net: New iface_stat module to monitor persistent network stats

Adding a new module that tracks the number of bytes/packets transfered
by a network interface, even after the interface has been
removed. This is relevant to track the total data usage in mobile
devices whose interfaces are added and removed quite frequently (WiFi,
Bluetooth, 3G,..).

Monitoring is done only for devices that are configured with a valid
IP address (check to exclude virtual/loopback/tunnel interfaces).

Change-Id: I8ac642af1990433ebd0784e8dbd72bf0714b5bf6
Signed-off-by: Ashish Sharma <ashishsharma@google.com>

drivers/misc/Kconfig

@@ -360,6 +360,10 @@ config UID_STAT
 	bool "UID based statistics tracking exported to /proc/uid_stat"
 	default n
 
+config IFACE_STAT
+	bool "Persistent interface statistics tracking exported to /proc/iface_stat"
+	default n
+
 config VMWARE_BALLOON
 	tristate "VMware Balloon Driver"
 	depends on X86

drivers/misc/Makefile

@@ -29,6 +29,7 @@ obj-$(CONFIG_EP93XX_PWM)	+= ep93xx_pwm.o
 obj-$(CONFIG_DS1682)		+= ds1682.o
 obj-$(CONFIG_TI_DAC7512)	+= ti_dac7512.o
 obj-$(CONFIG_UID_STAT)		+= uid_stat.o
+obj-$(CONFIG_IFACE_STAT)	+= iface_stat.o
 obj-$(CONFIG_C2PORT)		+= c2port/
 obj-$(CONFIG_IWMC3200TOP)      += iwmc3200top/
 obj-y				+= eeprom/

