Re: [PATCH 03/12] powerpc: Replace cpu_up/down with device_online/offline

[Qais Yousef]

On 11/19/19 12:19, Michael Ellerman wrote:
> Qais Yousef <qais.yousef@xxxxxxx> writes:
> > 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@xxxxxxx>
> > CC: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
> > CC: Paul Mackerras <paulus@xxxxxxxxx>
> > CC: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> > CC: Enrico Weigelt <info@xxxxxxxxx>
> > CC: Ram Pai <linuxram@xxxxxxxxxx>
> > CC: Nicholas Piggin <npiggin@xxxxxxxxx>
> > CC: Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxx>
> > CC: Christophe Leroy <christophe.leroy@xxxxxx>
> > CC: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> > CC: linuxppc-dev@xxxxxxxxxxxxxxxx
> > CC: linux-kernel@xxxxxxxxxxxxxxx
> > ---
> >  arch/powerpc/kernel/machine_kexec_64.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> My initial though is "what about kdump", but that function is not called
> during kdump, so there should be no issue with the extra locking leading
> to deadlocks in a crash.
> 
> Acked-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>

Thanks.

> 
> I assume you haven't actually tested it?

Only compile tested it I'm afraid. Would appreciate if you can give it a spin.
Otherwise I'd be happy to try it out on qemu.

Cheers

--
Qais Yousef