linux-kernel - Re: [PATCH] ALSA: cs4281: remove redundant assignment to variable val and remove a goto

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Message-ID: <s5hbly8zs28.wl-tiwai@suse.de>
Date:   Fri, 05 Jul 2019 12:36:31 +0200
From:   Takashi Iwai <tiwai@...e.de>
To:     wharms@....de
Cc:     "Colin King" <colin.king@...onical.com>,
        <alsa-devel@...a-project.org>, "Jaroslav Kysela" <perex@...ex.cz>,
        <kernel-janitors@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ALSA: cs4281: remove redundant assignment to variable val and remove a goto

On Fri, 05 Jul 2019 12:20:10 +0200,
walter harms wrote:
> 
> 
> 
> Am 05.07.2019 11:57, schrieb Colin King:
> > From: Colin Ian King <colin.king@...onical.com>
> > 
> > The variable val is being assigned with a value that is never
> > read and it is being updated later with a new value. The
> > assignment is redundant and can be removed.  Also remove a
> > goto statement and a label and replace with a break statement.
> > 
> > Addresses-Coverity: ("Unused value")
> > Signed-off-by: Colin Ian King <colin.king@...onical.com>
> > ---
> >  sound/pci/cs4281.c | 5 ++---
> >  1 file changed, 2 insertions(+), 3 deletions(-)
> > 
> > diff --git a/sound/pci/cs4281.c b/sound/pci/cs4281.c
> > index a2cce3ecda6f..04c712647853 100644
> > --- a/sound/pci/cs4281.c
> > +++ b/sound/pci/cs4281.c
> > @@ -694,7 +694,7 @@ static int snd_cs4281_trigger(struct snd_pcm_substream *substream, int cmd)
> >  
> >  static unsigned int snd_cs4281_rate(unsigned int rate, unsigned int *real_rate)
> >  {
> > -	unsigned int val = ~0;
> > +	unsigned int val;
> >  	
> >  	if (real_rate)
> >  		*real_rate = rate;
> > @@ -707,9 +707,8 @@ static unsigned int snd_cs4281_rate(unsigned int rate, unsigned int *real_rate)
> >  	case 44100:	return 1;
> >  	case 48000:	return 0;
> >  	default:
> > -		goto __variable;
> > +		break;
> >  	}
> > -      __variable:
> >  	val = 1536000 / rate;
> >  	if (real_rate)
> >  		*real_rate = 1536000 / val;
> 		^^^^^^^^^^^^^^^^^^^^^^^^^
> 
> this is confusing. is
> *real_rate = rate
> intended here ? (like above)
> 
> val could be eliminated by using
> 
> return  1536000 / rate ;

No, the current code is correct.
The purpose of this calculation is to consider the truncation by
division.


Takashi