Re: [PATCH] hrtimer: Annotate lockless access to timer->state

[Eric Dumazet]

On Wed, Nov 6, 2019 at 10:09 AM Thomas Gleixner <tglx@xxxxxxxxxxxxx> 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