Commit ff946833 authored May 09, 2019 by Parthasarathy Bhuvaragan Committed by David S. Miller May 09, 2019

tipc: fix hanging clients using poll with EPOLLOUT flag



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>

parent 9871a9e4

net/tipc/socket.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -736,11 +736,11 @@ 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 through */
		case TIPC_LISTEN:
		case TIPC_CONNECTING:
		if (!skb_queue_empty(&sk->sk_receive_queue))
		revents \|= EPOLLIN \| EPOLLRDNORM;
		break;
		@@ -2043,7 +2043,7 @@ static bool tipc_sk_filter_connect(struct tipc_sock tsk, struct sk_buff skb)
		if (msg_data_sz(hdr))
		return true;
		/* Empty ACK-, - wake up sleeping connect() and drop */
		sk->sk_data_ready(sk);
		sk->sk_state_change(sk);
		msg_set_dest_droppable(hdr, 1);
		return false;
		}

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