![David S. Miller](/assets/img/avatar_default.png)
Network devices can allocate reasources and private memory using netdev_ops->ndo_init(). However, the release of these resources can occur in one of two different places. Either netdev_ops->ndo_uninit() or netdev->destructor(). The decision of which operation frees the resources depends upon whether it is necessary for all netdev refs to be released before it is safe to perform the freeing. netdev_ops->ndo_uninit() presumably can occur right after the NETDEV_UNREGISTER notifier completes and the unicast and multicast address lists are flushed. netdev->destructor(), on the other hand, does not run until the netdev references all go away. Further complicating the situation is that netdev->destructor() almost universally does also a free_netdev(). This creates a problem for the logic in register_netdevice(). Because all callers of register_netdevice() manage the freeing of the netdev, and invoke free_netdev(dev) if register_netdevice() fails. If netdev_ops->ndo_init() succeeds, but something else fails inside of register_netdevice(), it does call ndo_ops->ndo_uninit(). But it is not able to invoke netdev->destructor(). This is because netdev->destructor() will do a free_netdev() and then the caller of register_netdevice() will do the same. However, this means that the resources that would normally be released by netdev->destructor() will not be. Over the years drivers have added local hacks to deal with this, by invoking their destructor parts by hand when register_netdevice() fails. Many drivers do not try to deal with this, and instead we have leaks. Let's close this hole by formalizing the distinction between what private things need to be freed up by netdev->destructor() and whether the driver needs unregister_netdevice() to perform the free_netdev(). netdev->priv_destructor() performs all actions to free up the private resources that used to be freed by netdev->destructor(), except for free_netdev(). netdev->needs_free_netdev is a boolean that indicates whether free_netdev() should be done at the end of unregister_netdevice(). Now, register_netdevice() can sanely release all resources after ndo_ops->ndo_init() succeeds, by invoking both ndo_ops->ndo_uninit() and netdev->priv_destructor(). And at the end of unregister_netdevice(), we invoke netdev->priv_destructor() and optionally call free_netdev(). Signed-off-by: David S. Miller <davem@davemloft.net>
357 lines
8.5 KiB
C
357 lines
8.5 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/interrupt.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_Q_LIMIT 32
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struct ifb_q_private {
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struct net_device *dev;
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struct tasklet_struct ifb_tasklet;
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int tasklet_pending;
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int txqnum;
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struct sk_buff_head rq;
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u64 rx_packets;
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u64 rx_bytes;
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struct u64_stats_sync rsync;
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struct u64_stats_sync tsync;
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u64 tx_packets;
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u64 tx_bytes;
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struct sk_buff_head tq;
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} ____cacheline_aligned_in_smp;
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struct ifb_dev_private {
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struct ifb_q_private *tx_private;
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};
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static netdev_tx_t 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 ifb_ri_tasklet(unsigned long _txp)
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{
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struct ifb_q_private *txp = (struct ifb_q_private *)_txp;
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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(txp->dev, txp->txqnum);
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skb = skb_peek(&txp->tq);
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if (!skb) {
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if (!__netif_tx_trylock(txq))
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goto resched;
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skb_queue_splice_tail_init(&txp->rq, &txp->tq);
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__netif_tx_unlock(txq);
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}
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while ((skb = __skb_dequeue(&txp->tq)) != NULL) {
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skb->tc_redirected = 0;
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skb->tc_skip_classify = 1;
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u64_stats_update_begin(&txp->tsync);
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txp->tx_packets++;
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txp->tx_bytes += skb->len;
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u64_stats_update_end(&txp->tsync);
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rcu_read_lock();
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skb->dev = dev_get_by_index_rcu(dev_net(txp->dev), skb->skb_iif);
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if (!skb->dev) {
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rcu_read_unlock();
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dev_kfree_skb(skb);
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txp->dev->stats.tx_dropped++;
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if (skb_queue_len(&txp->tq) != 0)
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goto resched;
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break;
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}
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rcu_read_unlock();
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skb->skb_iif = txp->dev->ifindex;
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if (!skb->tc_from_ingress) {
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dev_queue_xmit(skb);
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} else {
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skb_pull(skb, skb->mac_len);
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netif_receive_skb(skb);
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}
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}
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if (__netif_tx_trylock(txq)) {
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skb = skb_peek(&txp->rq);
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if (!skb) {
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txp->tasklet_pending = 0;
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if (netif_tx_queue_stopped(txq))
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netif_tx_wake_queue(txq);
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} else {
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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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txp->tasklet_pending = 1;
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tasklet_schedule(&txp->ifb_tasklet);
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}
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}
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static void ifb_stats64(struct net_device *dev,
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struct rtnl_link_stats64 *stats)
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{
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struct ifb_dev_private *dp = netdev_priv(dev);
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struct ifb_q_private *txp = dp->tx_private;
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unsigned int start;
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u64 packets, bytes;
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int i;
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for (i = 0; i < dev->num_tx_queues; i++,txp++) {
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do {
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start = u64_stats_fetch_begin_irq(&txp->rsync);
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packets = txp->rx_packets;
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bytes = txp->rx_bytes;
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} while (u64_stats_fetch_retry_irq(&txp->rsync, start));
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stats->rx_packets += packets;
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stats->rx_bytes += bytes;
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do {
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start = u64_stats_fetch_begin_irq(&txp->tsync);
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packets = txp->tx_packets;
