Re: [PATCH] ethdev: fix push new event

[Ferruh Yigit <ferruh.yigit@xilinx.com>]

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?

If the state flow will be as UNUSED -> ALLOCATED -> ATTACHED, above 
check should be against 'ATTACHED' I think.

>>       else
>>           return 1;
>> }
>>
>> uint16_t rte_eth_find_next(uint16_t port_id)
>> {
>>       while (port_id < RTE_MAX_ETHPORTS &&
>>               rte_eth_devices[port_id].state != *RTE_ETH_DEV_ALLOCATED*)
>>           port_id++;
>>
>>       if (port_id >= RTE_MAX_ETHPORTS)
>>           return RTE_MAX_ETHPORTS;
>>
>>       return port_id;
>> }
> 
> Yes this is what I mean.
> 
>