linux/drivers/net/ifb.c
Eric Dumazet 0287587884 net: better IFF_XMIT_DST_RELEASE support
Testing xmit_more support with netperf and connected UDP sockets,
I found strange dst refcount false sharing.

Current handling of IFF_XMIT_DST_RELEASE is not optimal.

Dropping dst in validate_xmit_skb() is certainly too late in case
packet was queued by cpu X but dequeued by cpu Y

The logical point to take care of drop/force is in __dev_queue_xmit()
before even taking qdisc lock.

As Julian Anastasov pointed out, need for skb_dst() might come from some
packet schedulers or classifiers.

This patch adds new helper to cleanly express needs of various drivers
or qdiscs/classifiers.

Drivers that need skb_dst() in their ndo_start_xmit() should call
following helper in their setup instead of the prior :

	dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
->
	netif_keep_dst(dev);

Instead of using a single bit, we use two bits, one being
eventually rebuilt in bonding/team drivers.

The other one, is permanent and blocks IFF_XMIT_DST_RELEASE being
rebuilt in bonding/team. Eventually, we could add something
smarter later.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Julian Anastasov <ja@ssi.bg>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-10-07 13:22:11 -04:00

327 lines
7.4 KiB
C

/* drivers/net/ifb.c:
The purpose of this driver is to provide a device that allows
for sharing of resources:
1) qdiscs/policies that are per device as opposed to system wide.
ifb allows for a device which can be redirected to thus providing
an impression of sharing.
2) Allows for queueing incoming traffic for shaping instead of
dropping.
The original concept is based on what is known as the IMQ
driver initially written by Martin Devera, later rewritten
by Patrick McHardy and then maintained by Andre Correa.
You need the tc action mirror or redirect to feed this device
packets.
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: Jamal Hadi Salim (2005)
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/moduleparam.h>
#include <net/pkt_sched.h>
#include <net/net_namespace.h>
#define TX_Q_LIMIT 32
struct ifb_private {
struct tasklet_struct ifb_tasklet;
int tasklet_pending;
struct u64_stats_sync rsync;
struct sk_buff_head rq;
u64 rx_packets;
u64 rx_bytes;
struct u64_stats_sync tsync;
struct sk_buff_head tq;
u64 tx_packets;
u64 tx_bytes;
};
static int numifbs = 2;
static void ri_tasklet(unsigned long dev);
static netdev_tx_t ifb_xmit(struct sk_buff *skb, struct net_device *dev);
static int ifb_open(struct net_device *dev);
static int ifb_close(struct net_device *dev);
static void ri_tasklet(unsigned long dev)
{
struct net_device *_dev = (struct net_device *)dev;
struct ifb_private *dp = netdev_priv(_dev);
struct netdev_queue *txq;
struct sk_buff *skb;
txq = netdev_get_tx_queue(_dev, 0);
if ((skb = skb_peek(&dp->tq)) == NULL) {
if (__netif_tx_trylock(txq)) {
skb_queue_splice_tail_init(&dp->rq, &dp->tq);
__netif_tx_unlock(txq);
} else {
/* reschedule */
goto resched;
}
}
while ((skb = __skb_dequeue(&dp->tq)) != NULL) {
u32 from = G_TC_FROM(skb->tc_verd);
skb->tc_verd = 0;
skb->tc_verd = SET_TC_NCLS(skb->tc_verd);
u64_stats_update_begin(&dp->tsync);
dp->tx_packets++;
dp->tx_bytes += skb->len;
u64_stats_update_end(&dp->tsync);
rcu_read_lock();
skb->dev = dev_get_by_index_rcu(dev_net(_dev), skb->skb_iif);
if (!skb->dev) {
rcu_read_unlock();
dev_kfree_skb(skb);
_dev->stats.tx_dropped++;
if (skb_queue_len(&dp->tq) != 0)
goto resched;
break;
}
rcu_read_unlock();
skb->skb_iif = _dev->ifindex;
if (from & AT_EGRESS) {
dev_queue_xmit(skb);
} else if (from & AT_INGRESS) {
skb_pull(skb, skb->dev->hard_header_len);
netif_receive_skb(skb);
} else
BUG();
}
if (__netif_tx_trylock(txq)) {
if ((skb = skb_peek(&dp->rq)) == NULL) {
dp->tasklet_pending = 0;
if (netif_queue_stopped(_dev))
netif_wake_queue(_dev);
} else {
__netif_tx_unlock(txq);
goto resched;
}
__netif_tx_unlock(txq);
} else {
resched:
dp->tasklet_pending = 1;
tasklet_schedule(&dp->ifb_tasklet);
}
}
static struct rtnl_link_stats64 *ifb_stats64(struct net_device *dev,
struct rtnl_link_stats64 *stats)
