295 lines
6.5 KiB
C
295 lines
6.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Linux network device link state notification
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*
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* Author:
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* Stefan Rompf <sux@loplof.de>
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*/
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#include <linux/module.h>
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#include <linux/netdevice.h>
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#include <linux/if.h>
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#include <net/sock.h>
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#include <net/pkt_sched.h>
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#include <linux/rtnetlink.h>
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#include <linux/jiffies.h>
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#include <linux/spinlock.h>
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#include <linux/workqueue.h>
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#include <linux/bitops.h>
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#include <linux/types.h>
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#include "dev.h"
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enum lw_bits {
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LW_URGENT = 0,
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};
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static unsigned long linkwatch_flags;
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static unsigned long linkwatch_nextevent;
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static void linkwatch_event(struct work_struct *dummy);
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static DECLARE_DELAYED_WORK(linkwatch_work, linkwatch_event);
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static LIST_HEAD(lweventlist);
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static DEFINE_SPINLOCK(lweventlist_lock);
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static unsigned char default_operstate(const struct net_device *dev)
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{
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if (netif_testing(dev))
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return IF_OPER_TESTING;
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/* Some uppers (DSA) have additional sources for being down, so
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* first check whether lower is indeed the source of its down state.
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*/
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if (!netif_carrier_ok(dev)) {
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int iflink = dev_get_iflink(dev);
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struct net_device *peer;
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if (iflink == dev->ifindex)
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return IF_OPER_DOWN;
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peer = __dev_get_by_index(dev_net(dev), iflink);
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if (!peer)
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return IF_OPER_DOWN;
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return netif_carrier_ok(peer) ? IF_OPER_DOWN :
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IF_OPER_LOWERLAYERDOWN;
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}
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if (netif_dormant(dev))
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return IF_OPER_DORMANT;
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return IF_OPER_UP;
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}
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static void rfc2863_policy(struct net_device *dev)
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{
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unsigned char operstate = default_operstate(dev);
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if (operstate == dev->operstate)
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return;
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write_lock(&dev_base_lock);
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switch(dev->link_mode) {
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case IF_LINK_MODE_TESTING:
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if (operstate == IF_OPER_UP)
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operstate = IF_OPER_TESTING;
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break;
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case IF_LINK_MODE_DORMANT:
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if (operstate == IF_OPER_UP)
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operstate = IF_OPER_DORMANT;
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break;
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case IF_LINK_MODE_DEFAULT:
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default:
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break;
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}
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dev->operstate = operstate;
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write_unlock(&dev_base_lock);
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}
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void linkwatch_init_dev(struct net_device *dev)
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{
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/* Handle pre-registration link state changes */
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if (!netif_carrier_ok(dev) || netif_dormant(dev) ||
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netif_testing(dev))
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rfc2863_policy(dev);
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}
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static bool linkwatch_urgent_event(struct net_device *dev)
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{
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if (!netif_running(dev))
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return false;
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if (dev->ifindex != dev_get_iflink(dev))
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return true;
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if (netif_is_lag_port(dev) || netif_is_lag_master(dev))
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return true;
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return netif_carrier_ok(dev) && qdisc_tx_changing(dev);
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}
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static void linkwatch_add_event(struct net_device *dev)
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{
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unsigned long flags;
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spin_lock_irqsave(&lweventlist_lock, flags);
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if (list_empty(&dev->link_watch_list)) {
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list_add_tail(&dev->link_watch_list, &lweventlist);
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netdev_hold(dev, &dev->linkwatch_dev_tracker, GFP_ATOMIC);
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}
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spin_unlock_irqrestore(&lweventlist_lock, flags);
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}
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static void linkwatch_schedule_work(int urgent)
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{
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unsigned long delay = linkwatch_nextevent - jiffies;
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if (test_bit(LW_URGENT, &linkwatch_flags))
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return;
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/* Minimise down-time: drop delay for up event. */
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if (urgent) {
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if (test_and_set_bit(LW_URGENT, &linkwatch_flags))
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return;
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delay = 0;
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}
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/* If we wrap around we'll delay it by at most HZ. */
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if (delay > HZ)
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delay = 0;
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/*
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* If urgent, schedule immediate execution; otherwise, don't
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* override the existing timer.
