linux-kernel - Re: sysctl: Reduce dput(child) calls in proc_sys_fill

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Message-ID: <3a94a3cb-1beb-4e48-ab78-4f24b18d9077@web.de>
Date: Wed, 23 Oct 2024 14:10:57 +0200
From: Markus Elfring <Markus.Elfring@....de>
To: Joel Granados <joel.granados@...nel.org>, linux-fsdevel@...r.kernel.org,
 Al Viro <viro@...iv.linux.org.uk>, Kees Cook <kees@...nel.org>,
 Luis Chamberlain <mcgrof@...nel.org>
Cc: Joel Granados <j.granados@...sung.com>,
 LKML <linux-kernel@...r.kernel.org>, kernel-janitors@...r.kernel.org
Subject: Re: sysctl: Reduce dput(child) calls in proc_sys_fill_cache()

>> A dput(child) call was immediately used after an error pointer check
>> for a d_splice_alias() call in this function implementation.
>> Thus call such a function instead directly before the check.
> This message reads funny, please re-write for your v2. Here is how I would write
> it.
>
> "
> Replace two dput(child) calls with one that occurs immediately before the IS_ERR
> evaluation. This is ok because dput gets called regardless of the value returned
> by IS_ERR(res).
> "

Do you prefer the mentioned macro name over the wording “error pointer check”?


>> This issue was transformed by using the Coccinelle software.
> How long is the coccinelle script? …

A related script for the semantic patch language was presented already according to
the clarification approach “Generalising a transformation with SmPL?”.
https://lore.kernel.org/kernel-janitors/300b5d1a-ab88-4548-91d2-0792bc15e15e@web.de/
https://lkml.org/lkml/2024/9/14/464
https://sympa.inria.fr/sympa/arc/cocci/2024-09/msg00004.html

Will further development ideas evolve accordingly?

Regards,
Markus