linux-kernel - Re: [PATCH 1/1] drivers/scsi/tmscsim.c: replace shift loop by ilog2

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Date:	Wed, 21 May 2014 17:28:22 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	Joe Perches <joe@...ches.com>
Cc:	Fabian Frederick <fabf@...net.be>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Kurt Garloff <garloff@...e.de>,
	akpm <akpm@...ux-foundation.org>
Subject: Re: [PATCH 1/1] drivers/scsi/tmscsim.c: replace shift loop by ilog2

On Tue, May 20, 2014 at 10:06:42AM -0700, Joe Perches wrote:
> On Tue, 2014-05-20 at 18:48 +0200, Fabian Frederick wrote:
> > Cc: Kurt Garloff <garloff@...e.de>
> > Cc: Andrew Morton <akpm@...ux-foundation.org>
> > Signed-off-by: Fabian Frederick <fabf@...net.be>
> > ---
> >  drivers/scsi/tmscsim.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/scsi/tmscsim.c b/drivers/scsi/tmscsim.c
> []
> > @@ -1611,7 +1611,7 @@ dc390_Reselect( struct dc390_acb* pACB )
> >        printk (KERN_ERR "DC390: Reselection must select host adapter: %02x!\n", lun);
> >      else
> >        lun ^= 1 << pACB->pScsiHost->this_id; /* Mask AdapterID */
> > -    id = 0; while (lun >>= 1) id++;
> > +    id = ilog2(lun);
> >      /* Get LUN */
> >      lun = DC390_read8 (ScsiFifo);
> >      if (!(lun & IDENTIFY_BASE)) printk (KERN_ERR "DC390: Resel: Expect identify message!\n");
> 
> Hey Fabian.
> 
> You've submitted several of these now.
> 
> Have you gone through all of these to make sure
> that the ilog2(<foo>) uses are always using a
> non-zero <foo>?
> 
Maybe I am missing something. Why not just use fls() ?

Guenter
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