kernel-ark/net/sched/sch_teql.c
Tom Hughes fa68a78227 Clear IFF_XMIT_DST_RELEASE for teql interfaces
https://bugzilla.kernel.org/show_bug.cgi?id=16183

The sch_teql module, which can be used to load balance over a set of
underlying interfaces, stopped working after 2.6.30 and has been
broken in all kernels since then for any underlying interface which
requires the addition of link level headers.

The problem is that the transmit routine relies on being able to
access the destination address in the skb in order to do address
resolution once it has decided which underlying interface it is going
to transmit through.

In 2.6.31 the IFF_XMIT_DST_RELEASE flag was introduced, and set by
default for all interfaces, which causes the destination address to be
released before the transmit routine for the interface is called.

The solution is to clear that flag for teql interfaces.

Signed-off-by: Tom Hughes <tom@compton.nu>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2010-06-16 14:47:30 -07:00

515 lines
12 KiB
C

/* net/sched/sch_teql.c "True" (or "trivial") link equalizer.
*
* 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>
*/
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/if_arp.h>
#include <linux/netdevice.h>
#include <linux/init.h>
#include <linux/skbuff.h>
#include <linux/moduleparam.h>
#include <net/dst.h>
#include <net/neighbour.h>
#include <net/pkt_sched.h>
/*
How to setup it.
----------------
After loading this module you will find a new device teqlN
and new qdisc with the same name. To join a slave to the equalizer
you should just set this qdisc on a device f.e.
# tc qdisc add dev eth0 root teql0
# tc qdisc add dev eth1 root teql0
That's all. Full PnP 8)
Applicability.
--------------
1. Slave devices MUST be active devices, i.e., they must raise the tbusy
signal and generate EOI events. If you want to equalize virtual devices
like tunnels, use a normal eql device.
2. This device puts no limitations on physical slave characteristics
f.e. it will equalize 9600baud line and 100Mb ethernet perfectly :-)
Certainly, large difference in link speeds will make the resulting
eqalized link unusable, because of huge packet reordering.
I estimate an upper useful difference as ~10 times.
3. If the slave requires address resolution, only protocols using
neighbour cache (IPv4/IPv6) will work over the equalized link.
Other protocols are still allowed to use the slave device directly,
which will not break load balancing, though native slave
traffic will have the highest priority. */
struct teql_master
{
struct Qdisc_ops qops;
struct net_device *dev;
struct Qdisc *slaves;
struct list_head master_list;
};
struct teql_sched_data
{
struct Qdisc *next;
struct teql_master *m;
struct neighbour *ncache;
struct sk_buff_head q;
};
#define NEXT_SLAVE(q) (((struct teql_sched_data*)qdisc_priv(q))->next)
#define FMASK (IFF_BROADCAST|IFF_POINTOPOINT)
/* "teql*" qdisc routines */
static int
teql_enqueue(struct sk_buff *skb, struct Qdisc* sch)
{
struct net_device *dev = qdisc_dev(sch);
struct teql_sched_data *q = qdisc_priv(sch);
if (q->q.qlen < dev->tx_queue_len) {
__skb_queue_tail(&q->q, skb);
sch->bstats.bytes += qdisc_pkt_len(skb);
sch->bstats.packets++;
return 0;
}
kfree_skb(skb);
sch->qstats.drops++;
return NET_XMIT_DROP;
}
static struct sk_buff *
teql_dequeue(struct Qdisc* sch)
{
struct teql_sched_data *dat = qdisc_priv(sch);
struct netdev_queue *dat_queue;
struct sk_buff *skb;
skb = __skb_dequeue(&dat->q);
dat_queue = netdev_get_tx_queue(dat->m->dev, 0);
if (skb == NULL) {
struct net_device *m = qdisc_dev(dat_queue->qdisc);
if (m) {
dat->m->slaves = sch;
netif_wake_queue(m);
}
}
sch->q.qlen = dat->q.qlen + dat_queue->qdisc->q.qlen;
return skb;
}
static struct sk_buff *
teql_peek(struct Qdisc* sch)
{
/* teql is meant to be used as root qdisc */
return NULL;
}
static __inline__ void
teql_neigh_release(struct neighbour *n)
{
if (n)
neigh_release(n);
}
static void
teql_reset(struct Qdisc* sch)
{
struct teql_sched_data *dat = qdisc_priv(sch);