{
struct ifb_private *dp = netdev_priv(dev);
unsigned int start;
do {
start = u64_stats_fetch_begin_irq(&dp->rsync);
stats->rx_packets = dp->rx_packets;
stats->rx_bytes = dp->rx_bytes;
} while (u64_stats_fetch_retry_irq(&dp->rsync, start));
do {
start = u64_stats_fetch_begin_irq(&dp->tsync);
stats->tx_packets = dp->tx_packets;
stats->tx_bytes = dp->tx_bytes;
} while (u64_stats_fetch_retry_irq(&dp->tsync, start));
stats->rx_dropped = dev->stats.rx_dropped;
stats->tx_dropped = dev->stats.tx_dropped;
return stats;
}
static const struct net_device_ops ifb_netdev_ops = {
.ndo_open = ifb_open,
.ndo_stop = ifb_close,
.ndo_get_stats64 = ifb_stats64,
.ndo_start_xmit = ifb_xmit,
.ndo_validate_addr = eth_validate_addr,
};
#define IFB_FEATURES (NETIF_F_HW_CSUM | NETIF_F_SG | NETIF_F_FRAGLIST | \
NETIF_F_TSO_ECN | NETIF_F_TSO | NETIF_F_TSO6 | \
NETIF_F_HIGHDMA | NETIF_F_HW_VLAN_CTAG_TX | \
NETIF_F_HW_VLAN_STAG_TX)
static void ifb_setup(struct net_device *dev)
{
/* Initialize the device structure. */
dev->destructor = free_netdev;
dev->netdev_ops = &ifb_netdev_ops;
/* Fill in device structure with ethernet-generic values. */
ether_setup(dev);
dev->tx_queue_len = TX_Q_LIMIT;
dev->features |= IFB_FEATURES;
dev->vlan_features |= IFB_FEATURES & ~(NETIF_F_HW_VLAN_CTAG_TX |
NETIF_F_HW_VLAN_STAG_TX);
dev->flags |= IFF_NOARP;
dev->flags &= ~IFF_MULTICAST;
dev->priv_flags &= ~IFF_TX_SKB_SHARING;
netif_keep_dst(dev);
eth_hw_addr_random(dev);
}
static netdev_tx_t ifb_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct ifb_private *dp = netdev_priv(dev);
u32 from = G_TC_FROM(skb->tc_verd);
u64_stats_update_begin(&dp->rsync);
dp->rx_packets++;
dp->rx_bytes += skb->len;
u64_stats_update_end(&dp->rsync);
if (!(from & (AT_INGRESS|AT_EGRESS)) || !skb->skb_iif) {
dev_kfree_skb(skb);
dev->stats.rx_dropped++;
return NETDEV_TX_OK;
}
if (skb_queue_len(&dp->rq) >= dev->tx_queue_len) {
netif_stop_queue(dev);
}
__skb_queue_tail(&dp->rq, skb);
if (!dp->tasklet_pending) {
dp->tasklet_pending = 1;
tasklet_schedule(&dp->ifb_tasklet);
}
return NETDEV_TX_OK;
}
static int ifb_close(struct net_device *dev)
{
struct ifb_private *dp = netdev_priv(dev);
tasklet_kill(&dp->ifb_tasklet);
netif_stop_queue(dev);
__skb_queue_purge(&dp->rq);
__skb_queue_purge(&dp->tq);
return 0;
}
static int ifb_open(struct net_device *dev)
{
struct ifb_private *dp = netdev_priv(dev);
tasklet_init(&dp->ifb_tasklet, ri_tasklet, (unsigned long)dev);
__skb_queue_head_init(&dp->rq);
__skb_queue_head_init(&dp->tq);
netif_start_queue(dev);
return 0;
}
static int ifb_validate(struct nlattr *tb[], struct nlattr *data[])
{
if (tb[IFLA_ADDRESS]) {
if (nla_len(tb[IFLA_ADDRESS]) != ETH_ALEN)
return -EINVAL;
if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS])))
return -EADDRNOTAVAIL;
}
return 0;
}
static struct rtnl_link_ops ifb_link_ops __read_mostly = {
.kind = "ifb",
.priv_size = sizeof(struct ifb_private),
.setup = ifb_setup,
.validate = ifb_validate,
};
/* Number of ifb devices to be set up by this module. */
module_param(numifbs, int, 0);
MODULE_PARM_DESC(numifbs, "Number of ifb devices");
static int __init ifb_init_one(int index)
{
struct net_device *dev_ifb;
struct ifb_private *dp;
int err;
dev_ifb = alloc_netdev(sizeof(struct ifb_private), "ifb%d",
NET_NAME_UNKNOWN, ifb_setup);
if (!dev_ifb)
return -ENOMEM;
dp = netdev_priv(dev_ifb);
u64_stats_init(&dp->rsync);
u64_stats_init(&dp->tsync);
dev_ifb->rtnl_link_ops = &ifb_link_ops;
err = register_netdevice(dev_ifb);
if (err < 0)
goto err;
return 0;
err:
free_netdev(dev_ifb);
return err;
}
static int __init ifb_init_module(void)
{
int i, err;
rtnl_lock();
err = __rtnl_link_register(&ifb_link_ops);
if (err < 0)
goto out;
for (i = 0; i < numifbs && !err; i++) {
err = ifb_init_one(i);
cond_resched();
}
if (err)
__rtnl_link_unregister(&ifb_link_ops);
out:
rtnl_unlock();
return err;
}
static void __exit ifb_cleanup_module(void)
{
rtnl_link_unregister(&ifb_link_ops);
}
module_init(ifb_init_module);
module_exit(ifb_cleanup_module);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Jamal Hadi Salim");
MODULE_ALIAS_RTNL_LINK("ifb");