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Subject[PATCH] networking: Add write/clear capability to /proc/net/dev
There is currently no way to reset networking statistics other than to
rmmod the interface and reinstall it.

This patch adds the capability to clear and/or set network statistics
counters using the /proc/net/dev file.

Please see the Documentation/networking/proc_net_dev file for full
details of the API.

Signed-off-by: John Mehaffey <mehaf_lkml@gedanken.com>
---

diff -purN orig new
--- orig/Documentation/networking/proc_net_dev.txt Wed Dec 31
16:00:00 1969
+++ new/Documentation/networking/proc_net_dev.txt Fri May 29 15:59:32
2009
@@ -0,0 +1,32 @@
+This document describes the interface provided by /proc/net/dev
+
+The proc/net/dev interface provides statistics about currently
+active network devices, both actual hardware and virtual devices.
+
+Reading /proc/net/dev provides both raw statistics and summaries
+from the struct net_dev_stats structure. If a device does not
+support statistics, an error message will print for that device.
+
+Writing /proc/net/dev can clear or set statistics for devices.
+
+There are 4 modes available for writing to /proc/net/dev.
+
+1. echo "clearall" > /proc/net/dev
+ This will clear (0 out) all statistics for all devices.
+2. echo "eth1 clear" > /proc/net/dev
+ Clears all stats for a single network device (eth1 in this case).
+3. echo "eth1 0 0 0 0" > /proc/net/dev
+ Clears rx and tx bytes and packets counters. The order of counters
+ cleared is that in struct net_device_stats. Counters not included
+ in the parameter list are not altered.
+4. echo "eth1 ,,,,0xFFFF 0xFFFF" > /proc/net/dev : sets rx and tx errors,
+ leaving byte and packet counters unchanged. Perhaps useful for testing
+ network health monitoring software. Each comma skips an element, so if
+ you want to set consecutive elements, DO NOT use a comma separated
list!
+
+ Whitespace is ignored, except as a separator. There is a limit of 256
+ bytes for the command. You can use mode 4 to break setting of stats
+ into smaller chunks, if necessary.
+
+NOTE: the order of parameters is that of struct net_device_stats,
+ NOT that of the statistics returned by reading /proc/net/dev!!!
--- orig/net/core/dev.c Fri May 29 15:13:15 2009
+++ new/net/core/dev.c Fri May 29 14:44:18 2009
@@ -2929,6 +2929,142 @@ static void dev_seq_printf_stats(struct
stats->tx_compressed);
}

