linux-kernel - Re: [PATCH 2/4] fscache: Fix race in fscache_op_complete() due to split atomic

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Message-ID: <20181017164848.GA9795@andrea>
Date:   Wed, 17 Oct 2018 18:48:48 +0200
From:   Andrea Parri <andrea.parri@...rulasolutions.com>
To:     David Howells <dhowells@...hat.com>
Cc:     gregkh@...ux-foundation.org,
        Kiran Kumar Modukuri <kiran.modukuri@...il.com>,
        viro@...iv.linux.org.uk, sandeen@...hat.com,
        linux-cachefs@...hat.com, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] fscache: Fix race in fscache_op_complete() due to
 split atomic_sub & read

On Wed, Oct 17, 2018 at 04:32:13PM +0100, David Howells wrote:
> Andrea Parri <andrea.parri@...rulasolutions.com> wrote:
> 
> > > Fix this by using atomic_sub_return() instead of two calls.
> > 
> > Seems a case for atomic_sub_return_relaxed()... why not?
> 
> Ummm...  In that case, should it be atomic_sub_return_release()?

Hard to tell for me: your diff./changelog is all I know about fs-cache
... (and this suggests -no-, given that atomic_sub() and atomic_read()
provide no ordering...); good question though. ;-)

  Andrea


> 
> David