netdev - [PATCH net v1 2/2] tipc: fix socket flow control accounting error at tipc_recv

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Date:   Mon, 24 Apr 2017 15:00:43 +0200
From:   Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@...csson.com>
To:     <netdev@...r.kernel.org>
CC:     <tipc-discussion@...ts.sourceforge.net>
Subject: [PATCH net v1 2/2] tipc: fix socket flow control accounting error at tipc_recv_stream

Until now in tipc_recv_stream(), we update the received
unacknowledged bytes based on a stack variable and not based on the
actual message size.
If the user buffer passed at tipc_recv_stream() is smaller than the
received skb, the size variable in stack differs from the actual
message size in the skb. This leads to a flow control accounting
error causing permanent congestion.

In this commit, we fix this accounting error by always using the
size of the incoming message.

Fixes: 10724cc7bb78 ("tipc: redesign connection-level flow control")
Signed-off-by: Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@...csson.com>
Reviewed-by: Jon Maloy <jon.maloy@...csson.com>
---
 net/tipc/socket.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index b28e94f1c739..566906795c8c 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -1484,7 +1484,7 @@ static int tipc_recv_stream(struct socket *sock, struct msghdr *m,
 	if (unlikely(flags & MSG_PEEK))
 		goto exit;

-	tsk->rcv_unacked += tsk_inc(tsk, hlen + sz);
+	tsk->rcv_unacked += tsk_inc(tsk, hlen + msg_data_sz(msg));
 	if (unlikely(tsk->rcv_unacked >= (tsk->rcv_win / 4)))
 		tipc_sk_send_ack(tsk);
 	tsk_advance_rx_queue(sk);
-- 
2.1.4