linux-kernel - Re: [alsa-devel] [PATCH] sound/oss/pss: Fix test of unsigned in pss_reset_dsp() and pss_download

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Message-ID: <s5hfx7aw0za.wl%tiwai@suse.de>
Date:	Thu, 17 Dec 2009 07:47:37 +0100
From:	Takashi Iwai <tiwai@...e.de>
To:	Troy Kisky <troy.kisky@...ndarydevices.com>
Cc:	Roel Kluin <roel.kluin@...il.com>,
	Jaroslav Kysela <perex@...ex.cz>, alsa-devel@...a-project.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [alsa-devel] [PATCH] sound/oss/pss: Fix test of unsigned in pss_reset_dsp() and pss_download_boot()

At Wed, 16 Dec 2009 17:23:03 -0700,
Troy Kisky wrote:
> 
> Roel Kluin wrote:
> > limit and jiffies are unsigned so the test does not work.
> > 
> > Signed-off-by: Roel Kluin <roel.kluin@...il.com>
> > ---
> > Found using coccinelle: http://coccinelle.lip6.fr/
> > 
> > diff --git a/sound/oss/pss.c b/sound/oss/pss.c
> > index 83f5ee2..9325f4d 100644
> > --- a/sound/oss/pss.c
> > +++ b/sound/oss/pss.c
> > @@ -269,7 +269,7 @@ static int pss_reset_dsp(pss_confdata * devc)
> >  	unsigned long   i, limit = jiffies + HZ/10;
> >  
> >  	outw(0x2000, REG(PSS_CONTROL));
> > -	for (i = 0; i < 32768 && (limit-jiffies >= 0); i++)
> 
> I think
> 	for (i = 0; i < 32768 && ( (int)(limit-jiffies) >= 0); i++)
> 
> works better when jiffies wrap

Yes, and time_after_eq() takes care of it nicely :)


Takashi
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