Re: [PATCH RFC ticketlock] v2 Auto-queued ticketlock

[Linus Torvalds]

Hmm. Something just struck me when reading this patch..

Our memory ordering semantics in our *current* locks are very very
subtle. We have just a "barrier()" between the

    inc.head = ACCESS_ONCE(lock->tickets.head);
    if (inc.head == inc.tail)
        break; /* success */

and the inside of the locked region.

I think it's safe because of the new memory ordering semantics (loads
are in-order, and stores only move *down*), but there's not even a
comment about it.

So let's at least comment the current locks before making them even
more complex and subtle..

              Linus
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/