linux-kernel - Re: [PATCH] staging: vchiq: rework remove

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Date:   Wed, 12 Dec 2018 17:24:40 +0100
From:   Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Eric Anholt <eric@...olt.net>,
        Stefan Wahren <stefan.wahren@...e.com>,
        gregkh <gregkh@...uxfoundation.org>, tn@...tmail.net,
        "moderated list:BROADCOM BCM2835 ARM ARCHITECTURE" 
        <linux-rpi-kernel@...ts.infradead.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        driverdevel <devel@...verdev.osuosl.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] staging: vchiq: rework remove_event handling

On Tue, 2018-12-11 at 15:20 +0100, Arnd Bergmann wrote:
> On Tue, Dec 11, 2018 at 1:36 PM Nicolas Saenz Julienne
> <nsaenzjulienne@...e.de> wrote:
> > On Mon, 2018-12-10 at 22:11 +0100, Arnd Bergmann wrote:
> > > @@ -447,26 +444,26 @@ remote_event_wait(VCHIQ_STATE_T *state,
> > > REMOTE_EVENT_T *event)
> > >  }
> > > 
> > >  static inline void
> > > -remote_event_signal_local(VCHIQ_STATE_T *state, REMOTE_EVENT_T
> > > *event)
> > > +remote_event_signal_local(wait_queue_head_t *wq, REMOTE_EVENT_T
> > > *event)
> > >  {
> > >       event->armed = 0;
> > > -     complete((struct completion *)((char *)state + event-
> > > >event));
> > > +     wake_up_all(wq);
> > 
> > Shouldn't this just be "wake_up(wq)"?
> 
> I wasn't entirely sure if we could get with more than one thread
> waiting
> for the wakeup. With the semaphore or completion that would already
> be broken because we'd only wake up one of them, but I was hoping
> to stay on the safe side with wake_up_all().

You're right. Had a look at the code and there shouldn't be more than
one thread waiting. wake_up_all() looks OK.

Reviewed-by: Nicolas Saenz Julienne <nsaenzjulienne@...e.de>

Regards,
Nicolas

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