On Tue, 2015-08-25 at 17:27 -0700, Paul E. McKenney wrote: > On Thu, Aug 20, 2015 at 04:56:04PM +0100, Will Deacon wrote: > > On Thu, Aug 20, 2015 at 10:45:05AM +0100, Michael Ellerman wrote: > > > On Tue, 2015-08-18 at 09:37 +0100, Will Deacon wrote: > > > > > > > > Thanks, that sounds great. FWIW, there are multiple ways of implementing > > > > the patch (i.e. whether you strengthen lock or unlock). I had a crack at > > > > something here, but it's not tested: > > > > > > > > http://marc.info/?l=linux-arch&m=143758379023849&w=2 > > > > > > I notice you are not changing PPC_RELEASE_BARRIER, but only the spin unlock > > > code. But from my reading of the docs we need to make sure any UNLOCK+LOCK is a > > > full barrier, not just spin unlock/lock? > > > > > > So don't we need to worry about some of the other locks as well? At least > > > rwlock, and mutex fast path? > > > > Hmm, that's a good question. I notice that you don't do any of the SYNC_IO > > stuff for any locks other than spinlocks but I don't know whether > > smp_mb__after_unlock_lock is similarly limited in scope. > > > > Paul? > > I would expect the various locks to have similar ordering characteristics. > > Or am I missing something subtle here? I don't think so. The docs just talk about ACQUIRE/RELEASE, so I think it needs to apply to all lock types. Or at least the list mentioned in the docs which is: (*) spin locks (*) R/W spin locks (*) mutexes (*) semaphores (*) R/W semaphores (*) RCU cheers -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
