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// SPDX-License-Identifier: GPL-2.0+
/*
* net/dsa/tag_trailer.c - Trailer tag format handling
* Copyright (c) 2008-2009 Marvell Semiconductor
*/
#include <linux/etherdevice.h>
#include <linux/list.h>
#include <linux/slab.h>
#include "dsa_priv.h"
static struct sk_buff *trailer_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct dsa_port *dp = dsa_slave_to_port(dev);
struct sk_buff *nskb;
int padlen;
u8 *trailer;
/*
* 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)
return NULL;
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));
consume_skb(skb);
if (padlen) {
skb_put_zero(nskb, padlen);
}
trailer = skb_put(nskb, 4);
trailer[0] = 0x80;
trailer[1] = 1 << dp->index;
trailer[2] = 0x10;
trailer[3] = 0x00;
return nskb;
}
static struct sk_buff *trailer_rcv(struct sk_buff *skb, struct net_device *dev,
struct packet_type *pt)
{
u8 *trailer;
int source_port;
if (skb_linearize(skb))
return NULL;
trailer = skb_tail_pointer(skb) - 4;
if (trailer[0] != 0x80 || (trailer[1] & 0xf8) != 0x00 ||
(trailer[2] & 0xef) != 0x00 || trailer[3] != 0x00)
return NULL;
source_port = trailer[1] & 7;
skb->dev = dsa_master_find_slave(dev, 0, source_port);
if (!skb->dev)
return NULL;
if (pskb_trim_rcsum(skb, skb->len - 4))
return NULL;
return skb;
}
static const struct dsa_device_ops trailer_netdev_ops = {
.name = "trailer",
.proto = DSA_TAG_PROTO_TRAILER,
.xmit = trailer_xmit,
.rcv = trailer_rcv,
.overhead = 4,
};
MODULE_LICENSE("GPL");
MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_TRAILER);
module_dsa_tag_driver(trailer_netdev_ops);
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