Re: shutdown not affecting connection?

[Andres Freund <andres@anarazel.de>]

Hi,

On 2020-02-08 08:55:25 -0500, Glauber Costa wrote:
> - A connect() call is issued (and in the backend I can choose if I use
> uring or not)
> - The connection is supposed to take a while to establish.
> - I call shutdown on the file descriptor
> 
> If io_uring is not used:
> - connect() starts by  returning EINPROGRESS as expected, and after
> the shutdown the file descriptor is finally made ready for epoll. I
> call getsockopt(SOL_SOCKET, SO_ERROR), and see the error (104)
> 
> if io_uring is used:
> - if the SQE has the IOSQE_ASYNC flag on, connect() never returns.

That should be easy enough to reproduce without seastar as it sounds
deterministic - how about modifying liburing's test/connect.c test to
behave this way?

Hm, any chance you set O_NONBLOCK on the fd, before calling the async
connect?

Wonder if io_connect()
	file_flags = force_nonblock ? O_NONBLOCK : 0;

	ret = __sys_connect_file(req->file, &io->connect.address,
					req->connect.addr_len, file_flags);
	if ((ret == -EAGAIN || ret == -EINPROGRESS) && force_nonblock) {
fully takes into account that __sys_connect_file
	err = sock->ops->connect(sock, (struct sockaddr *)address, addrlen,
				 sock->file->f_flags | file_flags);
appears to leave O_NONBLOCK set on the file in place, which'd then
not block in the wq?

Greetings,

Andres Freund