1 files changed, 294 insertions, 0 deletions
diff --git a/net/core/link_watch.c b/net/core/link_watch.c
new file mode 100644
index 0000000000..c469d1c4db
--- /dev/null
+++ b/net/core/link_watch.c
@@ -0,0 +1,294 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Linux network device link state notification
+ *
+ * Author:
+ *     Stefan Rompf <sux@loplof.de>
+ */
+
+#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>
+
+#include "dev.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_testing(dev))
+		return IF_OPER_TESTING;
+
+	/* Some uppers (DSA) have additional sources for being down, so
+	 * first check whether lower is indeed the source of its down state.
+	 */
+	if (!netif_carrier_ok(dev)) {
+		int iflink = dev_get_iflink(dev);
+		struct net_device *peer;
+
+		if (iflink == dev->ifindex)
+			return IF_OPER_DOWN;
+
+		peer = __dev_get_by_index(dev_net(dev), iflink);
+		if (!peer)
+			return IF_OPER_DOWN;
+
+		return netif_carrier_ok(peer) ? IF_OPER_DOWN :
+						IF_OPER_LOWERLAYERDOWN;
+	}
+
+	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(&dev_base_lock);
+
+	switch(dev->link_mode) {
+	case IF_LINK_MODE_TESTING:
+		if (operstate == IF_OPER_UP)
+			operstate = IF_OPER_TESTING;
+		break;
+
+	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(&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) ||
+	    netif_testing(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 (netif_is_lag_port(dev) || netif_is_lag_master(dev))
+		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);
+		netdev_hold(dev, &dev->linkwatch_dev_tracker, GFP_ATOMIC);
+	}
+	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);
+	}
+	/* Note: our callers are responsible for calling netdev_tracker_free().
+	 * This is the reason we use __dev_put() instead of dev_put().
+	 */
+	__dev_put(dev);
+}
+
+static void __linkwatch_run_queue(int urgent_only)
+{
+#define MAX_DO_DEV_PER_LOOP	100
+
+	int do_dev = MAX_DO_DEV_PER_LOOP;
+	struct net_device *dev;
+	LIST_HEAD(wrk);
+
+	/* Give urgent case more budget */
+	if (urgent_only)
+		do_dev += MAX_DO_DEV_PER_LOOP;
+
+	/*
+	 * 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) && do_dev > 0) {
+
+		dev = list_first_entry(&wrk, struct net_device, link_watch_list);
+		list_del_init(&dev->link_watch_list);
+
+		if (!netif_device_present(dev) ||
+		    (urgent_only && !linkwatch_urgent_event(dev))) {
+			list_add_tail(&dev->link_watch_list, &lweventlist);
+			continue;
+		}
+		/* We must free netdev tracker under
+		 * the spinlock protection.
+		 */
+		netdev_tracker_free(dev, &dev->linkwatch_dev_tracker);
+		spin_unlock_irq(&lweventlist_lock);
+		linkwatch_do_dev(dev);
+		do_dev--;
+		spin_lock_irq(&lweventlist_lock);
+	}
+
+	/* Add the remaining work back to lweventlist */
+	list_splice_init(&wrk, &lweventlist);
+
+	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;
+		/* We must release netdev tracker under
+		 * the spinlock protection.
+		 */
+		netdev_tracker_free(dev, &dev->linkwatch_dev_tracker);
+	}
+	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);