From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1756758AbcJGPHJ (ORCPT <rfc822;w@1wt.eu>);
        Fri, 7 Oct 2016 11:07:09 -0400
Received: from merlin.infradead.org ([205.233.59.134]:46336 "EHLO
        merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1752411AbcJGPGn (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Fri, 7 Oct 2016 11:06:43 -0400
Message-Id: <20161007150211.348310457@infradead.org>
User-Agent: quilt/0.63-1
Date: Fri, 07 Oct 2016 16:52:50 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Linus Torvalds <torvalds@linux-foundation.org>,
        Waiman Long <waiman.long@hpe.com>, Jason Low <jason.low2@hpe.com>,
        Ding Tianhong <dingtianhong@huawei.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Will Deacon <Will.Deacon@arm.com>, Ingo Molnar <mingo@redhat.com>,
        Imre Deak <imre.deak@intel.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Davidlohr Bueso <dave@stgolabs.net>,
        Tim Chen <tim.c.chen@linux.intel.com>, Terry Rudd <terry.rudd@hpe.com>,
        "Paul E. McKenney" <paulmck@us.ibm.com>, Jason Low <jason.low2@hp.com>,
        Peter Zijlstra <peterz@infradead.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>,
        Daniel Vetter <daniel.vetter@ffwll.ch>,
        Waiman Long <Waiman.Long@hpe.com>
Subject: [PATCH -v4 7/8] locking/mutex: Simplify some ww_mutex code in __mutex_lock_common()
References: <20161007145243.361481786@infradead.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Disposition: inline; filename=waiman_long-locking_mutex-simplify_some_ww_mutex_code_in___mutex_lock_common.patch
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

From: Waiman Long <Waiman.Long@hpe.com>

This patch removes some of the redundant ww_mutex code in
__mutex_lock_common().

Cc: Ingo Molnar <mingo@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Jason Low <jason.low2@hpe.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: Ding Tianhong <dingtianhong@huawei.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Will Deacon <Will.Deacon@arm.com>
Signed-off-by: Waiman Long <Waiman.Long@hpe.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 kernel/locking/mutex.c |   13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -580,10 +580,11 @@ __mutex_lock_common(struct mutex *lock,
 	struct mutex_waiter waiter;
 	unsigned long flags;
 	bool first = false;
+	struct ww_mutex *ww;
 	int ret;
 
 	if (use_ww_ctx) {
-		struct ww_mutex *ww = container_of(lock, struct ww_mutex, base);
+		ww = container_of(lock, struct ww_mutex, base);
 		if (unlikely(ww_ctx == READ_ONCE(ww->ctx)))
 			return -EALREADY;
 	}
@@ -595,12 +596,8 @@ __mutex_lock_common(struct mutex *lock,
 	    mutex_optimistic_spin(lock, ww_ctx, use_ww_ctx)) {
 		/* got the lock, yay! */
 		lock_acquired(&lock->dep_map, ip);
-		if (use_ww_ctx) {
-			struct ww_mutex *ww;
-			ww = container_of(lock, struct ww_mutex, base);
-
+		if (use_ww_ctx)
 			ww_mutex_set_context_fastpath(ww, ww_ctx);
-		}
 		preempt_enable();
 		return 0;
 	}
@@ -680,10 +677,8 @@ __mutex_lock_common(struct mutex *lock,
 	/* got the lock - cleanup and rejoice! */
 	lock_acquired(&lock->dep_map, ip);
 
-	if (use_ww_ctx) {
-		struct ww_mutex *ww = container_of(lock, struct ww_mutex, base);
+	if (use_ww_ctx)
 		ww_mutex_set_context_slowpath(ww, ww_ctx);
-	}
 
 	spin_unlock_mutex(&lock->wait_lock, flags);
 	preempt_enable();