From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andreas Fink Date: Sun, 07 Jun 2020 12:18:40 +0000 Subject: EAGAIN Message-Id: <0D6B7E65-36EC-4132-B02C-0371099E480A@list.fink.org> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-sctp@vger.kernel.org Hello folks, I run into a strange issue with SCTP under Linux and I'm not sure whats the right approach to fix this. I have a listener thread which listens on a port for multiple inbound connections I have a sender thread which sends packets to peers by using the same socket and doing a sctp_sendv call. Sockets are always in non blocking mode. When the remote side gets stopped (process killed), the sctp_sendv starts returning 0 and errno is set to EAGAIN and we constantly retry. We somehow didn't catch that this socket was down and end up in a busy loop (which we now fail after a certain amount of retries). My question to you is whats the correct way to deal with EAGAIN here? Why are we not catching the assoc being down? We have a sender thread and a receiver thread. The receiver thread is listening to events and should know. Furthermore if the assoc is down the sctp_sendv could simply return something like socket not connected error instead of EAGAIN. Or what am I missing here? Andreas PS: above was under Linux Debian Kernel 5.4.0-0.bpo.4.