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*/
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if (test_bit(LW_URGENT, &linkwatch_flags))
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mod_delayed_work(system_wq, &linkwatch_work, 0);
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else
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schedule_delayed_work(&linkwatch_work, delay);
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}
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static void linkwatch_do_dev(struct net_device *dev)
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{
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/*
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* Make sure the above read is complete since it can be
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* rewritten as soon as we clear the bit below.
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*/
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smp_mb__before_atomic();
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/* We are about to handle this device,
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* so new events can be accepted
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*/
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clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state);
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rfc2863_policy(dev);
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if (dev->flags & IFF_UP) {
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if (netif_carrier_ok(dev))
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dev_activate(dev);
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else
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dev_deactivate(dev);
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netdev_state_change(dev);
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}
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/* Note: our callers are responsible for calling netdev_tracker_free().
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* This is the reason we use __dev_put() instead of dev_put().
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*/
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__dev_put(dev);
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}
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static void __linkwatch_run_queue(int urgent_only)
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{
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#define MAX_DO_DEV_PER_LOOP 100
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int do_dev = MAX_DO_DEV_PER_LOOP;
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struct net_device *dev;
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LIST_HEAD(wrk);
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/* Give urgent case more budget */
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if (urgent_only)
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do_dev += MAX_DO_DEV_PER_LOOP;
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/*
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* Limit the number of linkwatch events to one
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* per second so that a runaway driver does not
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* cause a storm of messages on the netlink
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* socket. This limit does not apply to up events
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* while the device qdisc is down.
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*/
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if (!urgent_only)
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linkwatch_nextevent = jiffies + HZ;
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/* Limit wrap-around effect on delay. */
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else if (time_after(linkwatch_nextevent, jiffies + HZ))
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linkwatch_nextevent = jiffies;
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clear_bit(LW_URGENT, &linkwatch_flags);
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spin_lock_irq(&lweventlist_lock);
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list_splice_init(&lweventlist, &wrk);
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while (!list_empty(&wrk) && do_dev > 0) {
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dev = list_first_entry(&wrk, struct net_device, link_watch_list);
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list_del_init(&dev->link_watch_list);
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if (!netif_device_present(dev) ||
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(urgent_only && !linkwatch_urgent_event(dev))) {
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list_add_tail(&dev->link_watch_list, &lweventlist);
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continue;
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}
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/* We must free netdev tracker under
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* the spinlock protection.
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*/
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netdev_tracker_free(dev, &dev->linkwatch_dev_tracker);
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spin_unlock_irq(&lweventlist_lock);
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linkwatch_do_dev(dev);
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do_dev--;
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spin_lock_irq(&lweventlist_lock);
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}
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/* Add the remaining work back to lweventlist */
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list_splice_init(&wrk, &lweventlist);
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if (!list_empty(&lweventlist))
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linkwatch_schedule_work(0);
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spin_unlock_irq(&lweventlist_lock);
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}
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void linkwatch_forget_dev(struct net_device *dev)
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{
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unsigned long flags;
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int clean = 0;
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spin_lock_irqsave(&lweventlist_lock, flags);
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if (!list_empty(&dev->link_watch_list)) {
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list_del_init(&dev->link_watch_list);
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clean = 1;
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/* We must release netdev tracker under
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* the spinlock protection.
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*/
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netdev_tracker_free(dev, &dev->linkwatch_dev_tracker);
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}
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spin_unlock_irqrestore(&lweventlist_lock, flags);
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if (clean)
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linkwatch_do_dev(dev);
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}
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/* Must be called with the rtnl semaphore held */
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void linkwatch_run_queue(void)
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{
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__linkwatch_run_queue(0);
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}
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static void linkwatch_event(struct work_struct *dummy)
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{
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rtnl_lock();
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__linkwatch_run_queue(time_after(linkwatch_nextevent, jiffies));
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rtnl_unlock();
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}
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void linkwatch_fire_event(struct net_device *dev)
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{
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bool urgent = linkwatch_urgent_event(dev);
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if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) {
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linkwatch_add_event(dev);
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} else if (!urgent)
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return;
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linkwatch_schedule_work(urgent);
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}
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EXPORT_SYMBOL(linkwatch_fire_event);
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