On Wed, Aug 17, 2016 at 2:26 PM, Linus Torvalds <torva...@linux-foundation.org> wrote: > > Of course, if somebody uses native_restore_fl() to actually *disable* > interrupts (when they weren't already disabled), then this untested > patch will just not work. But why would you do somethign so stupid? > Famous last words...
Looking around, the vsmp code actually uses "native_restore_fl()" to not just set the interrupt flag, but AC as well. And the PV spinlock case has that "push;popf" sequence encoded in an alternate. So that trivial patch may (or may not - still not tested) work for some quick testing, but needs more effort for any *real* use. Linus