skb_queue_purge(&dat->q);
sch->q.qlen = 0;
teql_neigh_release(xchg(&dat->ncache, NULL));
}
static void
teql_destroy(struct Qdisc* sch)
{
struct Qdisc *q, *prev;
struct teql_sched_data *dat = qdisc_priv(sch);
struct teql_master *master = dat->m;
if ((prev = master->slaves) != NULL) {
do {
q = NEXT_SLAVE(prev);
if (q == sch) {
NEXT_SLAVE(prev) = NEXT_SLAVE(q);
if (q == master->slaves) {
master->slaves = NEXT_SLAVE(q);
if (q == master->slaves) {
struct netdev_queue *txq;
spinlock_t *root_lock;
txq = netdev_get_tx_queue(master->dev, 0);
master->slaves = NULL;
root_lock = qdisc_root_sleeping_lock(txq->qdisc);
spin_lock_bh(root_lock);
qdisc_reset(txq->qdisc);
spin_unlock_bh(root_lock);
}
}
skb_queue_purge(&dat->q);
teql_neigh_release(xchg(&dat->ncache, NULL));
break;
}
} while ((prev = q) != master->slaves);
}
}
static int teql_qdisc_init(struct Qdisc *sch, struct nlattr *opt)
{
struct net_device *dev = qdisc_dev(sch);
struct teql_master *m = (struct teql_master*)sch->ops;
struct teql_sched_data *q = qdisc_priv(sch);
if (dev->hard_header_len > m->dev->hard_header_len)
return -EINVAL;
if (m->dev == dev)
return -ELOOP;
q->m = m;
skb_queue_head_init(&q->q);
if (m->slaves) {
if (m->dev->flags & IFF_UP) {
if ((m->dev->flags & IFF_POINTOPOINT &&
!(dev->flags & IFF_POINTOPOINT)) ||
(m->dev->flags & IFF_BROADCAST &&
!(dev->flags & IFF_BROADCAST)) ||
(m->dev->flags & IFF_MULTICAST &&
!(dev->flags & IFF_MULTICAST)) ||
dev->mtu < m->dev->mtu)
return -EINVAL;
} else {
if (!(dev->flags&IFF_POINTOPOINT))
m->dev->flags &= ~IFF_POINTOPOINT;
if (!(dev->flags&IFF_BROADCAST))
m->dev->flags &= ~IFF_BROADCAST;
if (!(dev->flags&IFF_MULTICAST))
m->dev->flags &= ~IFF_MULTICAST;
if (dev->mtu < m->dev->mtu)
m->dev->mtu = dev->mtu;
}
q->next = NEXT_SLAVE(m->slaves);
NEXT_SLAVE(m->slaves) = sch;
} else {
q->next = sch;
m->slaves = sch;
m->dev->mtu = dev->mtu;
m->dev->flags = (m->dev->flags&~FMASK)|(dev->flags&FMASK);
}
return 0;
}
static int
__teql_resolve(struct sk_buff *skb, struct sk_buff *skb_res, struct net_device *dev)
{
struct netdev_queue *dev_queue = netdev_get_tx_queue(dev, 0);
struct teql_sched_data *q = qdisc_priv(dev_queue->qdisc);
struct neighbour *mn = skb_dst(skb)->neighbour;
struct neighbour *n = q->ncache;
if (mn->tbl == NULL)
return -EINVAL;
if (n && n->tbl == mn->tbl &&
memcmp(n->primary_key, mn->primary_key, mn->tbl->key_len) == 0) {
atomic_inc(&n->refcnt);
} else {
n = __neigh_lookup_errno(mn->tbl, mn->primary_key, dev);
if (IS_ERR(n))
return PTR_ERR(n);
}
if (neigh_event_send(n, skb_res) == 0) {
int err;
read_lock(&n->lock);
err = dev_hard_header(skb, dev, ntohs(skb->protocol),
n->ha, NULL, skb->len);
read_unlock(&n->lock);
if (err < 0) {
neigh_release(n);
return -EINVAL;
}
teql_neigh_release(xchg(&q->ncache, n));
return 0;
}
neigh_release(n);
return (skb_res == NULL) ? -EAGAIN : 1;
}
static inline int teql_resolve(struct sk_buff *skb,
struct sk_buff *skb_res, struct net_device *dev)
{
struct netdev_queue *txq = netdev_get_tx_queue(dev, 0);
if (txq->qdisc == &noop_qdisc)
return -ENODEV;
if (dev->header_ops == NULL ||
skb_dst(skb) == NULL ||
skb_dst(skb)->neighbour == NULL)
return 0;
return __teql_resolve(skb, skb_res, dev);
}
static netdev_tx_t teql_master_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct teql_master *master = netdev_priv(dev);
struct netdev_queue *txq = netdev_get_tx_queue(dev, 0);
struct Qdisc *start, *q;
int busy;
int nores;
int subq = skb_get_queue_mapping(skb);
struct sk_buff *skb_res = NULL;
start = master->slaves;
restart:
nores = 0;
busy = 0;
if ((q = start) == NULL)
goto drop;
do {
struct net_device *slave = qdisc_dev(q);
struct netdev_queue *slave_txq = netdev_get_tx_queue(slave, 0);
const struct net_device_ops *slave_ops = slave->netdev_ops;
if (slave_txq->qdisc_sleeping != q)
continue;
if (__netif_subqueue_stopped(slave, subq) ||
!netif_running(slave)) {
busy = 1;
continue;
}
switch (teql_resolve(skb, skb_res, slave)) {
case 0:
if (__netif_tx_trylock(slave_txq)) {
unsigned int length = qdisc_pkt_len(skb);
