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Subject: Re: BUG: null pointer deref in dmar_ir_support
From: Suresh Siddha <suresh.b.siddha@intel.com>
Reply-To: Suresh Siddha <suresh.b.siddha@intel.com>
To: Ingo Molnar <mingo@elte.hu>
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Organization: Intel Corp
Date: Fri, 02 Apr 2010 11:28:33 -0700
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On Fri, 2010-04-02 at 11:20 -0700, Ingo Molnar wrote:
> * Suresh Siddha <suresh.b.siddha@intel.com> wrote:
> 
> > @@ -1640,8 +1640,10 @@ int __init APIC_init_uniprocessor(void)
> >  	}
> >  #endif
> >  
> > +#ifndef CONFIG_SMP
> >  	enable_IR_x2apic();
> >  	default_setup_apic_routing();
> > +#endif
> 
> Instead of adding yet another ugly #ifdef please hide these details properly, 
> by making enable_IR_x2apic() and default_setup_apic_routing() a NOP on !SMP.

Ingo, These are not nops on !SMP. We should call these functions from
APIC_init_uniprocessor() only if it is a UP kernel. For SMP kernel they
are called from some where else.

With the current code, on SMP and with non SMP motherboard we were
calling these routines twice which cause problem.

I wanted to keep the patch simple for urgent/backport. I will clean this
by restructuring the init code for 2.6.35

thanks,
suresh