On Mon, May 21, 2018 at 08:16:59AM -0700, Linus Torvalds wrote: > On Mon, May 21, 2018 at 6:51 AM Roman Penyaev < > roman.penyaev@xxxxxxxxxxxxxxxx> wrote: > > > No, I continue from the pointer, which I assigned on the previous IO > > in order to send IO fairly and keep load balanced. > > Right. And that's exactly what has both me and Paul nervous. You're no > longer in the RCU domain. You're using a pointer where the lifetime has > nothing to do with RCU any more. > > Can it be done? Sure. But you need *other* locking for it (that you haven't > explained), and it's fragile as hell. He looks to actually have it right, but I would want to see a big comment on the read side noting the leak of the pointer and documenting why it is OK. Thanx, Paul > It's probably best to not use RCU for it at all, but depend on that "other > locking" that you have to have anyway, to keep the pointer valid over the > non-RCU region. > > Linus >
