Re: [dpdk-dev] [RFC] net/null: add empty promiscuous mode functions

[Andrew Rybchenko <arybchenko@solarflare.com>]

On 10/16/19 9:07 PM, Ferruh Yigit wrote:
> On 10/16/2019 4:46 PM, Ciara Power wrote:
>> Adding promiscuous functions prevents sample applications failing when run
>> on this virtual PMD. The sample applications call promiscuous functions,
>> and fail if this function call returns an error, which occurs when the
>> virtual PMD does not support the promiscuous function being called.
>>
>> This change will be implemented for all virtual PMDs that currently do not
>> have existing promiscuous functions. Multicast functions will also be
>> added for virtual PMDs to prevent sample application breakages here also.
> +Andrew
>
> With the some ethdev APIs returning error code, some sample applications stop
> working with virtual interfaces,
>
> We can,
> 1- update sample applications to ignore the errors
> 2- Add dummy dev_ops support to (almost all) virtual PMDs (what this RFC suggests)
>
> (1) puts us back to before the ethdev APIs updated status, and this may be wrong
> for the physical devices case, so I am for this RFC.
>
> Only perhaps we can have some common empty function and keep assigning that one
> to reduce the dummy code, what do you think?

I don't like the idea to have common empty/dummy functions.
If virtual PMD behaves in accordance with enabled promiscuous mode,
it should initialize it properly on init:
      eth_dev->data->promiscuous = 1;
If so, if application requires promiscuous mode, attempt to enable will
do nothing. If application requires non-promiscuous mode, disable will
fail and it is good.

>> Signed-off-by: Ciara Power <ciara.power@intel.com>
>> ---
>>   drivers/net/null/rte_eth_null.c | 14 ++++++++++++++
>>   1 file changed, 14 insertions(+)
>>
>> diff --git a/drivers/net/null/rte_eth_null.c b/drivers/net/null/rte_eth_null.c
>> index e2ff41a22..b8472a0cf 100644
>> --- a/drivers/net/null/rte_eth_null.c
>> +++ b/drivers/net/null/rte_eth_null.c
>> @@ -441,11 +441,25 @@ eth_mac_address_set(__rte_unused struct rte_eth_dev *dev,
>>   	return 0;
>>   }
>>   
>> +static int
>> +eth_dev_promiscuous_enable(__rte_unused struct rte_eth_dev *dev)
>> +{
>> +	return 0;
>> +}
>> +
>> +static int
>> +eth_dev_promiscuous_disable(__rte_unused struct rte_eth_dev *dev)
>> +{
>> +	return 0;
>> +}
>> +
>>   static const struct eth_dev_ops ops = {
>>   	.dev_start = eth_dev_start,
>>   	.dev_stop = eth_dev_stop,
>>   	.dev_configure = eth_dev_configure,
>>   	.dev_infos_get = eth_dev_info,
>> +	.promiscuous_enable = eth_dev_promiscuous_enable,
>> +	.promiscuous_disable = eth_dev_promiscuous_disable,
>>   	.rx_queue_setup = eth_rx_queue_setup,
>>   	.tx_queue_setup = eth_tx_queue_setup,
>>   	.rx_queue_release = eth_queue_release,
>>