Re: [PATCH io_uring-5.14 v2] io_uring: remove double poll wait entry for pure poll

[Pavel Begunkov <asml.silence@gmail.com>]

On 7/23/21 10:22 AM, Hao Xu wrote:
> For pure poll requests, we should remove the double poll wait entry.
> And io_poll_remove_double() is good enough for it compared with
> io_poll_remove_waitqs().

5.14 in the subject hints me that it's a fix. Is it?
Can you add what it fixes or expand on why it's better?


> Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
> ---
> 
> v1-->v2
>   delete redundant io_poll_remove_double()
> 
>  fs/io_uring.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index f2fe4eca150b..c5fe8b9e26b4 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -4903,7 +4903,6 @@ static bool io_poll_complete(struct io_kiocb *req, __poll_t mask)
>  	if (req->poll.events & EPOLLONESHOT)
>  		flags = 0;
>  	if (!io_cqring_fill_event(ctx, req->user_data, error, flags)) {
> -		io_poll_remove_waitqs(req);
>  		req->poll.done = true;
>  		flags = 0;
>  	}
> @@ -4926,6 +4925,7 @@ static void io_poll_task_func(struct io_kiocb *req)
>  
>  		done = io_poll_complete(req, req->result);
>  		if (done) {
> +			io_poll_remove_double(req);
>  			hash_del(&req->hash_node);
>  		} else {
>  			req->result = 0;
> @@ -5113,7 +5113,7 @@ static __poll_t __io_arm_poll_handler(struct io_kiocb *req,
>  		ipt->error = -EINVAL;
>  
>  	spin_lock_irq(&ctx->completion_lock);
> -	if (ipt->error)
> +	if (ipt->error || (mask && (poll->events & EPOLLONESHOT)))
>  		io_poll_remove_double(req);
>  	if (likely(poll->head)) {
>  		spin_lock(&poll->head->lock);
> @@ -5185,7 +5185,6 @@ static int io_arm_poll_handler(struct io_kiocb *req)
>  	ret = __io_arm_poll_handler(req, &apoll->poll, &ipt, mask,
>  					io_async_wake);
>  	if (ret || ipt.error) {
> -		io_poll_remove_double(req);
>  		spin_unlock_irq(&ctx->completion_lock);
>  		if (ret)
>  			return IO_APOLL_READY;
> 

-- 
Pavel Begunkov