--- /dev/null
+/* dummy.c: a dummy net driver
+
+ The purpose of this driver is to provide a device to point a
+ route through, but not to actually transmit packets.
+
+ Why? If you have a machine whose only connection is an occasional
+ PPP/SLIP/PLIP link, you can only connect to your own hostname
+ when the link is up. Otherwise you have to use localhost.
+ This isn't very consistent.
+
+ One solution is to set up a dummy link using PPP/SLIP/PLIP,
+ but this seems (to me) too much overhead for too little gain.
+ This driver provides a small alternative. Thus you can do
+
+ [when not running slip]
+ ifconfig dummy slip.addr.ess.here up
+ [to go to slip]
+ ifconfig dummy down
+ dip whatever
+
+ This was written by looking at Donald Becker's skeleton driver
+ and the loopback driver. I then threw away anything that didn't
+ apply! Thanks to Alan Cox for the key clue on what to do with
+ misguided packets.
+
+ Nick Holloway, 27th May 1994
+ [I tweaked this explanation a little but that's all]
+ Alan Cox, 30th May 1994
+*/
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/init.h>
+#include <linux/moduleparam.h>
+#include <linux/rtnetlink.h>
+#include <net/rtnetlink.h>
+#include <linux/u64_stats_sync.h>
+
+#define DRV_NAME "dummy"
+#define DRV_VERSION "1.0"
+
+static int numdummies = 1;
+
+/* fake multicast ability */
+static void set_multicast_list(struct net_device *dev)
+{
+}
+
+struct pcpu_dstats {
+ u64 tx_packets;
+ u64 tx_bytes;
+ struct u64_stats_sync syncp;
+};
+
+static struct rtnl_link_stats64 *dummy_get_stats64(struct net_device *dev,
+ struct rtnl_link_stats64 *stats)
+{
+ int i;
+
+ for_each_possible_cpu(i) {
+ const struct pcpu_dstats *dstats;
+ u64 tbytes, tpackets;
+ unsigned int start;
+
+ dstats = per_cpu_ptr(dev->dstats, i);
+ do {
+ start = u64_stats_fetch_begin_irq(&dstats->syncp);
+ tbytes = dstats->tx_bytes;
+ tpackets = dstats->tx_packets;
+ } while (u64_stats_fetch_retry_irq(&dstats->syncp, start));
+ stats->tx_bytes += tbytes;
+ stats->tx_packets += tpackets;
+ }
+ return stats;
+}
+
+static netdev_tx_t dummy_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+ struct pcpu_dstats *dstats = this_cpu_ptr(dev->dstats);
+
+ u64_stats_update_begin(&dstats->syncp);
+ dstats->tx_packets++;
+ dstats->tx_bytes += skb->len;
+ u64_stats_update_end(&dstats->syncp);
+
+ dev_kfree_skb(skb);
+ return NETDEV_TX_OK;
+}
+
+static int dummy_dev_init(struct net_device *dev)
+{
+ dev->dstats = netdev_alloc_pcpu_stats(struct pcpu_dstats);
+ if (!dev->dstats)
+ return -ENOMEM;
+
+ return 0;
+}
+
+static void dummy_dev_uninit(struct net_device *dev)
+{
+ free_percpu(dev->dstats);
+}
+
+static int dummy_change_carrier(struct net_device *dev, bool new_carrier)
+{
+ if (new_carrier)
+ netif_carrier_on(dev);
+ else
+ netif_carrier_off(dev);
+ return 0;
+}
+
+static const struct net_device_ops dummy_netdev_ops = {
+ .ndo_init = dummy_dev_init,
+ .ndo_uninit = dummy_dev_uninit,
+ .ndo_start_xmit = dummy_xmit,
+ .ndo_validate_addr = eth_validate_addr,
+ .ndo_set_rx_mode = set_multicast_list,
+ .ndo_set_mac_address = eth_mac_addr,
+ .ndo_get_stats64 = dummy_get_stats64,
+ .ndo_change_carrier = dummy_change_carrier,
+};
+
+static void dummy_get_drvinfo(struct net_device *dev,
+ struct ethtool_drvinfo *info)
+{
+ strlcpy(info->driver, DRV_NAME, sizeof(info->driver));
+ strlcpy(info->version, DRV_VERSION, sizeof(info->version));
+}
+
+static const struct ethtool_ops dummy_ethtool_ops = {
+ .get_drvinfo = dummy_get_drvinfo,
+};
+
+static void dummy_setup(struct net_device *dev)
+{
+ ether_setup(dev);
+
+ /* Initialize the device structure. */
+ dev->netdev_ops = &dummy_netdev_ops;
+ dev->ethtool_ops = &dummy_ethtool_ops;
+ dev->destructor = free_netdev;
+
+ /* Fill in device structure with ethernet-generic values. */
+ dev->tx_queue_len = 0;
+ dev->flags |= IFF_NOARP;
+ dev->flags &= ~IFF_MULTICAST;
+ dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
+ dev->features |= NETIF_F_SG | NETIF_F_FRAGLIST | NETIF_F_TSO;
+ dev->features |= NETIF_F_HW_CSUM | NETIF_F_HIGHDMA | NETIF_F_LLTX;
+ eth_hw_addr_random(dev);
+}
+
+static int dummy_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 dummy_link_ops __read_mostly = {
+ .kind = DRV_NAME,
+ .setup = dummy_setup,
+ .validate = dummy_validate,
+};
+
+/* Number of dummy devices to be set up by this module. */
+module_param(numdummies, int, 0);
+MODULE_PARM_DESC(numdummies, "Number of dummy pseudo devices");
+
+static int __init dummy_init_one(void)
+{
+ struct net_device *dev_dummy;
+ int err;
+
+ dev_dummy = alloc_netdev(0, "dummy%d", NET_NAME_UNKNOWN, dummy_setup);
+ if (!dev_dummy)
+ return -ENOMEM;
+
+ dev_dummy->rtnl_link_ops = &dummy_link_ops;
+ err = register_netdevice(dev_dummy);
+ if (err < 0)
+ goto err;
+ return 0;
+
+err:
+ free_netdev(dev_dummy);
+ return err;
+}
+
+static int __init dummy_init_module(void)
+{
+ int i, err = 0;
+
+ rtnl_lock();
+ err = __rtnl_link_register(&dummy_link_ops);
+ if (err < 0)
+ goto out;
+
+ for (i = 0; i < numdummies && !err; i++) {
+ err = dummy_init_one();
+ cond_resched();
+ }
+ if (err < 0)
+ __rtnl_link_unregister(&dummy_link_ops);
+
+out:
+ rtnl_unlock();
+
+ return err;
+}
+
+static void __exit dummy_cleanup_module(void)
+{
+ rtnl_link_unregister(&dummy_link_ops);
+}
+
+module_init(dummy_init_module);
+module_exit(dummy_cleanup_module);
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_RTNL_LINK(DRV_NAME);
+MODULE_VERSION(DRV_VERSION);
Code Review / kvmfornfv.git / blobdiff