X-Git-Url: http://pilppa.org/gitweb/gitweb.cgi?a=blobdiff_plain;f=net%2Fsched%2Fsch_generic.c;h=fa1a6f45dc416173f8b6d853f9ce0c5fa3565bc7;hb=b04cde34cf1d006dfaf8523640f3a18bbb15ebaa;hp=f4d34480a093d126061920e6f53e7b4fc8dfe83b;hpb=3e2ce4dae98f6b246eaeb12833914d22fd83e31d;p=linux-2.6-omap-h63xx.git diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c index f4d34480a09..fa1a6f45dc4 100644 --- a/net/sched/sch_generic.c +++ b/net/sched/sch_generic.c @@ -11,27 +11,19 @@ * - Ingress support */ -#include -#include #include #include #include #include #include #include -#include -#include -#include -#include #include -#include #include #include #include #include #include #include -#include #include /* Main transmission queue. */ @@ -59,122 +51,128 @@ void qdisc_unlock_tree(struct net_device *dev) spin_unlock_bh(&dev->queue_lock); } -/* - dev->queue_lock serializes queue accesses for this device - AND dev->qdisc pointer itself. +static inline int qdisc_qlen(struct Qdisc *q) +{ + return q->q.qlen; +} - netif_tx_lock serializes accesses to device driver. +static inline int dev_requeue_skb(struct sk_buff *skb, struct net_device *dev, + struct Qdisc *q) +{ + if (unlikely(skb->next)) + dev->gso_skb = skb; + else + q->ops->requeue(skb, q); - dev->queue_lock and netif_tx_lock are mutually exclusive, - if one is grabbed, another must be free. - */ + netif_schedule(dev); + return 0; +} +static inline struct sk_buff *dev_dequeue_skb(struct net_device *dev, + struct Qdisc *q) +{ + struct sk_buff *skb; -/* Kick device. + if ((skb = dev->gso_skb)) + dev->gso_skb = NULL; + else + skb = q->dequeue(q); - Returns: 0 - queue is empty or throttled. - >0 - queue is not empty. + return skb; +} - NOTE: Called under dev->queue_lock with locally disabled BH. -*/ +static inline int handle_dev_cpu_collision(struct sk_buff *skb, + struct net_device *dev, + struct Qdisc *q) +{ + int ret; + if (unlikely(dev->xmit_lock_owner == smp_processor_id())) { + /* + * Same CPU holding the lock. It may be a transient + * configuration error, when hard_start_xmit() recurses. We + * detect it by checking xmit owner and drop the packet when + * deadloop is detected. Return OK to try the next skb. + */ + kfree_skb(skb); + if (net_ratelimit()) + printk(KERN_WARNING "Dead loop on netdevice %s, " + "fix it urgently!\n", dev->name); + ret = qdisc_qlen(q); + } else { + /* + * Another cpu is holding lock, requeue & delay xmits for + * some time. + */ + __get_cpu_var(netdev_rx_stat).cpu_collision++; + ret = dev_requeue_skb(skb, dev, q); + } + + return ret; +} + +/* + * NOTE: Called under dev->queue_lock with locally disabled BH. + * + * __LINK_STATE_QDISC_RUNNING guarantees only one CPU can process this + * device at a time. dev->queue_lock serializes queue accesses for + * this device AND dev->qdisc pointer itself. + * + * netif_tx_lock serializes accesses to device driver. + * + * dev->queue_lock and netif_tx_lock are mutually exclusive, + * if one is grabbed, another must be free. + * + * Note, that this procedure can be called by a watchdog timer + * + * Returns to the caller: + * 0 - queue is empty or throttled. + * >0 - queue is not empty. + * + */ static inline int qdisc_restart(struct net_device *dev) { struct Qdisc *q = dev->qdisc; struct sk_buff *skb; + int ret; /* Dequeue packet */ - if (((skb = dev->gso_skb)) || ((skb = q->dequeue(q)))) { - unsigned nolock = (dev->features & NETIF_F_LLTX); + if (unlikely((skb = dev_dequeue_skb(dev, q)) == NULL)) + return 0; - dev->gso_skb = NULL; - /* - * When the driver has LLTX set it does its own locking - * in start_xmit. No need to add additional overhead by - * locking again. These checks are worth it because - * even uncongested locks can be quite expensive. - * The driver can do trylock like here too, in case - * of lock congestion it should return -1 and the packet - * will be requeued. - */ - if (!nolock) { - if (!netif_tx_trylock(dev)) { - collision: - /* So, someone grabbed the driver. */ - - /* It may be transient configuration error, - when hard_start_xmit() recurses. We detect - it by checking xmit owner and drop the - packet when deadloop is detected. - */ - if (dev->xmit_lock_owner == smp_processor_id()) { - kfree_skb(skb); - if (net_ratelimit()) - printk(KERN_DEBUG "Dead loop on netdevice %s, fix it urgently!