On Mon, Dec 13, 2021 at 11:28:45AM +0000, David Woodhouse wrote: > On Mon, 2021-12-13 at 12:22 +0100, Frederic Weisbecker wrote: > > I was about to ack the patch but, should we really add code that isn't going to > > be necessary before a long while? > > Yeah, I'm torn on that. In this case it's harmless enough and it makes > the code reentrant in its own right instead of relying on the fact that > the cpuhp code won't invoke it multiple times in parallel. So I think > that's reasonable defensive programming. > The thing is that RCU code is already quite complicated. Are we even at least sure that we'll ever make CPU hotplug allow concurrent CPU onlining/offlining? This will require much more thoughts and a new hotplug concurrency infrastructure that we'll need to base RCU on. IMHO it's a bit early to handle that on hotplug individual callbacks. But anyway, let's see what Paul thinks about it...
