/* * 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 * dev->queue_lock spinlock. * * The idea is the following: * - enqueue, dequeue are serialized via top level device * spinlock dev->queue_lock. * - ingress filtering is serialized via top level device * spinlock dev->ingress_lock. * - updates to tree and tree walking are only done under the rtnl mutex. */ void qdisc_lock_tree(struct net_device *dev) { spin_lock_bh(&dev->queue_lock); spin_lock(&dev->ingress_lock); } void qdisc_unlock_tree(struct net_device *dev) { spin_unlock(&dev->ingress_lock); spin_unlock_bh(&dev->queue_lock); } static inline int qdisc_qlen(struct Qdisc *q) { return q->q.qlen; } 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); netif_schedule(dev); return 0; } static inline struct sk_buff *dev_dequeue_skb(struct net_device *dev, struct Qdisc *q) { struct sk_buff *skb; if ((skb = dev->gso_skb)) dev->gso_skb = NULL; else skb = q->dequeue(q); return skb; } 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; unsigned lockless; int ret; /* Dequeue packet */ if (unlikely((skb = dev_dequeue_skb(dev, q)) == NULL)) return 0; /* * When the driver has LLTX set, it does its own locking in * start_xmit. These checks are worth it because even uncongested * locks can be quite expensive. The driver can do a trylock, as * is being done here; in case of lock contention it should return * NETDEV_TX_LOCKED and the packet will be requeued. */ lockless = (dev->features & NETIF_F_LLTX); if (!lockless && !netif_tx_trylock(dev)) { /* Another CPU grabbed the driver tx lock */ return handle_dev_cpu_collision(skb, dev, q); } /* And release queue */ spin_unlock(&dev->queue_lock); ret = dev_hard_start_xmit(skb, dev); if (!lockless) netif_tx_unlock(dev); spin_lock(&dev->queue_lock); q = dev->qdisc; 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, dev, 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, dev, q); break; } return ret; } void __qdisc_run(struct net_device *dev) { do { if (!qdisc_restart(dev)) break; } while (!netif_queue_stopped(dev)); clear_bit(__LINK_STATE_QDISC_RUNNING, &dev->state); } static void dev_watchdog(unsigned long arg) { struct net_device *dev = (struct net_device *)arg; netif_tx_lock(dev); if (dev->qdisc != &noop_qdisc) { if (netif_device_present(dev) && netif_running(dev) && netif_carrier_ok(dev)) { if (netif_queue_stopped(dev) && time_after(jiffies, dev->trans_start + dev->watchdog_timeo)) { printk(KERN_INFO "NETDEV WATCHDOG: %s: transmit timed out\n", dev->name); 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); } static void dev_watchdog_init(struct net_device *dev) { init_timer(&dev->watchdog_timer); dev->watchdog_timer.data = (unsigned long)dev; dev->watchdog_timer.function = dev_watchdog; } 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)) linkwatch_fire_event(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)) linkwatch_fire_event(dev); } /* "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 = { .id = "noop", .priv_size = 0, .enqueue = noop_enqueue, .dequeue = noop_dequeue, .requeue = noop_requeue, .owner = THIS_MODULE, }; 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), }; static struct Qdisc_ops noqueue_qdisc_ops = { .id = "noqueue", .priv_size = 0, .enqueue = noop_enqueue, .dequeue = noop_dequeue, .requeue = noop_requeue, .owner = THIS_MODULE, }; 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), }; 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->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); RTA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt); return skb->len; rtattr_failure: return -1; } static int pfifo_fast_init(struct Qdisc *qdisc, struct rtattr *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 = { .