\n", dev->name); - goto out; - } - __get_cpu_var(netdev_rx_stat).cpu_collision++; - goto requeue; - } - } + /* And release queue */ + spin_unlock(&dev->queue_lock); - { - /* And release queue */ - spin_unlock(&dev->queue_lock); - - if (!netif_queue_stopped(dev)) { - int ret; - - ret = dev_hard_start_xmit(skb, dev); - if (ret == NETDEV_TX_OK) { - if (!nolock) { - netif_tx_unlock(dev); - } - spin_lock(&dev->queue_lock); - q = dev->qdisc; - goto out; - } - if (ret == NETDEV_TX_LOCKED && nolock) { - spin_lock(&dev->queue_lock); - q = dev->qdisc; - goto collision; - } - } + HARD_TX_LOCK(dev, smp_processor_id()); + ret = dev_hard_start_xmit(skb, dev); + HARD_TX_UNLOCK(dev); - /* NETDEV_TX_BUSY - we need to requeue */ - /* Release the driver */ - if (!nolock) { - netif_tx_unlock(dev); - } - spin_lock(&dev->queue_lock); - q = dev->qdisc; - } + spin_lock(&dev->queue_lock); + q = dev->qdisc; - /* Device kicked us out :( - This is possible in three cases: + switch (ret) { + case NETDEV_TX_OK: + /* Driver sent out skb successfully */ + ret = qdisc_qlen(q); + break; - 0. driver is locked - 1. fastroute is enabled - 2. device cannot determine busy state - before start of transmission (f.e. dialout) - 3. device is buggy (ppp) - */ + case NETDEV_TX_LOCKED: + /* Driver try lock failed */ + ret = handle_dev_cpu_collision(skb, dev, q); + break; -requeue: - if (unlikely(q == &noop_qdisc)) - kfree_skb(skb); - else if (skb->next) - dev->gso_skb = skb; - else - q->ops->requeue(skb, q); - netif_schedule(dev); + default: + /* Driver returned NETDEV_TX_BUSY - requeue skb */ + if (unlikely (ret != NETDEV_TX_BUSY && net_ratelimit())) + printk(KERN_WARNING "BUG %s code %d qlen %d\n", + dev->name, ret, q->q.qlen); + + ret = dev_requeue_skb(skb, dev, q); + break; } - return 0; -out: - BUG_ON((int) q->q.qlen < 0); - return q->q.qlen; + return ret; } void __qdisc_run(struct net_device *dev) @@ -243,14 +241,27 @@ static void dev_watchdog_down(struct net_device *dev) netif_tx_unlock_bh(dev); } +/** + * netif_carrier_on - set carrier + * @dev: network device + * + * Device has detected that carrier. + */ void netif_carrier_on(struct net_device *dev) { - if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) + if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) { linkwatch_fire_event(dev); - if (netif_running(dev)) - __netdev_watchdog_up(dev); + if (netif_running(dev)) + __netdev_watchdog_up(dev); + } } +/** + * netif_carrier_off - clear carrier + * @dev: network device + * + * Device has detected loss of carrier. + */ void netif_carrier_off(struct net_device *dev) { if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state)) @@ -493,9 +504,7 @@ void qdisc_destroy(struct Qdisc *qdisc) return; list_del(&qdisc->list); -#ifdef CONFIG_NET_ESTIMATOR gen_kill_estimator(&qdisc->bstats, &qdisc->rate_est); -#endif if (ops->reset) ops->reset(qdisc); if (ops->destroy) @@ -547,6 +556,7 @@ void dev_deactivate(struct net_device *dev) { struct Qdisc *qdisc; struct sk_buff *skb; + int running; spin_lock_bh(&dev->queue_lock); qdisc = dev->qdisc; @@ -562,12 +572,31 @@ void dev_deactivate(struct net_device *dev) dev_watchdog_down(dev); - /* Wait for outstanding dev_queue_xmit calls. */ + /* Wait for outstanding qdisc-less dev_queue_xmit calls. */ synchronize_rcu(); /* Wait for outstanding qdisc_run calls. */ - while (test_bit(__LINK_STATE_QDISC_RUNNING, &dev->state)) - yield(); + do { + while (test_bit(__LINK_STATE_QDISC_RUNNING, &dev->state)) + yield(); + + /* + * Double-check inside queue lock to ensure that all effects + * of the queue run are visible when we return. + */ + spin_lock_bh(&dev->queue_lock); + running = test_bit(__LINK_STATE_QDISC_RUNNING, &dev->state); + spin_unlock_bh(&dev->queue_lock); + + /* + * The running flag should never be set at this point because + * we've already set dev->qdisc to noop_qdisc *inside* the same + * pair of spin locks. That is, if any qdisc_run starts after + * our initial test it should see the noop_qdisc and then + * clear the RUNNING bit before dropping the queue lock. So + * if it is set here then we've found a bug. + */ + } while (WARN_ON_ONCE(running)); } void dev_init_scheduler(struct net_device *dev)