/* * 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 <asm/uaccess.h> #include <asm/system.h> #include <linux/bitops.h> #include <linux/config.h> #include <linux/module.h> #include <linux/types.h> #include <linux/kernel.h> #include <linux/sched.h> #include <linux/string.h> #include <linux/mm.h> #include <linux/socket.h> #include <linux/sockios.h> #include <linux/in.h> #include <linux/errno.h> #include <linux/interrupt.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/sock.h> #include <net/pkt_sched.h> /* Main transmission queue. */ /* Main qdisc structure lock. However, modifications to data, participating in scheduling must be additionally protected with dev->queue_lock spinlock. The idea is the following: - enqueue, dequeue are serialized via top level device spinlock dev->queue_lock. - tree walking is protected by read_lock_bh(qdisc_tree_lock) and this lock is used only in process context. - updates to tree are made under rtnl semaphore or from softirq context (__qdisc_destroy rcu-callback) hence this lock needs local bh disabling. qdisc_tree_lock must be grabbed BEFORE dev->queue_lock! */ DEFINE_RWLOCK(qdisc_tree_lock); void qdisc_lock_tree(struct net_device *dev) { write_lock_bh(&qdisc_tree_lock); spin_lock_bh(&dev->queue_lock); } void qdisc_unlock_tree(struct net_device *dev) { spin_unlock_bh(&dev->queue_lock); write_unlock_bh(&qdisc_tree_lock); } /* dev->queue_lock serializes queue accesses for this device AND dev->qdisc pointer itself. dev->xmit_lock serializes accesses to device driver. dev->queue_lock and dev->xmit_lock are mutually exclusive, if one is grabbed, another must be free. */ /* Kick device. Note, that this procedure can be called by a watchdog timer, so that we do not check dev->tbusy flag here. Returns: 0 - queue is empty. >0 - queue is not empty, but throttled. <0 - queue is not empty. Device is throttled, if dev->tbusy != 0. NOTE: Called under dev->queue_lock with locally disabled BH. */ int qdisc_restart(struct net_device *dev) { struct Qdisc *q = dev->qdisc; struct sk_buff *skb; /* Dequeue packet */ if ((skb = q->dequeue(q)) != NULL) { unsigned nolock = (dev->features & NETIF_F_LLTX); /* * 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 (!spin_trylock(&dev->xmit_lock)) { 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); return -1; } __get_cpu_var(netdev_rx_stat).cpu_collision++; goto requeue; } /* Remember that the driver is grabbed by us. */ dev->xmit_lock_owner = smp_processor_id(); } { /* And release queue */ spin_unlock(&dev->queue_lock); if (!netif_queue_stopped(dev)) { int ret; if (netdev_nit) dev_queue_xmit_nit(skb, dev); ret = dev->hard_start_xmit(skb, dev); if (ret == NETDEV_TX_OK) { if (!nolock) { dev->xmit_lock_owner = -1; spin_unlock(&dev->xmit_lock); } spin_lock(&dev->queue_lock); return -1; } if (ret == NETDEV_TX_LOCKED && nolock) { spin_lock(&dev->queue_lock); goto collision; } } /* NETDEV_TX_BUSY - we need to requeue */ /* Release the driver */ if (!nolock) { dev->xmit_lock_owner = -1; spin_unlock(&dev->xmit_lock); } spin_lock(&dev->queue_lock); q = dev->qdisc; } /* Device kicked us out :( This is possible in three cases: 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) */ requeue: q->ops->requeue(skb, q); netif_schedule(dev); return 1; } BUG_ON((int) q->q.qlen < 0); return q->q.qlen; } static void dev_watchdog(unsigned long arg) { struct net_device *dev = (struct net_device *)arg; spin_lock(&dev->xmit_lock); if (dev->qdisc != &noop_qdisc) { if (netif_device_present(dev) && netif_running(dev) && netif_carrier_ok(dev)) { if (netif_queue_stopped(dev) && (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, jiffies + dev->watchdog_timeo)) dev_hold(dev); } } spin_unlock(&dev->xmit_lock); 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, jiffies + dev->watchdog_timeo)) dev_hold(dev); } } static void dev_watchdog_up(struct net_device *dev) { spin_lock_bh(&dev->xmit_lock); __netdev_watchdog_up(dev); spin_unlock_bh(&dev->xmit_lock); } static void dev_watchdog_down(struct net_device *dev) { spin_lock_bh(&dev->xmit_lock); if (del_timer(&dev->watchdog_timer)) __dev_put(dev); spin_unlock_bh(&dev->xmit_lock); } 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); } 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 = kmalloc(size, GFP_KERNEL); if (!p) goto errout; memset(p, 0, size); 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); sch->stats_lock = &dev->queue_lock; 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) { struct Qdisc *sch; sch = qdisc_alloc(dev, ops); if (IS_ERR(sch)) goto errout; 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); struct Qdisc_ops *ops = qdisc->ops; #ifdef CONFIG_NET_ESTIMATOR gen_kill_estimator(&qdisc->bstats, &qdisc->rate_est); #endif write_lock(&qdisc_tree_lock); if (ops->reset) ops->reset(qdisc); if (ops->destroy) ops->destroy(qdisc); write_unlock(&qdisc_tree_lock); module_put(ops->owner); dev_put(qdisc->dev); kfree((char *) qdisc - qdisc->padded); } /* Under dev->queue_lock and BH! */ void qdisc_destroy(struct Qdisc *qdisc) { struct list_head cql = LIST_HEAD_INIT(cql); struct Qdisc *cq, *q, *n; if (qdisc->flags & TCQ_F_BUILTIN || !atomic_dec_and_test(&qdisc->refcnt)) return; if (!list_empty(&qdisc->list)) { if (qdisc->ops->cl_ops == NULL) list_del(&qdisc->list); else list_move(&qdisc->list, &cql); } /* unlink inner qdiscs from dev->qdisc_list immediately */ list_for_each_entry(cq, &cql, list) list_for_each_entry_safe(q, n, &qdisc->dev->qdisc_list, list) if (TC_H_MAJ(q->parent) == TC_H_MAJ(cq->handle)) { if (q->ops->cl_ops == NULL) list_del_init(&q->list); else list_move_tail(&q->list, &cql); } list_for_each_entry_safe(cq, n, &cql, list) list_del_init(&cq->list); 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); if (qdisc == NULL) { printk(KERN_INFO "%s: activation failed\n", dev->name); return; } write_lock_bh(&qdisc_tree_lock); list_add_tail(&qdisc->list, &dev->qdisc_list); write_unlock_bh(&qdisc_tree_lock); } else { qdisc = &noqueue_qdisc; } write_lock_bh(&qdisc_tree_lock); dev->qdisc_sleeping = qdisc; write_unlock_bh(&qdisc_tree_lock); } 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; spin_lock_bh(&dev->queue_lock); qdisc = dev->qdisc; dev->qdisc = &noop_qdisc; qdisc_reset(qdisc); spin_unlock_bh(&dev->queue_lock); dev_watchdog_down(dev); while (test_bit(__LINK_STATE_SCHED, &dev->state)) yield(); spin_unlock_wait(&dev->xmit_lock); } 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(__netdev_watchdog_up); EXPORT_SYMBOL(netif_carrier_on); EXPORT_SYMBOL(netif_carrier_off); EXPORT_SYMBOL(noop_qdisc); EXPORT_SYMBOL(noop_qdisc_ops); EXPORT_SYMBOL(qdisc_create_dflt); EXPORT_SYMBOL(qdisc_alloc); EXPORT_SYMBOL(qdisc_destroy); EXPORT_SYMBOL(qdisc_reset); EXPORT_SYMBOL(qdisc_restart); EXPORT_SYMBOL(qdisc_lock_tree); EXPORT_SYMBOL(qdisc_unlock_tree);