linux/net/sched/sch_generic.c
Arjan van de Ven f5a6e01c09 [NET]: user of the jiffies rounding code: Networking
This patch introduces users of the round_jiffies() function in the
networking code.

These timers all were of the "about once a second" or "about once
every X seconds" variety and several showed up in the "what wakes the
cpu up" profiles that the tickless patches provide.  Some timers are
highly dynamic based on network load; but even on low activity systems
they still show up so the rounding is done only in cases of low
activity, allowing higher frequency timers in the high activity case.

The various hardware watchdogs are an obvious case; they run every 2
seconds but aren't otherwise specific of exactly when they need to
run.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-02-08 12:38:52 -08:00

620 lines
14 KiB
C

/*
* 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/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(qdisc_tree_lock)
and this lock is used only in process context.
- updates to tree are made only under rtnl semaphore,
hence this lock may be made without 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(&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(&qdisc_tree_lock);
}
/*
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.
*/
/* 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.
*/
static inline int qdisc_restart(struct net_device *dev)
{
struct Qdisc *q = dev->qdisc;
struct sk_buff *skb;
/* Dequeue packet */
if (((skb = dev->gso_skb)) || ((skb = q->dequeue(q)))) {
unsigned nolock = (dev->features & NETIF_F_LLTX);
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);
return -1;
}
__get_cpu_var(netdev_rx_stat).cpu_collision++;
goto requeue;
}
}
{
/* 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);
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) {
netif_tx_unlock(dev);
}
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:
if (skb->next)
dev->gso_skb = skb;
else
q->ops->requeue(skb, q);
netif_schedule(dev);
return 1;
}
BUG_ON((int) q->q.qlen < 0);
return q->q.qlen;
}
void __qdisc_run(struct net_device *dev)
{
if (unlikely(dev->qdisc == &noop_qdisc))
goto out;
while (qdisc_restart(dev) < 0 && !netif_queue_stopped(dev))
/* NOTHING */;
out:
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, 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);
}
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 = 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);
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,
unsigned int parentid)
{
struct Qdisc *sch;
sch = qdisc_alloc(dev, 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;
}
/* 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);
#ifdef CONFIG_NET_ESTIMATOR
gen_kill_estimator(&qdisc->bstats, &qdisc->rate_est);
#endif
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;
}
write_lock(&qdisc_tree_lock);
list_add_tail(&qdisc->list, &dev->qdisc_list);
write_unlock(&qdisc_tree_lock);
} else {
qdisc = &noqueue_qdisc;
}
write_lock(&qdisc_tree_lock);
dev->qdisc_sleeping = qdisc;
write_unlock(&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);
/* 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();
if (dev->gso_skb) {
kfree_skb(dev->gso_skb);
dev->gso_skb = NULL;
}
}
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);