On Mon, 21 Apr 2014, Oliver Neukum wrote: > > In addition, the following code in kfifo_get() does this: > > > > *(typeof(__tmp->type))__val = \ > > (__is_kfifo_ptr(__tmp) ? \ > > ((typeof(__tmp->type))__kfifo->data) : \ > > (__tmp->buf) \ > > )[__kfifo->out & __tmp->kfifo.mask]; \ > > smp_wmb(); \ > > __kfifo->out++; \ > > > > It looks like the smp_wmb() should really be smp_mb(), because it > > separates the _read_ for val from the _write_ of kfifo->out. > > On the third hand, I now think wmb() is sufficient, because > there's also a write to __val. It does depend on the read > of buf[out & mask], but if no CPU does speculative writes > it must be correct.
You are right; I missed that. Good point. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
