Re: [PATCH] cpu-hotplug: provide prototypes for arch CPU registration

From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Gavin Shan <gshan@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	linux-acpi@vger.kernel.org, James Morse <james.morse@arm.com>,
	loongarch@lists.linux.dev, linux-arch@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
	Ingo Molnar <mingo@redhat.com>,
	Jean-Philippe Brucker <jean-philippe@linaro.org>,
	jianyong.wu@arm.com, justin.he@arm.com,
	Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, Salil Mehta <salil.mehta@huawei.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Peter Zijlstra <peterz@infradead.org>,
	linux-ia64@vger.kernel.org
Subject: Re: [PATCH] cpu-hotplug: provide prototypes for arch CPU registration
Date: Tue, 26 Sep 2023 00:17:19 +0100	[thread overview]
Message-ID: <ZRIU/yFrbFbIR7zZ@shell.armlinux.org.uk> (raw)
In-Reply-To: <dd4dee9e-4d75-e1e6-04c8-82d84b28fd35@redhat.com>

On Tue, Sep 26, 2023 at 09:04:46AM +1000, Gavin Shan wrote:
> Hi Russell,
> 
> On 9/26/23 02:28, Russell King (Oracle) wrote:
> > Provide common prototypes for arch_register_cpu() and
> > arch_unregister_cpu(). These are called by acpi_processor.c, with
> > weak versions, so the prototype for this is already set. It is
> > generally not necessary for function prototypes to be conditional
> > on preprocessor macros.
> > 
> > Some architectures (e.g. Loongarch) are missing the prototype for this,
> > and rather than add it to Loongarch's asm/cpu.h, lets do the job once
> > for everyone.
> > 
> > Since this covers everyone, remove the now unnecessary prototypes in
> > asm/cpu.h, and we also need to remove the 'static' from one of ia64's
> > arch_register_cpu() definitions.
> > 
> > Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> > ---
> > Changes since RFC v2:
> >   - drop ia64 changes, as ia64 has already been removed.
> > 
> >   arch/x86/include/asm/cpu.h  | 2 --
> >   arch/x86/kernel/topology.c  | 2 +-
> >   include/linux/cpu.h         | 2 ++
> >   3 files changed, 3 insertions(+), 3 deletions(-)
> > 
> 
> In Linux 6.6.rc3, the prototypes are still existing in arch/ia64/include/asm/cpu.h.

Correct, but I have been told that IA64 has been removed, so I removed
those changes from my patch.

> They may have been dropped in other ia64 or x86 git repository, which this patch
> bases on.

I have no idea which repository they have been dropped from. I only know
what tglx told me, and despite asking the question, I never got any
answer. So I've done the best I can with this patch. If kernel devs want
to state things in vague terms, and then go silent when asked questions
to elaborate, then that leads to guessing.

Maybe someone else should adapt this patch to apply to whatever tree it
is going to end up being applied to - because I have no idea _which_
tree it'll end up being applied to.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!

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