linux-kernel - Re: [PATCH] timerfd: Protect the might cancel mechanism proper

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Message-ID: <alpine.DEB.2.20.1702101150400.4036@nanos>
Date:   Fri, 10 Feb 2017 11:51:31 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Dmitry Vyukov <dvyukov@...gle.com>
cc:     Al Viro <viro@...iv.linux.org.uk>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        syzkaller <syzkaller@...glegroups.com>
Subject: Re: [PATCH] timerfd: Protect the might cancel mechanism proper

On Fri, 10 Feb 2017, Dmitry Vyukov wrote:
> On Fri, Feb 10, 2017 at 11:13 AM, Thomas Gleixner <tglx@...utronix.de> wrote:
> > ctx->might_cancel and ctx->clist are always in sync with the new lock and
> > that's the only interesting thing. On destruction we don't look at clockid
> > or such, we only care about might_cancel.
> >
> > What is not guaranteed to be in sync is the timer expiry time and the
> > cancel stuff, if two threads operate on the same timerfd in
> > parallel. That's what I do not care about at all.
> 
> Ack. Thanks for looking at it bearing with me. Then:

Thanks for asking the questions. It's always good if we need to think it
over again.

Thanks,

	tglx