Re: [PATCH 3/4] lib/librte_port: add packet dumping to PCAP file support in sink port

["Zhang, Roy Fan" <roy.fan.zhang@intel.com>]

Hi Panu,

Thank you again for careful review and comments.

On 28/01/2016 11:43, Panu Matilainen wrote:
> On 01/27/2016 07:39 PM, Fan Zhang wrote:
>> Originally, sink ports in librte_port releases received mbufs back to
>> mempool. This patch adds optional packet dumping to PCAP feature in sink
>> port: the packets will be dumped to user defined PCAP file for 
>> storage or
>> debugging. The user may also choose the sink port's activity: either it
>> continuously dump the packets to the file, or stops at certain dumping
>>
>> This feature shares same CONFIG_RTE_PORT_PCAP compiler option as source
>> port PCAP file support feature. Users can enable or disable this feature
>> by setting CONFIG_RTE_PORT_PCAP compiler option "y" or "n".
>>
>> Signed-off-by: Fan Zhang <roy.fan.zhang@intel.com>
>> Acked-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>
>> ---
>>   lib/librte_port/rte_port_source_sink.c | 268 
>> +++++++++++++++++++++++++++++++--
>>   lib/librte_port/rte_port_source_sink.h |  11 +-
>>   2 files changed, 263 insertions(+), 16 deletions(-)
>>
> [...]
>> +#ifdef RTE_PORT_PCAP
>> +
>> +/**
>> + * Open PCAP file for dumping packets to the file later
>> + *
>> + * @param port
>> + *   Handle to sink port
>> + * @param p
>> + *   Sink port parameter
>> + * @return
>> + *   0 on SUCCESS
>> + *   error code otherwise
>> + */
> [...]
>> +
>> +#else
>> +
>> +static int
>> +pcap_sink_open(struct rte_port_sink *port,
>> +        __rte_unused struct rte_port_sink_params *p)
>> +{
>> +    port->dumper = NULL;
>> +    port->max_pkts = 0;
>> +    port->pkt_index = 0;
>> +    port->dump_finish = 0;
>> +
>> +    return 0;
>> +}
>
> Shouldn't this just return -ENOTSUP instead of success when the pcap 
> feature is not built in?

I agree, I will modify the code in v2.

