[PATCH] netdev: generate kobject uevent on network state

[Stephen Hemminger <shemminger@vyatta.com>]

It is easier for some applications to deal with text based interfaces
like uevent, rather than using netlink to listen for events.

Note, this does not deal with network namespaces but that is a generic
problem that already exists with kobjects (see rename events).

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>

---
 net/core/Makefile |    1 
 net/core/uevent.c |   61 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 62 insertions(+)

--- a/net/core/Makefile	2008-11-24 12:07:18.000000000 -0800
+++ b/net/core/Makefile	2008-11-24 12:07:22.000000000 -0800
@@ -17,3 +17,4 @@ obj-$(CONFIG_NET_PKTGEN) += pktgen.o
 obj-$(CONFIG_NETPOLL) += netpoll.o
 obj-$(CONFIG_NET_DMA) += user_dma.o
 obj-$(CONFIG_FIB_RULES) += fib_rules.o
+obj-$(CONFIG_HOTPLUG) += uevent.o
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ b/net/core/uevent.c	2008-11-24 12:11:46.000000000 -0800
@@ -0,0 +1,55 @@
+/*
+ * Linux network device event notification
+ *
+ * Author:
+ *	Stephen Hemminger <shemminger@vyatta.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/netdevice.h>
+#include <linux/kobject.h>
+#include <linux/notifier.h>
+
+/*
+ * Generate uevent in response to network device state changes.
+ * Other events are already handled by device subsystem.
+ */
+static int netdev_event(struct notifier_block *this, unsigned long event, void *ptr)
+{
+	struct net_device *netdev = ptr;
+
+	switch (event) {
+	case NETDEV_UP:
+		kobject_uevent(&netdev->dev.kobj, KOBJ_ONLINE);
+		break;
+
+	case NETDEV_DOWN:
+		kobject_uevent(&netdev->dev.kobj, KOBJ_OFFLINE);
+		break;
+
+	case NETDEV_CHANGE: {
+		char str[64] = "DEVSTATE=UP";
+		char *envp[2] = { str, NULL };
+
+		if (netif_oper_up(netdev))
+			strcat(str, ",RUNNING");
+		if (netif_carrier_ok(netdev))
+			strcat(str, ",LOWER_UP");
+		if (netif_dormant(netdev))
+			strcat(str, ",DORMANT");
+		kobject_uevent_env(&netdev->dev.kobj, KOBJ_CHANGE, envp);
+		break;
+		}
+	}
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block netdev_uevent_notifier = {
+	.notifier_call	= netdev_event,
+};
+
+static int __init netdev_uevent_init(void)
+{
+	return register_netdevice_notifier(&netdev_uevent_notifier);
+}
+device_initcall(netdev_uevent_init);