Re: [PATCH] io_uring: fix IO hang in io_wq_put_and_exit from do_exit()

Jens Axboe
2023-08-31T17:59:47Z

On 8/31/23 1:42 AM, Ming Lei wrote:
> @@ -3313,11 +3323,12 @@ __cold void io_uring_cancel_generic(bool cancel_all, struct io_sq_data *sqd)
> atomic_inc(&tctx->in_cancel);
> do {
> bool loop = false;
> + bool wq_cancelled;

Minor nit, but io_uring generally uses US spelling, so this should be
wq_canceled.

>
> io_uring_drop_tctx_refs(current);
> /* read completions before cancelations */
> inflight = tctx_inflight(tctx, !cancel_all);
> - if (!inflight)
> + if (!inflight && !tctx->io_wq)
> break;

Not sure I follow this one, is it just for checking of io_wq was ever
setup? How could it not be?

> - if (loop) {
> + if (!wq_cancelled || (inflight && loop)) {
> cond_resched();
> continue;
> }

And this one is a bit puzzling to me too - if we didn't cancel anything
but don't have anything inflight, why are we looping? Should it be
something ala:

if (inflight && (!wq_cancelled || loop)) {

?

--
Jens Axboe