/* * 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->netdev_ops->ndo_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->netdev_ops->ndo_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; } struct Qdisc_ops noop_qdisc_ops __read_mostly = { .id = "noop", .priv_size = 0, .enqueue = noop_enqueue, .dequeue = noop_dequeue, .peek = noop_dequeue, .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), .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, .peek = noop_dequeue, .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), .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 struct sk_buff *pfifo_fast_peek(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)) return skb_peek(list + prio); } return NULL; } 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, .peek = pfifo_fast_peek, .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->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); kfree_skb(qdisc->gso_skb); qdisc->gso_skb = NULL; } 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); 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)); }