diff options
Diffstat (limited to 'net/sched/sch_generic.c')
| -rw-r--r-- | net/sched/sch_generic.c | 741 |
1 files changed, 741 insertions, 0 deletions
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c new file mode 100644 index 0000000..cdcd16f --- /dev/null +++ b/net/sched/sch_generic.c @@ -0,0 +1,741 @@ +/* + * net/sched/sch_generic.c Generic packet scheduler routines. + * + * 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. + * + * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru> + * Jamal Hadi Salim, <hadi@cyberus.ca> 990601 + * - Ingress support + */ + +#include <linux/bitops.h> +#include <linux/module.h> +#include <linux/types.h> +#include <linux/kernel.h> +#include <linux/sched.h> +#include <linux/string.h> +#include <linux/errno.h> +#include <linux/netdevice.h> +#include <linux/skbuff.h> +#include <linux/rtnetlink.h> +#include <linux/init.h> +#include <linux/rcupdate.h> +#include <linux/list.h> +#include <net/pkt_sched.h> + +/* Main transmission queue. */ + +/* Modifications to data participating in scheduling must be protected with + * qdisc_lock(qdisc) spinlock. + * + * The idea is the following: + * - enqueue, dequeue are serialized via qdisc root lock + * - ingress filtering is also serialized via qdisc root lock + * - updates to tree and tree walking are only done under the rtnl mutex. + */ + +static inline int qdisc_qlen(struct Qdisc *q) +{ + return q->q.qlen; +} + +static inline int dev_requeue_skb(struct sk_buff *skb, struct Qdisc *q) +{ + q->gso_skb = skb; + q->qstats.requeues++; + __netif_schedule(q); + + return 0; +} + +static inline struct sk_buff *dequeue_skb(struct Qdisc *q) +{ + struct sk_buff *skb = q->gso_skb; + + if (unlikely(skb)) { + struct net_device *dev = qdisc_dev(q); + struct netdev_queue *txq; + + /* check the reason of requeuing without tx lock first */ + txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb)); + if (!netif_tx_queue_stopped(txq) && !netif_tx_queue_frozen(txq)) + q->gso_skb = NULL; + else + skb = NULL; + } else { + skb = q->dequeue(q); + } + + return skb; +} + +static inline int handle_dev_cpu_collision(struct sk_buff *skb, + struct netdev_queue *dev_queue, + struct Qdisc *q) +{ + int ret; + + if (unlikely(dev_queue->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_queue->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, q); + } + + return ret; +} + +/* + * NOTE: Called under qdisc_lock(q) with locally disabled BH. + * + * __QDISC_STATE_RUNNING guarantees only one CPU can process + * this qdisc at a time. qdisc_lock(q) serializes queue accesses for + * this queue. + * + * netif_tx_lock serializes accesses to device driver. + * + * qdisc_lock(q) 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 Qdisc *q) +{ + struct netdev_queue *txq; + int ret = NETDEV_TX_BUSY; + struct net_device *dev; + spinlock_t *root_lock; + struct sk_buff *skb; + + /* Dequeue packet */ + if (unlikely((skb = dequeue_skb(q)) == NULL)) + return 0; + + root_lock = qdisc_lock(q); + + /* And release qdisc */ + spin_unlock(root_lock); + + dev = qdisc_dev(q); + txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb)); + + HARD_TX_LOCK(dev, txq, smp_processor_id()); + if (!netif_tx_queue_stopped(txq) && + !netif_tx_queue_frozen(txq)) + ret = dev_hard_start_xmit(skb, dev, txq); + HARD_TX_UNLOCK(dev, txq); + + spin_lock(root_lock); + + switch (ret) { + case NETDEV_TX_OK: + /* Driver sent out skb successfully */ + ret = qdisc_qlen(q); + break; + + case NETDEV_TX_LOCKED: + /* Driver try lock failed */ + ret = handle_dev_cpu_collision(skb, txq, q); + break; + + 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, q); + break; + } + + if (ret && (netif_tx_queue_stopped(txq) || + netif_tx_queue_frozen(txq))) + ret = 0; + + return ret; +} + +void __qdisc_run(struct Qdisc *q) +{ + unsigned long start_time = jiffies; + + while (qdisc_restart(q)) { + /* + * Postpone processing if + * 1. another process needs the CPU; + * 2. we've been doing it for too long. + */ + if (need_resched() || jiffies != start_time) { + __netif_schedule(q); + break; + } + } + + clear_bit(__QDISC_STATE_RUNNING, &q->state); +} + +static void dev_watchdog(unsigned long arg) +{ + struct net_device *dev = (struct net_device *)arg; + + netif_tx_lock(dev); + if (!qdisc_tx_is_noop(dev)) { + if (netif_device_present(dev) && + netif_running(dev) && + netif_carrier_ok(dev)) { + int some_queue_stopped = 0; + unsigned int i; + + for (i = 0; i < dev->num_tx_queues; i++) { + struct netdev_queue *txq; + + txq = netdev_get_tx_queue(dev, i); + if (netif_tx_queue_stopped(txq)) { + some_queue_stopped = 1; + break; + } + } + + if (some_queue_stopped && + time_after(jiffies, (dev->trans_start + + dev->watchdog_timeo))) { + char drivername[64]; + WARN_ONCE(1, KERN_INFO "NETDEV WATCHDOG: %s (%s): transmit timed out\n", + dev->name, netdev_drivername(dev, drivername, 64)); + dev->tx_timeout(dev); + } + if (!mod_timer(&dev->watchdog_timer, + round_jiffies(jiffies + + dev->watchdog_timeo))) + dev_hold(dev); + } + } + netif_tx_unlock(dev); + + dev_put(dev); +} + +void __netdev_watchdog_up(struct net_device *dev) +{ + if (dev->tx_timeout) { + if (dev->watchdog_timeo <= 0) + dev->watchdog_timeo = 5*HZ; + if (!mod_timer(&dev->watchdog_timer, + round_jiffies(jiffies + dev->watchdog_timeo))) + dev_hold(dev); + } +} + +static void dev_watchdog_up(struct net_device *dev) +{ + __netdev_watchdog_up(dev); +} + +static void dev_watchdog_down(struct net_device *dev) +{ + netif_tx_lock_bh(dev); + if (del_timer(&dev->watchdog_timer)) + dev_put(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 (dev->reg_state == NETREG_UNINITIALIZED) + return; + linkwatch_fire_event(dev); + if (netif_running(dev)) + __netdev_watchdog_up(dev); + } +} +EXPORT_SYMBOL(netif_carrier_on); + +/** + * 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)) { + if (dev->reg_state == NETREG_UNINITIALIZED) + return; + linkwatch_fire_event(dev); + } +} +EXPORT_SYMBOL(netif_carrier_off); + +/* "NOOP" scheduler: the best scheduler, recommended for all interfaces + under all circumstances. It is difficult to invent anything faster or + cheaper. + */ + +static int noop_enqueue(struct sk_buff *skb, struct Qdisc * qdisc) +{ + kfree_skb(skb); + return NET_XMIT_CN; +} + +static struct sk_buff *noop_dequeue(struct Qdisc * qdisc) +{ + return NULL; +} + +static int noop_requeue(struct sk_buff *skb, struct Qdisc* qdisc) +{ + if (net_ratelimit()) + printk(KERN_DEBUG "%s deferred output. It is buggy.