Hello, while investigating a bug, we noticed that DLM tries to connect an SCTP socket in non-blocking mode using result = sock->ops->connect(sock, (struct sockaddr *)&daddr, addr_len, O_NONBLOCK); which does not work. The reason is that inet_dgram_connect() cannot pass its flags argument to sctp_connect() so that __sctp_connect() which does the actual waiting resorts to checking sk->sk_socket->file->f_flags instead. As the socket used by DLM is a kernel socket with no associated file, it ends up blocking. TCP doesn't suffer from this problem as for TCP, the waiting is done in inet_stream_connect() which has the flags argument. I also checked other proto::connect handlers and sctp_connect() seems to be the only one with this kind of problem. This could be worked around in DLM and further experiments indicate current DLM code wouldn't actually handle the non-blocking connect properly. But I still feel ignoring the flags argument is rather a trap that should be fixed. I have prepared a series adding flags argument to proto::connect and using it in sctp_connect() and __sctp_connect(). But I'm not sure if it's not too big hammer to address issue only affecting one handler. So my question is: would such generic approach be preferred or should we rather make SCTP work the way TCP does, i.e. move the waiting from proto::connect() to proto_ops::connect()? This would require introducing inet_seqpacket_connect() as inet_dgram_connect() is primarily intended for use with UDP.) Michal Kubecek -- To unsubscribe from this list: send the line "unsubscribe linux-sctp" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
