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![Vladimir Oltean](/assets/img/avatar_default.png)
RFC 2863 says: The lowerLayerDown state is also a refinement on the down state. This new state indicates that this interface runs "on top of" one or more other interfaces (see ifStackTable) and that this interface is down specifically because one or more of these lower-layer interfaces are down. DSA interfaces are virtual network devices, stacked on top of the DSA master, but they have a physical MAC, with a PHY that reports a real link status. But since DSA (perhaps improperly) uses an iflink to describe the relationship to its master since commitc084080151
("dsa: set ->iflink on slave interfaces to the ifindex of the parent"), default_operstate() will misinterpret this to mean that every time the carrier of a DSA interface is not ok, it is because of the master being not ok. In fact, since commitc0a8a9c274
("net: dsa: automatically bring user ports down when master goes down"), DSA cannot even in theory be in the lowerLayerDown state, because it just calls dev_close_many(), thereby going down, when the master goes down. We could revert the commit that creates an iflink between a DSA user port and its master, especially since now we have an alternative IFLA_DSA_MASTER which has less side effects. But there may be tooling in use which relies on the iflink, which has existed since 2009. We could also probably do something local within DSA to overwrite what rfc2863_policy() did, in a way similar to hsr_set_operstate(), but this seems like a hack. What seems appropriate is to follow the iflink, and check the carrier status of that interface as well. If that's down too, yes, keep reporting lowerLayerDown, otherwise just down. Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Signed-off-by: David S. Miller <davem@davemloft.net>
294 lines
6.5 KiB
C
294 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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