Re: [PATCH] ethdev: fix push new event

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

在 2022/6/3 15:42, Thomas Monjalon 写道:
> 02/06/2022 13:24, lihuisong (C):
>> 在 2022/5/30 19:10, Ferruh Yigit 写道:
>>> On 5/30/2022 9:28 AM, Thomas Monjalon wrote:
>>>> [CAUTION: External Email]
>>>>
>>>> 28/05/2022 10:53, lihuisong (C):
>>>>> 在 2022/5/23 22:36, Thomas Monjalon 写道:
>>>>>> 23/05/2022 11:51, David Marchand:
>>>>>>> On Sat, May 21, 2022 at 8:57 AM Min Hu
>>>>>>> (Connor)<humin29@huawei.com>  wrote:
>>>>>>>> From: Huisong Li<lihuisong@huawei.com>
>>>>>>>>
>>>>>>>> The 'state' in struct rte_eth_dev may be used to update some
>>>>>>>> information
>>>>>>>> when app receive these events. For example, when app receives a
>>>>>>>> new event,
>>>>>>>> app may get the socket id of this port by calling
>>>>>>>> rte_eth_dev_socket_id to
>>>>>>>> setup the attached port. The 'state' is used in
>>>>>>>> rte_eth_dev_socket_id.
>>>>>>>>
>>>>>>>> If the state isn't modified to RTE_ETH_DEV_ATTACHED before
>>>>>>>> pushing the new
>>>>>>>> event, app will get the socket id failed. So this patch moves
>>>>>>>> pushing event
>>>>>>>> operation after the state updated.
>>>>>>>>
>>>>>>>> Fixes: 99a2dd955fba ("lib: remove librte_ prefix from directory
>>>>>>>> names")
>>>>>>> A patch moving code is unlikely to be at fault.
>>>>>>>
>>>>>>>
>>>>>>> Looking at the patch which moved those notifications in this point of
>>>>>>> the code, the state update was pushed after the notification on
>>>>>>> purpose.
>>>>>>> See be8cd210379a ("ethdev: fix port probing notification")
>>>>>>>
>>>>>>>        ethdev: fix port probing notification
>>>>>>>
>>>>>>>        The new device was notified as soon as it was allocated.
>>>>>>>        It leads to use a device which is not yet initialized.
>>>>>>>
>>>>>>>        The notification must be published after the initialization
>>>>>>> is done
>>>>>>>        by the PMD, but before the state is changed, in order to let
>>>>>>>        notified entities taking ownership before general availability.
>>>>>>>
>>>>>>>
>>>>>>> Do we need an intermediate state during probing?
>>>>>> Possibly. Currently we have only 3 states:
>>>>>>       RTE_ETH_DEV_UNUSED
>>>>>>       RTE_ETH_DEV_ATTACHED
>>>>>>       RTE_ETH_DEV_REMOVED
>>>>>>
>>>>>> We may add RTE_ETH_DEV_ALLOCATED just before calling
>>>>>>       rte_eth_dev_callback_process(dev, RTE_ETH_EVENT_NEW, NULL);
>>>>>> Then we would need to check against RTE_ETH_DEV_ALLOCATED
>>>>>> in some ethdev functions.
>>>>>>
>>>>> Hi, Thomas,
>>>>>
>>>>> Do you mean that we need to modify some funcions like following?
>>>>>
>>>>> int rte_eth_dev_is_valid_port(uint16_t port_id)
>>>>> {
>>>>>        if (port_id >= RTE_MAX_ETHPORTS ||
>>>>>            (rte_eth_devices[port_id].state != *RTE_ETH_DEV_ALLOCATED*))
>>>>>            return 0;
>>> Won't this mark ATTACHED devices as invalid?
>> Yes, You are right.
>>
>>> If the state flow will be as UNUSED -> ALLOCATED -> ATTACHED, above
>>> check should be against 'ATTACHED' I think.
> It should validate both ALLOCATED and ATTACHED.
Actually, we can only pick one, because it is an enumeration.
>
>
>> If these check is against 'ATTACHED', it goes back to the issue this
>> patch mentioned.
>>
>> The failsafe PMD applications expect sending event before device state
>> set to 'ATTACHED'.
>> But other applications expect the device with 'ATTACHED' state before
>> send event.
>> They are in conflict with each other. So we can't solve this issue by
>> adding an
>> 'RTE_ETH_DEV_ALLOCATED' state.
>
>
> .