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

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Date:   Thu, 08 Jul 2021 09:13:39 +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 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)
 		return;
 
 	spin_lock_irqsave(&chip->reg_lock, flags);