Re: [PATCH 09/18] mbuf: support Mpls in software packet type parser

["Liang, Cunming" <cunming.liang@intel.com>]

Hi Olivier,

On 7/5/2016 11:41 PM, Olivier Matz wrote:
> Add a new RTE_PTYPE_L2_ETHER_MPLS packet type, and its support in
> rte_pktmbuf_get_ptype().
>
> Signed-off-by: Didier Pallard <didier.pallard@6wind.com>
> Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
> ---
>   lib/librte_mbuf/rte_mbuf_ptype.c | 25 +++++++++++++++++++++++++
>   lib/librte_mbuf/rte_mbuf_ptype.h |  9 ++++++++-
>   lib/librte_net/Makefile          |  4 +++-
>   lib/librte_net/rte_ether.h       |  2 ++
>   4 files changed, 38 insertions(+), 2 deletions(-)
>
> diff --git a/lib/librte_mbuf/rte_mbuf_ptype.c b/lib/librte_mbuf/rte_mbuf_ptype.c
> index 5d46608..0dea600 100644
> --- a/lib/librte_mbuf/rte_mbuf_ptype.c
> +++ b/lib/librte_mbuf/rte_mbuf_ptype.c
> @@ -41,6 +41,7 @@
>   #include <rte_tcp.h>
>   #include <rte_udp.h>
>   #include <rte_sctp.h>
> +#include <rte_mpls.h>
>   
>   /* get l3 packet type from ip6 next protocol */
>   static uint32_t
> @@ -166,6 +167,9 @@ uint32_t rte_pktmbuf_get_ptype(const struct rte_mbuf *m,
>   	off = sizeof(*eh);
>   	hdr_lens->l2_len = off;
>   
> +	if (proto == rte_cpu_to_be_16(ETHER_TYPE_IPv4))
> +		goto l3; /* fast path if packet is IPv4 */
> +
>   	if (proto == rte_cpu_to_be_16(ETHER_TYPE_VLAN)) {
>   		const struct vlan_hdr *vh;
>   		struct vlan_hdr vh_copy;
> @@ -189,8 +193,29 @@ uint32_t rte_pktmbuf_get_ptype(const struct rte_mbuf *m,
>   		off += 2 * sizeof(*vh);
>   		hdr_lens->l2_len += 2 * sizeof(*vh);
>   		proto = vh->eth_proto;
> +	} else if ((proto == rte_cpu_to_be_16(ETHER_TYPE_MPLS)) ||
> +			(proto == rte_cpu_to_be_16(ETHER_TYPE_MPLSM))) {
> +		unsigned int i;
> +		const struct mpls_hdr *mh;
> +		struct mpls_hdr mh_copy;
> +
> +#define MAX_MPLS_HDR 5
> +		for (i = 0; i < MAX_MPLS_HDR; i++) {
> +			mh = rte_pktmbuf_read(m, off + (i * sizeof(*mh)),
> +				sizeof(*mh), &mh_copy);
> +			if (unlikely(mh == NULL))
> +				return pkt_type;
> +			if (mh->bs)
> +				break;
> +		}
> +		if (i == MAX_MPLS_HDR)
> +			return pkt_type;
> +		pkt_type = RTE_PTYPE_L2_ETHER_MPLS;
> +		hdr_lens->l2_len += (sizeof(*mh) * (i + 1));
[LC] l2_len includes Eth, Vlan(opt.), MPLS(opt.). For VLAN and MPLS, it 
may include #n times overlay.
These layer recognition knowledge are lost after the detection logic. 
Once the APP takes the ptype, for the layer(L2, L3, L4) which has more 
shim-layer, the xxx_len can't help to avoid the re-parse cost.
> +		return pkt_type;
>   	}
>   
> [...]