, file, line) do {				\
 	uintptr_t _tid = (uintptr_t)(tid);				\
 									\
-	if ((rw)->rw_lock != RW_UNLOCKED || !_rw_write_lock((rw), _tid))\
+	if (!_rw_write_lock((rw), _tid))				\
 		_rw_wlock_hard((rw), _tid, (file), (line));		\
 	else 								\
 		LOCKSTAT_PROFILE_OBTAIN_RWLOCK_SUCCESS(rw__acquire, rw,	\
@@ -112,7 +112,7 @@
 	else {								\
 		LOCKSTAT_PROFILE_RELEASE_RWLOCK(rw__release, rw,	\
 		    LOCKSTAT_WRITER);					\
-		if ((rw)->rw_lock != _tid || !_rw_write_unlock((rw), _tid))\
+		if (!_rw_write_unlock((rw), _tid))			\
 			_rw_wunlock_hard((rw), _tid, (file), (line));	\
 	}								\
 } while (0)