Commit c4fc298a authored Oct 16, 2012 by Erik Hugne Committed by Paul Gortmaker Nov 21, 2012

tipc: return POLLOUT for sockets in an unconnected state

If an implied connect is attempted on a nonblocking STREAM/SEQPACKET
socket during link congestion, the connect message will be discarded
and sendmsg will return EAGAIN. This is normal behavior, and the
application is expected to poll the socket until POLLOUT is set,
after which the connection attempt can be retried.
However, the POLLOUT flag is never set for unconnected sockets and
poll() always returns a zero mask. The application is then left without
a trigger for when it can make another attempt at sending the message.

The solution is to check if we're polling on an unconnected socket
and set the POLLOUT flag if the TIPC port owned by this socket
is not congested. The TIPC ports waiting on a specific link will be
marked as 'not congested' when the link congestion have abated.

Signed-off-by: Erik Hugne <erik.hugne@ericsson.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

parent f288bef4

net/tipc/socket.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -412,7 +412,7 @@ static int get_name(struct socket sock, struct sockaddr uaddr,
		* socket state flags set
		* ------------ ---------
		* unconnected no read flags
		* no write flags
		* POLLOUT if port is not congested
		*
		* connecting POLLIN/POLLRDNORM if ACK/NACK in rx queue
		* no write flags
		@@ -442,6 +442,10 @@ static unsigned int poll(struct file file, struct socket sock,
		sock_poll_wait(file, sk_sleep(sk), wait);

		switch ((int)sock->state) {
		case SS_UNCONNECTED:
		if (!tipc_sk_port(sk)->congested)
		mask \|= POLLOUT;
		break;
		case SS_READY:
		case SS_CONNECTED:
		if (!tipc_sk_port(sk)->congested)

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