linux/net/dsa/tag_trailer.c
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   1/*
   2 * net/dsa/tag_trailer.c - Trailer tag format handling
   3 * Copyright (c) 2008-2009 Marvell Semiconductor
   4 *
   5 * This program is free software; you can redistribute it and/or modify
   6 * it under the terms of the GNU General Public License as published by
   7 * the Free Software Foundation; either version 2 of the License, or
   8 * (at your option) any later version.
   9 */
  10
  11#include <linux/etherdevice.h>
  12#include <linux/list.h>
  13#include <linux/netdevice.h>
  14#include <linux/slab.h>
  15#include "dsa_priv.h"
  16
  17netdev_tx_t trailer_xmit(struct sk_buff *skb, struct net_device *dev)
  18{
  19        struct dsa_slave_priv *p = netdev_priv(dev);
  20        struct sk_buff *nskb;
  21        int padlen;
  22        u8 *trailer;
  23
  24        dev->stats.tx_packets++;
  25        dev->stats.tx_bytes += skb->len;
  26
  27        /*
  28         * We have to make sure that the trailer ends up as the very
  29         * last 4 bytes of the packet.  This means that we have to pad
  30         * the packet to the minimum ethernet frame size, if necessary,
  31         * before adding the trailer.
  32         */
  33        padlen = 0;
  34        if (skb->len < 60)
  35                padlen = 60 - skb->len;
  36
  37        nskb = alloc_skb(NET_IP_ALIGN + skb->len + padlen + 4, GFP_ATOMIC);
  38        if (nskb == NULL) {
  39                kfree_skb(skb);
  40                return NETDEV_TX_OK;
  41        }
  42        skb_reserve(nskb, NET_IP_ALIGN);
  43
  44        skb_reset_mac_header(nskb);
  45        skb_set_network_header(nskb, skb_network_header(skb) - skb->head);
  46        skb_set_transport_header(nskb, skb_transport_header(skb) - skb->head);
  47        skb_copy_and_csum_dev(skb, skb_put(nskb, skb->len));
  48        kfree_skb(skb);
  49
  50        if (padlen) {
  51                u8 *pad = skb_put(nskb, padlen);
  52                memset(pad, 0, padlen);
  53        }
  54
  55        trailer = skb_put(nskb, 4);
  56        trailer[0] = 0x80;
  57        trailer[1] = 1 << p->port;
  58        trailer[2] = 0x10;
  59        trailer[3] = 0x00;
  60
  61        nskb->protocol = htons(ETH_P_TRAILER);
  62
  63        nskb->dev = p->parent->dst->master_netdev;
  64        dev_queue_xmit(nskb);
  65
  66        return NETDEV_TX_OK;
  67}
  68
  69static int trailer_rcv(struct sk_buff *skb, struct net_device *dev,
  70                       struct packet_type *pt, struct net_device *orig_dev)
  71{
  72        struct dsa_switch_tree *dst = dev->dsa_ptr;
  73        struct dsa_switch *ds;
  74        u8 *trailer;
  75        int source_port;
  76
  77        if (unlikely(dst == NULL))
  78                goto out_drop;
  79        ds = dst->ds[0];
  80
  81        skb = skb_unshare(skb, GFP_ATOMIC);
  82        if (skb == NULL)
  83                goto out;
  84
  85        if (skb_linearize(skb))
  86                goto out_drop;
  87
  88        trailer = skb_tail_pointer(skb) - 4;
  89        if (trailer[0] != 0x80 || (trailer[1] & 0xf8) != 0x00 ||
  90            (trailer[3] & 0xef) != 0x00 || trailer[3] != 0x00)
  91                goto out_drop;
  92
  93        source_port = trailer[1] & 7;
  94        if (source_port >= DSA_MAX_PORTS || ds->ports[source_port] == NULL)
  95                goto out_drop;
  96
  97        pskb_trim_rcsum(skb, skb->len - 4);
  98
  99        skb->dev = ds->ports[source_port];
 100        skb_push(skb, ETH_HLEN);
 101        skb->pkt_type = PACKET_HOST;
 102        skb->protocol = eth_type_trans(skb, skb->dev);
 103
 104        skb->dev->stats.rx_packets++;
 105        skb->dev->stats.rx_bytes += skb->len;
 106
 107        netif_receive_skb(skb);
 108
 109        return 0;
 110
 111out_drop:
 112        kfree_skb(skb);
 113out:
 114        return 0;
 115}
 116
 117struct packet_type trailer_packet_type __read_mostly = {
 118        .type   = cpu_to_be16(ETH_P_TRAILER),
 119        .func   = trailer_rcv,
 120};
 121
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