[PATCH v4] net/af_xdp: re-enable secondary process support

[Ferruh Yigit]

On 2/9/2022 5:55 PM, Ferruh Yigit wrote:
> On 2/9/2022 9:48 AM, Ciara Loftus wrote:
>> Secondary process support had been disabled for the AF_XDP PMD because
>> there was no logic in place to share the AF_XDP socket file descriptors
>> between the processes. This commit introduces this logic using the IPC
>> APIs.
>>
>> Rx and Tx are disabled in the secondary process due to memory mapping of
>> the AF_XDP rings being assigned by the kernel in the primary process only.
>> However other operations including retrieval of stats are permitted.
>>
>> Signed-off-by: Ciara Loftus <ciara.loftus at intel.com>
>>
>> ---
>> v3 -> v4:
>> * Rebase to next-net
>> * Reword limitation which requires Rx and Tx to be disabled.
>>
>> v2 -> v3:
>> * Rebase to next-net
>> * Updated logs to be more specific about multi-process IPC
>> * Free process_private in _close and _remove functions
>> * Use rte_eth_dev_get_by_name instead of global array
>>
>> v1 -> v2:
>> * Rebase to next-net
>>
>> RFC -> v1:
>> * Added newline to af_xdp.rst
>> * Fixed spelling errors
>> * Fixed potential NULL dereference in init_internals
>> * Fixed potential free of address-of expression in afxdp_mp_request_fds
>> ---
>>   doc/guides/nics/af_xdp.rst             |   9 ++
>>   doc/guides/nics/features/af_xdp.ini    |   1 +
>>   doc/guides/rel_notes/release_22_03.rst |   1 +
>>   drivers/net/af_xdp/rte_eth_af_xdp.c    | 215 +++++++++++++++++++++++--
>>   4 files changed, 211 insertions(+), 15 deletions(-)
>>

<...>

>> +
>> +/* Secondary process rx function. RX is disabled because memory mapping of the
>> + * rings being assigned by the kernel in the primary process only.
>> + */
>> +static uint16_t
>> +eth_af_xdp_rx_noop(void *queue __rte_unused,
>> +        struct rte_mbuf **bufs __rte_unused,
>> +        uint16_t nb_pkts __rte_unused)
>> +{
>> +    return 0;
>> +}
>> +
>> +/* Secondary process tx function. TX is disabled because memory mapping of the
>> + * rings being assigned by the kernel in the primary process only.
>> + */
>> +static uint16_t
>> +eth_af_xdp_tx_noop(void *queue __rte_unused,
>> +            struct rte_mbuf **bufs __rte_unused,
>> +            uint16_t nb_pkts __rte_unused)
>> +{
>> +    return 0;
>> +}
>> +
> 
> Hi Ciara,
> 
> Can you please review following patch, if it is good we can merge it first
> and rebase this patch on top of it to use generic dummy burst functions.
> 
> "ethdev: introduce generic dummy packet burst function"
> https://patches.dpdk.org/project/dpdk/patch/20220208194437.426143-1-ferruh.yigit@intel.com/
> 

That ethdev patch can be delayed, so I will proceed with this patch.
noop burst functions in the PMD can be updated later.