Re: [PATCH] bitops: add _local bitops

Benjamin Herrenschmidt
2012-05-10T23:02:34Z

On Wed, 2012-05-09 at 13:10 -0700, H. Peter Anvin wrote:
> On 05/09/2012 01:07 PM, Michael S. Tsirkin wrote:
> >
> > In practice ATM any of the above will work. We probably don't even need
> > to add barrier() calls since what we do afterwards is apic access which
> > has an optimization barrier anyway. But I'm fine with adding them in
> > there just in case if that's what people want.
> >
>
> If you have the optimization barrier anyway, then I'd be fine with you
> just using __test_and_clear_bit() and add to a comment in
> arch/x86/include/asm/bitops.h that KVM needs it to be locally atomic.
>
>
What is it used for ? IE. Is this strictly a requirement of x86 KVM ?

Cheers,
Ben.