On Wed, Apr 30, 2014 at 04:14:14PM -0700, Linus Torvalds wrote: > On Wed, Apr 30, 2014 at 4:04 PM, Linus Torvalds > <torva...@linux-foundation.org> wrote: > > > > Let me go talk to the paravirt people. Maybe they don't need this, and > > I don't know exactly *how* they use that lock pointer after the unlock > > in the "kick waiters" part. Maybe it's all good. > > .. looking at current users (xen and kvm) it does in fact look all > good. Yes, we "kick" possible waiters after the unlock, but the lock > itself is not touched by that, it just uses the pointer to the lock as > a way to figure out who to kick. > > In fact, I kind of knew that, but had forgotten. We very much depend > on spin_unlock being safe wrt immediate deleton already: the > "completion" code very much depends on it. It does a "spin_unlock()" > to release the completion, and it can get reused immediately (it might > be on the stack, it might be in some data structure that gets freed). > > So I'd suggest removing that whole RCU thing, because it should be > safe to unlock something that can go away immediately. We'd have huge > problems elsewhere if it wasn't safe.
OK, done and force-pushed. Should propagate in a few... -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
