linux-kernel - Re: ALSA: intel8x0: div by zero in snd_intel8x0

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Date:   Thu, 08 Jul 2021 11:00:11 +0200
From:   Takashi Iwai <tiwai@...e.de>
To:     Max Filippov <jcmvbkbc@...il.com>
Cc:     Sergey Senozhatsky <senozhatsky@...omium.org>,
        alsa-devel@...a-project.org, Leon Romanovsky <leon@...nel.org>,
        Takashi Iwai <tiwai@...e.com>,
        LKML <linux-kernel@...r.kernel.org>,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>
Subject: Re: ALSA: intel8x0: div by zero in snd_intel8x0_update()

On Thu, 08 Jul 2021 10:41:50 +0200,
Max Filippov wrote:
> 
> On Thu, Jul 8, 2021 at 12:13 AM Takashi Iwai <tiwai@...e.de> wrote:
> > On Wed, 07 Jul 2021 22:33:22 +0200,
> > Max Filippov wrote:
> > >
> > > On Wed, Jul 7, 2021 at 11:14 AM Takashi Iwai <tiwai@...e.de> wrote:
> > > > On Wed, 07 Jul 2021 19:50:07 +0200, Max Filippov wrote:
> > > > > It didn't change anything in my case. My further observation is that
> > > > > the snd_intel8x0_update is called before the ichdev->prepared
> > > > > is set to one and as a result IRQ is apparently never cleared.
> > > >
> > > > So it's broken in anyway no matter whether
> > > > intel8x0_measure_ac97_clock() is called or not, right?
> > >
> > > The change that you suggested didn't eliminate the call to
> > > intel8x0_measure_ac97_clock, it's still called and an interrupt
> > > flood happens at the same place.
> >
> > Ah I see the point.  Then the fix would be a oneliner like below.
> >
> >
> > Takashi
> >
> > --- a/sound/pci/intel8x0.c
> > +++ b/sound/pci/intel8x0.c
> > @@ -694,7 +694,7 @@ static inline void snd_intel8x0_update(struct intel8x0 *chip, struct ichdev *ich
> >         int status, civ, i, step;
> >         int ack = 0;
> >
> > -       if (!ichdev->prepared || ichdev->suspended)
> > +       if (!(ichdev->prepared || ichdev->in_measurement) || ichdev->suspended)
> 
> There's no ichdev::in_measurement, but if replaced with
> chip->in_measurement it indeed fixes my issue.

One must compile the code before sending out :-<

> So with this change:
> Tested-by: Max Filippov <jcmvbkbc@...il.com>

Great, thanks for quick testing, I'll prepare the fix patch now.


Takashi