Re: [PATCH v2 1/2] mips: cm: Convert __mips_cm_l2sync_phys_base() to weak function

From: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
To: Serge Semin <fancer.lancer@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>,
	Jiaxun Yang <jiaxun.yang@flygoat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>,
	linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/2] mips: cm: Convert __mips_cm_l2sync_phys_base() to weak function
Date: Mon, 11 Mar 2024 14:07:19 +0100	[thread overview]
Message-ID: <Ze8CB27Ad427Gk3K@alpha.franken.de> (raw)
In-Reply-To: <6n2synlvazjh2gptxtioju7dciwshwqyei4xnfzorns66b3hqx@c7blt5kwnpbl>

On Mon, Feb 26, 2024 at 04:11:05PM +0300, Serge Semin wrote:
> On Mon, Feb 26, 2024 at 01:29:54PM +0100, Arnd Bergmann wrote:
> > 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.
> 
> Why would I need it if after this patch is applied the
> mips_cm_l2sync_phys_base() method will be converted to a global weak
> implementation?
> 
> > 
> > > 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.
> 
> + a lot of them in kernel/*, some in mm/* .)
> 
> > 
> > Ifdef checks in .c files are not great, but at least they
> > are much more common than __weak functions and self-documenting.
> 
> Ok. I don't have concretely strong opinion about what is better. Let's
> wait for what Thomas thinks about this.

I've taken your patches as we get rid of this alias thing. As long as
there is no big push against __weak I'm ok with this case.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]