drivers/misc/iface_stat.c

@@ -0,0 +1,234 @@
+/* drivers/misc/iface_stat.c
+ *
+ * Copyright (C) 2011 Google, Inc.
+ *
+ * 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/err.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/in.h>
+#include <linux/list.h>
+#include <linux/proc_fs.h>
+#include <linux/slab.h>
+#include <linux/stat.h>
+#include <linux/netdevice.h>
+#include <linux/inetdevice.h>
+#include <linux/rtnetlink.h>
+#include <linux/iface_stat.h>
+
+static LIST_HEAD(iface_list);
+static struct proc_dir_entry *iface_stat_procdir;
+
+struct iface_stat {
+	struct list_head if_link;
+	char *iface_name;
+	unsigned long tx_bytes;
+	unsigned long rx_bytes;
+	unsigned long tx_packets;
+	unsigned long rx_packets;
+	bool active;
+};
+
+static int read_proc_entry(char *page, char **start, off_t off,
+		int count, int *eof, void *data)
+{
+	int len;
+	unsigned long value;
+	char *p = page;
+	unsigned long *iface_entry = (unsigned long *) data;
+	if (!data)
+		return 0;
+
+	value = (unsigned long) (*iface_entry);
+	p += sprintf(p, "%lu\n", value);
+	len = (p - page) - off;
+	*eof = (len <= count) ? 1 : 0;
+	*start = page + off;
+	return len;
+}
+
+static int read_proc_bool_entry(char *page, char **start, off_t off,
+		int count, int *eof, void *data)
+{
+	int len;
+	bool value;
+	char *p = page;
+	unsigned long *iface_entry = (unsigned long *) data;
+	if (!data)
+		return 0;
+
+	value = (bool) (*iface_entry);
+	p += sprintf(p, "%u\n", value ? 1 : 0);
+	len = (p - page) - off;
+	*eof = (len <= count) ? 1 : 0;
+	*start = page + off;
+	return len;
+}
+
+/* Find the entry for tracking the specified interface. */
+static struct iface_stat *get_iface_stat(const char *ifname)
+{
+	struct iface_stat *iface_entry;
+	if (!ifname)
+		return NULL;
+
+	list_for_each_entry(iface_entry, &iface_list, if_link) {
+		if (!strcmp(iface_entry->iface_name, ifname))
+			return iface_entry;
+	}
+	return NULL;
+}
+
+/*
+ * Create a new entry for tracking the specified interface.
+ * Do nothing if the entry already exists.
+ * Called when an interface is configured with a valid IP address.
+ */
+void create_iface_stat(const struct in_device *in_dev)
+{
+	struct iface_stat *new_iface;
+	struct proc_dir_entry *proc_entry;
+	const struct net_device *dev;
+	const char *ifname;
+	struct iface_stat *entry;
+	__be32 ipaddr = 0;
+	struct in_ifaddr *ifa = NULL;
+
+	ASSERT_RTNL(); /* No need for separate locking */
+
+	dev = in_dev->dev;
+	if (!dev) {
+		pr_err("iface_stat: This should never happen.\n");
+		return;
+	}
+
+	ifname = dev->name;
+	for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next)
+		if (!strcmp(dev->name, ifa->ifa_label))
+			break;
+
+	if (ifa)
+		ipaddr = ifa->ifa_local;
+	else {
+		pr_err("iface_stat: Interface not found.\n");
+		return;
+	}
+
+	entry = get_iface_stat(dev->name);
+	if (entry != NULL) {
+		pr_debug("iface_stat: Already monitoring device %s\n", ifname);
+		if (ipv4_is_loopback(ipaddr)) {
+			entry->active = false;
+			pr_debug("iface_stat: Disabling monitor for "
+					"loopback device %s\n", ifname);
+		} else {
+			entry->active = true;
+			pr_debug("iface_stat: Re-enabling monitor for "
+					"device %s with ip %pI4\n",
+					ifname, &ipaddr);
+		}
+		return;
+	} else if (ipv4_is_loopback(ipaddr)) {
+		pr_debug("iface_stat: Ignoring monitor for "
+				"loopback device %s with ip %pI4\n",
+				ifname, &ipaddr);
+		return;
+	}
+
+	/* Create a new entry for tracking the specified interface. */
+	new_iface = kmalloc(sizeof(struct iface_stat), GFP_KERNEL);
+	if (new_iface == NULL)
+		return;
+
+	new_iface->iface_name = kmalloc((strlen(ifname)+1)*sizeof(char),
+						GFP_KERNEL);
+	if (new_iface->iface_name == NULL) {
+		kfree(new_iface);
+		return;
+	}
+
+	strcpy(new_iface->iface_name, ifname);
+	/* Counters start at 0, so we can track 4GB of network traffic. */
+	new_iface->tx_bytes = 0;
+	new_iface->rx_bytes = 0;
+	new_iface->rx_packets = 0;
+	new_iface->tx_packets = 0;
+	new_iface->active = true;
+
+	/* Append the newly created iface stat struct to the list. */
+	list_add_tail(&new_iface->if_link, &iface_list);
+	proc_entry = proc_mkdir(ifname, iface_stat_procdir);
+
+	/* Keep reference to iface_stat so we know where to read stats from. */
+	create_proc_read_entry("tx_bytes", S_IRUGO, proc_entry,
+			read_proc_entry, &new_iface->tx_bytes);
+
+	create_proc_read_entry("rx_bytes", S_IRUGO, proc_entry,
+			read_proc_entry, &new_iface->rx_bytes);
+
+	create_proc_read_entry("tx_packets", S_IRUGO, proc_entry,
+			read_proc_entry, &new_iface->tx_packets);
+
+	create_proc_read_entry("rx_packets", S_IRUGO, proc_entry,
+			read_proc_entry, &new_iface->rx_packets);
+
+	create_proc_read_entry("active", S_IRUGO, proc_entry,
+			read_proc_bool_entry, &new_iface->active);
+
+	pr_debug("iface_stat: Now monitoring device %s with ip %pI4\n",
+			ifname, &ipaddr);
+}
+
+/*
+ * Update stats for the specified interface. Do nothing if the entry
+ * does not exist (when a device was never configured with an IP address).
+ * Called when an device is being unregistered.
+ */
+void iface_stat_update(struct net_device *dev)
+{
+	const struct net_device_stats *stats = dev_get_stats(dev);
+	struct iface_stat *entry;
+
+	ASSERT_RTNL();
+
+	entry = get_iface_stat(dev->name);
+	if (entry == NULL) {
+		pr_debug("iface_stat: dev %s monitor not found\n", dev->name);
+		return;
+	}
+
+	if (entry->active) { /* FIXME: Support for more than 4GB */
+		entry->tx_bytes += stats->tx_bytes;
+		entry->tx_packets += stats->tx_packets;
+		entry->rx_bytes += stats->rx_bytes;
+		entry->rx_packets += stats->rx_packets;
+		entry->active = false;
+		pr_debug("iface_stat: Updating stats for "
+			       "dev %s which went down\n", dev->name);
+	} else
+		pr_debug("iface_stat: Didn't update stats for "
+				"dev %s which went down\n", dev->name);
+}
+
+static int __init iface_stat_init(void)
+{
+	iface_stat_procdir = proc_mkdir("iface_stat", NULL);
+	if (!iface_stat_procdir) {
+		pr_err("iface_stat: failed to create proc entry\n");
+		return -1;
+	}
+
+	return 0;
+}
+
+device_initcall(iface_stat_init);

