On 21/02/20 13:59, Stefan Hajnoczi wrote:
> 1. It doesn't crash if the node is currently not on a list.
> 2. It clears the node's linked list pointers so that future linked
> list operations (like QLIST_SAFE_REMOVE()) aren't accidentally
> performed on stale pointers.
>
> The node has a long lifespan and will be inserted into ready_lists
> multiple times. We need to safely remove it from ready_list to protect
> against a corruption the next time the node is inserted into a
> ready_list again:
Ah, so the one I singled out is for (2) (we know the node is currently
on a list), while the one below is for (1). Would it make sense to move
(2) to Q*_REMOVE_*? We can do it separately after this pull request.
> /* Add a handler to a ready list */
> static void add_ready_handler(AioHandlerList *ready_list,
> AioHandler *node,
> int revents)
> {
> QLIST_SAFE_REMOVE(node, node_ready); /* remove from nested parent's
> list */
> ^---- would cause corruption if node->node_ready was stale!
>
> Would you like me to add a comment?
No, it's okay.
Paolo
