v4.19.13 snapshot.
diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c
new file mode 100644
index 0000000..d192936
--- /dev/null
+++ b/drivers/net/loopback.c
@@ -0,0 +1,237 @@
+/*
+ * INET An implementation of the TCP/IP protocol suite for the LINUX
+ * operating system. INET is implemented using the BSD Socket
+ * interface as the means of communication with the user level.
+ *
+ * Pseudo-driver for the loopback interface.
+ *
+ * Version: @(#)loopback.c 1.0.4b 08/16/93
+ *
+ * Authors: Ross Biro
+ * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
+ * Donald Becker, <becker@scyld.com>
+ *
+ * Alan Cox : Fixed oddments for NET3.014
+ * Alan Cox : Rejig for NET3.029 snap #3
+ * Alan Cox : Fixed NET3.029 bugs and sped up
+ * Larry McVoy : Tiny tweak to double performance
+ * Alan Cox : Backed out LMV's tweak - the linux mm
+ * can't take it...
+ * Michael Griffith: Don't bother computing the checksums
+ * on packets received on the loopback
+ * interface.
+ * Alexey Kuznetsov: Potential hang under some extreme
+ * cases removed.
+ *
+ * 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.
+ */
+#include <linux/kernel.h>
+#include <linux/jiffies.h>
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/fs.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/socket.h>
+#include <linux/errno.h>
+#include <linux/fcntl.h>
+#include <linux/in.h>
+
+#include <linux/uaccess.h>
+#include <linux/io.h>
+
+#include <linux/inet.h>
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/skbuff.h>
+#include <linux/ethtool.h>
+#include <net/sock.h>
+#include <net/checksum.h>
+#include <linux/if_ether.h> /* For the statistics structure. */
+#include <linux/if_arp.h> /* For ARPHRD_ETHER */
+#include <linux/ip.h>
+#include <linux/tcp.h>
+#include <linux/percpu.h>
+#include <linux/net_tstamp.h>
+#include <net/net_namespace.h>
+#include <linux/u64_stats_sync.h>
+
+struct pcpu_lstats {
+ u64 packets;
+ u64 bytes;
+ struct u64_stats_sync syncp;
+};
+
+/* The higher levels take care of making this non-reentrant (it's
+ * called with bh's disabled).
+ */
+static netdev_tx_t loopback_xmit(struct sk_buff *skb,
+ struct net_device *dev)
+{
+ struct pcpu_lstats *lb_stats;
+ int len;
+
+ skb_tx_timestamp(skb);
+
+ /* do not fool net_timestamp_check() with various clock bases */
+ skb->tstamp = 0;
+
+ skb_orphan(skb);
+
+ /* Before queueing this packet to netif_rx(),
+ * make sure dst is refcounted.
+ */
+ skb_dst_force(skb);
+
+ skb->protocol = eth_type_trans(skb, dev);
+
+ /* it's OK to use per_cpu_ptr() because BHs are off */
+ lb_stats = this_cpu_ptr(dev->lstats);
+
+ len = skb->len;
+ if (likely(netif_rx(skb) == NET_RX_SUCCESS)) {
+ u64_stats_update_begin(&lb_stats->syncp);
+ lb_stats->bytes += len;
+ lb_stats->packets++;
+ u64_stats_update_end(&lb_stats->syncp);
+ }
+
+ return NETDEV_TX_OK;
+}
+
+static void loopback_get_stats64(struct net_device *dev,
+ struct rtnl_link_stats64 *stats)
+{
+ u64 bytes = 0;
+ u64 packets = 0;
+ int i;
+
+ for_each_possible_cpu(i) {
+ const struct pcpu_lstats *lb_stats;
+ u64 tbytes, tpackets;
