linux-kernel - Re: [PATCH] drm/i915/backlight: Remove a useless kstrdup

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Message-ID: <86f6269f-e367-4192-ab71-5d82b1c88309@wanadoo.fr>
Date: Wed, 2 Oct 2024 18:43:32 +0200
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: Jani Nikula <jani.nikula@...ux.intel.com>,
 Rodrigo Vivi <rodrigo.vivi@...el.com>,
 Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
 Tvrtko Ursulin <tursulin@...ulin.net>, David Airlie <airlied@...il.com>,
 Simona Vetter <simona@...ll.ch>
Cc: linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
 intel-gfx@...ts.freedesktop.org, intel-xe@...ts.freedesktop.org,
 dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH] drm/i915/backlight: Remove a useless kstrdup_const()

Le 02/10/2024 à 13:51, Jani Nikula a écrit :
> On Tue, 01 Oct 2024, Christophe JAILLET <christophe.jaillet@...adoo.fr> wrote:
>> Le 30/09/2024 à 09:48, Jani Nikula a écrit :
>>> On Sat, 28 Sep 2024, Christophe JAILLET <christophe.jaillet@...adoo.fr> wrote:
>>>> "name" is allocated and freed in intel_backlight_device_register().
>>>> The initial allocation just duplicates "intel_backlight".
>>>>
>>>> Later, if a device with this name has already been registered, another
>>>> dynamically generated one is allocated using kasprintf().
>>>>
>>>> So at the end of the function, when "name" is freed, it can point either to
>>>> the initial static literal "intel_backlight" or to the kasprintf()'ed one.
>>>>
>>>> So kfree_const() is used.
>>>>
>>>> However, when built as a module, kstrdup_const() and kfree_const() don't
>>>> work as one would expect and are just plain kstrdup() and kfree().
>>>>
>>>>
>>>> Slightly change the logic and introduce a new variable to hold the
>>>> address returned by kasprintf() should it be used.
>>>>
>>>> This saves a memory allocation/free and avoids these _const functions,
>>>> which names can be confusing when used with code built as module.
>>>
>>> Okay, I'd rather revert your earlier commit 379b63e7e682
>>> ("drm/i915/display: Save a few bytes of memory in
>>> intel_backlight_device_register()") than add this.
>>
>> Hi,
>>
>> that works for me. Thanks and sorry for the noise.
> 
> Will you send the revert?
> 
> BR,
> Jani.
> 
> 

Will do.

CJ