net-sysfs: expose number of carrier on/off changes
This allows to monitor carrier on/off transitions and detect link
flapping issues:
- new /sys/class/net/X/carrier_changes
- new rtnetlink IFLA_CARRIER_CHANGES (getlink)
Tested:
- grep . /sys/class/net/*/carrier_changes
+ ip link set dev X down/up
+ plug/unplug cable
- updated iproute2: prints IFLA_CARRIER_CHANGES
- iproute2 20121211-2 (debian): unchanged behavior
Signed-off-by: David Decotigny <decot@googlers.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 daed9a6..4623962 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -253,6 +253,16 @@
}
static DEVICE_ATTR_RO(operstate);
+static ssize_t carrier_changes_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct net_device *netdev = to_net_dev(dev);
+ return sprintf(buf, fmt_dec,
+ atomic_read(&netdev->carrier_changes));
+}
+static DEVICE_ATTR_RO(carrier_changes);
+
/* read-write attributes */
static int change_mtu(struct net_device *net, unsigned long new_mtu)
@@ -386,6 +396,7 @@
&dev_attr_duplex.attr,
&dev_attr_dormant.attr,
&dev_attr_operstate.attr,
+ &dev_attr_carrier_changes.attr,
&dev_attr_ifalias.attr,
&dev_attr_carrier.attr,
&dev_attr_mtu.attr,