Re: [PATCH] x86, kasan: add KASAN checks to atomic operations

[Mark Rutland <mark.rutland@arm.com>]

On Tue, Mar 14, 2017 at 04:32:30PM +0100, Peter Zijlstra wrote:
> On Tue, Mar 14, 2017 at 04:22:52PM +0100, Dmitry Vyukov wrote:
> > -static __always_inline int atomic_read(const atomic_t *v)
> > +static __always_inline int arch_atomic_read(const atomic_t *v)
> >  {
> > -	return READ_ONCE((v)->counter);
> > +	return READ_ONCE_NOCHECK((v)->counter);
> 
> Should NOCHEKC come with a comment, because i've no idea why this is so.

I suspect the idea is that given the wrapper will have done the KASAN
check, duplicating it here is either sub-optimal, or results in
duplicate splats. READ_ONCE() has an implicit KASAN check,
READ_ONCE_NOCHECK() does not.

If this is to solve duplicate splats, it'd be worth having a
WRITE_ONCE_NOCHECK() for arch_atomic_set().

Agreed on the comment, regardless.

Thanks,
Mark.

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