LXR linux/net/dsa/tag

   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/slab.h>
  14#include "dsa_priv.h"
  15
  16static struct sk_buff *trailer_xmit(struct sk_buff *skb, struct net_device *dev)
  17{
  18        struct dsa_slave_priv *p = netdev_priv(dev);
  19        struct sk_buff *nskb;
  20        int padlen;
  21        u8 *trailer;
  22
  23        /*
  24         * We have to make sure that the trailer ends up as the very
  25         * last 4 bytes of the packet.  This means that we have to pad
  26         * the packet to the minimum ethernet frame size, if necessary,
  27         * before adding the trailer.
  28         */
  29        padlen = 0;
  30        if (skb->len < 60)
  31                padlen = 60 - skb->len;
  32
  33        nskb = alloc_skb(NET_IP_ALIGN + skb->len + padlen + 4, GFP_ATOMIC);
  34        if (nskb == NULL) {
  35                kfree_skb(skb);
  36                return NULL;
  37        }
  38        skb_reserve(nskb, NET_IP_ALIGN);
  39
  40        skb_reset_mac_header(nskb);
  41        skb_set_network_header(nskb, skb_network_header(skb) - skb->head);
  42        skb_set_transport_header(nskb, skb_transport_header(skb) - skb->head);
  43        skb_copy_and_csum_dev(skb, skb_put(nskb, skb->len));
  44        kfree_skb(skb);
  45
  46        if (padlen) {
  47                u8 *pad = skb_put(nskb, padlen);
  48                memset(pad, 0, padlen);
  49        }
  50
  51        trailer = skb_put(nskb, 4);
  52        trailer[0] = 0x80;
  53        trailer[1] = 1 << p->port;
  54        trailer[2] = 0x10;
  55        trailer[3] = 0x00;
  56
  57        return nskb;
  58}
  59
  60static int trailer_rcv(struct sk_buff *skb, struct net_device *dev,
  61                       struct packet_type *pt, struct net_device *orig_dev)
  62{
  63        struct dsa_switch_tree *dst = dev->dsa_ptr;
  64        struct dsa_switch *ds;
  65        u8 *trailer;
  66        int source_port;
  67
  68        if (unlikely(dst == NULL))
  69                goto out_drop;
  70        ds = dst->ds[0];
  71
  72        skb = skb_unshare(skb, GFP_ATOMIC);
  73        if (skb == NULL)
  74                goto out;
  75
  76        if (skb_linearize(skb))
  77                goto out_drop;
  78
  79        trailer = skb_tail_pointer(skb) - 4;
  80        if (trailer[0] != 0x80 || (trailer[1] & 0xf8) != 0x00 ||
  81            (trailer[2] & 0xef) != 0x00 || trailer[3] != 0x00)
  82                goto out_drop;
  83
  84        source_port = trailer[1] & 7;
  85        if (source_port >= DSA_MAX_PORTS || ds->ports[source_port] == NULL)
  86                goto out_drop;
  87
  88        pskb_trim_rcsum(skb, skb->len - 4);
  89
  90        skb->dev = ds->ports[source_port];
  91        skb_push(skb, ETH_HLEN);
  92        skb->pkt_type = PACKET_HOST;
  93        skb->protocol = eth_type_trans(skb, skb->dev);
  94
  95        skb->dev->stats.rx_packets++;
  96        skb->dev->stats.rx_bytes += skb->len;
  97
  98        netif_receive_skb(skb);
  99
 100        return 0;
 101
 102out_drop:
 103        kfree_skb(skb);
 104out:
 105        return 0;
 106}
 107
 108const struct dsa_device_ops trailer_netdev_ops = {
 109        .xmit   = trailer_xmit,
 110        .rcv    = trailer_rcv,
 111};
 112