net/dsa/tag_trailer.c

   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
  17 netdev_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
  69 static 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
 111 out_drop:
 112         kfree_skb(skb);
 113 out:
 114         return 0;
 115 }
 116
 117 struct packet_type trailer_packet_type __read_mostly = {
 118         .type   = cpu_to_be16(ETH_P_TRAILER),
 119         .func   = trailer_rcv,
 120 };