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From: Eric Dumazet <edumazet@google.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
	Eric Dumazet <eric.dumazet@gmail.com>,
	syzbot <syzkaller@googlegroups.com>
Subject: Re: [PATCH] hrtimer: Annotate lockless access to timer->state
Date: Wed, 6 Nov 2019 10:19:44 -0800	[thread overview]
Message-ID: <CANn89iK12QGBagUiNr+j-ToawJ9J1behtySyL9vLattYPAD-7w@mail.gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.21.1911061908070.1869@nanos.tec.linutronix.de>

On Wed, Nov 6, 2019 at 10:09 AM Thomas Gleixner <tglx@linutronix.de> wrote:
>
> On Wed, 6 Nov 2019, Eric Dumazet wrote:
> > @@ -1013,8 +1013,9 @@ static void __remove_hrtimer(struct hrtimer *timer,
> >  static inline int
> >  remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base, bool restart)
> >  {
> > -     if (hrtimer_is_queued(timer)) {
> > -             u8 state = timer->state;
> > +     u8 state = timer->state;
>
> Shouldn't that be a read once then at least for consistency sake?

We own the lock here, this is not really needed ?

Note they are other timer->state reads I chose to leave unchanged.

But no big deal if you prefer I can add a READ_ONCE()

Thanks.
>
> > +
> > +     if (state & HRTIMER_STATE_ENQUEUED) {
> >               int reprogram;
>
> Thanks,
>
>         tglx

  reply	other threads:[~2019-11-06 18:20 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-06 17:48 [PATCH] hrtimer: Annotate lockless access to timer->state Eric Dumazet
2019-11-06 18:09 ` Thomas Gleixner
2019-11-06 18:19   ` Eric Dumazet [this message]
2019-11-06 19:15     ` Thomas Gleixner
2019-11-06 20:00       ` Eric Dumazet
2019-11-06 21:06 ` [tip: timers/core] " tip-bot2 for Eric Dumazet
2019-11-06 22:02   ` Eric Dumazet
2019-11-06 22:16     ` Thomas Gleixner
2019-11-06 22:24 ` tip-bot2 for Eric Dumazet
2019-11-06 22:53   ` Eric Dumazet
2019-11-06 22:59     ` Eric Dumazet
2019-11-07  8:52       ` Paul E. McKenney
2019-11-07 15:48         ` Eric Dumazet
2019-11-07 16:11           ` Paul E. McKenney
2019-11-07 16:35             ` Eric Dumazet
2019-11-07 16:39               ` Eric Dumazet
2019-11-07 16:54                 ` Paul E. McKenney
2019-11-07 16:59                   ` Eric Dumazet
2019-11-07 17:07                     ` Paul E. McKenney

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