linux-kernel - Re: checkpatch? (was: Re: [PATCH v3] coccinelle: misc: add uninitialized

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Date:   Wed, 2 Sep 2020 08:17:02 +0300
From:   Denis Efremov <efremov@...ux.com>
To:     Joe Perches <joe@...ches.com>, julia.lawall@...ia.fr
Cc:     cocci@...teme.lip6.fr, linux-kernel@...r.kernel.org,
        Kees Cook <keescook@...omium.org>,
        "Gustavo A . R . Silva" <gustavoars@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: checkpatch? (was: Re: [PATCH v3] coccinelle: misc: add
 uninitialized_var.cocci script)



On 9/1/20 5:37 PM, Joe Perches wrote:
> On Tue, 2020-09-01 at 12:48 +0300, Denis Efremov wrote:
>> uninitialized_var() macro was removed from the sources [1] and
>> other warning-silencing tricks were deprecated [2]. The purpose of this
>> cocci script is to prevent new occurrences of uninitialized_var()
>> open-coded variants.
> 
>> +(
>> +* T var =@p var;
>> +|
>> +* T var =@p *(&(var));
>> +|
>> +* var =@p var
>> +|
>> +* var =@p *(&(var))
>> +)
> 
> Adding a checkpatch test might be a good thing too.
> 
> ---
>  scripts/checkpatch.pl | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index 149518d2a6a7..300b2659aab3 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -3901,6 +3901,17 @@ sub process {
>  #ignore lines not being added
>  		next if ($line =~ /^[^\+]/);
>  
> +# check for self assigments used to avoid compiler warnings
> +# e.g.:	int foo = foo, *bar = NULL;
> +#	struct foo bar = *(&(bar));
> +		if ($line =~ /^\+\s*(?:$Declare)?([A-Za-z_][A-Za-z\d_]*)\s*=/) {
> +			my $var = $1;
> +			if ($line =~ /^\+\s*(?:$Declare)?$var\s*=\s*(?:$var|\*\s*\(?\s*&\s*\(?\s*$var\s*\)?\s*\)?)\s*[;,]/) {
> +				WARN("SELF_ASSIGNMENT",
> +				     "Do not use self-assignments to avoid compiler warnings\n" . $herecurr);
> +			}
> +		}
> +
>  # check for dereferences that span multiple lines
>  		if ($prevline =~ /^\+.*$Lval\s*(?:\.|->)\s*$/ &&
>  		    $line =~ /^\+\s*(?!\#\s*(?!define\s+|if))\s*$Lval/) {

Looks good. I also faced this kind of assignments after declarations.
https://lkml.org/lkml/2020/8/31/85

I'm not sure if they are used to suppress compiler warnings, through.

Denis