93f154b594
One point of contention in high network loads is the dst_release() performed
when a transmited skb is freed. This is because NIC tx completion calls
dev_kree_skb() long after original call to dev_queue_xmit(skb).
CPU cache is cold and the atomic op in dst_release() stalls. On SMP, this is
quite visible if one CPU is 100% handling softirqs for a network device,
since dst_clone() is done by other cpus, involving cache line ping pongs.
It seems right place to release dst is in dev_hard_start_xmit(), for most
devices but ones that are virtual, and some exceptions.
David Miller suggested to define a new device flag, set in alloc_netdev_mq()
(so that most devices set it at init time), and carefuly unset in devices
which dont want a NULL skb->dst in their ndo_start_xmit().
List of devices that must clear this flag is :
- loopback device, because it calls netif_rx() and quoting Patrick :
"ip_route_input() doesn't accept loopback addresses, so loopback packets
already need to have a dst_entry attached."
- appletalk/ipddp.c : needs skb->dst in its xmit function
- And all devices that call again dev_queue_xmit() from their xmit function
(as some classifiers need skb->dst) : bonding, vlan, macvlan, eql, ifb, hdlc_fr
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
291 lines
6.8 KiB
C
291 lines
6.8 KiB
C
/* drivers/net/ifb.c:
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The purpose of this driver is to provide a device that allows
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for sharing of resources:
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1) qdiscs/policies that are per device as opposed to system wide.
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ifb allows for a device which can be redirected to thus providing
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an impression of sharing.
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2) Allows for queueing incoming traffic for shaping instead of
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dropping.
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The original concept is based on what is known as the IMQ
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driver initially written by Martin Devera, later rewritten
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by Patrick McHardy and then maintained by Andre Correa.
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You need the tc action mirror or redirect to feed this device
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packets.
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version
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2 of the License, or (at your option) any later version.
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Authors: Jamal Hadi Salim (2005)
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/netdevice.h>
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#include <linux/etherdevice.h>
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#include <linux/init.h>
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#include <linux/moduleparam.h>
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#include <net/pkt_sched.h>
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#include <net/net_namespace.h>
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#define TX_TIMEOUT (2*HZ)
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#define TX_Q_LIMIT 32
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struct ifb_private {
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struct tasklet_struct ifb_tasklet;
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int tasklet_pending;
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/* mostly debug stats leave in for now */
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unsigned long st_task_enter; /* tasklet entered */
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unsigned long st_txq_refl_try; /* transmit queue refill attempt */
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unsigned long st_rxq_enter; /* receive queue entered */
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unsigned long st_rx2tx_tran; /* receive to trasmit transfers */
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unsigned long st_rxq_notenter; /*receiveQ not entered, resched */
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unsigned long st_rx_frm_egr; /* received from egress path */
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unsigned long st_rx_frm_ing; /* received from ingress path */
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unsigned long st_rxq_check;
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unsigned long st_rxq_rsch;
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struct sk_buff_head rq;
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struct sk_buff_head tq;
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};
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static int numifbs = 2;
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static void ri_tasklet(unsigned long dev);
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static int ifb_xmit(struct sk_buff *skb, struct net_device *dev);
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static int ifb_open(struct net_device *dev);
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static int ifb_close(struct net_device *dev);
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static void ri_tasklet(unsigned long dev)
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{
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struct net_device *_dev = (struct net_device *)dev;
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struct ifb_private *dp = netdev_priv(_dev);
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struct net_device_stats *stats = &_dev->stats;
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struct netdev_queue *txq;
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struct sk_buff *skb;
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txq = netdev_get_tx_queue(_dev, 0);
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dp->st_task_enter++;
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if ((skb = skb_peek(&dp->tq)) == NULL) {
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dp->st_txq_refl_try++;
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if (__netif_tx_trylock(txq)) {
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dp->st_rxq_enter++;
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while ((skb = skb_dequeue(&dp->rq)) != NULL) {
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skb_queue_tail(&dp->tq, skb);
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dp->st_rx2tx_tran++;
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}
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__netif_tx_unlock(txq);
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} else {
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/* reschedule */
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dp->st_rxq_notenter++;
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goto resched;
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}
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}
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while ((skb = skb_dequeue(&dp->tq)) != NULL) {
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u32 from = G_TC_FROM(skb->tc_verd);
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skb->tc_verd = 0;
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skb->tc_verd = SET_TC_NCLS(skb->tc_verd);
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stats->tx_packets++;
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stats->tx_bytes +=skb->len;
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skb->dev = __dev_get_by_index(&init_net, skb->iif);
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if (!skb->dev) {
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dev_kfree_skb(skb);
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stats->tx_dropped++;
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break;
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}
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skb->iif = _dev->ifindex;
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if (from & AT_EGRESS) {
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dp->st_rx_frm_egr++;
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dev_queue_xmit(skb);
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} else if (from & AT_INGRESS) {
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dp->st_rx_frm_ing++;
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skb_pull(skb, skb->dev->hard_header_len);
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netif_rx(skb);
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} else
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BUG();
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}
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if (__netif_tx_trylock(txq)) {
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dp->st_rxq_check++;
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if ((skb = skb_peek(&dp->rq)) == NULL) {
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dp->tasklet_pending = 0;
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if (netif_queue_stopped(_dev))
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netif_wake_queue(_dev);
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} else {
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dp->st_rxq_rsch++;
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__netif_tx_unlock(txq);
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goto resched;
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}
