On Mon, Sep 01, 2008 at 10:34:44AM +1000, Benjamin Herrenschmidt wrote:
> On Sun, 2008-08-31 at 10:31 -0700, Paul E. McKenney wrote:
> > Make powerpc refrain from clearing a given to-be-offlined CPU's bit in the
> > cpu_online_mask until it has processed pending irqs. This change
> > prevents other CPUs from being blindsided by an apparently offline CPU
> > nevertheless changing globally visible state.
> >
> > Signed-off-by: Paul E. McKenney <[EMAIL PROTECTED]>
> > ---
>
> Sounds reasonable... the only possible worry here is if somebody tries
> an IPI ... The IPI code will and the target CPU mask with the online
> map, so it may try to send to the to-be-offlined CPU and timeout, no ?
OK. Do we need separate IPI and online masks?
Thanx, Paul
> Cheers,
> Ben.
>
> > smp.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
> > index 5337ca7..1fedd7d 100644
> > --- a/arch/powerpc/kernel/smp.c
> > +++ b/arch/powerpc/kernel/smp.c
> > @@ -250,11 +250,11 @@ int generic_cpu_disable(void)
> > if (cpu == boot_cpuid)
> > return -EBUSY;
> >
> > - cpu_clear(cpu, cpu_online_map);
> > #ifdef CONFIG_PPC64
> > vdso_data->processorCount--;
> > fixup_irqs(cpu_online_map);
> > #endif
> > + cpu_clear(cpu, cpu_online_map);
> > return 0;
> > }
> >
>
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