/*
* 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/config.h>
#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/list.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#include <linux/bitops.h>
#include <asm/types.h>
enum lw_bits {
LW_RUNNING = 0,
LW_SE_USED
};
static unsigned long linkwatch_flags;
static unsigned long linkwatch_nextevent;
static void linkwatch_event(void *dummy);
static DECLARE_WORK(linkwatch_work, linkwatch_event, NULL);
static LIST_HEAD(lweventlist);
static DEFINE_SPINLOCK(lweventlist_lock);
struct lw_event {
struct list_head list;
struct net_device *dev;
};
/* Avoid kmalloc() for most systems */
static struct lw_event singleevent;
/* Must be called with the rtnl semaphore held */
void linkwatch_run_queue(void)
{
LIST_HEAD(head);
struct list_head *n, *next;
spin_lock_irq(&lweventlist_lock);
list_splice_init(&lweventlist, &head);
spin_unlock_irq(&lweventlist_lock);
list_for_each_safe(n, next, &head) {
struct lw_event *event = list_entry(n, struct lw_event, list);
struct net_device *dev = event->dev;
if (event == &singleevent) {
clear_bit(LW_SE_USED, &linkwatch_flags);
} else {
kfree(event);
}
/* We are about to handle this device,
* so new events can be accepted
*/
clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state);
if (dev->flags & IFF_UP) {
if (netif_carrier_ok(dev)) {
WARN_ON(dev->qdisc_sleeping == &noop_qdisc);
dev_activate(dev);
} else
dev_deactivate(dev);
netdev_state_change(dev);
}
dev_put(dev);
}
}
static void linkwatch_event(void *dummy)
{
/* 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
*/
linkwatch_nextevent = jiffies + HZ;
clear_bit(LW_RUNNING, &linkwatch_flags);
rtnl_shlock();
linkwatch_run_queue();
rtnl_shunlock();
}
void linkwatch_fire_event(struct net_device *dev)
{
if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) {
unsigned long flags;
struct lw_event *event;
if (test_and_set_bit(LW_SE_USED, &linkwatch_flags)) {
event = kmalloc(sizeof(struct lw_event), GFP_ATOMIC);
if (unlikely(event == NULL)) {
clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state);
return;
}
} else {
event = &singleevent;
}
dev_hold(dev);
event->dev = dev;
spin_lock_irqsave(&lweventlist_lock, flags);
list_add_tail(&event->list, &lweventlist);
spin_unlock_irqrestore(&lweventlist_lock, flags);
if (!test_and_set_bit(LW_RUNNING, &linkwatch_flags)) {
unsigned long thisevent = jiffies;
if (thisevent >= linkwatch_nextevent) {
schedule_work(&linkwatch_work);
} else {
schedule_delayed_work(&linkwatch_work, linkwatch_nextevent - thisevent);
}
}
}
}
EXPORT_SYMBOL(linkwatch_fire_event);
