Re: [Xen-devel] [PATCH] sched: fix race between sched_move_domain() and vcpu_wake()

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 11.10.13 at 11:02, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
> On 11/10/2013 09:07, Keir Fraser wrote:
>> It feels to me like this is separate from Andrew's concern. Also I think
>> that holding the schedule_lock should protect you from changes to
>> v->processor. But if that's really unreasonable (e.g., inefficient) then
>> your suggestion here is perfectly sensible.
>>
>> Improving the vcpu_schedule_lock_irq implementations to use the providied
>> underlying spin_lock_irq functions would also be nice, I guess :)
> 
> This is an orthogonal issue which could do with fixing.  Do note that
> simply making changes to vcpu_schedule_lock() to return the appropriate
> lock is not sufficient to fix this issue, as the race with changing
> v->processor can cause two cpus to "successfully" lock the vcpu schedule
> lock for a particular vcpu.

Yes indeed. It's just that with such adjustments the fix here
would become more "natural" in no longer having to open-code
the schedule_lock access.

I suppose you scanned the code for other cases like this, and
there are none?

Jan


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