linux-kernel - Re: [PATCH v2 1/2] mips: cm: Convert __mips_cm_l2sync_phys

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Date: Mon, 26 Feb 2024 13:29:54 +0100
From: "Arnd Bergmann" <arnd@...db.de>
To: "Serge Semin" <fancer.lancer@...il.com>
Cc: "Thomas Bogendoerfer" <tsbogend@...ha.franken.de>,
 "Jiaxun Yang" <jiaxun.yang@...goat.com>,
 "Andrew Morton" <akpm@...ux-foundation.org>,
 "Alexey Malahov" <Alexey.Malahov@...kalelectronics.ru>,
 linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] mips: cm: Convert __mips_cm_l2sync_phys_base() to weak
 function

On Mon, Feb 26, 2024, at 13:20, Serge Semin wrote:
> On Mon, Feb 26, 2024 at 01:04:33PM +0100, Arnd Bergmann wrote:
>> On Mon, Feb 26, 2024, at 12:27, Serge Semin wrote:

> I see your point now. Thanks for clarification. IMO it would be less
> readable due to the ifdef-ery and the new config, and less
> maintainable due to the conditional compilation, but would provide a
> more performant solution since the compiler will be able to inline the
> singly used static method. Basically you suggest to emulate the weak
> implementation by an additional kernel config.

I mean the kernel config that you already need here, since
the strong version of the function is already optional.

> Not sure whether it would be better than a well-known
> weak-attribute-based pattern. Anyway let's wait for the
> Thomas' opinion about your suggestion. If he thinks
> it would be better I'll update the patches.

Weak functions are not used all that much outside of a
couple of parts of the kernel. There is a lot of them
in drivers/pci/, a little bit in acpi and efi, and
then a bit in arch/*/, though most of that is in mips.

Ifdef checks in .c files are not great, but at least they
are much more common than __weak functions and self-documenting.

     Arnd