On 11/30, Oleg Nesterov wrote: > > On 11/29, Paul E. McKenney wrote: > > > > Hmmm... Now I am wondering if the memory barriers inherent in the > > __wait_event() suffice for this last barrier... :-/ Thoughts? > > > > > + smp_mb(); > > Fastpath skips __wait_event(), and it is possible that the reader does > lock/unlock between the first 'mb()' and 'if (atomic_read() == 1)'.
In fact, a slow path needs (I think) it too. We can have an unrelated wakeup, and then the reader does unlock() before we check !atomic_read() in the __wait_event()'s loop. The reader removes us from ->wq, in that case finish_wait() does nothing. Oleg. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
