net: add sysfs entry for device group

The group of a network device can be queried or changed from userspace
using sysfs.

For example, considering sysfs mounted in /sys, one can change the group
that interface lo belongs to:
	echo 1 > /sys/class/net/lo/group

Signed-off-by: Vlad Dogaru <ddvlad@rosedu.org>
Acked-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 81367cc..2e4a393 100644 (file)
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -295,6 +295,20 @@ static ssize_t show_ifalias(struct device *dev,
        return ret;
 }
 
+NETDEVICE_SHOW(group, fmt_dec);
+
+static int change_group(struct net_device *net, unsigned long new_group)
+{
+       dev_set_group(net, (int) new_group);
+       return 0;
+}
+
+static ssize_t store_group(struct device *dev, struct device_attribute *attr,
+                        const char *buf, size_t len)
+{
+       return netdev_store(dev, attr, buf, len, change_group);
+}
+
 static struct device_attribute net_class_attributes[] = {
        __ATTR(addr_assign_type, S_IRUGO, show_addr_assign_type, NULL),
        __ATTR(addr_len, S_IRUGO, show_addr_len, NULL),
@@ -316,6 +330,7 @@ static struct device_attribute net_class_attributes[] = {
        __ATTR(flags, S_IRUGO | S_IWUSR, show_flags, store_flags),
        __ATTR(tx_queue_len, S_IRUGO | S_IWUSR, show_tx_queue_len,
               store_tx_queue_len),
+       __ATTR(group, S_IRUGO | S_IWUSR, show_group, store_group),
        {}
 };