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

From: Joe Perches
Date: Wed May 21 2014 - 21:04:01 EST


On Wed, 2014-05-21 at 17:28 -0700, Guenter Roeck wrote:
> 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@xxxxxxx>
> > > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > > Signed-off-by: Fabian Frederick <fabf@xxxxxxxxx>
> > > ---
> > > 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() ?

fls strains Andrew Morton's brain.

https://lkml.org/lkml/2014/5/19/771


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