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Date: Sat, 30 Dec 2023 08:04:32 +0100
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Subject: Re: scsi: ses: Move a label in ses_enclosure_data_process()
Content-Language: en-GB
To: James Bottomley <jejb@linux.ibm.com>, linux-scsi@vger.kernel.org,
 kernel-janitors@vger.kernel.org,
 "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: LKML <linux-kernel@vger.kernel.org>
References: <4616e325-e313-4078-9788-dd1e6e51b9e0@web.de>
 <9d24844f30604f969ac10da456801f594ce72f2d.camel@linux.ibm.com>
From: Markus Elfring <Markus.Elfring@web.de>
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>> The kfree() function was called in up to three cases by
>> the ses_enclosure_data_process() function during error handling
>> even if the passed variable contained a null pointer.
>> This issue was detected by using the Coccinelle software.
>
> Why is this an issue?  The whole point of having kfree(NULL) be a nop

Such =E2=80=9Ca nop=E2=80=9D can trigger the allocation of extra data proc=
essing resources,
can't it?


> is so we don't have to special case the free path.

A bit more development attention can hopefully connect the mentioned label
with a more appropriate jump target directly.


>                                                     The reason we do
> that is because multiple special case paths through code leads to more
> complex control flows and more potential bugs.

You probably know some advices from another information source.

https://wiki.sei.cmu.edu/confluence/display/c/MEM12-C.+Consider+using+a+go=
to+chain+when+leaving+a+function+on+error+when+using+and+releasing+resourc=
es


>                                                 If coccinelle suddenly
> thinks this is a problem, it's coccinelle that needs fixing.

This software tool can help to point source code places out for further co=
nsiderations.
The search patterns are evolving accordingly.

Regards,
Markus