On Tue, Dec 05, 2017 at 08:57:46PM +0200, Michael S. Tsirkin wrote: > I don't see WRITE_ONCE inserting any barriers, release or > write. Correct, never claimed there was. Just saying that: obj = READ_ONCE(*foo); val = READ_ONCE(obj->val); Never needs a barrier (except on Alpha and we want to make that go away). Simply because a CPU needs to complete the load of @obj before it can compute the address &obj->val. Thus the second load _must_ come after the first load and we get LOAD-LOAD ordering. Alpha messing that up is a royal pain, and Alpha not being an active/living architecture is just not worth the pain of keeping this in the generic model.
