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

From: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
To: "Russell King (Oracle)" <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Peter Zijlstra <peterz@infradead.org>, <linux-pm@vger.kernel.org>,
	<loongarch@lists.linux.dev>, <linux-acpi@vger.kernel.org>,
	<linux-arch@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>, <kvmarm@lists.linux.dev>,
	<x86@kernel.org>, "Rafael J . Wysocki" <rafael@kernel.org>,
	Miguel Luis <miguel.luis@oracle.com>,
	James Morse <james.morse@arm.com>,
	Salil Mehta <salil.mehta@huawei.com>,
	Jean-Philippe Brucker <jean-philippe@linaro.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Ingo Molnar <mingo@redhat.com>,
	Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>, <linuxarm@huawei.com>,
	<justin.he@arm.com>, <jianyong.wu@arm.com>
Subject: Re: [PATCH v6 02/16] cpu: Do not warn on arch_register_cpu() returning -EPROBE_DEFER
Date: Wed, 17 Apr 2024 15:41:38 +0100	[thread overview]
Message-ID: <20240417154138.0000511b@Huawei.com> (raw)
In-Reply-To: <Zh/WPYMJYepLbST/@shell.armlinux.org.uk>

On Wed, 17 Apr 2024 15:01:33 +0100
"Russell King (Oracle)" <linux@armlinux.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@kernel.org>
> > Acked-by: Rafael J. Wysocki <rafael@kernel.org>
> > Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.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

> 