[PATCH net-next 01/12] tipc: change socket buffer overflow control to respect sk_rcvbuf

[Paul Gortmaker <paul.gortmaker@windriver.com>]

From: Jon Maloy <jon.maloy@ericsson.com>

As per feedback from the netdev community, we change the buffer
overflow protection algorithm in receiving sockets so that it
always respects the nominal upper limit set in sk_rcvbuf.

Instead of scaling up from a small sk_rcvbuf value, which leads to
violation of the configured sk_rcvbuf limit, we now calculate the
weighted per-message limit by scaling down from a much bigger value,
still in the same field, according to the importance priority of the
received message.

Cc: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
 net/tipc/socket.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index 515ce38..2dfabc7 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -1,7 +1,7 @@
 /*
  * net/tipc/socket.c: TIPC socket API
  *
- * Copyright (c) 2001-2007, 2012 Ericsson AB
+ * Copyright (c) 2001-2007, 2012-2013, Ericsson AB
  * Copyright (c) 2004-2008, 2010-2012, Wind River Systems
  * All rights reserved.
  *
@@ -203,6 +203,7 @@ static int tipc_create(struct net *net, struct socket *sock, int protocol,
 
 	sock_init_data(sock, sk);
 	sk->sk_backlog_rcv = backlog_rcv;
+	sk->sk_rcvbuf = CONN_OVERLOAD_LIMIT;
 	sk->sk_data_ready = tipc_data_ready;
 	sk->sk_write_space = tipc_write_space;
 	tipc_sk(sk)->p = tp_ptr;
@@ -1233,10 +1234,10 @@ static u32 filter_connect(struct tipc_sock *tsock, struct sk_buff **buf)
  * For all connectionless messages, by default new queue limits are
  * as belows:
  *
- * TIPC_LOW_IMPORTANCE       (5MB)
- * TIPC_MEDIUM_IMPORTANCE    (10MB)
- * TIPC_HIGH_IMPORTANCE      (20MB)
- * TIPC_CRITICAL_IMPORTANCE  (40MB)
+ * TIPC_LOW_IMPORTANCE       (4 MB)
+ * TIPC_MEDIUM_IMPORTANCE    (8 MB)
+ * TIPC_HIGH_IMPORTANCE      (16 MB)
+ * TIPC_CRITICAL_IMPORTANCE  (32 MB)
  *
  * Returns overload limit according to corresponding message importance
  */
@@ -1248,7 +1249,7 @@ static unsigned int rcvbuf_limit(struct sock *sk, struct sk_buff *buf)
 	if (msg_connected(msg))
 		limit = CONN_OVERLOAD_LIMIT;
 	else
-		limit = sk->sk_rcvbuf << (msg_importance(msg) + 5);
+		limit = sk->sk_rcvbuf >> 4 << msg_importance(msg);
 	return limit;
 }
 
-- 
1.8.1.2