Re: [PATCH 1/3] asm-generic/atomic64: Add support for ARCH_ATOMIC

[Nicholas Piggin]

Excerpts from Peter Zijlstra's message of November 11, 2020 11:44 pm:
> On Wed, Nov 11, 2020 at 02:39:01PM +0100, Christophe Leroy wrote:
>> Hello,
>> 
>> Le 11/11/2020 à 12:07, Nicholas Piggin a écrit :
>> > This passes atomic64 selftest on ppc32 on qemu (uniprocessor only)
>> > both before and after powerpc is converted to use ARCH_ATOMIC.
>> 
>> Can you explain what this change does and why it is needed ?
> 
> That certainly should've been in the Changelog. This enables atomic
> instrumentation, see asm-generic/atomic-instrumented.h. IOW, it makes
> atomic ops visible to K*SAN.
> 

Right. This specific patch doesn't actually "do" anything except
allow generic atomic64 to be used with ARCH_ATOMIC. It does that
by re-naming some things to avoid name collisions and also providing
the arch_ prefix that ARCH_ATOMIC expects.

I don't know what should be in the changelog. I suppose the latter,
the former is discoverable by looking at ARCH_ATOMIC code and
patches but I guess it's polite and doesn't hurt to include the
former as well.

I'll send an update before long.

Thanks,
Nick