Re: [PATCH] x86: check for valid irq_cfg pointer in smp_irq_move_cleanup_interrupt

[Dimitri Sivanich <sivanich@sgi.com>]

On Mon, May 21, 2012 at 02:05:53PM -0700, Suresh Siddha wrote:
> On Mon, 2012-05-21 at 11:49 -0500, Dimitri Sivanich wrote:
> > The smp_irq_move_cleanup_interrupt routine should be checking for a valid
> > irq_cfg pointer prior to accessing it.  It also seems that this should be
> > done after taking the desc lock.
> 
> I think these changes are correct. Did you see any crashes during module
> unload etc?

Yes, we have seen these on occasion during boot.

> 
> Reviewed-by: Suresh Siddha <suresh.b.siddha@intel.com>
> 
> > 
> > Signed-off-by: Dimitri Sivanich <sivanich@sgi.com>
> > ---
> >  arch/x86/kernel/apic/io_apic.c |    5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> > Index: linux/arch/x86/kernel/apic/io_apic.c
> > ===================================================================
> > --- linux.orig/arch/x86/kernel/apic/io_apic.c
> > +++ linux/arch/x86/kernel/apic/io_apic.c
> > @@ -2478,9 +2478,12 @@ asmlinkage void smp_irq_move_cleanup_int
> >  		if (!desc)
> >  			continue;
> >  
> > -		cfg = irq_cfg(irq);
> >  		raw_spin_lock(&desc->lock);
> >  
> > +		cfg = irq_cfg(irq);
> > +		if (!cfg)
> > +			goto unlock;
> > +
> >  		/*
> >  		 * Check if the irq migration is in progress. If so, we
> >  		 * haven't received the cleanup request yet for this irq.
>