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 net_device *dev, 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 = dev; dev_hold(dev); atomic_set(&sch->refcnt, 1); return sch; errout: return ERR_PTR(-err); } struct Qdisc * qdisc_create_dflt(struct net_device *dev, struct Qdisc_ops *ops, unsigned int parentid) { struct Qdisc *sch; sch = qdisc_alloc(dev, ops); if (IS_ERR(sch)) goto errout; sch->stats_lock = &dev->queue_lock; sch->parent = parentid; if (!ops->init || ops->init(sch, NULL) == 0) return sch; qdisc_destroy(sch); errout: return NULL; } /* Under dev->queue_lock and BH! */ void qdisc_reset(struct Qdisc *qdisc) { struct Qdisc_ops *ops = qdisc->ops; if (ops->reset) ops->reset(qdisc); } /* this is the rcu callback function to clean up a qdisc when there * are no further references to it */ static void __qdisc_destroy(struct rcu_head *head) { struct Qdisc *qdisc = container_of(head, struct Qdisc, q_rcu); kfree((char *) qdisc - qdisc->padded); } /* Under dev->queue_lock and BH! */ void qdisc_destroy(struct Qdisc *qdisc) { struct Qdisc_ops *ops = qdisc->ops; if (qdisc->flags & TCQ_F_BUILTIN || !atomic_dec_and_test(&qdisc->refcnt)) return; list_del(&qdisc->list); 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); call_rcu(&qdisc->q_rcu, __qdisc_destroy); } void dev_activate(struct net_device *dev) { /* 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->qdisc_sleeping == &noop_qdisc) { struct Qdisc *qdisc; if (dev->tx_queue_len) { qdisc = qdisc_create_dflt(dev, &pfifo_fast_ops, TC_H_ROOT); if (qdisc == NULL) { printk(KERN_INFO "%s: activation failed\n", dev->name); return; } list_add_tail(&qdisc->list, &dev->qdisc_list); } else { qdisc = &noqueue_qdisc; } dev->qdisc_sleeping = qdisc; } if (!netif_carrier_ok(dev)) /* Delay activation until next carrier-on event */ return; spin_lock_bh(&dev->queue_lock); rcu_assign_pointer(dev->qdisc, dev->qdisc_sleeping); if (dev->qdisc != &noqueue_qdisc) { dev->trans_start = jiffies; dev_watchdog_up(dev); } spin_unlock_bh(&dev->queue_lock); } void dev_deactivate(struct net_device *dev) { struct Qdisc *qdisc; struct sk_buff *skb; spin_lock_bh(&dev->queue_lock); qdisc = dev->qdisc; dev->qdisc = &noop_qdisc; qdisc_reset(qdisc); skb = dev->gso_skb; dev->gso_skb = NULL; spin_unlock_bh(&dev->queue_lock); kfree_skb(skb); dev_watchdog_down(dev); /* Wait for outstanding dev_queue_xmit calls. */ synchronize_rcu(); /* Wait for outstanding qdisc_run calls. */ while (test_bit(__LINK_STATE_QDISC_RUNNING, &dev->state)) yield(); } void dev_init_scheduler(struct net_device *dev) { qdisc_lock_tree(dev); dev->qdisc = &noop_qdisc; dev->qdisc_sleeping = &noop_qdisc; INIT_LIST_HEAD(&dev->qdisc_list); qdisc_unlock_tree(dev); dev_watchdog_init(dev); } void dev_shutdown(struct net_device *dev) { struct Qdisc *qdisc; qdisc_lock_tree(dev); qdisc = dev->qdisc_sleeping; dev->qdisc = &noop_qdisc; dev->qdisc_sleeping = &noop_qdisc; qdisc_destroy(qdisc); #if defined(CONFIG_NET_SCH_INGRESS) || defined(CONFIG_NET_SCH_INGRESS_MODULE) if ((qdisc = dev->qdisc_ingress) != NULL) { dev->qdisc_ingress = NULL; qdisc_destroy(qdisc); } #endif BUG_TRAP(!timer_pending(&dev->watchdog_timer)); qdisc_unlock_tree(dev); } EXPORT_SYMBOL(netif_carrier_on); EXPORT_SYMBOL(netif_carrier_off); EXPORT_SYMBOL(noop_qdisc); EXPORT_SYMBOL(qdisc_create_dflt); EXPORT_SYMBOL(qdisc_destroy); EXPORT_SYMBOL(qdisc_reset); EXPORT_SYMBOL(qdisc_lock_tree); EXPORT_SYMBOL(qdisc_unlock_tree);