linux-kernel - Re: [PATCH][ppc] logical/bitand typo in powerpc/boot/4xx.c

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Message-ID: <20080129105531.GA651@shadowen.org>
Date:	Tue, 29 Jan 2008 10:55:31 +0000
From:	Andy Whitcroft <apw@...dowen.org>
To:	Roel Kluin <12o3l@...cali.nl>
Cc:	Joe Perches <joe@...ches.com>, jwboyer@...ux.vnet.ibm.com,
	lkml <linux-kernel@...r.kernel.org>, linuxppc-dev@...abs.org
Subject: Re: [PATCH][ppc] logical/bitand typo in powerpc/boot/4xx.c

On Thu, Jan 24, 2008 at 01:18:48AM +0100, Roel Kluin wrote:
> Joe Perches wrote:
> > On Wed, 2008-01-23 at 23:37 +0100, Roel Kluin wrote:
> >> Signed-off-by: Roel Kluin <12o3l@...cali.nl>
> >> ---
> >> diff --git a/arch/powerpc/boot/4xx.c b/arch/powerpc/boot/4xx.c
> >> index ebf9e21..dcfb459 100644
> >> --- a/arch/powerpc/boot/4xx.c
> >> +++ b/arch/powerpc/boot/4xx.c
> >> @@ -104,7 +104,7 @@ void ibm4xx_denali_fixup_memsize(void)
> >>  	val = DDR_GET_VAL(val, DDR_CS_MAP, DDR_CS_MAP_SHIFT);
> >>  	cs = 0;
> >>  	while (val) {
> >> -		if (val && 0x1)
> >> +		if (val & 0x1)
> >>  			cs++;
> >>  		val = val >> 1;
> > 
> > I think this pattern should be added to checkpatch
> 
> I agree but...
> 
> > Signed-off-by: Joe Perches <joe@...ches.com>
> > 
> > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> > index 579f50f..147e573 100755
> > --- a/scripts/checkpatch.pl
> > +++ b/scripts/checkpatch.pl
> > @@ -1337,6 +1337,11 @@ sub process {
> >  			}
> >  		}
> >  
> > +# Check for bitwise tests written as boolean
> > +		if ($line =~ /\&\&\s*0[xX]/) {
> > +			WARN("boolean test with hexadecimal, perhaps just 1 \&?\n" . $herecurr);
> > +		}
> > +
> 
> when you use git-grep -n "\(&&\|||\)${s}0x\([A-Z0-9]*\|[a-z0-9]*\)",
> (with s="[[:space:]]*") there will be false positives like
> 
> if (relocation < -0x20000 || 0x1fffc < relocation)
> if (ARCH_SUN4C_SUN4 && addr < 0xe0000000 && 0x20000000 - len < addr) {
> (and more)
> 
> However, if you search with
> git-grep -n " \(&&\|||\)${s}0x\([A-Z0-9]*\|[a-z0-9]*\)$s\()\|&&\|||\)"
> you won't get these false positives, but you do get the one I fixed.
> 
> Also there is the same logic flipped (though it did not give matches at
> this time):
> git-grep -n " \(&&\|||\|(\)${s}0x\([A-Z0-9]*\|[a-z0-9]*\)$s\(&&\|||\)"
> 
> so i'd propose to change that to
> --
> Catch boolean tests with hexadecimals, based on suggestion by Joe Perches
> 
> Signed-off-by: Roel Kluin <12o3l@...cali.nl>
> ---
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index 579f50f..8ac7c7b 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -1337,6 +1337,12 @@ sub process {
>  			}
>  		}
>  
> +# Check for bitwise tests written as boolean
> +		if ($line =~ /(?:(?:\(|\&\&|\|\|)\s*0[xX]\s*(?:&&|\|\|)|
> +				(?:\&\&|\|\|)\s*0[xX]\s*(?:\)|&&|\|\|))/) {
> +			WARN("boolean test with hexadecimal, perhaps just 1 \& or \|?\n" . $herecurr);
> +		}
> +
>  # if and else should not have general statements after it
>  		if ($line =~ /^.\s*(?:}\s*)?else\b(.*)/ &&
>  		    $1 !~ /^\s*(?:\sif|{|\\|$)/) {

That one doesn't even match the original example.  Seems to be missing
some number matching.  The concept seems sound though.  Basically
looking for numbers which are definatly adjacent to a boolean or a brace
on both sides.

/me goes play with some examples to see if the falsies are better than
the reports.

-apw
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