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-rw-r--r--net/core/link_watch.c137
1 files changed, 137 insertions, 0 deletions
diff --git a/net/core/link_watch.c b/net/core/link_watch.c
new file mode 100644
index 000000000000..4859b7446c6f
--- /dev/null
+++ b/net/core/link_watch.c
@@ -0,0 +1,137 @@
+/*
+ * Linux network device link state notification
+ *
+ * Author:
+ * Stefan Rompf <sux@loplof.de>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/if.h>
+#include <net/sock.h>
+#include <linux/rtnetlink.h>
+#include <linux/jiffies.h>
+#include <linux/spinlock.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/workqueue.h>
+#include <linux/bitops.h>
+#include <asm/types.h>
+
+
+enum lw_bits {
+ LW_RUNNING = 0,
+ LW_SE_USED
+};
+
+static unsigned long linkwatch_flags;
+static unsigned long linkwatch_nextevent;
+
+static void linkwatch_event(void *dummy);
+static DECLARE_WORK(linkwatch_work, linkwatch_event, NULL);
+
+static LIST_HEAD(lweventlist);
+static DEFINE_SPINLOCK(lweventlist_lock);
+
+struct lw_event {
+ struct list_head list;
+ struct net_device *dev;
+};
+
+/* Avoid kmalloc() for most systems */
+static struct lw_event singleevent;
+
+/* Must be called with the rtnl semaphore held */
+void linkwatch_run_queue(void)
+{
+ LIST_HEAD(head);
+ struct list_head *n, *next;
+
+ spin_lock_irq(&lweventlist_lock);
+ list_splice_init(&lweventlist, &head);
+ spin_unlock_irq(&lweventlist_lock);
+
+ list_for_each_safe(n, next, &head) {
+ struct lw_event *event = list_entry(n, struct lw_event, list);
+ struct net_device *dev = event->dev;
+
+ if (event == &singleevent) {
+ clear_bit(LW_SE_USED, &linkwatch_flags);
+ } else {
+ kfree(event);
+ }
+
+ /* We are about to handle this device,
+ * so new events can be accepted
+ */
+ clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state);
+
+ if (dev->flags & IFF_UP) {
+ netdev_state_change(dev);
+ }
+
+ dev_put(dev);
+ }
+}
+
+
+static void linkwatch_event(void *dummy)
+{
+ /* Limit the number of linkwatch events to one
+ * per second so that a runaway driver does not
+ * cause a storm of messages on the netlink
+ * socket
+ */
+ linkwatch_nextevent = jiffies + HZ;
+ clear_bit(LW_RUNNING, &linkwatch_flags);
+
+ rtnl_shlock();
+ linkwatch_run_queue();
+ rtnl_shunlock();
+}
+
+
+void linkwatch_fire_event(struct net_device *dev)
+{
+ if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) {
+ unsigned long flags;
+ struct lw_event *event;
+
+ if (test_and_set_bit(LW_SE_USED, &linkwatch_flags)) {
+ event = kmalloc(sizeof(struct lw_event), GFP_ATOMIC);
+
+ if (unlikely(event == NULL)) {
+ clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state);
+ return;
+ }
+ } else {
+ event = &singleevent;
+ }
+
+ dev_hold(dev);
+ event->dev = dev;
+
+ spin_lock_irqsave(&lweventlist_lock, flags);
+ list_add_tail(&event->list, &lweventlist);
+ spin_unlock_irqrestore(&lweventlist_lock, flags);
+
+ if (!test_and_set_bit(LW_RUNNING, &linkwatch_flags)) {
+ unsigned long thisevent = jiffies;
+
+ if (thisevent >= linkwatch_nextevent) {
+ schedule_work(&linkwatch_work);
+ } else {
+ schedule_delayed_work(&linkwatch_work, linkwatch_nextevent - thisevent);
+ }
+ }
+ }
+}
+
+EXPORT_SYMBOL(linkwatch_fire_event);