On Tue, Nov 26, 2013 at 11:00:50AM -0800, Linus Torvalds wrote: > On Tue, Nov 26, 2013 at 1:59 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > > > > If you now want to weaken this definition, then that needs consideration > > because we actually rely on things like > > > > spin_unlock(l1); > > spin_lock(l2); > > > > being full barriers. > > Btw, maybe we should just stop that assumption. I'd be fine with that; it was one of the options listed. I was just somewhat concerned that the definitions given by the Document and the reality of proposed implementations was drifting. > IOW, where do we really care about the "unlock+lock" is a memory > barrier? And could we make those places explicit, and then do > something similar to the above to them? So I don't know :-( I do know myself and Oleg have often talked about it, and I'm fairly sure we must have used it at some point. I think that introduction of smp_mb__before_spinlock() actually killed a few of those, but I can't recall. Oleg doesn't actually seem to be on the CC list -- lets amend that. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>