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

["Min Hu (Connor)" <humin29@huawei.com>]

Hi, Ferruh,
	what do you think of this patch?


在 2021/11/8 14:55, lihuisong (C) 写道:
> 
> 在 2021/10/26 18:21, Ferruh Yigit 写道:
>> On 10/22/2021 3:04 AM, lihuisong (C) wrote:
>>>
>>> 在 2021/10/21 16:30, Ferruh Yigit 写道:
>>>> On 10/21/2021 3:05 AM, lihuisong (C) wrote:
>>>>>
>>>>> 在 2021/10/21 0:32, Ferruh Yigit 写道:
>>>>>> On 10/20/2021 11:15 AM, Kevin Traynor wrote:
>>>>>>> On 20/10/2021 08:41, Ferruh Yigit wrote:
>>>>>>>> On 10/20/2021 7:49 AM, lihuisong (C) wrote:
>>>>>>>>> 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.
>>>>>>>>
>>>>>>>> True, it is a waste. But if there is no other visible user 
>>>>>>>> impact, we can
>>>>>>>> handle the issue with lower priority and clarifying the impact 
>>>>>>>> in commit log
>>>>>>>> helps to others.
>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>> 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.
>>>>>>>>
>>>>>>>> I am not sure all PMD take this into account, I briefly checked 
>>>>>>>> the ixgbe
>>>>>>>> code and I am not sure if it handles this.
>>>>>>>>
>>>>>>>> Also it is possible to think that this responsibility is pushed 
>>>>>>>> to the
>>>>>>>> application, like application should remove a MAC address before 
>>>>>>>> setting
>>>>>>>> it as default MAC...
>>>>>>>>
>>>>>>>
>>>>>>> Yes, the API view is more important than saving one entry in an 
>>>>>>> array. From API perspective with this patch,
>>>>>>>
>>>>>>> set_default(MAC1)
>>>>>>> add(MAC2)
>>>>>>> add(MAC3)
>>>>>>> add(MAC4)
>>>>>>> default=MAC1, Filters=MAC2, MAC3, MAC4
>>>>>>>
>>>>>>> set_default(MAC2)
>>>>>>> default=MAC2, Filters= MAC3, MAC4
>>>>>>>
>>>>>>> set_default(MAC3)
>>>>>>> default=MAC3, Filters= MAC4
>>>>>>>
>>>>>>> set_default(MAC4)
>>>>>>> default=MAC4, Filters=
>>>>>>>
>>>>>>> set_default(MAC5)
>>>>>>> default=MAC5, Filters=
>>>>>>>
>>>>>>> Did I get it right? If so, it seems wrong to silently remove the 
>>>>>>> filters. In which case, it would be easier to just not remove 
>>>>>>> them in the first place (current behaviour).
>>>>>>>
>>>>>>
>>>>>> Yep, this is the updated behavior. And agree it looks wrong when you
>>>>>> show like this. (btw, this is only ethdev record of MAC filters, what
>>>>>> is updated in this patch, HW still may be keeping all filters.)
>>>>>
>>>>> Whether HW saves all filters depends on the implementation of the 
>>>>> set_default()
>>>>>
>>>>> in the driver. According to the implementation of this API of all 
>>>>> PMDs, some drivers
>>>>>
>>>>> will first remove the old default MAC in HW and then add the new 
>>>>> one when calling
>>>>>
>>>>> the set_default(). I am not sure if the HW that didn't do this 
>>>>> would remove the old
>>>>>
>>>>> default MAC. If not, we may need to standardize this API in the 
>>>>> ethdev layer.
>>>>>
>>>>>>
>>>>>>> If they really need to be removed from the filter list when they 
>>>>>>> are set_default(), then perhaps they should be restored to it 
>>>>>>> when there is a new set_default().
>>>>>>>
>>>>>>
>>>>>> I am for keeping current behavior. Application always can 
>>>>>> explicitly remove a
>>>>>> MAC filter before setting it default if required.
>>>>>
>>>>> But application can not remove the duplicate MAC if the MAC is the 
>>>>> current default
>>>>>
>>>>> MAC by rte_eth_dev_mac_addr_remove(). In this case, it will failed 
>>>>> to remove.
>>>>>
>>>>
>>>> But can do other-way around, first remove (the non default one), later
>>>> 'rte_eth_dev_default_mac_addr_set()'.
>>>
>>> This introduces a usage dependency on the user. We don't have a 
>>> statement in some place
>>>
>>> for the dependency. What's more, if the user does not follow this 
>>> dependency, the user
>>>
>>> will no longer be able to remove the MAC.
>>>
>>> So it may be more appropriate to deal with problem in ethdev layer.
>>>
>>>
>>> **Scheme A:**
>>>
>>> The decision is left to the user, but there are usage dependency and 
>>> irremovable possibility.**
>>> **
>>>
>>> *Scheme B:*
>>>
>>> index = eth_dev_get_mac_addr_index(port_id, addr);
>>> if (index > 0) {
>>>      mac_pool_sel_bk = dev->data->mac_pool_sel[index];
>>>      rte_eth_dev_mac_addr_remove(port_id, addr);
>>> }
>>> ret = (*dev->dev_ops->mac_addr_set)(dev, addr);
>>> if (ret < 0) {
>>>      if (index > 0) {
>>>          rte_eth_dev_mac_addr_add(port_id, addr, 0);
>>>          dev->data->mac_pool_sel[index] = mac_pool_sel_bk;
>>>      }
>>>
>>>      return ret;
>>> }
>>>
>>> * Scheme C:*
>>>
>>>   Use the method in this patch. It assumes that the driver has only 
>>> one HW entry for a MAC.
>>>
>>> What do you think we should do?
>>>
>>
>> If the impact is only loosing one entry in the array without any 
>> functional
>> effect, I am OK to keep behavior as it is.
>>
>> If there is more motivation for fix, I would prefer option B to be 
>> sure all
>> drivers behave same by explicit remove.
>> .
> 
> Hi, Ferruh
> 
> There may be a functional problem in one scenario if we don't fix this.
> 
> Testpmd does the following steps:
> 
> 1) add MAC1/2/3
> 
> mac_addr add 0 MAC1
> 
> mac_addr add 0 MAC2
> 
> mac_addr add 0 MAC3
> 
> 2) then set new default MAC3
> 
> mac_addr set 0 MAC3
> 
> 3）show mac_addrs list
> 
> MAC3
> 
> MAC1
> 
> MAC2
> 
> MAC3
> 
> 4）then set new default MAC4
> 
> mac_addr set 0 MAC4
> 
> 5) now, the mac_addrs list is as follows:
> 
> MAC4
> 
> MAC1
> 
> MAC2
> 
> MAC3
> 
> 
> As a result, the network engine cannot receive packets from MAC3.
> 
> But application can see the MAC3 in mac_addrs list.
> 
> Btw, rte_eth_dev_default_mac_addr_set() will replace the old default MAC 
> with
> 
> the new one, and the old one will be deleted.
> 
> 
> So, we should fix it. What do you think? Thanks.
> 
> 
> 
> 
> 
> 
> 
> .