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__netif_tx_unlock(txq);
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} else {
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resched:
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dp->tasklet_pending = 1;
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tasklet_schedule(&dp->ifb_tasklet);
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}
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}
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static const struct net_device_ops ifb_netdev_ops = {
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.ndo_open = ifb_open,
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.ndo_stop = ifb_close,
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.ndo_start_xmit = ifb_xmit,
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.ndo_validate_addr = eth_validate_addr,
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};
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static void ifb_setup(struct net_device *dev)
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{
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/* Initialize the device structure. */
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dev->destructor = free_netdev;
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dev->netdev_ops = &ifb_netdev_ops;
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/* Fill in device structure with ethernet-generic values. */
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ether_setup(dev);
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dev->tx_queue_len = TX_Q_LIMIT;
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dev->flags |= IFF_NOARP;
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dev->flags &= ~IFF_MULTICAST;
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dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
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random_ether_addr(dev->dev_addr);
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}
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static int ifb_xmit(struct sk_buff *skb, struct net_device *dev)
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{
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struct ifb_private *dp = netdev_priv(dev);
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struct net_device_stats *stats = &dev->stats;
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int ret = 0;
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u32 from = G_TC_FROM(skb->tc_verd);
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stats->rx_packets++;
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stats->rx_bytes+=skb->len;
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if (!(from & (AT_INGRESS|AT_EGRESS)) || !skb->iif) {
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dev_kfree_skb(skb);
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stats->rx_dropped++;
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return ret;
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}
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if (skb_queue_len(&dp->rq) >= dev->tx_queue_len) {
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netif_stop_queue(dev);
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}
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dev->trans_start = jiffies;
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skb_queue_tail(&dp->rq, skb);
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if (!dp->tasklet_pending) {
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dp->tasklet_pending = 1;
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tasklet_schedule(&dp->ifb_tasklet);
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}
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return ret;
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}
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static int ifb_close(struct net_device *dev)
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{
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struct ifb_private *dp = netdev_priv(dev);
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tasklet_kill(&dp->ifb_tasklet);
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netif_stop_queue(dev);
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skb_queue_purge(&dp->rq);
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skb_queue_purge(&dp->tq);
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return 0;
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}
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static int ifb_open(struct net_device *dev)
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{
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struct ifb_private *dp = netdev_priv(dev);
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tasklet_init(&dp->ifb_tasklet, ri_tasklet, (unsigned long)dev);
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skb_queue_head_init(&dp->rq);
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skb_queue_head_init(&dp->tq);
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netif_start_queue(dev);
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return 0;
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}
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static int ifb_validate(struct nlattr *tb[], struct nlattr *data[])
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{
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if (tb[IFLA_ADDRESS]) {
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if (nla_len(tb[IFLA_ADDRESS]) != ETH_ALEN)
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return -EINVAL;
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if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS])))
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return -EADDRNOTAVAIL;
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}
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return 0;
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}
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static struct rtnl_link_ops ifb_link_ops __read_mostly = {
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.kind = "ifb",
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.priv_size = sizeof(struct ifb_private),
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.setup = ifb_setup,
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.validate = ifb_validate,
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};
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/* Number of ifb devices to be set up by this module. */
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module_param(numifbs, int, 0);
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MODULE_PARM_DESC(numifbs, "Number of ifb devices");
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static int __init ifb_init_one(int index)
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{
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struct net_device *dev_ifb;
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int err;
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dev_ifb = alloc_netdev(sizeof(struct ifb_private),
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"ifb%d", ifb_setup);
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if (!dev_ifb)
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return -ENOMEM;
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err = dev_alloc_name(dev_ifb, dev_ifb->name);
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if (err < 0)
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goto err;
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dev_ifb->rtnl_link_ops = &ifb_link_ops;
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err = register_netdevice(dev_ifb);
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if (err < 0)
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goto err;
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return 0;
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err:
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free_netdev(dev_ifb);
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return err;
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}
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static int __init ifb_init_module(void)
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{
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int i, err;
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rtnl_lock();
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err = __rtnl_link_register(&ifb_link_ops);
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for (i = 0; i < numifbs && !err; i++)
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err = ifb_init_one(i);
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if (err)
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__rtnl_link_unregister(&ifb_link_ops);
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rtnl_unlock();
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return err;
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}
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static void __exit ifb_cleanup_module(void)
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{
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rtnl_link_unregister(&ifb_link_ops);
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}
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module_init(ifb_init_module);
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module_exit(ifb_cleanup_module);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Jamal Hadi Salim");
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MODULE_ALIAS_RTNL_LINK("ifb");
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