netdev - [PATCH net-next v1 01/16] tipc: return early for non-blocking sockets at link congestion

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Date:   Thu, 27 Oct 2016 16:22:22 +0200
From:   Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@...csson.com>
To:     <netdev@...r.kernel.org>
CC:     <tipc-discussion@...ts.sourceforge.net>, <jon.maloy@...csson.com>,
        <maloy@...jonn.com>, <ying.xue@...driver.com>
Subject: [PATCH net-next v1 01/16] tipc: return early for non-blocking sockets at link congestion

Until now, in stream/mcast send() we pass the message to the link
layer even when the link is congested and add the socket to the
link's wakeup queue. This is unnecessary for non-blocking sockets.
If a socket is set to non-blocking and sends multicast with zero
back off time while receiving EAGAIN, we exhaust the memory.

In this commit, we return immediately at stream/mcast send() for
non-blocking sockets.

Acked-by: Jon Maloy <jon.maloy@...csson.com>
Signed-off-by: Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@...csson.com>
---
 net/tipc/socket.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index f9f5f3c3dab5..adf3e6ecf61e 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -697,6 +697,9 @@ static int tipc_sendmcast(struct  socket *sock, struct tipc_name_seq *seq,
 	uint mtu;
 	int rc;
 
+	if (!timeo && tsk->link_cong)
+		return -ELINKCONG;
+
 	msg_set_type(mhdr, TIPC_MCAST_MSG);
 	msg_set_lookup_scope(mhdr, TIPC_CLUSTER_SCOPE);
 	msg_set_destport(mhdr, 0);
@@ -1072,6 +1075,9 @@ static int __tipc_send_stream(struct socket *sock, struct msghdr *m, size_t dsz)
 	}
 
 	timeo = sock_sndtimeo(sk, m->msg_flags & MSG_DONTWAIT);
+	if (!timeo && tsk->link_cong)
+		return -ELINKCONG;
+
 	dnode = tsk_peer_node(tsk);
 	skb_queue_head_init(&pktchain);
 
-- 
2.1.4