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/*
* 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@nortelnetworks.com> 990601
* - Ingress support
*/
#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/bitops.h>
#include <linux/config.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 <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!
*/
rwlock_t qdisc_tree_lock = RW_LOCK_UNLOCKED;
/*
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) {
if (spin_trylock(&dev->xmit_lock)) {
/* 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)) {
if (netdev_nit)
dev_queue_xmit_nit(skb, dev);
if (dev->hard_start_xmit(skb, dev) == 0) {
dev->xmit_lock_owner = -1;
spin_unlock(&dev->xmit_lock);
spin_lock(&dev->queue_lock);
return -1;
}
}
/* Release the driver */
dev->xmit_lock_owner = -1;
spin_unlock(&dev->xmit_lock);
spin_lock(&dev->queue_lock);
q = dev->qdisc;
} else {
/* 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;
}
netdev_rx_stat[smp_processor_id()].cpu_collision++;
}
/* 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)
*/
q->ops->requeue(skb, q);
netif_schedule(dev);
return 1;
}
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);
}
/* "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 =
{
NULL,
NULL,
"noop",
0,
noop_enqueue,
noop_dequeue,
noop_requeue,
};
struct Qdisc noop_qdisc =
{
noop_enqueue,
noop_dequeue,
TCQ_F_BUILTIN,
&noop_qdisc_ops,
};
struct Qdisc_ops noqueue_qdisc_ops =
{
NULL,
NULL,
"noqueue",
0,
noop_enqueue,
noop_dequeue,
noop_requeue,
};
struct Qdisc noqueue_qdisc =
{
NULL,
noop_dequeue,
TCQ_F_BUILTIN,
&noqueue_qdisc_ops,
};
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.
*/
static int
pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc* qdisc)
{
struct sk_buff_head *list;
list = ((struct sk_buff_head*)qdisc->data) +
prio2band[skb->priority&TC_PRIO_MAX];
if (list->qlen <= skb->dev->tx_queue_len) {
__skb_queue_tail(list, skb);
qdisc->q.qlen++;
return 0;
}
qdisc->stats.drops++;
kfree_skb(skb);
return NET_XMIT_DROP;
}
static struct sk_buff *
pfifo_fast_dequeue(struct Qdisc* qdisc)
{
int prio;
struct sk_buff_head *list = ((struct sk_buff_head*)qdisc->data);
struct sk_buff *skb;
for (prio = 0; prio < 3; prio++, list++) {
skb = __skb_dequeue(list);
if (skb) {
qdisc->q.qlen--;
return skb;
}
}
return NULL;
}
static int
pfifo_fast_requeue(struct sk_buff *skb, struct Qdisc* qdisc)
{
struct sk_buff_head *list;
list = ((struct sk_buff_head*)qdisc->data) +
prio2band[skb->priority&TC_PRIO_MAX];
__skb_queue_head(list, skb);
qdisc->q.qlen++;
return 0;
}
static void
pfifo_fast_reset(struct Qdisc* qdisc)
{
int prio;
struct sk_buff_head *list = ((struct sk_buff_head*)qdisc->data);
for (prio=0; prio < 3; prio++)
skb_queue_purge(list+prio);
qdisc->q.qlen = 0;
}
static int pfifo_fast_init(struct Qdisc *qdisc, struct rtattr *opt)
{
int i;
struct sk_buff_head *list;
list = ((struct sk_buff_head*)qdisc->data);
for (i=0; i<3; i++)
skb_queue_head_init(list+i);
return 0;
}
static struct Qdisc_ops pfifo_fast_ops =
{
NULL,
NULL,
"pfifo_fast",
3 * sizeof(struct sk_buff_head),
pfifo_fast_enqueue,
pfifo_fast_dequeue,
pfifo_fast_requeue,
NULL,
pfifo_fast_init,
pfifo_fast_reset,
};
struct Qdisc * qdisc_create_dflt(struct net_device *dev, struct Qdisc_ops *ops)
{
struct Qdisc *sch;
int size = sizeof(*sch) + ops->priv_size;
sch = kmalloc(size, GFP_KERNEL);
if (!sch)
return NULL;
memset(sch, 0, size);
skb_queue_head_init(&sch->q);
sch->ops = ops;
sch->enqueue = ops->enqueue;
sch->dequeue = ops->dequeue;
sch->dev = dev;
sch->stats.lock = &dev->queue_lock;
atomic_set(&sch->refcnt, 1);
if (!ops->init || ops->init(sch, NULL) == 0)
return sch;
kfree(sch);
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);
}
/* Under dev->queue_lock and BH! */
void qdisc_destroy(struct Qdisc *qdisc)
{
struct Qdisc_ops *ops = qdisc->ops;
struct net_device *dev;
if (!atomic_dec_and_test(&qdisc->refcnt))
return;
dev = qdisc->dev;
#ifdef CONFIG_NET_SCHED
if (dev) {
struct Qdisc *q, **qp;
for (qp = &qdisc->dev->qdisc_list; (q=*qp) != NULL; qp = &q->next) {
if (q == qdisc) {
*qp = q->next;
break;
}
}
}
#ifdef CONFIG_NET_ESTIMATOR
qdisc_kill_estimator(&qdisc->stats);
#endif
#endif
if (ops->reset)
ops->reset(qdisc);
if (ops->destroy)
ops->destroy(qdisc);
if (!(qdisc->flags&TCQ_F_BUILTIN))
kfree(qdisc);
}
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;
}
} else {
qdisc = &noqueue_qdisc;
}
write_lock(&qdisc_tree_lock);
dev->qdisc_sleeping = qdisc;
write_unlock(&qdisc_tree_lock);
}
spin_lock_bh(&dev->queue_lock);
if ((dev->qdisc = dev->qdisc_sleeping) != &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)) {
current->policy |= SCHED_YIELD;
schedule();
}
spin_unlock_wait(&dev->xmit_lock);
}
void dev_init_scheduler(struct net_device *dev)
{
write_lock(&qdisc_tree_lock);
spin_lock_bh(&dev->queue_lock);
dev->qdisc = &noop_qdisc;
spin_unlock_bh(&dev->queue_lock);
dev->qdisc_sleeping = &noop_qdisc;
dev->qdisc_list = NULL;
write_unlock(&qdisc_tree_lock);
dev_watchdog_init(dev);
}
void dev_shutdown(struct net_device *dev)
{
struct Qdisc *qdisc;
write_lock(&qdisc_tree_lock);
spin_lock_bh(&dev->queue_lock);
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(dev->qdisc_list == NULL);
BUG_TRAP(!timer_pending(&dev->watchdog_timer));
dev->qdisc_list = NULL;
spin_unlock_bh(&dev->queue_lock);
write_unlock(&qdisc_tree_lock);
}
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