Re: [LKML] [PATCH] Fix NULL pointer for Xen guests

[Prarit Bhargava]

On 04/27/2010 12:58 PM, Konrad Rzeszutek Wilk wrote:
> On Tue, Apr 27, 2010 at 11:24:42AM -0400, Prarit Bhargava wrote:
>    
> > Upstream PV guests fail to boot because of a NULL pointer.  It is possible that
> > xen guests have irq_desc->chip_data = NULL.
> >      
> Can you provide a short example of test scenario? As in what I should do
> to reproduce this problem?
>    

Take the latest upstream (well ... to be honest, a bit older than that 
because of some other bugs) -- take 2.6.33 and try to boot it as a PV 
guest.  I'm using a RHEL5 Xen HV fwiw ...

P.

> > Test for NULL chip_data pointer before attempting to complete an irq move.
> >
> > Signed-off-by: Prarit Bhargava<prarit@xxxxxxxxxx>
> > Acked-by: Suresh Siddha<suresh.b.siddha@xxxxxxxxx>
> >
> > diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
> > index 127b871..eb2789c 100644
> > --- a/arch/x86/kernel/apic/io_apic.c
> > +++ b/arch/x86/kernel/apic/io_apic.c
> > @@ -2545,6 +2545,9 @@ void irq_force_complete_move(int irq)
> >   	struct irq_desc *desc = irq_to_desc(irq);
> >   	struct irq_cfg *cfg = desc->chip_data;
> >
> > +	if (!cfg)
> > +		return;
> > +
> >   	__irq_complete_move(&desc, cfg->vector);
> >   }
> >   #else
> > --
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