linux-kernel - RE: [PATCH] media: atomisp: silence "dubious: !x

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Date:   Sat, 17 Apr 2021 21:31:32 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Mauro Carvalho Chehab' <mchehab@...nel.org>,
        Ashish Kalra <eashishkalra@...il.com>
CC:     Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
        "devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] media: atomisp: silence "dubious: !x | !y" warning

From: Mauro Carvalho Chehab
> Sent: 17 April 2021 19:56
> 
> Em Sat, 17 Apr 2021 21:06:27 +0530
> Ashish Kalra <eashishkalra@...il.com> escreveu:
> 
> > Upon running sparse, "warning: dubious: !x | !y" is brought to notice
> > for this file.  Logical and bitwise OR are basically the same in this
> > context so it doesn't cause a runtime bug.  But let's change it to
> > logical OR to make it cleaner and silence the Sparse warning.

The old code is very likely to by slightly more efficient.

It may not matter here, but it might in a really hot path.

Since !x | !y and !x || !y always have the same value
why is sparse complaining at all.

	David

> >
> > Signed-off-by: Ashish Kalra <eashishkalra@...il.com>
> > ---
> >  .../media/atomisp/pci/isp/kernels/vf/vf_1.0/ia_css_vf.host.c    | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/staging/media/atomisp/pci/isp/kernels/vf/vf_1.0/ia_css_vf.host.c
> b/drivers/staging/media/atomisp/pci/isp/kernels/vf/vf_1.0/ia_css_vf.host.c
> > index 358cb7d2cd4c..3b850bb2d39d 100644
> > --- a/drivers/staging/media/atomisp/pci/isp/kernels/vf/vf_1.0/ia_css_vf.host.c
> > +++ b/drivers/staging/media/atomisp/pci/isp/kernels/vf/vf_1.0/ia_css_vf.host.c
> > @@ -58,7 +58,7 @@ sh_css_vf_downscale_log2(
> >  	unsigned int ds_log2 = 0;
> >  	unsigned int out_width;
> >
> > -	if ((!out_info) | (!vf_info))
> > +	if ((!out_info) || (!vf_info))
> 
> 
> While here, please get rid of the unneeded parenthesis:
> 
> 	if (!out_info || !vf_info)
> 
> 
> >  		return -EINVAL;
> >
> >  	out_width = out_info->res.width;
> 
> 
> 
> Thanks,
> Mauro

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