On Apr 22, 2013, at 5:12 , ext Simon Horman wrote:
> diff --git a/datapath/actions.c b/datapath/actions.c
...
> +static int push_mpls(struct sk_buff *skb,
> + const struct ovs_action_push_mpls *mpls,
> + unsigned *mpls_stack_depth)
> +{
> + __be32 *new_mpls_lse;
> + int err;
> +
> + err = make_writable(skb, skb->mac_len + MPLS_HLEN);
> + if (unlikely(err))
> + return err;
> +
> + skb_push(skb, MPLS_HLEN);
> + memmove(skb_mac_header(skb) - MPLS_HLEN, skb_mac_header(skb),
> + skb->mac_len);
> + skb_reset_mac_header(skb);
> + skb_set_network_header(skb, skb->mac_len);
> +
> + new_mpls_lse = (__be32 *)skb_network_header(skb);
> + *new_mpls_lse = mpls->mpls_lse;
> +
Note: Now the skb_network_header points to the MPLS header. But see below...
> + if (get_ip_summed(skb) == OVS_CSUM_COMPLETE)
> + skb->csum = csum_add(skb->csum, csum_partial(new_mpls_lse,
> + MPLS_HLEN, 0));
> +
> + set_ethertype(skb, mpls->mpls_ethertype);
> + if (!eth_p_mpls(skb->protocol))
> + (*mpls_stack_depth)++;
Here mpls_stack_depth is increased only conditionally. What would be the case
where mpls_stack_depth would remain unchanged here? And how does that relate to
what follows below...
> + return 0;
> +}
> +
> +static int pop_mpls(struct sk_buff *skb, const __be16 *ethertype,
> + unsigned *mpls_stack_depth)
> +{
> + int err;
> +
> + err = make_writable(skb, skb->mac_len + MPLS_HLEN);
> + if (unlikely(err))
> + return err;
> +
> + if (get_ip_summed(skb) == OVS_CSUM_COMPLETE)
> + skb->csum = csum_sub(skb->csum,
> + csum_partial(skb_network_header(skb),
> + MPLS_HLEN, 0));
> +
> + memmove(skb_mac_header(skb) + MPLS_HLEN, skb_mac_header(skb),
> + skb->mac_len);
> +
> + skb_pull(skb, MPLS_HLEN);
> + skb_reset_mac_header(skb);
> + skb_set_network_header(skb, skb->mac_len);
> +
> + set_ethertype(skb, *ethertype);
> + if (!eth_p_mpls(skb->protocol))
> + (*mpls_stack_depth)--;
Ditto?
> + return 0;
> +}
> +
> +static int set_mpls(struct sk_buff *skb, const __be32 *mpls_lse)
> +{
> + __be32 *stack = (__be32 *)skb_network_header(skb);
> + int err;
> +
> + err = make_writable(skb, skb->mac_len + MPLS_HLEN);
> + if (unlikely(err))
> + return err;
> +
> + if (get_ip_summed(skb) == OVS_CSUM_COMPLETE) {
> + __be32 diff[] = { ~(*stack), *mpls_lse };
> + skb->csum = ~csum_partial((char *)diff, sizeof(diff),
> + ~skb->csum);
> + }
> +
> + *stack = *mpls_lse;
> +
> + return 0;
> +}
> +
> /* remove VLAN header from packet and update csum accordingly. */
> static int __pop_vlan_tci(struct sk_buff *skb, __be16 *current_tci)
> {
> @@ -115,6 +210,9 @@ static int push_vlan(struct sk_buff *skb, const struct
> ovs_action_push_vlan *vla
> if (!__vlan_put_tag(skb, current_tag))
> return -ENOMEM;
>
> + /* update mac_len for MPLS functions */
> + skb_reset_mac_len(skb);
> +
> if (get_ip_summed(skb) == OVS_CSUM_COMPLETE)
> skb->csum = csum_add(skb->csum, csum_partial(skb->data
> + (2 * ETH_ALEN), VLAN_HLEN, 0));
> @@ -352,13 +450,31 @@ static int set_tcp(struct sk_buff *skb, const struct
> ovs_key_tcp *tcp_port_key)
> return 0;
> }
>
> -static int do_output(struct datapath *dp, struct sk_buff *skb, int out_port)
> +static int do_output(struct datapath *dp, struct sk_buff *skb, int out_port,
> + unsigned mpls_stack_depth)
> {
> struct vport *vport;
>
> if (unlikely(!skb))
> return -ENOMEM;
>
> + /* During action execution the network_header, and mac_len,
> + * correspondingly, have tracked the end of the L2 frame (including
> + * any VLAN headers), but proper skb output processing of GSO skbs
> + * requires the network_header (and mac_len) to track the start of
> + * the L3 header instead. These differ in the presence of MPLS
> + * headers.
> + *
> + * mpls_stack_depth is only non-zero if a non-MPLS skb is turned
> + * into an MPLS skb via an MPLS push action. This is the only case
> + * where an MPLS skb may be a GSO skb.
> + */
> + if (mpls_stack_depth) {
> + skb->mac_len += MPLS_HLEN * mpls_stack_depth;
> + skb_set_network_header(skb, skb->mac_len);
> + skb_set_encapsulation_features(skb);
> + }
> +
Here the skb_network_header is changed to point to the L3 header. Is it
significant that in some cases (?) mpls_stack_depth may remain at zero, even
when a MPLS header was in fact added? (See above).
> vport = ovs_vport_rcu(dp, out_port);
> if (unlikely(!vport)) {
> kfree_skb(skb);
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