\n", + skb->dev->name); + kfree_skb(skb); + return NET_XMIT_CN; +} + +struct Qdisc_ops noop_qdisc_ops __read_mostly = { + .id = "noop", + .priv_size = 0, + .enqueue = noop_enqueue, + .dequeue = noop_dequeue, + .requeue = noop_requeue, + .owner = THIS_MODULE, +}; + +static struct netdev_queue noop_netdev_queue = { + .qdisc = &noop_qdisc, + .qdisc_sleeping = &noop_qdisc, +}; + +struct Qdisc noop_qdisc = { + .enqueue = noop_enqueue, + .dequeue = noop_dequeue, + .flags = TCQ_F_BUILTIN, + .ops = &noop_qdisc_ops, + .list = LIST_HEAD_INIT(noop_qdisc.list), + .requeue.lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock), + .q.lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock), + .dev_queue = &noop_netdev_queue, +}; +EXPORT_SYMBOL(noop_qdisc); + +static struct Qdisc_ops noqueue_qdisc_ops __read_mostly = { + .id = "noqueue", + .priv_size = 0, + .enqueue = noop_enqueue, + .dequeue = noop_dequeue, + .requeue = noop_requeue, + .owner = THIS_MODULE, +}; + +static struct Qdisc noqueue_qdisc; +static struct netdev_queue noqueue_netdev_queue = { + .qdisc = &noqueue_qdisc, + .qdisc_sleeping = &noqueue_qdisc, +}; + +static struct Qdisc noqueue_qdisc = { + .enqueue = NULL, + .dequeue = noop_dequeue, + .flags = TCQ_F_BUILTIN, + .ops = &noqueue_qdisc_ops, + .list = LIST_HEAD_INIT(noqueue_qdisc.list), + .requeue.lock = __SPIN_LOCK_UNLOCKED(noqueue_qdisc.q.lock), + .q.lock = __SPIN_LOCK_UNLOCKED(noqueue_qdisc.q.lock), + .dev_queue = &noqueue_netdev_queue, +}; + + +static const u8 prio2band[TC_PRIO_MAX+1] = + { 1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1 }; + +/* 3-band FIFO queue: old style, but should be a bit faster than + generic prio+fifo combination. + */ + +#define PFIFO_FAST_BANDS 3 + +static inline struct sk_buff_head *prio2list(struct sk_buff *skb, + struct Qdisc *qdisc) +{ + struct sk_buff_head *list = qdisc_priv(qdisc); + return list + prio2band[skb->priority & TC_PRIO_MAX]; +} + +static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc* qdisc) +{ + struct sk_buff_head *list = prio2list(skb, qdisc); + + if (skb_queue_len(list) < qdisc_dev(qdisc)->tx_queue_len) { + qdisc->q.qlen++; + return __qdisc_enqueue_tail(skb, qdisc, list); + } + + return qdisc_drop(skb, qdisc); +} + +static struct sk_buff *pfifo_fast_dequeue(struct Qdisc* qdisc) +{ + int prio; + struct sk_buff_head *list = qdisc_priv(qdisc); + + for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) { + if (!skb_queue_empty(list + prio)) { + qdisc->q.qlen--; + return __qdisc_dequeue_head(qdisc, list + prio); + } + } + + return NULL; +} + +static int pfifo_fast_requeue(struct sk_buff *skb, struct Qdisc* qdisc) +{ + qdisc->q.qlen++; + return __qdisc_requeue(skb, qdisc, prio2list(skb, qdisc)); +} + +static void pfifo_fast_reset(struct Qdisc* qdisc) +{ + int prio; + struct sk_buff_head *list = qdisc_priv(qdisc); + + for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) + __qdisc_reset_queue(qdisc, list + prio); + + qdisc->qstats.backlog = 0; + qdisc->q.qlen = 0; +} + +static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb) +{ + struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS }; + + memcpy(&opt.priomap, prio2band, TC_PRIO_MAX+1); + NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt); + return skb->len; + +nla_put_failure: + return -1; +} + +static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt) +{ + int prio; + struct sk_buff_head *list = qdisc_priv(qdisc); + + for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) + skb_queue_head_init(list + prio); + + return 0; +} + +static struct Qdisc_ops