On 4/2/20 12:54 PM, Bijan Mottahedeh wrote:
> A request that completes with an -EAGAIN result after it has been added
> to the poll list, will not be removed from that list in io_do_iopoll()
> because the f_op->iopoll() will not succeed for that request.
>
> Maintain a retryable local list similar to the done list, and explicity
> reissue requests with an -EAGAIN result.
I think this looks reasonable. You could make the loop here:
> +static void io_iopoll_queue(struct list_head *again)
> +{
> + struct io_kiocb *req;
> +
> + while (!list_empty(again)) {
> + req = list_first_entry(again, struct io_kiocb, list);
> + list_del(&req->list);
> + refcount_inc(&req->refs);
> + io_queue_async_work(req);
> + }
> +}
be:
do {
req = list_first_entry(again, struct io_kiocb, list);
list_del(&req->list);
refcount_inc(&req->refs);
io_queue_async_work(req);
} while (!list_empty(again));
as you always enter with it non-empty, at least that eliminates one
check per list.
We could also issue inline again, instead of punting these async. But
probably not worth the bother.
--
Jens Axboe
