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From 75090d40ffbd9b4863238e1d62b43f8598da5e5e Mon Sep 17 00:00:00 2001
From: Robert Love <rlove@google.com>
Date: Thu, 31 Jul 2008 11:12:44 -0400
Subject: [PATCH 082/134] sysfs_net_ipv4: Add sysfs-based knobs for controlling TCP window size
Add a family of knobs to /sys/kernel/ipv4 for controlling the TCP window size:
tcp_wmem_min
tcp_wmem_def
tcp_wmem_max
tcp_rmem_min
tcp_rmem_def
tcp_rmem_max
This six values mirror the sysctl knobs in /proc/sys/net/ipv4/tcp_wmem and
/proc/sys/net/ipv4/tcp_rmem.
Sysfs, unlike sysctl, allows us to set and manage the files' permissions and
owners.
Signed-off-by: Robert Love <rlove@google.com>
---
net/ipv4/Makefile | 1 +
net/ipv4/sysfs_net_ipv4.c | 88 +++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 89 insertions(+), 0 deletions(-)
create mode 100644 net/ipv4/sysfs_net_ipv4.c
--- a/net/ipv4/Makefile
+++ b/net/ipv4/Makefile
@@ -14,6 +14,7 @@ obj-y := route.o inetpeer.o protocol
inet_fragment.o
obj-$(CONFIG_SYSCTL) += sysctl_net_ipv4.o
+obj-$(CONFIG_SYSFS) += sysfs_net_ipv4.o
obj-$(CONFIG_IP_FIB_HASH) += fib_hash.o
obj-$(CONFIG_IP_FIB_TRIE) += fib_trie.o
obj-$(CONFIG_PROC_FS) += proc.o
--- /dev/null
+++ b/net/ipv4/sysfs_net_ipv4.c
@@ -0,0 +1,88 @@
+/*
+ * net/ipv4/sysfs_net_ipv4.c
+ *
+ * sysfs-based networking knobs (so we can, unlike with sysctl, control perms)
+ *
+ * Copyright (C) 2008 Google, Inc.
+ *
+ * Robert Love <rlove@google.com>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/kobject.h>
+#include <linux/string.h>
+#include <linux/sysfs.h>
+#include <linux/init.h>
+#include <net/tcp.h>
+
+#define CREATE_IPV4_FILE(_name, _var) \
+static ssize_t _name##_show(struct kobject *kobj, \
+ struct kobj_attribute *attr, char *buf) \
+{ \
+ return sprintf(buf, "%d\n", _var); \
+} \
+static ssize_t _name##_store(struct kobject *kobj, \
+ struct kobj_attribute *attr, \
+ const char *buf, size_t count) \
+{ \
+ int val, ret; \
+ ret = sscanf(buf, "%d", &val); \
+ if (ret != 1) \
+ return -EINVAL; \
+ if (val < 0) \
+ return -EINVAL; \
+ _var = val; \
+ return count; \
+} \
+static struct kobj_attribute _name##_attr = \
+ __ATTR(_name, 0644, _name##_show, _name##_store)
+
+CREATE_IPV4_FILE(tcp_wmem_min, sysctl_tcp_wmem[0]);
+CREATE_IPV4_FILE(tcp_wmem_def, sysctl_tcp_wmem[1]);
+CREATE_IPV4_FILE(tcp_wmem_max, sysctl_tcp_wmem[2]);
+
+CREATE_IPV4_FILE(tcp_rmem_min, sysctl_tcp_rmem[0]);
+CREATE_IPV4_FILE(tcp_rmem_def, sysctl_tcp_rmem[1]);
+CREATE_IPV4_FILE(tcp_rmem_max, sysctl_tcp_rmem[2]);
+
+static struct attribute *ipv4_attrs[] = {
+ &tcp_wmem_min_attr.attr,
+ &tcp_wmem_def_attr.attr,
+ &tcp_wmem_max_attr.attr,
+ &tcp_rmem_min_attr.attr,
+ &tcp_rmem_def_attr.attr,
+ &tcp_rmem_max_attr.attr,
+ NULL
+};
+
+static struct attribute_group ipv4_attr_group = {
+ .attrs = ipv4_attrs,
+};
+
+static __init int sysfs_ipv4_init(void)
+{
+ struct kobject *ipv4_kobject;
+ int ret;
+
+ ipv4_kobject = kobject_create_and_add("ipv4", kernel_kobj);
+ if (!ipv4_kobject)
+ return -ENOMEM;
+
+ ret = sysfs_create_group(ipv4_kobject, &ipv4_attr_group);
+ if (ret) {
+ kobject_put(ipv4_kobject);
+ return ret;
+ }
+
+ return 0;
+}
+
+subsys_initcall(sysfs_ipv4_init);
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