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

[Jens Axboe <axboe@kernel.dk>]

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