include/linux/iface_stat.h

@@ -0,0 +1,50 @@
+/* include/linux/iface_stat.h
+ *
+ * Copyright (C) 2011 Google, Inc.
+ *
+ * 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.
+ *
+ */
+
+#ifndef __IFACE_STAT_H
+#define __IFACE_STAT_H
+
+/*
+ * Contains definitions for persistent data usage tracking per
+ * network interface.
+ */
+
+#ifdef CONFIG_IFACE_STAT
+/*
+ * Create a new entry for tracking the specified interface.
+ * Do nothing if the entry already exists.
+ * Called when an interface is configured with a valid IP address.
+ */
+void create_iface_stat(const struct in_device *in_dev);
+
+/*
+ * Update stats for the specified interface.
+ * Do nothing if the entry does not exist (when a device was never
+ * configured with an IP address). Called when an device is being
+ * unregistered.
+ */
+void iface_stat_update(struct net_device *dev);
+
+#else
+
+static inline void create_iface_stat(in_dev)
+{ }
+
+static inline void iface_stat_update(dev)
+{ }
+
+#endif
+
+#endif /* __IFACE_STAT_H */

net/core/dev.c

@@ -131,6 +131,7 @@
 #include <linux/random.h>
 #include <trace/events/napi.h>
 #include <linux/pci.h>
+#include <linux/iface_stat.h>
 
 #include "net-sysfs.h"
 
@@ -4803,6 +4804,9 @@ static void rollback_registered_many(struct list_head *head)
 	synchronize_net();
 
 	list_for_each_entry(dev, head, unreg_list) {
+		/* Store stats for this device in persistent iface_stat */
+		iface_stat_update(dev);
+
 		/* Shutdown queueing discipline. */
 		dev_shutdown(dev);
 

net/ipv4/devinet.c

@@ -55,6 +55,7 @@
 #include <linux/sysctl.h>
 #endif
 #include <linux/kmod.h>
+#include <linux/iface_stat.h>
 
 #include <net/arp.h>
 #include <net/ip.h>
@@ -375,6 +376,9 @@ static int __inet_insert_ifa(struct in_ifaddr *ifa, struct nlmsghdr *nlh,
 	rtmsg_ifa(RTM_NEWADDR, ifa, nlh, pid);
 	blocking_notifier_call_chain(&inetaddr_chain, NETDEV_UP, ifa);
 
+	/* Start persistent interface stat monitoring. Ignores if loopback. */
+	create_iface_stat(in_dev);
+
 	return 0;
 }