Re: [PULL 14/14] s390x/pci: fix set_ind_atomic

[Halil Pasic]

On Fri,  3 Jul 2020 12:06:50 +0200
Cornelia Huck <cohuck@redhat.com> wrote:

> From: Halil Pasic <pasic@linux.ibm.com>
> 
> The atomic_cmpxchg() loop is broken because we occasionally end up with
> old and _old having different values (a legit compiler can generate code
> that accessed *ind_addr again to pick up a value for _old instead of
> using the value of old that was already fetched according to the
> rules of the abstract machine). This means the underlying CS instruction
> may use a different old (_old) than the one we intended to use if
> atomic_cmpxchg() performed the xchg part.
> 

[..]

I believe this fix should be considered for stable -- much like the ccw
counterpart.

Regards,
Halil