if (!netif_tx_queue_stopped(slave_txq) &&
!netif_tx_queue_frozen(slave_txq) &&
slave_ops->ndo_start_xmit(skb, slave) == NETDEV_TX_OK) {
txq_trans_update(slave_txq);
__netif_tx_unlock(slave_txq);
master->slaves = NEXT_SLAVE(q);
netif_wake_queue(dev);
txq->tx_packets++;
txq->tx_bytes += length;
return NETDEV_TX_OK;
}
__netif_tx_unlock(slave_txq);
}
if (netif_queue_stopped(dev))
busy = 1;
break;
case 1:
master->slaves = NEXT_SLAVE(q);
return NETDEV_TX_OK;
default:
nores = 1;
break;
}
__skb_pull(skb, skb_network_offset(skb));
} while ((q = NEXT_SLAVE(q)) != start);
if (nores && skb_res == NULL) {
skb_res = skb;
goto restart;
}
if (busy) {
netif_stop_queue(dev);
return NETDEV_TX_BUSY;
}
dev->stats.tx_errors++;
drop:
txq->tx_dropped++;
dev_kfree_skb(skb);
return NETDEV_TX_OK;
}
static int teql_master_open(struct net_device *dev)
{
struct Qdisc * q;
struct teql_master *m = netdev_priv(dev);
int mtu = 0xFFFE;
unsigned flags = IFF_NOARP|IFF_MULTICAST;
if (m->slaves == NULL)
return -EUNATCH;
flags = FMASK;
q = m->slaves;
do {
struct net_device *slave = qdisc_dev(q);
if (slave == NULL)
return -EUNATCH;
if (slave->mtu < mtu)
mtu = slave->mtu;
if (slave->hard_header_len > LL_MAX_HEADER)
return -EINVAL;
/* If all the slaves are BROADCAST, master is BROADCAST
If all the slaves are PtP, master is PtP
Otherwise, master is NBMA.
*/
if (!(slave->flags&IFF_POINTOPOINT))
flags &= ~IFF_POINTOPOINT;
if (!(slave->flags&IFF_BROADCAST))
flags &= ~IFF_BROADCAST;
if (!(slave->flags&IFF_MULTICAST))
flags &= ~IFF_MULTICAST;
} while ((q = NEXT_SLAVE(q)) != m->slaves);
m->dev->mtu = mtu;
m->dev->flags = (m->dev->flags&~FMASK) | flags;
netif_start_queue(m->dev);
return 0;
}
static int teql_master_close(struct net_device *dev)
{
netif_stop_queue(dev);
return 0;
}
static int teql_master_mtu(struct net_device *dev, int new_mtu)
{
struct teql_master *m = netdev_priv(dev);
struct Qdisc *q;
if (new_mtu < 68)
return -EINVAL;
q = m->slaves;
if (q) {
do {
if (new_mtu > qdisc_dev(q)->mtu)
return -EINVAL;
} while ((q=NEXT_SLAVE(q)) != m->slaves);
}
dev->mtu = new_mtu;
return 0;
}
static const struct net_device_ops teql_netdev_ops = {
.ndo_open = teql_master_open,
.ndo_stop = teql_master_close,
.ndo_start_xmit = teql_master_xmit,
.ndo_change_mtu = teql_master_mtu,
};
static __init void teql_master_setup(struct net_device *dev)
{
struct teql_master *master = netdev_priv(dev);
struct Qdisc_ops *ops = &master->qops;
master->dev = dev;
ops->priv_size = sizeof(struct teql_sched_data);
ops->enqueue = teql_enqueue;
ops->dequeue = teql_dequeue;
ops->peek = teql_peek;
ops->init = teql_qdisc_init;
ops->reset = teql_reset;
ops->destroy = teql_destroy;
ops->owner = THIS_MODULE;
dev->netdev_ops = &teql_netdev_ops;
dev->type = ARPHRD_VOID;
dev->mtu = 1500;
dev->tx_queue_len = 100;
dev->flags = IFF_NOARP;
dev->hard_header_len = LL_MAX_HEADER;
dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
}
static LIST_HEAD(master_dev_list);
static int max_equalizers = 1;
module_param(max_equalizers, int, 0);
MODULE_PARM_DESC(max_equalizers, "Max number of link equalizers");
static int __init teql_init(void)
{
int i;
int err = -ENODEV;
for (i = 0; i < max_equalizers; i++) {
struct net_device *dev;
struct teql_master *master;
dev = alloc_netdev(sizeof(struct teql_master),
"teql%d", teql_master_setup);
if (!dev) {
err = -ENOMEM;
break;
}
if ((err = register_netdev(dev))) {
free_netdev(dev);
break;
}
master = netdev_priv(dev);
strlcpy(master->qops.id, dev->name, IFNAMSIZ);
err = register_qdisc(&master->qops);
if (err) {
unregister_netdev(dev);
free_netdev(dev);
break;
}
list_add_tail(&master->master_list, &master_dev_list);
}
return i ? 0 : err;
}
static void __exit teql_exit(void)
{
struct teql_master *master, *nxt;
list_for_each_entry_safe(master, nxt, &master_dev_list, master_list) {
list_del(&master->master_list);
unregister_qdisc(&master->qops);
unregister_netdev(master->dev);
free_netdev(master->dev);
}
}
module_init(teql_init);
module_exit(teql_exit);
MODULE_LICENSE("GPL");