Re: [dpdk-dev] [PATCH v3] examples/ipsec-secgw: fix usage of incorrect port

[Radu Nicolau <radu.nicolau@intel.com>]

Hi,


On 12/6/2017 11:08 AM, Anoob wrote:
> Hi Akhil,
>
> On 12/04/2017 01:19 PM, Akhil Goyal wrote:
>> Hi Anoob,
>> On 11/29/2017 9:51 AM, Anoob Joseph wrote:
>>> Hi Akhil,
>>>
>>>
>>> On 24-11-2017 16:19, Akhil Goyal wrote:
>>>> Hi Anoob,
>>>>
>>>> On 11/24/2017 3:28 PM, Anoob wrote:
>>>>>>>   static inline void
>>>>>>>   route4_pkts(struct rt_ctx *rt_ctx, struct rte_mbuf *pkts[], 
>>>>>>> uint8_t nb_pkts)
>>>>>>>   {
>>>>>>>       uint32_t hop[MAX_PKT_BURST * 2];
>>>>>>>       uint32_t dst_ip[MAX_PKT_BURST * 2];
>>>>>>> +    int32_t pkt_hop = 0;
>>>>>>>       uint16_t i, offset;
>>>>>>> +    uint16_t lpm_pkts = 0;
>>>>>>>         if (nb_pkts == 0)
>>>>>>>           return;
>>>>>>>   +    /* Need to do an LPM lookup for non-offload packets. 
>>>>>>> Offload packets
>>>>>>> +     * will have port ID in the SA
>>>>>>> +     */
>>>>>>> +
>>>>>>>       for (i = 0; i < nb_pkts; i++) {
>>>>>>> -        offset = offsetof(struct ip, ip_dst);
>>>>>>> -        dst_ip[i] = *rte_pktmbuf_mtod_offset(pkts[i],
>>>>>>> -                uint32_t *, offset);
>>>>>>> -        dst_ip[i] = rte_be_to_cpu_32(dst_ip[i]);
>>>>>>> +        if (!(pkts[i]->ol_flags & PKT_TX_SEC_OFFLOAD)) {
>>>>>>> +            /* Security offload not enabled. So an LPM lookup is
>>>>>>> +             * required to get the hop
>>>>>>> +             */
>>>>>>> +            offset = offsetof(struct ip, ip_dst);
>>>>>>> +            dst_ip[lpm_pkts] = *rte_pktmbuf_mtod_offset(pkts[i],
>>>>>>> +                    uint32_t *, offset);
>>>>>>> +            dst_ip[lpm_pkts] = rte_be_to_cpu_32(dst_ip[lpm_pkts]);
>>>>>>> +            lpm_pkts++;
>>>>>>> +        }
>>>>>>>       }
>>>>>>>   -    rte_lpm_lookup_bulk((struct rte_lpm *)rt_ctx, dst_ip, 
>>>>>>> hop, nb_pkts);
>>>>>>> +    rte_lpm_lookup_bulk((struct rte_lpm *)rt_ctx, dst_ip, hop, 
>>>>>>> lpm_pkts);
>>>>>>> +
>>>>>>> +    lpm_pkts = 0;
>>>>>>>         for (i = 0; i < nb_pkts; i++) {
>>>>>>> -        if ((hop[i] & RTE_LPM_LOOKUP_SUCCESS) == 0) {
>>>>>>> +        if (pkts[i]->ol_flags & PKT_TX_SEC_OFFLOAD) {
>>>>>>> +            /* Read hop from the SA */
>>>>>>> +            pkt_hop = get_hop_for_offload_pkt(pkts[i]);
>>>>>>> +        } else {
>>>>>>> +            /* Need to use hop returned by lookup */
>>>>>>> +            pkt_hop = hop[lpm_pkts++];
>>>>>>> +            if ((pkt_hop & RTE_LPM_LOOKUP_SUCCESS) == 0)
>>>>>>> +                pkt_hop = -1;
>>>>>>> +        }
>>>>>>> +
>>>>>> I believe the following check is redundant for non inline case. I 
>>>>>> believe get_hop_for_offload_pkt can also set the 
>>>>>> RTE_LPM_LOOKUP_SUCCESS if route is success and take the (pkt_hop 
>>>>>> & RTE_LPM_LOOKUP_SUCCESS) == 0 check outside the if else block 
>>>>>> and free the packet if it is unsuccessful.
>>>>>>
>>>>>> Same comment for route6_pkts. Checking with -1 may not be a good 
>>>>>> idea if we have a flag available for the same.
>>>>>> Others can comment.
>>>>> The problem is ipv4 & ipv6 LPM lookups return different error 
>>>>> values, but we are using a single routine to get the hop for 
>>>>> offload packets. The flag(RTE_LPM_LOOKUP_SUCCESS) is only for ipv4 
>>>>> lookups. For ipv6, error is -1. If we need a cleaner solution, we 
>>>>> can have ipv4 & ipv6 variants of "get_hop_for_offload_pkt". But 
>>>>> that would be repetition of some code.
>>>>
>>>> my concern over this patch is that there is an addition of an extra 
>>>> check in the non inline case and we can get rid of that with some 
>>>> changes in the code(lib/app). Regarding route6_pkts, the code looks 
>>>> cleaner than route4_pkts
>>> If we have ipv4 and ipv6 variants of the 
>>> "get_hop_for_offload_packet" function, the code would look much 
>>> cleaner. Shall I update the patch with such a change and send v4?
>>
>> I believe we shall get rid of "RTE_LPM_LOOKUP_SUCCESS" from the 
>> rte_lpm_lookup_bulk(), we shall have similar error flags for v4 and 
>> v6 APIs. Either we can have RTE_LPM_LOOKUP_SUCCESS or -1 as check for 
>> errors.
> This will call for an ABI change. And LPM library has multiple 
> variants for v4 & v6 lookups. We will need to modify all such 
> instances. I've CCed Bruce for his opinion on this matter. If 
> maintainers can decide on how to address this properly, I can plan my 
> next steps accordingly.
Maybe this alternative approach will help: change the 
get_hop_for_offload_packet to return -1 for v6 and clear 
RTE_LPM_LOOKUP_SUCCESS flag for v4 errors. This will be on the error 
path so the extra code to check the pkt type will have no performance 
impact, and the route function can be cleaner and we can lose the extra 
if in the v4 one.
>> Sergio can comment on this.
>>
>> Duplicating code for get_hop_for_offload_packet may not be a good idea.
>>
>> -Akhil
>>
>