Re: [dpdk-dev] [PATCH v2] ethdev: fix one MAC address occupies two index in mac addrs

["lihuisong (C)" <lihuisong@huawei.com>]

Hi Ferruh

在 2021/10/20 1:45, Ferruh Yigit 写道:
> On 10/11/2021 10:28 AM, Min Hu (Connor) wrote:
>> From: Huisong Li <lihuisong@huawei.com>
>>
>> The dev->data->mac_addrs[0] will be changed to a new MAC address when
>> applications modify the default MAC address by
>> rte_eth_dev_default_mac_addr_set() API. However, If the new default
>> MAC address has been added as a non-default MAC address by
>> rte_eth_dev_mac_addr_add() API, the rte_eth_dev_default_mac_addr_set()
>> API doesn't remove it from dev->data->mac_addrs[]. As a result, one MAC
>> address occupies two index capacities in dev->data->mac_addrs[].
>>
>
> Hi Connor,
>
> I see the problem, but can you please clarify what is the impact to 
> the end user?
>
> If application does as following:
>   rte_eth_dev_mac_addr_add(MAC1);
>   rte_eth_dev_mac_addr_add(MAC2);
>   rte_eth_dev_mac_addr_add(MAC3);
>   rte_eth_dev_default_mac_addr_set(MAC2);
>
> The 'dev->data->mac_addrs[]' will have: "MAC2,MAC2,MAC3" which has 
> 'MAC2' duplicated.
>
> Will this cause any problem for the application to receive the packets
> with 'MAC2' address?
> Or is the only problem one extra space used in 'dev->data->mac_addrs[]'
> without any other impact to the application?
I think it's just a waste of space.
>
>> This patch adds the logic of removing MAC addresses for this scenario.
>>
>> Fixes: 854d8ad4ef68 ("ethdev: add default mac address modifier")
>> Cc: stable@dpdk.org
>>
>> Signed-off-by: Huisong Li <lihuisong@huawei.com>
>> Signed-off-by: Min Hu (Connor) <humin29@huawei.com>
>> ---
>> v2:
>> * fixed commit log.
>> ---
>>   lib/ethdev/rte_ethdev.c | 15 +++++++++++++++
>>   1 file changed, 15 insertions(+)
>>
>> diff --git a/lib/ethdev/rte_ethdev.c b/lib/ethdev/rte_ethdev.c
>> index 028907bc4b..7faff17d9a 100644
>> --- a/lib/ethdev/rte_ethdev.c
>> +++ b/lib/ethdev/rte_ethdev.c
>> @@ -4340,6 +4340,7 @@ int
>>   rte_eth_dev_default_mac_addr_set(uint16_t port_id, struct 
>> rte_ether_addr *addr)
>>   {
>>       struct rte_eth_dev *dev;
>> +    int index;
>>       int ret;
>>         RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
>> @@ -4361,6 +4362,20 @@ rte_eth_dev_default_mac_addr_set(uint16_t 
>> port_id, struct rte_ether_addr *addr)
>>       if (ret < 0)
>>           return ret;
>>   +    /*
>> +     * If the address has been added as a non-default MAC address by
>> +     * rte_eth_dev_mac_addr_add API, it should be removed from
>> +     * dev->data->mac_addrs[].
>> +     */
>> +    index = eth_dev_get_mac_addr_index(port_id, addr);
>> +    if (index > 0) {
>> +        /* remove address in NIC data structure */
>> +        rte_ether_addr_copy(&null_mac_addr,
>> +                    &dev->data->mac_addrs[index]);
>> +        /* reset pool bitmap */
>> +        dev->data->mac_pool_sel[index] = 0;
>> +    }
>> +
>
> Here only 'dev->data->mac_addrs[]' array is updated and it assumes
> driver removes similar duplication itself, but I am not sure if this is
> valid for all drivers.
>
> If driver is not removing the duplicate in the HW configuration, the 
> driver
> config and 'dev->data->mac_addrs[]' will diverge, which is not good.
The same MAC address does not occupy two HW entries, which is also a
waste for HW. After all, HW entry resources are also limited.
The PMD should also take this into account.
So, I think, we don't have to think about it here.
>
> What about following logic to be sure HW configuration and
> 'dev->data->mac_addrs[]' is same:
>
>   index = eth_dev_get_mac_addr_index(port_id, addr);
>   if (index > 0)
> rte_eth_dev_mac_addr_remove(port_id, addr);
>   (*dev->dev_ops->mac_addr_set)(dev, addr);
The logic above seems to be good. But if .mac_addr_set() failed to
execute, the addr has been removed from HW and 'dev->data->mac_addrs[]'.
It's not good.

Hope for your reply.  Thanks.
>>       /* Update default address in NIC data structure */
>>       rte_ether_addr_copy(addr, &dev->data->mac_addrs[0]);
>>
>
> .