linux/net/mpls/mpls_gso.c
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   1/*
   2 *      MPLS GSO Support
   3 *
   4 *      Authors: Simon Horman (horms@verge.net.au)
   5 *
   6 *      This program is free software; you can redistribute it and/or
   7 *      modify it under the terms of the GNU General Public License
   8 *      as published by the Free Software Foundation; either version
   9 *      2 of the License, or (at your option) any later version.
  10 *
  11 *      Based on: GSO portions of net/ipv4/gre.c
  12 */
  13
  14#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  15
  16#include <linux/err.h>
  17#include <linux/module.h>
  18#include <linux/netdev_features.h>
  19#include <linux/netdevice.h>
  20#include <linux/skbuff.h>
  21
  22static struct sk_buff *mpls_gso_segment(struct sk_buff *skb,
  23                                       netdev_features_t features)
  24{
  25        struct sk_buff *segs = ERR_PTR(-EINVAL);
  26        netdev_features_t mpls_features;
  27        __be16 mpls_protocol;
  28
  29        if (unlikely(skb_shinfo(skb)->gso_type &
  30                                ~(SKB_GSO_TCPV4 |
  31                                  SKB_GSO_TCPV6 |
  32                                  SKB_GSO_UDP |
  33                                  SKB_GSO_DODGY |
  34                                  SKB_GSO_TCP_ECN |
  35                                  SKB_GSO_GRE |
  36                                  SKB_GSO_MPLS)))
  37                goto out;
  38
  39        /* Setup inner SKB. */
  40        mpls_protocol = skb->protocol;
  41        skb->protocol = skb->inner_protocol;
  42
  43        /* Push back the mac header that skb_mac_gso_segment() has pulled.
  44         * It will be re-pulled by the call to skb_mac_gso_segment() below
  45         */
  46        __skb_push(skb, skb->mac_len);
  47
  48        /* Segment inner packet. */
  49        mpls_features = skb->dev->mpls_features & netif_skb_features(skb);
  50        segs = skb_mac_gso_segment(skb, mpls_features);
  51
  52
  53        /* Restore outer protocol. */
  54        skb->protocol = mpls_protocol;
  55
  56        /* Re-pull the mac header that the call to skb_mac_gso_segment()
  57         * above pulled.  It will be re-pushed after returning
  58         * skb_mac_gso_segment(), an indirect caller of this function.
  59         */
  60        __skb_push(skb, skb->data - skb_mac_header(skb));
  61
  62out:
  63        return segs;
  64}
  65
  66static int mpls_gso_send_check(struct sk_buff *skb)
  67{
  68        return 0;
  69}
  70
  71static struct packet_offload mpls_mc_offload = {
  72        .type = cpu_to_be16(ETH_P_MPLS_MC),
  73        .callbacks = {
  74                .gso_send_check =       mpls_gso_send_check,
  75                .gso_segment    =       mpls_gso_segment,
  76        },
  77};
  78
  79static struct packet_offload mpls_uc_offload = {
  80        .type = cpu_to_be16(ETH_P_MPLS_UC),
  81        .callbacks = {
  82                .gso_send_check =       mpls_gso_send_check,
  83                .gso_segment    =       mpls_gso_segment,
  84        },
  85};
  86
  87static int __init mpls_gso_init(void)
  88{
  89        pr_info("MPLS GSO support\n");
  90
  91        dev_add_offload(&mpls_uc_offload);
  92        dev_add_offload(&mpls_mc_offload);
  93
  94        return 0;
  95}
  96
  97static void __exit mpls_gso_exit(void)
  98{
  99        dev_remove_offload(&mpls_uc_offload);
 100        dev_remove_offload(&mpls_mc_offload);
 101}
 102
 103module_init(mpls_gso_init);
 104module_exit(mpls_gso_exit);
 105
 106MODULE_DESCRIPTION("MPLS GSO support");
 107MODULE_AUTHOR("Simon Horman (horms@verge.net.au)");
 108MODULE_LICENSE("GPL");
 109
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