From mboxrd@z Thu Jan  1 00:00:00 1970
From: Al Viro <viro@ZenIV.linux.org.uk>
Subject: Re: Potential data race in dput and __d_lookup
Date: Thu, 20 Nov 2014 18:11:46 +0000
Message-ID: <20141120181145.GO7996@ZenIV.linux.org.uk>
References: <CAAeHK+zQZ=sJYQA=BKLS2i7hu8NyXn6GXngvDqG9WD96yd9acg@mail.gmail.com>
 <20141120174101.GT19126@arm.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Cc: Andrey Konovalov <andreyknvl@google.com>,
	Ingo Molnar <mingo@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Davidlohr Bueso <davidlohr@hp.com>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Dmitry Vyukov <dvyukov@google.com>,
	Kostya Serebryany <kcc@google.com>,
	"ktsan@googlegroups.com" <ktsan@googlegroups.com>
To: Will Deacon <will.deacon@arm.com>
Return-path: <linux-kernel-owner@vger.kernel.org>
Content-Disposition: inline
In-Reply-To: <20141120174101.GT19126@arm.com>
Sender: linux-kernel-owner@vger.kernel.org
List-Id: linux-fsdevel.vger.kernel.org

On Thu, Nov 20, 2014 at 05:41:01PM +0000, Will Deacon wrote:

> I think it should be fine. d_lock is #defined as d_lockref.lock, and the
> whole way the lockref works is that you can either cmpxchg the lock and the
> counter

... both by a single operation, that is.