+#define USR_BUF_SIZE 256
+
+static void get_usr_buf(char *buffer, const char __user *input, size_t
size)
+{
+ if (size < USR_BUF_SIZE) {
+ copy_from_user(buffer, input, size - 1);
+ buffer[size - 1]='\0';
+ } else {
+ printk(KERN_WARNING "Dev: Ignoring characters past size %d\n",
+ USR_BUF_SIZE - 1);
+ copy_from_user(buffer, input, USR_BUF_SIZE - 1);
+ buffer[USR_BUF_SIZE - 1] = '\0';
+ }
+}
+
+static inline void clear_stats(struct net_device_stats *stats)
+{
+ if (stats)
+ memset(stats, 0, sizeof(struct net_device_stats));
+}
+
+static inline char *skip_whitespace(char *start)
+{
+ while (isspace(*start))
+ ++start;
+ return start;
+}
+
+static int get_net_dev(char **scan_start, struct net_device **net_dev)
+{
+ char tmp;
+ char *scan_end = *scan_start;
+
+ while ((*scan_end) && !(*scan_end == ',') && !isspace(*scan_end))
+ ++scan_end;
+
+ tmp = *scan_end;
+ if (!tmp) {
+ printk(KERN_ERR "Dev: Invalid parameter(s)\n");
+ return -EINVAL;
+ }
+
+ *scan_end = '\0';
+ *net_dev = dev_get_by_name(*scan_start);
+ if (!*net_dev) {
+ printk(KERN_ERR "Dev: network device not found: \"%s\"\n",
+ *scan_start);
+ return -ENOENT;
+ }
+
+ *scan_end = tmp;
+ *scan_start = skip_whitespace(scan_end);
+
+ return 0;
+}
+
+static int set_stats(struct net_device *net_dev, char *scan_start)
+{
+ char * scan_end;
+ unsigned long *stat_ptr = (unsigned long *)net_dev->get_stats(net_dev);
+
+ while (*scan_start) {
+ if (isdigit(*scan_start))
+ *stat_ptr = simple_strtoul(scan_start, &scan_end, 0);
+ else if (*scan_start == ',')
+ scan_end = scan_start + 1;
+ else {
+ printk(KERN_ERR "Dev: Invalid scan character:\"%c\"\n",
+ *scan_start);
+ return -EINVAL;
+ }
+
+ scan_start = skip_whitespace(scan_end);
+ ++stat_ptr;
+ }
+
+ return 0;
+}
+
+/*
+ * dev_stats_write - clear or set stats for network devices
+ * syntax:
+ * echo "clearall" > /proc/net/dev : clears all stats for all (current)
+ * network devices.
+ * echo "eth1 clear" > /proc/net/dev : clears all stats for a single
network
+ * device (eth1 in this case).
+ * echo "eth1 0 0 0 0" > /proc/net/dev : clears rx and tx bytes and packets
+ * counters.
+ * echo "eth1 ,,,,0xFFFF 0xFFFF" > /proc/net/dev : sets rx and tx errors,
+ * leaving byte and packet counters unchanged. Perhaps useful for
testing
+ * network health monitoring software. Each comma skips an
element, so if
+ * you want to set consecutive elements, DO NOT use a comma
separated list!
+ * Whitespace is ignored, except as a separator.
+ * NOTE: the order of parameters is that of struct net_device_stats,
+ * NOT that of the statistics returned by reading /proc/net/dev!!!
+ */
+
+static ssize_t dev_stats_write(struct file *file, const char __user *input,
+ size_t size, loff_t *ofs)
+{
+ char usr_buf[USR_BUF_SIZE];
+ char *scan_start;
+ int retval;
+ struct net_device *net_dev = dev_base;
+
+ if (!capable(CAP_NET_ADMIN))
+ return -EPERM;
+ if (size < 2)
+ return -EINVAL;
+
+ get_usr_buf(usr_buf, input, size);
+
+ scan_start = strstrip(usr_buf);
+
+ if (!strcmp(scan_start, "clearall")) {
+ while (net_dev) {
+ clear_stats(net_dev->get_stats(net_dev));
+ net_dev = net_dev->next;
+ }
+ return size;
+ }
+
+ if ((retval = get_net_dev(&scan_start, &net_dev)))
+ return retval;
+
+ if (!strcmp(scan_start, "clear")) {
+ clear_stats(net_dev->get_stats(net_dev));
+ return size;
+ }
+
+ if ((retval = set_stats(net_dev, scan_start)))
+ return retval;
+ else
+ return size;
+}
+
/*
* Called from the PROCfs module. This now uses the new arbitrary sized
* /proc/net interface to create /proc/net/dev
@@ -3002,6 +3138,7 @@ static const struct file_operations dev_
.owner = THIS_MODULE,
.open = dev_seq_open,
.read = seq_read,
+ .write = dev_stats_write,
.llseek = seq_lseek,
.release = seq_release_net,
};
@@ -3135,7 +3272,7 @@ static int __net_init dev_proc_net_init(
{
int rc = -ENOMEM;

- if (!proc_net_fops_create(net, "dev", S_IRUGO, &dev_seq_fops))
+ if (!proc_net_fops_create(net, "dev", S_IRUGO | S_IWUSR,
&dev_seq_fops))
goto out;
if (!proc_net_fops_create(net, "softnet_stat", S_IRUGO,
&softnet_seq_fops))
goto out_dev;


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