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cacaddf57e
Some network drivers call netif_stop_queue() when detecting loss of carrier. This leads to packets being queued up at the qdisc level for an unbound period of time. In order to prevent this effect, the core networking stack will now cease to queue packets for any device, that is operationally down (i.e. the queue is flushed and disabled). Signed-off-by: Tommy S. Christensen <tommy.christensen@tpack.net> Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
144 lines
3.3 KiB
C
144 lines
3.3 KiB
C
/*
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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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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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*/
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#include <linux/config.h>
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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/list.h>
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#include <linux/slab.h>
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#include <linux/workqueue.h>
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#include <linux/bitops.h>
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#include <asm/types.h>
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enum lw_bits {
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LW_RUNNING = 0,
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LW_SE_USED
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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(void *dummy);
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static DECLARE_WORK(linkwatch_work, linkwatch_event, NULL);
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static LIST_HEAD(lweventlist);
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static DEFINE_SPINLOCK(lweventlist_lock);
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struct lw_event {
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struct list_head list;
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struct net_device *dev;
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};
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/* Avoid kmalloc() for most systems */
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static struct lw_event singleevent;
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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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LIST_HEAD(head);
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struct list_head *n, *next;
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spin_lock_irq(&lweventlist_lock);
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list_splice_init(&lweventlist, &head);
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spin_unlock_irq(&lweventlist_lock);
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list_for_each_safe(n, next, &head) {
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struct lw_event *event = list_entry(n, struct lw_event, list);
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struct net_device *dev = event->dev;
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if (event == &singleevent) {
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clear_bit(LW_SE_USED, &linkwatch_flags);
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} else {
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kfree(event);
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}
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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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if (dev->flags & IFF_UP) {
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if (netif_carrier_ok(dev)) {
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WARN_ON(dev->qdisc_sleeping == &noop_qdisc);
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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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dev_put(dev);
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}
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}
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static void linkwatch_event(void *dummy)
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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
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*/
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linkwatch_nextevent = jiffies + HZ;
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clear_bit(LW_RUNNING, &linkwatch_flags);
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rtnl_shlock();
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linkwatch_run_queue();
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rtnl_shunlock();
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}
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void linkwatch_fire_event(struct net_device *dev)
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{
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if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) {
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unsigned long flags;
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struct lw_event *event;
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if (test_and_set_bit(LW_SE_USED, &linkwatch_flags)) {
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event = kmalloc(sizeof(struct lw_event), GFP_ATOMIC);
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if (unlikely(event == NULL)) {
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clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state);
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return;
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}
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} else {
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event = &singleevent;
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}
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dev_hold(dev);
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event->dev = dev;
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spin_lock_irqsave(&lweventlist_lock, flags);
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list_add_tail(&event->list, &lweventlist);
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spin_unlock_irqrestore(&lweventlist_lock, flags);
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if (!test_and_set_bit(LW_RUNNING, &linkwatch_flags)) {
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unsigned long thisevent = jiffies;
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if (thisevent >= linkwatch_nextevent) {
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schedule_work(&linkwatch_work);
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} else {
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schedule_delayed_work(&linkwatch_work, linkwatch_nextevent - thisevent);
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}
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}
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}
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}
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EXPORT_SYMBOL(linkwatch_fire_event);
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