On Tue, 2020-01-07 at 19:14 +0100, Greg Kroah-Hartman wrote:
On Tue, Jan 07, 2020 at 05:48:55PM +0000, Ben Hutchings wrote:
I noticed that backports of commit 69d927bba395 "x86/atomic: Fix smp_mb__{before,after}_atomic()" didn't touch atomic_or_long() (present in 3.16) or atomic_inc_short() (present in 4.9 and earlier).
These functions were only implemented on x86 and not actually used in- tree. But it's possible they are used by some out-of-tree module, and that commit removed compiler barriers for them.
Would it might make sense to either
- Add the memory clobber to these functions, or
- Delete them
on the affected stable branches?
Looks like we can drop atomic_inc_short for 4.9 as there are no users, same for 4.4. I'll go do that now. It's not like the "fix" is really needed here because of that :)
Upstream commit for this is:
commit 31b35f6b4d5285a311e10753f4eb17304326b211 Author: Dmitry Vyukov dvyukov@google.com Date: Fri May 26 19:29:00 2017 +0200
locking/x86: Remove the unused atomic_inc_short() methd
Ben.