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bytes = txp->tx_bytes;
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} while (u64_stats_fetch_retry_irq(&txp->tsync, start));
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stats->tx_packets += packets;
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stats->tx_bytes += bytes;
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}
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stats->rx_dropped = dev->stats.rx_dropped;
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stats->tx_dropped = dev->stats.tx_dropped;
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}
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static int ifb_dev_init(struct net_device *dev)
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{
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struct ifb_dev_private *dp = netdev_priv(dev);
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struct ifb_q_private *txp;
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int i;
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txp = kcalloc(dev->num_tx_queues, sizeof(*txp), GFP_KERNEL);
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if (!txp)
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return -ENOMEM;
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dp->tx_private = txp;
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for (i = 0; i < dev->num_tx_queues; i++,txp++) {
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txp->txqnum = i;
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txp->dev = dev;
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__skb_queue_head_init(&txp->rq);
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__skb_queue_head_init(&txp->tq);
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u64_stats_init(&txp->rsync);
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u64_stats_init(&txp->tsync);
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tasklet_init(&txp->ifb_tasklet, ifb_ri_tasklet,
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(unsigned long)txp);
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netif_tx_start_queue(netdev_get_tx_queue(dev, i));
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}
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return 0;
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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_get_stats64 = ifb_stats64,
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.ndo_start_xmit = ifb_xmit,
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.ndo_validate_addr = eth_validate_addr,
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.ndo_init = ifb_dev_init,
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};
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#define IFB_FEATURES (NETIF_F_HW_CSUM | NETIF_F_SG | NETIF_F_FRAGLIST | \
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NETIF_F_TSO_ECN | NETIF_F_TSO | NETIF_F_TSO6 | \
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NETIF_F_GSO_ENCAP_ALL | \
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NETIF_F_HIGHDMA | NETIF_F_HW_VLAN_CTAG_TX | \
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NETIF_F_HW_VLAN_STAG_TX)
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static void ifb_dev_free(struct net_device *dev)
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{
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struct ifb_dev_private *dp = netdev_priv(dev);
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struct ifb_q_private *txp = dp->tx_private;
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int i;
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for (i = 0; i < dev->num_tx_queues; i++,txp++) {
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tasklet_kill(&txp->ifb_tasklet);
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__skb_queue_purge(&txp->rq);
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__skb_queue_purge(&txp->tq);
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}
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kfree(dp->tx_private);
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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->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->features |= IFB_FEATURES;
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dev->hw_features |= dev->features;
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dev->hw_enc_features |= dev->features;
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dev->vlan_features |= IFB_FEATURES & ~(NETIF_F_HW_VLAN_CTAG_TX |
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NETIF_F_HW_VLAN_STAG_TX);
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dev->flags |= IFF_NOARP;
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dev->flags &= ~IFF_MULTICAST;
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dev->priv_flags &= ~IFF_TX_SKB_SHARING;
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netif_keep_dst(dev);
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eth_hw_addr_random(dev);
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dev->needs_free_netdev = true;
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dev->priv_destructor = ifb_dev_free;
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}
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static netdev_tx_t ifb_xmit(struct sk_buff *skb, struct net_device *dev)
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{
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struct ifb_dev_private *dp = netdev_priv(dev);
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struct ifb_q_private *txp = dp->tx_private + skb_get_queue_mapping(skb);
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u64_stats_update_begin(&txp->rsync);
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txp->rx_packets++;
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txp->rx_bytes += skb->len;
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u64_stats_update_end(&txp->rsync);
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if (!skb->tc_redirected || !skb->skb_iif) {
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dev_kfree_skb(skb);
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dev->stats.rx_dropped++;
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return NETDEV_TX_OK;
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}
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if (skb_queue_len(&txp->rq) >= dev->tx_queue_len)
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netif_tx_stop_queue(netdev_get_tx_queue(dev, txp->txqnum));
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__skb_queue_tail(&txp->rq, skb);
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if (!txp->tasklet_pending) {
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txp->tasklet_pending = 1;
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tasklet_schedule(&txp->ifb_tasklet);
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}
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return NETDEV_TX_OK;
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}
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static int ifb_close(struct net_device *dev)
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{
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netif_tx_stop_all_queues(dev);
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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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netif_tx_start_all_queues(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_dev_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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* Note that these legacy devices have one queue.
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* Prefer something like : ip link add ifb10 numtxqueues 8 type ifb
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*/
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static int numifbs = 2;
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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_dev_private), "ifb%d",
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NET_NAME_UNKNOWN, ifb_setup);
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if (!dev_ifb)
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return -ENOMEM;
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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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if (err < 0)
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goto out;
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for (i = 0; i < numifbs && !err; i++) {
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err = ifb_init_one(i);
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cond_resched();
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}
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if (err)
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__rtnl_link_unregister(&ifb_link_ops);
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out:
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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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