linux-kernel - Re: [PATCH v6 02/16] cpu: Do not warn on arch_register_cpu() returning -EPROBE

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Message-ID: <20240417154138.0000511b@Huawei.com>
Date: Wed, 17 Apr 2024 15:41:38 +0100
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: "Russell King (Oracle)" <linux@...linux.org.uk>
CC: Thomas Gleixner <tglx@...utronix.de>, Peter Zijlstra
	<peterz@...radead.org>, <linux-pm@...r.kernel.org>,
	<loongarch@...ts.linux.dev>, <linux-acpi@...r.kernel.org>,
	<linux-arch@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <kvmarm@...ts.linux.dev>,
	<x86@...nel.org>, "Rafael J . Wysocki" <rafael@...nel.org>, Miguel Luis
	<miguel.luis@...cle.com>, James Morse <james.morse@....com>, Salil Mehta
	<salil.mehta@...wei.com>, Jean-Philippe Brucker <jean-philippe@...aro.org>,
	Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>,
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, Dave Hansen
	<dave.hansen@...ux.intel.com>, <linuxarm@...wei.com>, <justin.he@....com>,
	<jianyong.wu@....com>
Subject: Re: [PATCH v6 02/16] cpu: Do not warn on arch_register_cpu()
 returning -EPROBE_DEFER

On Wed, 17 Apr 2024 15:01:33 +0100
"Russell King (Oracle)" <linux@...linux.org.uk> wrote:

> On Wed, Apr 17, 2024 at 02:18:55PM +0100, Jonathan Cameron wrote:
> > For arm64 the CPU registration cannot complete until the ACPI
> > interpreter us up and running so in those cases the arch specific
> > arch_register_cpu() will return -EPROBE_DEFER at this stage and the
> > registration will be attempted later.
> > 
> > Suggested-by: Rafael J. Wysocki <rafael@...nel.org>
> > Acked-by: Rafael J. Wysocki <rafael@...nel.org>
> > Signed-off-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> > 
> > ---
> > v6: tags
> > ---
> >  drivers/base/cpu.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
> > index 56fba44ba391..b9d0d14e5960 100644
> > --- a/drivers/base/cpu.c
> > +++ b/drivers/base/cpu.c
> > @@ -558,7 +558,7 @@ static void __init cpu_dev_register_generic(void)
> >  
> >  	for_each_present_cpu(i) {
> >  		ret = arch_register_cpu(i);
> > -		if (ret)
> > +		if (ret != -EPROBE_DEFER)
> >  			pr_warn("register_cpu %d failed (%d)\n", i, ret);  
> 
> This looks very broken to me.
> 
> 		if (ret && ret != -EPROBE_DEFER)
> 
> surely, because we don't want to print a warning if arch_register_cpu()
> was successful?

Gah.  Excellent point.

thanks,

Jonathan

>