tipc: change socket buffer overflow control to respect sk_rcvbuf

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.

To allow for administrative tunability of the socket receive buffer
size, we create a tipc_rmem sysctl variable to allow the user to
configure an even bigger value via sysctl command.  It is a size of
three (min/default/max) to be consistent with things like tcp_rmem.

By default, the value initialized in tipc_rmem[1] is equal to the
receive socket size needed by a TIPC_CRITICAL_IMPORTANCE message.
This value is also set as the default value of sk_rcvbuf.

Originally-by: Jon Maloy <jon.maloy@ericsson.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: Jon Maloy <jon.maloy@ericsson.com>
[Ying: added sysctl variation to Jon's original patch]
Signed-off-by: Ying Xue <ying.xue@windriver.com>
[PG: don't compile sysctl.c if not config'd; add Documentation]
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/sysctl/net.txt

@@ -26,7 +26,7 @@ Table : Subdirectories in /proc/sys/net
  ipv4      IP version 4        x25        X.25 protocol
  ipx       IPX                 token-ring IBM token ring
  bridge    Bridging            decnet     DEC net
- ipv6      IP version 6
+ ipv6      IP version 6        tipc       TIPC
 ..............................................................................
 
 1. /proc/sys/net/core - Network core options
@@ -207,3 +207,18 @@ IPX.
 The /proc/net/ipx_route  table  holds  a list of IPX routes. For each route it
 gives the  destination  network, the router node (or Directly) and the network
 address of the router (or Connected) for internal networks.
+
+6. TIPC
+-------------------------------------------------------
+
+The TIPC protocol now has a tunable for the receive memory, similar to the
+tcp_rmem - i.e. a vector of 3 INTEGERs: (min, default, max)
+
+    # cat /proc/sys/net/tipc/tipc_rmem
+    4252725 34021800        68043600
+    #
+
+The max value is set to CONN_OVERLOAD_LIMIT, and the default and min values
+are scaled (shifted) versions of that same value.  Note that the min value
+is not at this point in time used in any meaningful way, but the triplet is
+preserved in order to be consistent with things like tcp_rmem.

net/tipc/Makefile

@@ -11,3 +11,4 @@ tipc-y	+= addr.o bcast.o bearer.o config.o \
 	   socket.o log.o eth_media.o
 
 tipc-$(CONFIG_TIPC_MEDIA_IB)	+= ib_media.o
+tipc-$(CONFIG_SYSCTL)		+= sysctl.o

net/tipc/core.c

@@ -39,6 +39,7 @@
 #include "name_table.h"
 #include "subscr.h"
 #include "config.h"
+#include "port.h"
 
 #include <linux/module.h>
 
@@ -50,7 +51,7 @@ u32 tipc_own_addr __read_mostly;
 int tipc_max_ports __read_mostly;
 int tipc_net_id __read_mostly;
 int tipc_remote_management __read_mostly;
-
+int sysctl_tipc_rmem[3] __read_mostly;	/* min/default/max */
 
 /**
  * tipc_buf_acquire - creates a TIPC message buffer
@@ -118,6 +119,7 @@ static void tipc_core_stop(void)
 	tipc_nametbl_stop();
 	tipc_ref_table_stop();
 	tipc_socket_stop();
+	tipc_unregister_sysctl();
 }
 
 /**
@@ -142,13 +144,14 @@ static int tipc_core_start(void)
 		res = tipc_netlink_start();
 	if (!res)
 		res = tipc_socket_init();
+	if (!res)
+		res = tipc_register_sysctl();
 	if (res)
 		tipc_core_stop();
 
 	return res;
 }
 
-
 static int __init tipc_init(void)
 {
 	int res;
@@ -160,6 +163,11 @@ static int __init tipc_init(void)
 	tipc_max_ports = CONFIG_TIPC_PORTS;
 	tipc_net_id = 4711;
 
+	sysctl_tipc_rmem[0] = CONN_OVERLOAD_LIMIT >> 4 << TIPC_LOW_IMPORTANCE;
+	sysctl_tipc_rmem[1] = CONN_OVERLOAD_LIMIT >> 4 <<
+			      TIPC_CRITICAL_IMPORTANCE;
+	sysctl_tipc_rmem[2] = CONN_OVERLOAD_LIMIT;
+
 	res = tipc_core_start();
 	if (res)
 		pr_err("Unable to start in single node mode\n");

net/tipc/core.h

@@ -80,6 +80,7 @@ extern u32 tipc_own_addr __read_mostly;
 extern int tipc_max_ports __read_mostly;
 extern int tipc_net_id __read_mostly;
 extern int tipc_remote_management __read_mostly;
+extern int sysctl_tipc_rmem[3] __read_mostly;
 
