Fixed MTP to work with TWRP

drivers/net/dummy.c

@@ -0,0 +1,212 @@
+/* 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>
+
+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_setup(struct net_device *dev)
+{
+	ether_setup(dev);
+
+	/* Initialize the device structure. */
+	dev->netdev_ops = &dummy_netdev_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		= "dummy",
+	.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("dummy");