On Fri, Oct 09, 2015 at 10:45:32AM +0200, Paolo Bonzini wrote: > So you need another smp_mb() after prepare_to_wait(). I'm not sure > if it's needed also for your original tty report, but I think it is > for https://lkml.org/lkml/2015/10/8/989 ("mei: fix waitqueue_active > without memory barrier in mei drivers"). > > I wonder if it makes sense to introduce smp_mb__before_spin_lock() > and smp_mb__after_spin_unlock(). On x86 the former could be a > simple compiler barrier, and on s390 both of them could. But that > should be a separate patch. Not having actually read or thought about the issue at hand, its perfectly valid to pair an smp_mb() with either spin_lock() or spin_unlock(). IOW. MB <-> {ACQUIRE, RELEASE} is a valid pairing. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
