On 03/28, Jann Horn wrote: > > Since we're just talking about RCU stuff now, adding Paul McKenney to > the thread. Since you added Paul let me add more confusion to this thread ;) There were some concerns about the lack of barriers in put_pid(), but I can't find that old discussion and I forgot the result of that discussion... Paul, could you confirm that this code CPU_0 CPU_1 X = 1; if (READ_ONCE(Y)) mb(); X = 2; Y = 1; BUG_ON(X != 2); is correct? I think it is, control dependency pairs with mb(), right? If not, then put_pid() needs atomic_read_acquire() as it was proposed in that discussion. Oleg.
