[ovs-dev] [PATCH 01/16] User-Space MPLS actions and matches

Ben Pfaff blp at nicira.com
Wed Jan 16 07:05:45 UTC 2013

On Tue, Jan 08, 2013 at 02:46:02PM +0900, Simon Horman wrote:
> diff --git a/include/linux/openvswitch.h b/include/linux/openvswitch.h
> index 5e32965..b421753 100644
> --- a/include/linux/openvswitch.h
> +++ b/include/linux/openvswitch.h
> @@ -282,6 +282,7 @@ enum ovs_key_attr {
>  	OVS_KEY_ATTR_ARP,       /* struct ovs_key_arp */
>  	OVS_KEY_ATTR_ND,        /* struct ovs_key_nd */
>  	OVS_KEY_ATTR_SKB_MARK,  /* u32 skb mark */
> +	OVS_KEY_ATTR_MPLS,      /* struct ovs_key_mpls */
>  	OVS_KEY_ATTR_IPV4_TUNNEL,  /* struct ovs_key_ipv4_tunnel */
>  	OVS_KEY_ATTR_TUN_ID = 63,  /* be64 tunnel ID */

I'm pretty sure we shouldn't be inserting OVS_KEY_ATTR_MPLS in front of
another value that we're already aiming to get upstream.  I'd suggest a
value of 62.  

Jesse, does that sound reasonable to you?  Another alternative would be
to avoid modifying <linux/openvswitch.h> entirely, one way or another,
until we have real kernel support, which would be a little extra work.

I'm not sure why we have OVS_ACTION_ATTR_SET_MPLS instead of using

> +/* Action structure for NXAST_PUSH_VLAN/MPLS. */
> +struct nx_action_push {
> +    ovs_be16 type;                  /* OFPAT_PUSH_VLAN/MPLS. */

The above two comments are wrong, there's no NXAST_PUSH_VLAN.  And the
struct should be named nx_action_push_mpls, not more generically.  (This
must be a leftover from Ravi's initial patch that also added QinQ.)

> +    ovs_be16 len;                   /* Length is 8. */
> +    ovs_be32 vendor;                /* NX_VENDOR_ID. */
> +    ovs_be16 subtype;               /* NXAST_PUSH_MPLS. */
> +    ovs_be16 ethertype;             /* Ethertype */
> +    uint8_t  pad[4];
> +};
> +OFP_ASSERT(sizeof(struct nx_action_push) == 16);

> @@ -1271,6 +1272,20 @@ dp_netdev_execute_actions(struct dp_netdev *dp,
>              eth_pop_vlan(packet);
>              break;
> +        case OVS_ACTION_ATTR_PUSH_MPLS: {
> +            const struct ovs_action_push_mpls *mpls = nl_attr_get(a);
> +            push_mpls(packet, mpls->mpls_ethertype, mpls->mpls_label);
> +            break;

The similar OVS_ACTION_ATTR_PUSH_VLAN case declares its variable at the
outer block.  Please make the code consistent one way or another on this

The breakdown of code between parse_mpls() and parse_remaining_mpls()
seems odd.  I'd just write one function.

In mf_is_value_valid(), I think that the MFF_MPLS_TC and MFF_MPLS_BOS
cases should check the u8 member, not be32.  Same for
mf_random_value().  Also htonl won't be needed for u8.

Most of the meta-flow functions present the cases in the order label,
tc, bos, but mf_set_value() uses a different order.  Can you make it

In enum mf_prereqs, it might be best to add an "L2.5" category for MPLS.

This adds a double blank line in nx_put_raw().  (Oh the horror!)

Also in nx_put_raw(), missing space after the comma here:
+            nxm_put_8(b,OXM_OF_MPLS_TC, mpls_lse_to_tc(flow->mpls_lse));

parse_l3_onward() has a ";;":
+    ovs_be16 dl_type = flow->dl_type;;

parse_l3_onward() could use flow_innermost_dl_type() since that's what
it's effectively calculating as 'dl_type' (maybe it should be
'inner_dl_type' or 'innermost_dl_type').

Is there any sense in handling cases in commit_mpls_action() where the
mpls_depth has to change by more than 1?  Should we log an error at

The comment on struct ofpact_push is getting ahead of ourselves, since
we have an OFPACT_PUSH_VLAN but it doesn't use this structure and no one
has even mentioned PBB for OVS yet, at least not to me:

+ *
+struct ofpact_push {
+    struct ofpact ofpact;
+    ovs_be16 ethertype;

You can remove the bit about "negotiation of an OF1.3 session is not yet
supported" from this comment in ofputil_usable_protocols():
+    /* NXM and OF1.3+ support matching MPLS label */
+    /* Allow for OF1.2 as there doesn't seem to be a
+     * particularly good reason not to and negotiation
+     * of an OF1.3 session is not yet supported. */

In ofputil_normalize_match__() should we also mask off mpls_depth if
!MAY_MPLS?  I guess so.

It's getting late here so I'll resume looking at this patch starting at
lib/packets.c next chance I get.

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