Re: [PATCH] io_uring: fix skipping disabling sqo on exec

[Jens Axboe <axboe@kernel.dk>]

On 1/16/21 4:37 PM, Pavel Begunkov wrote:
> If there are no requests at the time __io_uring_task_cancel() is called,
> tctx_inflight() returns zero and and it terminates not getting a chance
> to go through __io_uring_files_cancel() and do
> io_disable_sqo_submit(). And we absolutely want them disabled by the
> time cancellation ends.
> 
> Also a fix potential false positive warning because of ctx->sq_data
> check before io_disable_sqo_submit().
> 
> Reported-by: Jens Axboe <axboe@kernel.dk>
> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
> ---
> 
> To not grow diffstat now will be cleaned for-next
> 
>  fs/io_uring.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index d494c4269fc5..0d50845f1f3f 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -8937,10 +8937,12 @@ static void io_uring_cancel_task_requests(struct io_ring_ctx *ctx,
>  {
>  	struct task_struct *task = current;
>  
> -	if ((ctx->flags & IORING_SETUP_SQPOLL) && ctx->sq_data) {
> +	if (ctx->flags & IORING_SETUP_SQPOLL) {
>  		/* for SQPOLL only sqo_task has task notes */
>  		WARN_ON_ONCE(ctx->sqo_task != current);
>  		io_disable_sqo_submit(ctx);
> +	}
> +	if ((ctx->flags & IORING_SETUP_SQPOLL) && ctx->sq_data) {
>  		task = ctx->sq_data->thread;
>  		atomic_inc(&task->io_uring->in_idle);
>  		io_sq_thread_park(ctx->sq_data);

Maybe just nest that inside?

	if (ctx->flags & IORING_SETUP_SQPOLL) {
  		/* for SQPOLL only sqo_task has task notes */
  		WARN_ON_ONCE(ctx->sqo_task != current);
  		io_disable_sqo_submit(ctx);
		if (ctx->sq_data) {
			...
		}
	}

That'd look a bit cleaner imho.
 
-- 
Jens Axboe