On Apr 3, 2013, at 8:24 , ext Simon Horman wrote:
> In the case where a non-MPLS packet is recieved and an MPLS stack is
> added it may well be the case that the original skb is GSO but the
> NIC used for transmit does not support GSO of MPLS packets.
>
...
> diff --git a/include/linux/netdev_features.h b/include/linux/netdev_features.h
> index d6ee2d0..e7bffa8 100644
> --- a/include/linux/netdev_features.h
> +++ b/include/linux/netdev_features.h
> @@ -43,6 +43,7 @@ enum {
> NETIF_F_FSO_BIT, /* ... FCoE segmentation */
> NETIF_F_GSO_GRE_BIT, /* ... GRE with TSO */
> NETIF_F_GSO_UDP_TUNNEL_BIT, /* ... UDP TUNNEL with TSO */
> + NETIF_F_GSO_MPLS_BIT, /* ... MPLS segmentation */
> /**/NETIF_F_GSO_LAST = /* last bit, see GSO_MASK */
> NETIF_F_GSO_UDP_TUNNEL_BIT,
>
NETIF_F_GSO_LAST needs an update here?
...
>
> diff --git a/net/mpls/mpls_gso.c b/net/mpls/mpls_gso.c
> new file mode 100644
> index 0000000..583de9e
> --- /dev/null
> +++ b/net/mpls/mpls_gso.c
> @@ -0,0 +1,125 @@
> +/*
> + * MPLS GSO Support
> + *
> + * Authors: Simon Horman (ho...@verge.net.au)
> + *
> + * 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.
> + *
> + * Based on: GSO portions of net/ipv4/gre.c
> + */
> +
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include <linux/err.h>
> +#include <linux/module.h>
> +#include <linux/netdev_features.h>
> +#include <linux/netdevice.h>
> +#include <linux/skbuff.h>
> +
> +#define MPLS_BOS_MASK 0x00000100 /* Bottom of Stack bit */
> +#define MPLS_HLEN (sizeof(__be32))
> +
> +static struct sk_buff *mpls_gso_segment(struct sk_buff *skb,
> + netdev_features_t features)
> +{
> + struct sk_buff *segs = ERR_PTR(-EINVAL);
> + netdev_features_t enc_features;
> + int stack_len = 0;
> + int mac_len = skb->mac_len;
> +
> + if (unlikely(skb_shinfo(skb)->gso_type &
> + ~(SKB_GSO_TCPV4 |
> + SKB_GSO_TCPV6 |
> + SKB_GSO_UDP |
> + SKB_GSO_DODGY |
> + SKB_GSO_TCP_ECN |
> + SKB_GSO_GRE |
> + SKB_GSO_MPLS)))
> + goto out;
> +
> + while (1) {
> + __be32 lse = *(__be32 *)(skb_network_header(skb) + stack_len);
> +
> + stack_len += MPLS_HLEN;
> + if (unlikely(!pskb_may_pull(skb, MPLS_HLEN)))
> + goto out;
> + __skb_pull(skb, MPLS_HLEN);
> +
> + if (lse & htonl(MPLS_BOS_MASK))
> + break;
> + }
> +
> + /* setup inner skb. */
> + skb_reset_mac_header(skb);
> + skb_reset_network_header(skb);
> + skb->mac_len = 0;
> + skb->protocol = SKB_GSO_CB(skb)->encap_eth_type;
> + skb->encapsulation = 0;
> +
> + /* segment inner packet. */
> + enc_features = skb->dev->hw_enc_features & netif_skb_features(skb) &
> + ~(NETIF_F_IP_CSUM|NETIF_F_IPV6_CSUM);
Add spaces around "|" to make this more readable.
> + segs = skb_mac_gso_segment(skb, enc_features);
> + if (IS_ERR_OR_NULL(segs))
> + goto out;
> +
> + skb = segs;
> + do {
> + __skb_push(skb, stack_len + mac_len);
> + skb_reset_mac_header(skb);
> + skb_set_network_header(skb, mac_len);
> + skb->mac_len = mac_len;
> + } while ((skb = skb->next));
> +out:
> + return segs;
> +}
> +
> +static int mpls_gso_send_check(struct sk_buff *skb)
> +{
> + if (!skb->encapsulation)
> + return -EINVAL;
> + return 0;
> +}
> +
> +static struct packet_offload mpls_mc_offload = {
> + .type = cpu_to_be16(ETH_P_MPLS_UC),
Should have ETH_P_MPLS_MC here?
> + .callbacks = {
> + .gso_send_check = mpls_gso_send_check,
> + .gso_segment = mpls_gso_segment,
> + },
> +};
> +
> +static struct packet_offload mpls_uc_offload = {
> + .type = cpu_to_be16(ETH_P_MPLS_UC),
> + .callbacks = {
> + .gso_send_check = mpls_gso_send_check,
> + .gso_segment = mpls_gso_segment,
> + },
> +};
> +
> +static int __init mpls_gso_init(void)
> +{
> + pr_info("MPLS GSO support\n");
> +
> + dev_add_offload(&mpls_uc_offload);
> + dev_add_offload(&mpls_mc_offload);
> +
> + return 0;
> +}
> +
> +static void __exit mpls_gso_exit(void)
> +{
> + dev_remove_offload(&mpls_uc_offload);
> + dev_remove_offload(&mpls_mc_offload);
> +}
> +
> +module_init(mpls_gso_init);
> +module_exit(mpls_gso_exit);
> +
> +MODULE_DESCRIPTION("MPLS GSO support");
> +MODULE_AUTHOR("Simon Horman (ho...@verge.net.au)");
> +MODULE_LICENSE("GPL");
> +
> --
> 1.7.10.4
>
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