pfifo_fast_ops __read_mostly = { + .id = "pfifo_fast", + .priv_size = PFIFO_FAST_BANDS * sizeof(struct sk_buff_head), + .enqueue = pfifo_fast_enqueue, + .dequeue = pfifo_fast_dequeue, + .requeue = pfifo_fast_requeue, + .init = pfifo_fast_init, + .reset = pfifo_fast_reset, + .dump = pfifo_fast_dump, + .owner = THIS_MODULE, +}; + +struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue, + struct Qdisc_ops *ops) +{ + void *p; + struct Qdisc *sch; + unsigned int size; + int err = -ENOBUFS; + + /* ensure that the Qdisc and the private data are 32-byte aligned */ + size = QDISC_ALIGN(sizeof(*sch)); + size += ops->priv_size + (QDISC_ALIGNTO - 1); + + p = kzalloc(size, GFP_KERNEL); + if (!p) + goto errout; + sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p); + sch->padded = (char *) sch - (char *) p; + + INIT_LIST_HEAD(&sch->list); + skb_queue_head_init(&sch->requeue); + skb_queue_head_init(&sch->q); + sch->ops = ops; + sch->enqueue = ops->enqueue; + sch->dequeue = ops->dequeue; + sch->dev_queue = dev_queue; + dev_hold(qdisc_dev(sch)); + atomic_set(&sch->refcnt, 1); + + return sch; +errout: + return ERR_PTR(err); +} + +struct Qdisc * qdisc_create_dflt(struct net_device *dev, + struct netdev_queue *dev_queue, + struct Qdisc_ops *ops, + unsigned int parentid) +{ + struct Qdisc *sch; + + sch = qdisc_alloc(dev_queue, ops); + if (IS_ERR(sch)) + goto errout; + sch->parent = parentid; + + if (!ops->init || ops->init(sch, NULL) == 0) + return sch; + + qdisc_destroy(sch); +errout: + return NULL; +} +EXPORT_SYMBOL(qdisc_create_dflt); + +/* Under qdisc_lock(qdisc) and BH! */ + +void qdisc_reset(struct Qdisc *qdisc) +{ + const struct Qdisc_ops *ops = qdisc->ops; + + if (ops->reset) + ops->reset(qdisc); +} +EXPORT_SYMBOL(qdisc_reset); + +void qdisc_destroy(struct Qdisc *qdisc) +{ + const struct Qdisc_ops *ops = qdisc->ops; + + if (qdisc->flags & TCQ_F_BUILTIN || + !atomic_dec_and_test(&qdisc->refcnt)) + return; + +#ifdef CONFIG_NET_SCHED + qdisc_list_del(qdisc); + + qdisc_put_stab(qdisc->stab); +#endif + gen_kill_estimator(&qdisc->bstats, &qdisc->rate_est); + if (ops->reset) + ops->reset(qdisc); + if (ops->destroy) + ops->destroy(qdisc); + + module_put(ops->owner); + dev_put(qdisc_dev(qdisc)); + + kfree_skb(qdisc->gso_skb); + __skb_queue_purge(&qdisc->requeue); + + kfree((char *) qdisc - qdisc->padded); +} +EXPORT_SYMBOL(qdisc_destroy); + +static bool dev_all_qdisc_sleeping_noop(struct net_device *dev) +{ + unsigned int i; + + for (i = 0; i < dev->num_tx_queues; i++) { + struct netdev_queue *txq = netdev_get_tx_queue(dev, i); + + if (txq->qdisc_sleeping != &noop_qdisc) + return false; + } + return true; +} + +static void attach_one_default_qdisc(struct net_device *dev, + struct netdev_queue *dev_queue, + void *_unused) +{ + struct Qdisc *qdisc; + + if (dev->tx_queue_len) { + qdisc = qdisc_create_dflt(dev, dev_queue, + &pfifo_fast_ops, TC_H_ROOT); + if (!qdisc) { + printk(KERN_INFO "%s: activation failed\n", dev->name); + return; + } + } else { + qdisc = &noqueue_qdisc; + } + dev_queue->qdisc_sleeping = qdisc; +} + +static void transition_one_qdisc(struct net_device *dev, + struct netdev_queue *dev_queue, + void *_need_watchdog) +{ + struct Qdisc *new_qdisc = dev_queue->qdisc_sleeping; + int *need_watchdog_p = _need_watchdog; + + if (!