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32 results

guest.c

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  • loopback.c 6.48 KiB
    /*
     * 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/init.h>
    
    #include <asm/system.h>
    #include <asm/uaccess.h>
    #include <asm/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 <net/net_namespace.h>
    
    struct pcpu_lstats {
    	u64 packets;
    	u64 bytes;
    #if BITS_PER_LONG==32 && defined(CONFIG_SMP)
    	seqcount_t seq;
    #endif
    	unsigned long drops;
    };
    
    #if BITS_PER_LONG==32 && defined(CONFIG_SMP)
    static void inline lstats_update_begin(struct pcpu_lstats *lstats)
    {
    	write_seqcount_begin(&lstats->seq);
    }
    static void inline lstats_update_end(struct pcpu_lstats *lstats)
    {
    	write_seqcount_end(&lstats->seq);
    }
    static void inline lstats_fetch_and_add(u64 *packets, u64 *bytes, const struct pcpu_lstats *lstats)
    {
    	u64 tpackets, tbytes;
    	unsigned int seq;
    
    	do {
    		seq = read_seqcount_begin(&lstats->seq);
    		tpackets = lstats->packets;
    		tbytes = lstats->bytes;
    	} while (read_seqcount_retry(&lstats->seq, seq));
    
    	*packets += tpackets;
    	*bytes += tbytes;
    }
    #else
    static void inline lstats_update_begin(struct pcpu_lstats *lstats)
    {
    }
    static void inline lstats_update_end(struct pcpu_lstats *lstats)
    {
    }
    static void inline lstats_fetch_and_add(u64 *packets, u64 *bytes, const struct pcpu_lstats *lstats)
    {
    	*packets += lstats->packets;
    	*bytes += lstats->bytes;
    }
    #endif
    
    /*
     * 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 __percpu *pcpu_lstats;
    	struct pcpu_lstats *lb_stats;
    	int len;
    
    	skb_orphan(skb);
    
    	skb->protocol = eth_type_trans(skb, dev);
    
    	/* it's OK to use per_cpu_ptr() because BHs are off */
    	pcpu_lstats = (void __percpu __force *)dev->ml_priv;
    	lb_stats = this_cpu_ptr(pcpu_lstats);
    
    	len = skb->len;
    	if (likely(netif_rx(skb) == NET_RX_SUCCESS)) {
    		lstats_update_begin(lb_stats);
    		lb_stats->bytes += len;
    		lb_stats->packets++;
    		lstats_update_end(lb_stats);
    	} else
    		lb_stats->drops++;
    
    	return NETDEV_TX_OK;
    }
    
    static struct rtnl_link_stats64 *loopback_get_stats64(struct net_device *dev)
    {
    	const struct pcpu_lstats __percpu *pcpu_lstats;
    	struct rtnl_link_stats64 *stats = &dev->stats64;
    	u64 bytes = 0;
    	u64 packets = 0;
    	u64 drops = 0;
    	int i;
    
    	pcpu_lstats = (void __percpu __force *)dev->ml_priv;
    	for_each_possible_cpu(i) {
    		const struct pcpu_lstats *lb_stats;
    
    		lb_stats = per_cpu_ptr(pcpu_lstats, i);
    		lstats_fetch_and_add(&packets, &bytes, lb_stats);
    		drops   += lb_stats->drops;
    	}
    	stats->rx_packets = packets;
    	stats->tx_packets = packets;
    	stats->rx_dropped = drops;
    	stats->rx_errors  = drops;
    	stats->rx_bytes   = bytes;
    	stats->tx_bytes   = bytes;
    	return stats;
    }
    
    static u32 always_on(struct net_device *dev)
    {
    	return 1;
    }
    
    static const struct ethtool_ops loopback_ethtool_ops = {
    	.get_link		= always_on,
    	.set_tso		= ethtool_op_set_tso,
    	.get_tx_csum		= always_on,
    	.get_sg			= always_on,
    	.get_rx_csum		= always_on,
    };
    
    static int loopback_dev_init(struct net_device *dev)
    {
    	struct pcpu_lstats __percpu *lstats;
    
    	lstats = alloc_percpu(struct pcpu_lstats);
    	if (!lstats)
    		return -ENOMEM;
    
    	dev->ml_priv = (void __force *)lstats;
    	return 0;
    }
    
    static void loopback_dev_free(struct net_device *dev)
    {
    	struct pcpu_lstats __percpu *lstats =
    		(void __percpu __force *)dev->ml_priv;
    
    	free_percpu(lstats);
    	free_netdev(dev);
    }
    
    static const struct net_device_ops loopback_ops = {
    	.ndo_init      = loopback_dev_init,
    	.ndo_start_xmit= loopback_xmit,
    	.ndo_get_stats64 = loopback_get_stats64,
    };
    
    /*
     * The loopback device is special. There is only one instance
     * per network namespace.
     */
    static void loopback_setup(struct net_device *dev)
    {
    	dev->mtu		= (16 * 1024) + 20 + 20 + 12;
    	dev->hard_header_len	= ETH_HLEN;	/* 14	*/
    	dev->addr_len		= ETH_ALEN;	/* 6	*/
    	dev->tx_queue_len	= 0;
    	dev->type		= ARPHRD_LOOPBACK;	/* 0x0001*/
    	dev->flags		= IFF_LOOPBACK;
    	dev->priv_flags	       &= ~IFF_XMIT_DST_RELEASE;
    	dev->features 		= NETIF_F_SG | NETIF_F_FRAGLIST
    		| NETIF_F_TSO
    		| NETIF_F_NO_CSUM
    		| NETIF_F_HIGHDMA
    		| NETIF_F_LLTX
    		| NETIF_F_NETNS_LOCAL;
    	dev->ethtool_ops	= &loopback_ethtool_ops;
    	dev->header_ops		= &eth_header_ops;
    	dev->netdev_ops		= &loopback_ops;
    	dev->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", loopback_setup);
    	if (!dev)
    		goto out;
    
    	dev_net_set(dev, net);
    	err = register_netdev(dev);
    	if (err)
    		goto out_free_netdev;
    
    	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,
    };