[PATCH 4.14 111/115] tipc: fix hanging clients using poll with EPOLLOUT flag

Greg Kroah-Hartman
2019-05-15T11:52:33Z

From: Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@gmail.com>

[ Upstream commit ff946833b70e0c7f93de9a3f5b329b5ae2287b38 ]

commit 517d7c79bdb398 ("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 517d7c79bdb398
("tipc: fix hanging poll() for stream sockets").

Fixes: 517d7c79bdb398 ("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>
---
net/tipc/socket.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -709,11 +709,11 @@ static unsigned int tipc_poll(struct fil

switch (sk->sk_state) {
case TIPC_ESTABLISHED:
- case TIPC_CONNECTING:
if (!tsk->cong_link_cnt && !tsk_conn_cong(tsk))
mask |= POLLOUT;
/* fall thru' */
case TIPC_LISTEN:
+ case TIPC_CONNECTING:
if (!skb_queue_empty(&sk->sk_receive_queue))
mask |= (POLLIN | POLLRDNORM);
break;
@@ -1588,7 +1588,7 @@ static bool filter_connect(struct tipc_s
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);