Commit cda91d5b authored by Xin Long's avatar Xin Long Committed by David S. Miller
Browse files

sctp: cancel a blocking accept when shutdown a listen socket 



As David Laight noticed,

"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."

sctp_disconnect() is eventually called when shutdown a listen socket,
but nothing is done in this function. This patch sets RCV_SHUTDOWN
flag in sk->sk_shutdown there, and adds the check (sk->sk_shutdown &
RCV_SHUTDOWN) to break and return in sctp_accept().

Note that shutdown() is only supported on TCP-style SCTP socket.

Reported-by: default avatarDavid Laight <David.Laight@aculab.com>
Signed-off-by: default avatarXin Long <lucien.xin@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 2e3ed20c

net/sctp/socket.c

+10 −4
Original line number Diff line number Diff line
@@ -4834,10 +4834,14 @@ int sctp_inet_connect(struct socket *sock, struct sockaddr *uaddr, 
	return sctp_connect(sock->sk, uaddr, addr_len, flags);

}



/* FIXME: Write comments. */

/* Only called when shutdown a listening SCTP socket. */

static int sctp_disconnect(struct sock *sk, int flags)

{

	return -EOPNOTSUPP; /* STUB */

	if (!sctp_style(sk, TCP))

		return -EOPNOTSUPP;



	sk->sk_shutdown |= RCV_SHUTDOWN;

	return 0;

}



/* 4.1.4 accept() - TCP Style Syntax
@@ -4866,7 +4870,8 @@ static struct sock *sctp_accept(struct sock *sk, struct proto_accept_arg *arg) 
		goto out;

	}



	if (!sctp_sstate(sk, LISTENING)) {

	if (!sctp_sstate(sk, LISTENING) ||

	    (sk->sk_shutdown & RCV_SHUTDOWN)) {

		error = -EINVAL;

		goto out;

	}
@@ -9393,7 +9398,8 @@ static int sctp_wait_for_accept(struct sock *sk, long timeo) 
		}



		err = -EINVAL;

		if (!sctp_sstate(sk, LISTENING))

		if (!sctp_sstate(sk, LISTENING) ||

		    (sk->sk_shutdown & RCV_SHUTDOWN))

			break;



		err = 0;