linux-kernel - Re: [PATCH 06/12] parisc: Replace cpu_up/down with device

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Message-ID: <20191124102021.k4oi3r4rgorikxnc@e107158-lin.cambridge.arm.com>
Date:   Sun, 24 Nov 2019 10:20:22 +0000
From:   Qais Yousef <qais.yousef@....com>
To:     Helge Deller <deller@....de>
Cc:     "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
        Richard Fontana <rfontana@...hat.com>,
        Armijn Hemel <armijn@...ldur.nl>, linux-parisc@...r.kernel.org,
        linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH 06/12] parisc: Replace cpu_up/down with
 device_online/offline

On 11/22/19 20:51, Helge Deller wrote:
> On 20.11.19 12:09, Qais Yousef wrote:
> > On 10/30/19 15:38, Qais Yousef wrote:
> >> The core device API performs extra housekeeping bits that are missing
> >> from directly calling cpu_up/down.
> >>
> >> See commit a6717c01ddc2 ("powerpc/rtas: use device model APIs and
> >> serialization during LPM") for an example description of what might go
> >> wrong.
> >>
> >> This also prepares to make cpu_up/down a private interface for anything
> >> but the cpu subsystem.
> >>
> >> Signed-off-by: Qais Yousef <qais.yousef@....com>
> >> CC: "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>
> >> CC: Helge Deller <deller@....de>
> >> CC: Richard Fontana <rfontana@...hat.com>
> >> CC: Armijn Hemel <armijn@...ldur.nl>
> >> CC: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> >> CC: Thomas Gleixner <tglx@...utronix.de>
> >> CC: linux-parisc@...r.kernel.org
> >> CC: linux-kernel@...r.kernel.org
> >> ---
> >>
> >> Couldn't compile test this one.
> >>
> >> I'm not confident that this is a correct patch to be honest. This __init
> >> indicates we're booting the secondary cpus and that might be too early in the
> >> process to use the core API..?
> >
> > Helge, James
> >
> > Do you have any comment on this? I have no means to test it and I'd
> > appreciate if you can spin it through one of your systems.
> 
> I pulled your cpu-hp-cleanup branch from git://linux-arm.org/linux-qy
> and compiled a 32- and a 64-bit parisc kernel.
> 
> I faced one compile warning:
> linux-2.6/kernel/cpu.c: In function ‘hibernation_bringup_sleep_cpu’:
> linux-2.6/kernel/cpu.c:1237:1: warning: control reaches end of non-void function [-Wreturn-type]
> 
> Other than that the 32- and 64-bit SMP kernel booted nicely.
> You may add to the series:
> Acked-by: Helge Deller <deller@....de>   # parisc

Great! Thanks for testing it and reporting the warning.

Cheers

--
Qais Yousef

> 
> Thanks,
> Helge
> 
> 
> >>
> >>  arch/parisc/kernel/processor.c | 4 +++-
> >>  1 file changed, 3 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/arch/parisc/kernel/processor.c b/arch/parisc/kernel/processor.c
> >> index 13f771f74ee3..4dde5fe78f0c 100644
> >> --- a/arch/parisc/kernel/processor.c
> >> +++ b/arch/parisc/kernel/processor.c
> >> @@ -212,7 +212,9 @@ static int __init processor_probe(struct parisc_device *dev)
> >>  #ifdef CONFIG_SMP
> >>  	if (cpuid) {
> >>  		set_cpu_present(cpuid, true);
> >> -		cpu_up(cpuid);
> >> +		lock_device_hotplug();
> >> +		device_online(get_cpu_device(cpuid));
> >> +		unlock_device_hotplug();
> >>  	}
> >>  #endif
> >>
> >> --
> >> 2.17.1
> >>
>