Commit afa485dc authored May 09, 2019 by Parthasarathy Bhuvaragan Committed by Greg Kroah-Hartman May 16, 2019

tipc: fix hanging clients using poll with EPOLLOUT flag



[ Upstream commit ff946833b70e0c7f93de9a3f5b329b5ae2287b38 ]

commit 517d7c79 ("tipc: fix hanging poll() for stream sockets")
introduced a regression for clients using non-blocking sockets.
After the commit, we send EPOLLOUT event to the client even in
TIPC_CONNECTING state. This causes the subsequent send() to fail
with ENOTCONN, as the socket is still not in TIPC_ESTABLISHED state.

In this commit, we:
- improve the fix for hanging poll() by replacing sk_data_ready()
  with sk_state_change() to wake up all clients.
- revert the faulty updates introduced by commit 517d7c79
  ("tipc: fix hanging poll() for stream sockets").

Fixes: 517d7c79 ("tipc: fix hanging poll() for stream sockets")
Signed-off-by: Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@gmail.com>
Acked-by: Jon Maloy <jon.maloy@ericsson.se>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 98652e0b

net/tipc/socket.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -726,11 +726,11 @@ static __poll_t tipc_poll(struct file file, struct socket sock,

		switch (sk->sk_state) {
		case TIPC_ESTABLISHED:
		case TIPC_CONNECTING:
		if (!tsk->cong_link_cnt && !tsk_conn_cong(tsk))
		revents \|= EPOLLOUT;
		/* fall thru' */
		case TIPC_LISTEN:
		case TIPC_CONNECTING:
		if (!skb_queue_empty(&sk->sk_receive_queue))
		revents \|= EPOLLIN \| EPOLLRDNORM;
		break;
		@@ -2039,7 +2039,7 @@ static bool tipc_sk_filter_connect(struct tipc_sock tsk, struct sk_buff skb)
		return true;

		/* If empty 'ACK-' message, wake up sleeping connect() */
		sk->sk_data_ready(sk);
		sk->sk_state_change(sk);

		/* 'ACK-' message is neither accepted nor rejected: */
		msg_set_dest_droppable(hdr, 1);