 /*
  * Other global variables
@@ -97,6 +98,14 @@ extern void tipc_netlink_stop(void);
 extern int  tipc_socket_init(void);
 extern void tipc_socket_stop(void);
 
+#ifdef CONFIG_SYSCTL
+extern int tipc_register_sysctl(void);
+extern void tipc_unregister_sysctl(void);
+#else
+#define tipc_register_sysctl() 0
+#define tipc_unregister_sysctl()
+#endif
+
 /*
  * TIPC timer and signal code
  */

net/tipc/port.h

@@ -43,6 +43,8 @@
 #include "node_subscr.h"
 
 #define TIPC_FLOW_CONTROL_WIN 512
+#define CONN_OVERLOAD_LIMIT	((TIPC_FLOW_CONTROL_WIN * 2 + 1) * \
+				SKB_TRUESIZE(TIPC_MAX_USER_MSG_SIZE))
 
 typedef void (*tipc_msg_err_event) (void *usr_handle, u32 portref,
 		struct sk_buff **buf, unsigned char const *data,

net/tipc/socket.c

@@ -43,8 +43,6 @@
 #define SS_LISTENING	-1	/* socket is listening */
 #define SS_READY	-2	/* socket is connectionless */
 
-#define CONN_OVERLOAD_LIMIT	((TIPC_FLOW_CONTROL_WIN * 2 + 1) * \
-				SKB_TRUESIZE(TIPC_MAX_USER_MSG_SIZE))
 #define CONN_TIMEOUT_DEFAULT	8000	/* default connect timeout = 8s */
 
 struct tipc_sock {
@@ -203,6 +201,7 @@ 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 = sysctl_tipc_rmem[1];
 	sk->sk_data_ready = tipc_data_ready;
 	sk->sk_write_space = tipc_write_space;
 	tipc_sk(sk)->p = tp_ptr;
@@ -1233,10 +1232,10 @@ 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
  */
@@ -1246,9 +1245,10 @@ static unsigned int rcvbuf_limit(struct sock *sk, struct sk_buff *buf)
 	unsigned int limit;
 
 	if (msg_connected(msg))
-		limit = CONN_OVERLOAD_LIMIT;
+		limit = sysctl_tipc_rmem[2];
 	else
-		limit = sk->sk_rcvbuf << (msg_importance(msg) + 5);
+		limit = sk->sk_rcvbuf >> TIPC_CRITICAL_IMPORTANCE <<
+			msg_importance(msg);
 	return limit;
 }
 
@@ -1847,7 +1847,8 @@ static const struct net_proto_family tipc_family_ops = {
 static struct proto tipc_proto = {
 	.name		= "TIPC",
 	.owner		= THIS_MODULE,
-	.obj_size	= sizeof(struct tipc_sock)
+	.obj_size	= sizeof(struct tipc_sock),
+	.sysctl_rmem	= sysctl_tipc_rmem
 };
 
 /**

net/tipc/sysctl.c

@@ -0,0 +1,64 @@
+/*
+ * net/tipc/sysctl.c: sysctl interface to TIPC subsystem
+ *
+ * Copyright (c) 2013, Wind River Systems
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the names of the copyright holders nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * Alternatively, this software may be distributed under the terms of the
+ * GNU General Public License ("GPL") version 2 as published by the Free
+ * Software Foundation.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "core.h"
+
+#include <linux/sysctl.h>
+
+static struct ctl_table_header *tipc_ctl_hdr;
+
+static struct ctl_table tipc_table[] = {
+	{
+		.procname	= "tipc_rmem",
+		.data		= &sysctl_tipc_rmem,
+		.maxlen		= sizeof(sysctl_tipc_rmem),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+	{}
+};
+
+int tipc_register_sysctl(void)
+{
+	tipc_ctl_hdr = register_net_sysctl(&init_net, "net/tipc", tipc_table);
+	if (tipc_ctl_hdr == NULL)
+		return -ENOMEM;
+	return 0;
+}
+
+void tipc_unregister_sysctl(void)
+{
+	unregister_net_sysctl_table(tipc_ctl_hdr);
+}