(new_qdisc->flags & TCQ_F_BUILTIN)) + clear_bit(__QDISC_STATE_DEACTIVATED, &new_qdisc->state); + + rcu_assign_pointer(dev_queue->qdisc, new_qdisc); + if (need_watchdog_p && new_qdisc != &noqueue_qdisc) + *need_watchdog_p = 1; +} + +void dev_activate(struct net_device *dev) +{ + int need_watchdog; + + /* No queueing discipline is attached to device; + create default one i.e. pfifo_fast for devices, + which need queueing and noqueue_qdisc for + virtual interfaces + */ + + if (dev_all_qdisc_sleeping_noop(dev)) + netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL); + + if (!netif_carrier_ok(dev)) + /* Delay activation until next carrier-on event */ + return; + + need_watchdog = 0; + netdev_for_each_tx_queue(dev, transition_one_qdisc, &need_watchdog); + transition_one_qdisc(dev, &dev->rx_queue, NULL); + + if (need_watchdog) { + dev->trans_start = jiffies; + dev_watchdog_up(dev); + } +} + +static void dev_deactivate_queue(struct net_device *dev, + struct netdev_queue *dev_queue, + void *_qdisc_default) +{ + struct Qdisc *qdisc_default = _qdisc_default; + struct Qdisc *qdisc; + + qdisc = dev_queue->qdisc; + if (qdisc) { + spin_lock_bh(qdisc_lock(qdisc)); + + if (!(qdisc->flags & TCQ_F_BUILTIN)) + set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state); + + rcu_assign_pointer(dev_queue->qdisc, qdisc_default); + qdisc_reset(qdisc); + + spin_unlock_bh(qdisc_lock(qdisc)); + } +} + +static bool some_qdisc_is_busy(struct net_device *dev) +{ + unsigned int i; + + for (i = 0; i < dev->num_tx_queues; i++) { + struct netdev_queue *dev_queue; + spinlock_t *root_lock; + struct Qdisc *q; + int val; + + dev_queue = netdev_get_tx_queue(dev, i); + q = dev_queue->qdisc_sleeping; + root_lock = qdisc_lock(q); + + spin_lock_bh(root_lock); + + val = (test_bit(__QDISC_STATE_RUNNING, &q->state) || + test_bit(__QDISC_STATE_SCHED, &q->state)); + + spin_unlock_bh(root_lock); + + if (val) + return true; + } + return false; +} + +void dev_deactivate(struct net_device *dev) +{ + netdev_for_each_tx_queue(dev, dev_deactivate_queue, &noop_qdisc); + dev_deactivate_queue(dev, &dev->rx_queue, &noop_qdisc); + + dev_watchdog_down(dev); + + /* Wait for outstanding qdisc-less dev_queue_xmit calls. */ + synchronize_rcu(); + + /* Wait for outstanding qdisc_run calls. */ + while (some_qdisc_is_busy(dev)) + yield(); +} + +static void dev_init_scheduler_queue(struct net_device *dev, + struct netdev_queue *dev_queue, + void *_qdisc) +{ + struct Qdisc *qdisc = _qdisc; + + dev_queue->qdisc = qdisc; + dev_queue->qdisc_sleeping = qdisc; +} + +void dev_init_scheduler(struct net_device *dev) +{ + netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc); + dev_init_scheduler_queue(dev, &dev->rx_queue, &noop_qdisc); + + setup_timer(&dev->watchdog_timer, dev_watchdog, (unsigned long)dev); +} + +static void shutdown_scheduler_queue(struct net_device *dev, + struct netdev_queue *dev_queue, + void *_qdisc_default) +{ + struct Qdisc *qdisc = dev_queue->qdisc_sleeping; + struct Qdisc *qdisc_default = _qdisc_default; + + if (qdisc) { + rcu_assign_pointer(dev_queue->qdisc, qdisc_default); + dev_queue->qdisc_sleeping = qdisc_default; + + qdisc_destroy(qdisc); + } +} + +void dev_shutdown(struct net_device *dev) +{ + netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc); + shutdown_scheduler_queue(dev, &dev->rx_queue, &noop_qdisc); + WARN_ON(timer_pending(&dev->watchdog_timer)); +} |