>> +
>> +static void
>> +pcap_sink_dump_pkt(__rte_unused struct rte_port_sink *port,
>> +        __rte_unused struct rte_mbuf *mbuf) {}
>> +
>> +static void
>> +pcap_sink_flush_pkt(__rte_unused void *dumper) {}
>> +
>> +static void
>> +pcap_sink_close(__rte_unused void *dumper) {}
>> +
>> +#endif
>> +
>>   static void *
>>   rte_port_sink_create(__rte_unused void *params, int socket_id)
>>   {
>>       struct rte_port_sink *port;
>> +    struct rte_port_sink_params *p = params;
>> +    int status;
>>
>>       /* Memory allocation */
>>       port = rte_zmalloc_socket("PORT", sizeof(*port),
>> @@ -360,6 +532,19 @@ rte_port_sink_create(__rte_unused void *params, 
>> int socket_id)
>>           return NULL;
>>       }
>>
>> +    /* Try to open PCAP file for dumping, if possible */
>> +    status = pcap_sink_open(port, p);
>> +    if (status < 0) {
>> +        RTE_LOG(ERR, PORT, "%s: Failed to enable PCAP support "
>> +                "support\n", __func__);
>> +        rte_free(port);
>> +        port = NULL;
>> +    } else {
>> +        if (port->dumper != NULL)
>> +            RTE_LOG(INFO, PORT, "Ready to dump packets to file "
>> +                    "%s\n", p->file_name);
>> +    }
>> +
>>       return port;
>>   }
>>
>> @@ -369,6 +554,8 @@ rte_port_sink_tx(void *port, struct rte_mbuf *pkt)
>>       __rte_unused struct rte_port_sink *p = (struct rte_port_sink *) 
>> port;
>>
>>       RTE_PORT_SINK_STATS_PKTS_IN_ADD(p, 1);
>> +    if (p->dumper != NULL)
>> +        pcap_sink_dump_pkt(p, pkt);
>>       rte_pktmbuf_free(pkt);
>>       RTE_PORT_SINK_STATS_PKTS_DROP_ADD(p, 1);
>>
>> @@ -387,21 +574,44 @@ rte_port_sink_tx_bulk(void *port, struct 
>> rte_mbuf **pkts,
>>
>>           RTE_PORT_SINK_STATS_PKTS_IN_ADD(p, n_pkts);
>>           RTE_PORT_SINK_STATS_PKTS_DROP_ADD(p, n_pkts);
>> -        for (i = 0; i < n_pkts; i++) {
>> -            struct rte_mbuf *pkt = pkts[i];
>> -
>> -            rte_pktmbuf_free(pkt);
>> +        if (p->dumper) {
>> +            for (i = 0; i < n_pkts; i++) {
>> +                struct rte_mbuf *pkt = pkts[i];
>> +
>> +                pcap_sink_dump_pkt(p, pkt);
>> +                rte_pktmbuf_free(pkt);
>> +            }
>> +        } else {
>> +            for (i = 0; i < n_pkts; i++) {
>> +                struct rte_mbuf *pkt = pkts[i];
>> +
>> +                rte_pktmbuf_free(pkt);
>> +            }
>>           }
>>       } else {
>> -        for ( ; pkts_mask; ) {
>> -            uint32_t pkt_index = __builtin_ctzll(pkts_mask);
>> -            uint64_t pkt_mask = 1LLU << pkt_index;
>> -            struct rte_mbuf *pkt = pkts[pkt_index];
>> -
>> -            RTE_PORT_SINK_STATS_PKTS_IN_ADD(p, 1);
>> -            RTE_PORT_SINK_STATS_PKTS_DROP_ADD(p, 1);
>> -            rte_pktmbuf_free(pkt);
>> -            pkts_mask &= ~pkt_mask;
>> +        if (p->dumper) {
>> +            for ( ; pkts_mask; ) {
>> +                uint32_t pkt_index = __builtin_ctzll(pkts_mask);
>> +                uint64_t pkt_mask = 1LLU << pkt_index;
>> +                struct rte_mbuf *pkt = pkts[pkt_index];
>> +
>> +                RTE_PORT_SINK_STATS_PKTS_IN_ADD(p, 1);
>> +                RTE_PORT_SINK_STATS_PKTS_DROP_ADD(p, 1);
>> +                pcap_sink_dump_pkt(p, pkt);
>> +                rte_pktmbuf_free(pkt);
>> +                pkts_mask &= ~pkt_mask;
>> +            }
>> +        } else {
>> +            for ( ; pkts_mask; ) {
>> +                uint32_t pkt_index = __builtin_ctzll(pkts_mask);
>> +                uint64_t pkt_mask = 1LLU << pkt_index;
>> +                struct rte_mbuf *pkt = pkts[pkt_index];
>> +
>> +                RTE_PORT_SINK_STATS_PKTS_IN_ADD(p, 1);
>> +                RTE_PORT_SINK_STATS_PKTS_DROP_ADD(p, 1);
>> +                rte_pktmbuf_free(pkt);
>> +                pkts_mask &= ~pkt_mask;
>> +            }
>
> These add quite a fair chunk of nearly identical duplicate code, which 
> could be easily avoided with an _ops-style function pointer between 
> say, null_sink_dump_pkt() which is a no-op function and 
> pcap_sink_dump_pkt().

The reason of doing this is to avoid using if/else in for loop to speed 
up a little. But your suggestion is quite nice, I will think better way 
like this and modify the code.

>     - Panu -

Best regards,
Fan