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:

quoted

Hello,

Le 11/11/2020 à 12:07, Nicholas Piggin a écrit :

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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