--- /dev/null
+/*
+ * 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/module.h>
+#include <linux/netdevice.h>
+#include <linux/if.h>
+#include <net/sock.h>
+#include <net/pkt_sched.h>
+#include <linux/rtnetlink.h>
+#include <linux/jiffies.h>
+#include <linux/spinlock.h>
+#include <linux/workqueue.h>
+#include <linux/bitops.h>
+#include <linux/types.h>
+
+
+enum lw_bits {
+ LW_URGENT = 0,
+};
+
+static unsigned long linkwatch_flags;
+static unsigned long linkwatch_nextevent;
+
+static void linkwatch_event(struct work_struct *dummy);
+static DECLARE_DELAYED_WORK(linkwatch_work, linkwatch_event);
+
+static LIST_HEAD(lweventlist);
+static DEFINE_SPINLOCK(lweventlist_lock);
+
+static unsigned char default_operstate(const struct net_device *dev)
+{
+ if (!netif_carrier_ok(dev))
+ return (dev->ifindex != dev_get_iflink(dev) ?
+ IF_OPER_LOWERLAYERDOWN : IF_OPER_DOWN);
+
+ if (netif_dormant(dev))
+ return IF_OPER_DORMANT;
+
+ return IF_OPER_UP;
+}
+
+
+static void rfc2863_policy(struct net_device *dev)
+{
+ unsigned char operstate = default_operstate(dev);
+
+ if (operstate == dev->operstate)
+ return;
+
+ write_lock_bh(&dev_base_lock);
+
+ switch(dev->link_mode) {
+ case IF_LINK_MODE_DORMANT:
+ if (operstate == IF_OPER_UP)
+ operstate = IF_OPER_DORMANT;
+ break;
+
+ case IF_LINK_MODE_DEFAULT:
+ default:
+ break;
+ }
+
+ dev->operstate = operstate;
+
+ write_unlock_bh(&dev_base_lock);
+}
+
+
+void linkwatch_init_dev(struct net_device *dev)
+{
+ /* Handle pre-registration link state changes */
+ if (!netif_carrier_ok(dev) || netif_dormant(dev))
+ rfc2863_policy(dev);
+}
+
+
+static bool linkwatch_urgent_event(struct net_device *dev)
+{
+ if (!netif_running(dev))
+ return false;
+
+ if (dev->ifindex != dev_get_iflink(dev))
+ return true;
+
+ if (dev->priv_flags & IFF_TEAM_PORT)
+ return true;
+
+ return netif_carrier_ok(dev) && qdisc_tx_changing(dev);
+}
+
+
+static void linkwatch_add_event(struct net_device *dev)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&lweventlist_lock, flags);
+ if (list_empty(&dev->link_watch_list)) {
+ list_add_tail(&dev->link_watch_list, &lweventlist);
+ dev_hold(dev);
+ }
+ spin_unlock_irqrestore(&lweventlist_lock, flags);
+}
+
+
+static void linkwatch_schedule_work(int urgent)
+{
+ unsigned long delay = linkwatch_nextevent - jiffies;
+
+ if (test_bit(LW_URGENT, &linkwatch_flags))
+ return;
+
+ /* Minimise down-time: drop delay for up event. */
+ if (urgent) {
+ if (test_and_set_bit(LW_URGENT, &linkwatch_flags))
+ return;
+ delay = 0;
+ }
+
+ /* If we wrap around we'll delay it by at most HZ. */
+ if (delay > HZ)
+ delay = 0;
+
+ /*
+ * If urgent, schedule immediate execution; otherwise, don't
+ * override the existing timer.
+ */
+ if (test_bit(LW_URGENT, &linkwatch_flags))
+ mod_delayed_work(system_wq, &linkwatch_work, 0);
+ else
+ schedule_delayed_work(&linkwatch_work, delay);
+}
+
+
+static void linkwatch_do_dev(struct net_device *dev)
+{
+ /*
+ * Make sure the above read is complete since it can be
+ * rewritten as soon as we clear the bit below.
+ */
+ smp_mb__before_atomic();
+
+ /* We are about to handle this device,
+ * so new events can be accepted
+ */
+ clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state);
+
+ rfc2863_policy(dev);
+ if (dev->flags & IFF_UP) {
+ if (netif_carrier_ok(dev))
+ dev_activate(dev);
+ else
+ dev_deactivate(dev);
+
+ netdev_state_change(dev);
+ }
+ dev_put(dev);
+}
+
+static void __linkwatch_run_queue(int urgent_only)
+{
+ struct net_device *dev;
+ LIST_HEAD(wrk);
+
+ /*
+ * 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. This limit does not apply to up events
+ * while the device qdisc is down.
+ */
+ if (!urgent_only)
+ linkwatch_nextevent = jiffies + HZ;
+ /* Limit wrap-around effect on delay. */
+ else if (time_after(linkwatch_nextevent, jiffies + HZ))
+ linkwatch_nextevent = jiffies;
+
+ clear_bit(LW_URGENT, &linkwatch_flags);
+
+ spin_lock_irq(&lweventlist_lock);
+ list_splice_init(&lweventlist, &wrk);
+
+ while (!list_empty(&wrk)) {
+
+ dev = list_first_entry(&wrk, struct net_device, link_watch_list);
+ list_del_init(&dev->link_watch_list);
+
+ if (urgent_only && !linkwatch_urgent_event(dev)) {
+ list_add_tail(&dev->link_watch_list, &lweventlist);
+ continue;
+ }
+ spin_unlock_irq(&lweventlist_lock);
+ linkwatch_do_dev(dev);
+ spin_lock_irq(&lweventlist_lock);
+ }
+
+ if (!list_empty(&lweventlist))
+ linkwatch_schedule_work(0);
+ spin_unlock_irq(&lweventlist_lock);
+}
+
+void linkwatch_forget_dev(struct net_device *dev)
+{
+ unsigned long flags;
+ int clean = 0;
+
+ spin_lock_irqsave(&lweventlist_lock, flags);
+ if (!list_empty(&dev->link_watch_list)) {
+ list_del_init(&dev->link_watch_list);
+ clean = 1;
+ }
+ spin_unlock_irqrestore(&lweventlist_lock, flags);
+ if (clean)
+ linkwatch_do_dev(dev);
+}
+
+
+/* Must be called with the rtnl semaphore held */
+void linkwatch_run_queue(void)
+{
+ __linkwatch_run_queue(0);
+}
+
+
+static void linkwatch_event(struct work_struct *dummy)
+{
+ rtnl_lock();
+ __linkwatch_run_queue(time_after(linkwatch_nextevent, jiffies));
+ rtnl_unlock();
+}
+
+
+void linkwatch_fire_event(struct net_device *dev)
+{
+ bool urgent = linkwatch_urgent_event(dev);
+
+ if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) {
+ linkwatch_add_event(dev);
+ } else if (!urgent)
+ return;
+
+ linkwatch_schedule_work(urgent);
+}
+EXPORT_SYMBOL(linkwatch_fire_event);
Code Review / kvmfornfv.git / blobdiff