Re: [PATCH] x86/IO-APIC: refine EOI-ing of migrating level interrupts

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 18/11/11 08:31, Jan Beulich wrote:
> Now that this is in, could you try (again on the offending system)
> whether adding e.g. a WARN_ON(vector != desc->arch.old_vector)
> prior to the just added call to eoi_IO_APIC_irq() (but inside the
> surrounding if()) would ever trigger (obviously you'd want to make
> sure that the code path actually gets executed at all - perhaps
> counting and printing the count once in a while would be the easiest
> thing to do)?
>
> If it does, we obviously need to stay with passing in vector. If not,
> we'd need to do another round of code inspection to determine
> whether indeed there's no race when relying on just the stored
> data.
>
> Thanks, Jan

So long as you also check for arch.old_vector != IRQ_UNASSIGNED_VECTOR,
this appears to be fine.

I will sort out a patch to change this behavior

-- 
Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer
T: +44 (0)1223 225 900, http://www.citrix.com