diff options
Diffstat (limited to 'net/core/link_watch.c')
| -rw-r--r-- | net/core/link_watch.c | 228 |
1 files changed, 228 insertions, 0 deletions
diff --git a/net/core/link_watch.c b/net/core/link_watch.c new file mode 100644 index 0000000..bf8f7af --- /dev/null +++ b/net/core/link_watch.c @@ -0,0 +1,228 @@ +/* + * 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/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/slab.h> +#include <linux/workqueue.h> +#include <linux/bitops.h> +#include <asm/types.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 struct net_device *lweventlist; +static DEFINE_SPINLOCK(lweventlist_lock); + +static unsigned char default_operstate(const struct net_device *dev) +{ + if (!netif_carrier_ok(dev)) + return (dev->ifindex != dev->iflink ? + IF_OPER_LOWERLAYERDOWN : IF_OPER_DOWN); + + 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_bh(&dev_base_lock); + + switch(dev->link_mode) { + 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_bh(&dev_base_lock); +} + + +static bool linkwatch_urgent_event(struct net_device *dev) +{ + return netif_running(dev) && 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); + dev->link_watch_next = lweventlist; + lweventlist = dev; + 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; + + /* + * This is true if we've scheduled it immeditately or if we don't + * need an immediate execution and it's already pending. + */ + if (schedule_delayed_work(&linkwatch_work, delay) == !delay) + return; + + /* Don't bother if there is nothing urgent. */ + if (!test_bit(LW_URGENT, &linkwatch_flags)) + return; + + /* It's already running which is good enough. */ + if (!cancel_delayed_work(&linkwatch_work)) + return; + + /* Otherwise we reschedule it again for immediate exection. */ + schedule_delayed_work(&linkwatch_work, 0); +} + + +static void __linkwatch_run_queue(int urgent_only) +{ + struct net_device *next; + + /* + * 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); + next = lweventlist; + lweventlist = NULL; + spin_unlock_irq(&lweventlist_lock); + + while (next) { + struct net_device *dev = next; + + next = dev->link_watch_next; + + if (urgent_only && !linkwatch_urgent_event(dev)) { + linkwatch_add_event(dev); + continue; + } + + /* + * Make sure the above read is complete since it can be + * rewritten as soon as we clear the bit below. + */ + smp_mb__before_clear_bit(); + + /* 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); + } + + dev_put(dev); + } + + if (lweventlist) + linkwatch_schedule_work(0); +} + + +/* 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)) { + dev_hold(dev); + + linkwatch_add_event(dev); + } else if (!urgent) + return; + + linkwatch_schedule_work(urgent); +} + +EXPORT_SYMBOL(linkwatch_fire_event); |
