linux-kernel - Re: [PATCH v3] scripts: checkpatch.pl: add 2 new checks on memset

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Date:	Sun, 01 Mar 2015 14:13:21 -0800
From:	Joe Perches <joe@...ches.com>
To:	Aya Mahfouz <mahfouz.saif.elyazal@...il.com>
Cc:	Andy Whitcroft <apw@...onical.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] scripts: checkpatch.pl: add 2 new checks on memset

On Sun, 2015-03-01 at 23:43 +0200, Aya Mahfouz wrote:
> calls 
> Reply-To: 
> 
> Add 2 new checks on memset calls in the file checkpatch.pl as follows:

Hi again Aya

The initial 3 lines here aren't necessary.

I think it'd be a better subject line with something like
"checkpatch: prefer eth_<foo>_addr over memset(,,ETH_ALEN)"

Please cc Andrew Morton <akpm@...ux-foundation.org>
And please also don't add Signed-off-by: lines for
anyone other than yourself.

Other than those things:
Acked-by: Joe Perches <joe@...ches.com>

> replace memset by eth_zero_addr if the second argument is
> an address of zeros (0x00). eth_zero_addr is a wrapper function
> for memset that takes an address array to set as zero. The size
> address has to be ETH_ALEN.
> 
> replace memset by eth_broadcast_addr if the second argument is
> the broadcast address (0xff). eth_broadcast_addr is a wrapper
> function for memset that sets the passed array the broadcast
> address. The size of the address has to be ETH_ALEN.
> 
> In addition, the regex assigned to the variable $stat has been
> restricted to handle memset function calls of the form:
> [<identifer> =]* memset(<arg1>, <arg2>, <arg3>)
> 
> Cc: Julia Lawall <julia.lawall@...6.fr>
> Signed-off-by: Aya Mahfouz <mahfouz.saif.elyazal@...il.com>
> Signed-off-by: Joe Perches <joe@...ches.com>
> ---
> v2: adjusted all checks on memset calls to be in one body
> v3: adjusted all regular expressions per Joe Perches suggestions. Added
> a Signed-off-by tag for Joe since all the important regular expressions
> are written by him.
> 
>  scripts/checkpatch.pl | 17 +++++++++++++++--
>  1 file changed, 15 insertions(+), 2 deletions(-)
> 
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index d124359..cbe973e 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -4890,10 +4890,11 @@ sub process {
>  			}
>  		}
>  
> -# Check for misused memsets
> +# Check for misused memsets then check for memset(foo, 0x00|0xff, ETH_ALEN)
> +# calls that could be eth_zero_addr(foo)|eth_broadcast_addr(foo)
>  		if ($^V && $^V ge 5.10.0 &&
>  		    defined $stat &&
> -		    $stat =~ /^\+(?:.*?)\bmemset\s*\(\s*$FuncArg\s*,\s*$FuncArg\s*\,\s*$FuncArg\s*\)/s) {
> +		    $stat =~ /^\+(?:\s*$Ident\s*=)?\s*memset\s*\(\s*$FuncArg\s*,\s*$FuncArg\s*\,\s*$FuncArg\s*\)/s) {
>  
>  			my $ms_addr = $2;
>  			my $ms_val = $7;
> @@ -4905,6 +4906,18 @@ sub process {
>  			} elsif ($ms_size =~ /^(0x|)1$/i) {
>  				WARN("MEMSET",
>  				     "single byte memset is suspicious. Swapped 2nd/3rd argument?\n" . "$here\n$stat\n");
> +			} elsif ($ms_val =~ /^(?:0x)?0+$/i &&
> +				 $ms_size =~ /^ETH_ALEN$/ &&
> +				 WARN("PREFER_ETH_ADDR",
> +				     "Prefer eth_zero_addr() over memset() if the second address is 0\n" . $herecurr) &&
> +				 $fix) {
> +				$fixed[$fixlinenr] =~ s/\bmemset\s*\(\s*\Q$ms_addr\E\s*,\s*\Q$ms_val\E\s*,\s*ETH_ALEN\s*\)/eth_zero_addr($ms_addr)/;
> +			} elsif ($ms_val =~ /^(?:0xff|255)$/i &&
> +				 $ms_size =~ /^ETH_ALEN$/ &&
> +				 WARN("PREFER_ETH_ADDR",
> +				      "Prefer eth_broadcast_addr() over memset() if the second address is 0xff\n" . $herecurr) &&
> +				 $fix) {
> +				$fixed[$fixlinenr] =~ s/\bmemset\s*\(\s*\Q$ms_addr\E\s*,\s*\Q$ms_val\E\s*,\s*ETH_ALEN\s*\)/eth_broadcast_addr($ms_addr)/;
>  			}
>  		}
>  
> -- 
> 1.9.3
> 
> 



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