+ unsigned int start;
+
+ lb_stats = per_cpu_ptr(dev->lstats, i);
+ do {
+ start = u64_stats_fetch_begin_irq(&lb_stats->syncp);
+ tbytes = lb_stats->bytes;
+ tpackets = lb_stats->packets;
+ } while (u64_stats_fetch_retry_irq(&lb_stats->syncp, start));
+ bytes += tbytes;
+ packets += tpackets;
+ }
+ stats->rx_packets = packets;
+ stats->tx_packets = packets;
+ stats->rx_bytes = bytes;
+ stats->tx_bytes = bytes;
+}
+
+static u32 always_on(struct net_device *dev)
+{
+ return 1;
+}
+
+static int loopback_get_ts_info(struct net_device *netdev,
+ struct ethtool_ts_info *ts_info)
+{
+ ts_info->so_timestamping = SOF_TIMESTAMPING_TX_SOFTWARE |
+ SOF_TIMESTAMPING_RX_SOFTWARE |
+ SOF_TIMESTAMPING_SOFTWARE;
+
+ ts_info->phc_index = -1;
+
+ return 0;
+};
+
+static const struct ethtool_ops loopback_ethtool_ops = {
+ .get_link = always_on,
+ .get_ts_info = loopback_get_ts_info,
+};
+
+static int loopback_dev_init(struct net_device *dev)
+{
+ dev->lstats = netdev_alloc_pcpu_stats(struct pcpu_lstats);
+ if (!dev->lstats)
+ return -ENOMEM;
+ return 0;
+}
+
+static void loopback_dev_free(struct net_device *dev)
+{
+ dev_net(dev)->loopback_dev = NULL;
+ free_percpu(dev->lstats);
+}
+
+static const struct net_device_ops loopback_ops = {
+ .ndo_init = loopback_dev_init,
+ .ndo_start_xmit = loopback_xmit,
+ .ndo_get_stats64 = loopback_get_stats64,
+ .ndo_set_mac_address = eth_mac_addr,
+};
+
+/* The loopback device is special. There is only one instance
+ * per network namespace.
+ */
+static void loopback_setup(struct net_device *dev)
+{
+ dev->mtu = 64 * 1024;
+ dev->hard_header_len = ETH_HLEN; /* 14 */
+ dev->min_header_len = ETH_HLEN; /* 14 */
+ dev->addr_len = ETH_ALEN; /* 6 */
+ dev->type = ARPHRD_LOOPBACK; /* 0x0001*/
+ dev->flags = IFF_LOOPBACK;
+ dev->priv_flags |= IFF_LIVE_ADDR_CHANGE | IFF_NO_QUEUE;
+ netif_keep_dst(dev);
+ dev->hw_features = NETIF_F_GSO_SOFTWARE;
+ dev->features = NETIF_F_SG | NETIF_F_FRAGLIST
+ | NETIF_F_GSO_SOFTWARE
+ | NETIF_F_HW_CSUM
+ | NETIF_F_RXCSUM
+ | NETIF_F_SCTP_CRC
+ | NETIF_F_HIGHDMA
+ | NETIF_F_LLTX
+ | NETIF_F_NETNS_LOCAL
+ | NETIF_F_VLAN_CHALLENGED
+ | NETIF_F_LOOPBACK;
+ dev->ethtool_ops = &loopback_ethtool_ops;
+ dev->header_ops = ð_header_ops;
+ dev->netdev_ops = &loopback_ops;
+ dev->needs_free_netdev = true;
+ dev->priv_destructor = loopback_dev_free;
+}
+
+/* Setup and register the loopback device. */
+static __net_init int loopback_net_init(struct net *net)
+{
+ struct net_device *dev;
+ int err;
+
+ err = -ENOMEM;
+ dev = alloc_netdev(0, "lo", NET_NAME_UNKNOWN, loopback_setup);
+ if (!dev)
+ goto out;
+
+ dev_net_set(dev, net);
+ err = register_netdev(dev);
+ if (err)
+ goto out_free_netdev;
+
+ BUG_ON(dev->ifindex != LOOPBACK_IFINDEX);
+ net->loopback_dev = dev;
+ return 0;
+
+out_free_netdev:
+ free_netdev(dev);
+out:
+ if (net_eq(net, &init_net))
+ panic("loopback: Failed to register netdevice: %d\n", err);
+ return err;
+}
+
+/* Registered in net/core/dev.c */
+struct pernet_operations __net_initdata loopback_net_ops = {
+ .init = loopback_net_init,
+};