drivers/net/loopback.c

/* */
This source file includes following definitions.
loopback_xmit
get_stats
loopback_open
loopback_init
   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              Pseudo-driver for the loopback interface.
   7  *
   8  * Version:     @(#)loopback.c  1.0.4b  08/16/93
   9  *
  10  * Authors:     Ross Biro, <bir7@leland.Stanford.Edu>
  11  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  12  *              Donald Becker, <becker@cesdis.gsfc.nasa.gov>
  13  *
  14  *              Alan Cox        :       Fixed oddments for NET3.014
  15  *              Alan Cox        :       Rejig for NET3.029 snap #3
  16  *              Alan Cox        :       Fixed NET3.029 bugs and sped up
  17  *              Larry McVoy     :       Tiny tweak to double performance
  18  *              Alan Cox        :       Backed out LMV's tweak - the linux mm
  19  *                                      can't take it...
  20  *
  21  *              This program is free software; you can redistribute it and/or
  22  *              modify it under the terms of the GNU General Public License
  23  *              as published by the Free Software Foundation; either version
  24  *              2 of the License, or (at your option) any later version.
  25  */
  26 #include <linux/config.h>
  27 #include <linux/kernel.h>
  28 #include <linux/sched.h>
  29 #include <linux/interrupt.h>
  30 #include <linux/fs.h>
  31 #include <linux/types.h>
  32 #include <linux/string.h>
  33 #include <linux/socket.h>
  34 #include <linux/errno.h>
  35 #include <linux/fcntl.h>
  36 #include <linux/in.h>
  37 
  38 #include <asm/system.h>
  39 #include <asm/segment.h>
  40 #include <asm/io.h>
  41 
  42 #include <linux/inet.h>
  43 #include <linux/netdevice.h>
  44 #include <linux/etherdevice.h>
  45 #include <linux/skbuff.h>
  46 #include <net/sock.h>
  47 #include <linux/if_ether.h>     /* For the statistics structure. */
  48 #include <linux/if_arp.h>       /* For ARPHRD_ETHER */
  49 
  50 #define LOOPBACK_MTU (PAGE_SIZE*7/8)
  51 
  52 /*
  53  * The higher levels take care of making this non-reentrant (it's
  54  * called with bh's disabled).
  55  */
  56 static int loopback_xmit(struct sk_buff *skb, struct device *dev)
     /*  */
  57 {
  58         struct enet_statistics *stats = (struct enet_statistics *)dev->priv;
  59         int unlock=1;
  60   
  61         if (skb == NULL || dev == NULL) 
  62                 return(0);
  63 
  64         /*
  65          *      Optimise so buffers with skb->free=1 are not copied but
  66          *      instead are lobbed from tx queue to rx queue 
  67          */
  68 
  69         if(skb->free==0)
  70         {
  71                 struct sk_buff *skb2=skb;
  72                 skb=skb_clone(skb, GFP_ATOMIC);         /* Clone the buffer */
  73                 if(skb==NULL)
  74                         return 1;
  75                 dev_kfree_skb(skb2, FREE_WRITE);
  76                 unlock=0;
  77         }
  78         else if(skb->sk)
  79         {
  80                 /*
  81                  *      Packet sent but looped back around. Cease to charge
  82                  *      the socket for the frame.
  83                  */
  84                 atomic_sub(skb->truesize, &skb->sk->wmem_alloc);
  85                 skb->sk->write_space(skb->sk);
  86         }
  87 
  88         skb->protocol=eth_type_trans(skb,dev);
  89         skb->dev=dev;
  90 #ifndef LOOPBACK_MUST_CHECKSUM
  91         skb->ip_summed = CHECKSUM_UNNECESSARY;
  92 #endif
  93         netif_rx(skb);
  94         if(unlock)
  95                 skb_device_unlock(skb);
  96   
  97         stats->rx_packets++;
  98         stats->tx_packets++;
  99 
 100         return(0);
 101 }
 102 
 103 static struct enet_statistics *get_stats(struct device *dev)
     /*  */
 104 {
 105         return (struct enet_statistics *)dev->priv;
 106 }
 107 
 108 static int loopback_open(struct device *dev)
     /*  */
 109 {
 110         dev->flags|=IFF_LOOPBACK;
 111         return 0;
 112 }
 113 
 114 /* Initialize the rest of the LOOPBACK device. */
 115 int loopback_init(struct device *dev)
     /*  */
 116 {
 117         int i;
 118 
 119         dev->mtu                = LOOPBACK_MTU;
 120         dev->tbusy              = 0;
 121         dev->hard_start_xmit    = loopback_xmit;
 122         dev->open               = NULL;
 123         dev->hard_header        = eth_header;
 124         dev->hard_header_len    = ETH_HLEN;             /* 14                   */
 125         dev->addr_len           = ETH_ALEN;             /* 6                    */
 126         dev->tx_queue_len       = 50000;                /* No limit on loopback */
 127         dev->type               = ARPHRD_LOOPBACK;      /* 0x0001               */
 128         dev->rebuild_header     = eth_rebuild_header;
 129         dev->open               = loopback_open;
 130         dev->flags              = IFF_LOOPBACK|IFF_BROADCAST;
 131         dev->family             = AF_INET;
 132 #ifdef CONFIG_INET    
 133         dev->pa_addr            = in_aton("127.0.0.1");
 134         dev->pa_brdaddr         = in_aton("127.255.255.255");
 135         dev->pa_mask            = in_aton("255.0.0.0");
 136         dev->pa_alen            = 4;
 137 #endif  
 138         dev->priv = kmalloc(sizeof(struct enet_statistics), GFP_KERNEL);
 139         if (dev->priv == NULL)
 140                         return -ENOMEM;
 141         memset(dev->priv, 0, sizeof(struct enet_statistics));
 142         dev->get_stats = get_stats;
 143 
 144         /*
 145          *      Fill in the generic fields of the device structure. 
 146          */
 147    
 148         for (i = 0; i < DEV_NUMBUFFS; i++)
 149                 skb_queue_head_init(&dev->buffs[i]);
 150   
 151         return(0);
 152 };
/* */
root/drivers/net/loopback.c

DEFINITIONS
