root/net/dsa/tag_trailer.c

DEFINITIONS

1. trailer_xmit
2. trailer_rcv
3. trailer_init_module
4. trailer_cleanup_module

/*
 * net/dsa/tag_trailer.c - Trailer tag format handling
 * Copyright (c) 2008 Marvell Semiconductor
 *
 * 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/etherdevice.h>
#include <linux/list.h>
#include <linux/netdevice.h>
#include "dsa_priv.h"

int trailer_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct dsa_slave_priv *p = netdev_priv(dev);
        struct sk_buff *nskb;
        int padlen;
        u8 *trailer;

        dev->stats.tx_packets++;
        dev->stats.tx_bytes += skb->len;

        /*
         * We have to make sure that the trailer ends up as the very
         * last 4 bytes of the packet.  This means that we have to pad
         * the packet to the minimum ethernet frame size, if necessary,
         * before adding the trailer.
         */
        padlen = 0;
        if (skb->len < 60)
                padlen = 60 - skb->len;

        nskb = alloc_skb(NET_IP_ALIGN + skb->len + padlen + 4, GFP_ATOMIC);
        if (nskb == NULL) {
                kfree_skb(skb);
                return NETDEV_TX_OK;
        }
        skb_reserve(nskb, NET_IP_ALIGN);

        skb_reset_mac_header(nskb);
        skb_set_network_header(nskb, skb_network_header(skb) - skb->head);
        skb_set_transport_header(nskb, skb_transport_header(skb) - skb->head);
        skb_copy_and_csum_dev(skb, skb_put(nskb, skb->len));
        kfree_skb(skb);

        if (padlen) {
                u8 *pad = skb_put(nskb, padlen);
                memset(pad, 0, padlen);
        }

        trailer = skb_put(nskb, 4);
        trailer[0] = 0x80;
        trailer[1] = 1 << p->port;
        trailer[2] = 0x10;
        trailer[3] = 0x00;

        nskb->protocol = htons(ETH_P_TRAILER);

        nskb->dev = p->parent->master_netdev;
        dev_queue_xmit(nskb);

        return NETDEV_TX_OK;
}

static int trailer_rcv(struct sk_buff *skb, struct net_device *dev,
                       struct packet_type *pt, struct net_device *orig_dev)
{
        struct dsa_switch *ds = dev->dsa_ptr;
        u8 *trailer;
        int source_port;

        if (unlikely(ds == NULL))
                goto out_drop;

        skb = skb_unshare(skb, GFP_ATOMIC);
        if (skb == NULL)
                goto out;

        if (skb_linearize(skb))
                goto out_drop;

        trailer = skb_tail_pointer(skb) - 4;
        if (trailer[0] != 0x80 || (trailer[1] & 0xf8) != 0x00 ||
            (trailer[3] & 0xef) != 0x00 || trailer[3] != 0x00)
                goto out_drop;

        source_port = trailer[1] & 7;
        if (source_port >= DSA_MAX_PORTS || ds->ports[source_port] == NULL)
                goto out_drop;

        pskb_trim_rcsum(skb, skb->len - 4);

        skb->dev = ds->ports[source_port];
        skb_push(skb, ETH_HLEN);
        skb->protocol = eth_type_trans(skb, skb->dev);

        skb->dev->last_rx = jiffies;
        skb->dev->stats.rx_packets++;
        skb->dev->stats.rx_bytes += skb->len;

        netif_receive_skb(skb);

        return 0;

out_drop:
        kfree_skb(skb);
out:
        return 0;
}

static struct packet_type trailer_packet_type = {
        .type   = __constant_htons(ETH_P_TRAILER),
        .func   = trailer_rcv,
};

static int __init trailer_init_module(void)
{
        dev_add_pack(&trailer_packet_type);
        return 0;
}
module_init(trailer_init_module);

static void __exit trailer_cleanup_module(void)
{
        dev_remove_pack(&trailer_packet_type);
}
module_exit(trailer_cleanup_module);