In a multithreaded program it is reasonable to have a thread blocked in accept(). With TCP a subsequent shutdown(listen_fd, SHUT_RDWR) causes the accept to fail. But nothing happens for SCTP. I think the 'magic' happens when tcp_disconnect() calls inet_csk_listen_stop(sk) but sctp_disconnect() is an empty function and nothing happens. I can't see any calls to inet_csk_listen_stop() in the sctp code - so I suspect it isn't possible at all. This all relates to a very old (pre git) comment in inet_shutdown() that shutdown needs to act on listening and connecting sockets until the VFS layer is 'fixed' (presumably to let close() through - not going to happen.) I also suspect that a blocking connect() can't be cancelled either? Clearly the application can avoid the issue by using poll() and an extra eventfd() for the wakeup - but it is all a faff for code that otherwise straight forward. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
