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>

6 files changed, 96 insertions, 11 deletions

diff --git a/net/tipc/Makefile b/net/tipc/Makefile
index 4df8e02d9008..02636d0a90cf 100644
--- a/net/tipc/Makefile
+++ b/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
diff --git a/net/tipc/core.c b/net/tipc/core.c
index 7ec2c1eb94f1..b0e42a087291 100644
--- a/net/tipc/core.c
+++ b/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");
diff --git a/net/tipc/core.h b/net/tipc/core.h
index 0207db04179a..fe7f2b7c19fe 100644
--- a/net/tipc/core.h
+++ b/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
  */
diff --git a/net/tipc/port.h b/net/tipc/port.h
index fb66e2e5f4d1..2485649c408a 100644
--- a/net/tipc/port.h
+++ b/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,
diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index 515ce38e4f4c..aba4255f297b 100644
--- a/net/tipc/socket.c
+++ b/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
 };
 
 /**
diff --git a/net/tipc/sysctl.c b/net/tipc/sysctl.c
new file mode 100644
index 000000000000..f3fef93325a8
--- /dev/null
+++ b/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);
+}