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SubjectRe: [PATCH] checkpatch: add check for wrong "if (IS_ERR_OR_NULL(<foo>)) return PTR_ERR(<foo>)" uses
From
Hi Joe,

Thank you for looking into this.

On Tue, May 14, 2013 at 7:36 AM, Joe Perches <joe@perches.com> wrote:
> On Tue, 2013-05-14 at 03:41 +0300, Ruslan Bilovol wrote:
>> This was many times discussed by Russell King
>> and I also was about wrong usage of IS_ERR_OR_NULL()
>> in my patch. So I added this check and other people will
>> be at least warned about potentially wrong usage
>> of mentioned macro.
> []
>> Tested on:
>> + if (IS_ERR_OR_NULL(soc_dev))
>> + return PTR_ERR(soc_dev);
>> +
>> + if (IS_ERR_OR_NULL(soc_dev))en
>> + return soc_dev ? PTR_ERR(soc_dev) : -ENODEV;
>
> I did a grep for IS_ERR_OR_NULL and this misses variants like:
>
> if (unlikely(IS_ERR_OR_NULL(etc...

Agree, I checked and you are right

>
> Perhaps something like this?

hmm.. your variant have false positives.
I used next 2 examples for verification:

This one - is incorrect usage of IS_ERR_OR_NULL
+ if (IS_ERR_OR_NULL(soc_dev))
+ return PTR_ERR(soc_dev);

But this one is correct and checkpach shouldn't react here but in your
version does react
+ if (IS_ERR_OR_NULL(soc_dev))
+ return soc_dev ? PTR_ERR(soc_dev) : -ENODEV;

Care to fix it?

Best regards,
Ruslan

> ---
> scripts/checkpatch.pl | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index b954de5..18c7d8c 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -2184,6 +2184,15 @@ sub process {
> WARN("SUSPECT_CODE_INDENT",
> "suspect code indent for conditional statements ($indent, $sindent)\n" . $herecurr . "$stat_real\n");
> }
> +
> +# check for misuses of IS_ERR_OR_NULL
> + if ($stat =~ /^\+.*\bIS_ERR_OR_NULL\s*\(\s*($Lval)\s*\)/) {
> + my $test = $1;
> + if ($stat =~ /\bPTR_ERR\s*\(\s*${test}\s*\)/) {
> + WARN("IS_ERR_OR_NULL",
> + "Use of IS_ERR_OR_NULL($test) with PTR_ERR($test) is usually wrong: see http://permalink.gmane.org/gmane.linux.ports.arm.omap/97874\n" . $herecurr . "$stat_real\n");
> + }
> + }
> }
>
> # Track the 'values' across context and added lines.
>
>
> --
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