linux-kernel - Re: [PATCH] fix incorrect test in trident_ac97

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Message-ID: <2c0942db0711071043p7cd31f6di9031816c1fed81ca@mail.gmail.com>
Date:	Wed, 7 Nov 2007 10:43:56 -0800
From:	"Ray Lee" <ray-lk@...rabbit.org>
To:	"Roel Kluin" <12o3l@...cali.nl>
Cc:	lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] fix incorrect test in trident_ac97_set(); sound/oss/trident.c

On Nov 7, 2007 10:34 AM, Roel Kluin <12o3l@...cali.nl> wrote:
> If count reaches zero, the loop ends, but the postfix decrement subtracts it.
> so, testing for 'count == 0' will not work.
>
> Signed-off-by: Roel Kluin <12o3l@...cali.nl>
> ---
> diff --git a/sound/oss/trident.c b/sound/oss/trident.c
> index 96adc47..94b5fb4 100644
> --- a/sound/oss/trident.c
> +++ b/sound/oss/trident.c
> @@ -2939,7 +2939,7 @@ trident_ac97_set(struct ac97_codec *codec, u8 reg, u16 val)
>
>         data |= (mask | (reg & AC97_REG_ADDR));
>
> -       if (count == 0) {
> +       if (count == -1) {
>                 printk(KERN_ERR "trident: AC97 CODEC write timed out.\n");
>                 spin_unlock_irqrestore(&card->lock, flags);
>                 return;
> @@ -2999,7 +2999,7 @@ trident_ac97_get(struct ac97_codec *codec, u8 reg)
>         } while (count--);
>         spin_unlock_irqrestore(&card->lock, flags);
>
> -       if (count == 0) {
> +       if (count == -1) {
>                 printk(KERN_ERR "trident: AC97 CODEC read timed out.\n");
>                 data = 0;
>         }

You didn't test this: count is unsigned. Change the loop condition to
be --count instead.

Ray
-
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