Re: [dpdk-dev] [RFC V1] examples/l3fwd-power: fix memory leak for rte_pci_device

[Huisong Li <lihuisong@huawei.com>]

Hi. Thomas

I've summed up our previous discussion.

Can you look at the final proposal again?

Do you think we should deal with the problem better?


在 2021/9/27 9:44, Huisong Li 写道:
>
> 在 2021/9/27 3:16, Thomas Monjalon 写道:
>> 26/09/2021 14:20, Huisong Li:
>>> 在 2021/9/18 16:46, Thomas Monjalon 写道:
>>>> 18/09/2021 05:24, Huisong Li:
>>>>> 在 2021/9/17 20:50, Thomas Monjalon 写道:
>>>>>> 17/09/2021 04:13, Huisong Li:
>>>>>>> How should PMD free it? What should we do? Any good suggestions?
>>>>>> Check that there is no other port sharing the same PCI device,
>>>>>> then call the PMD callback for rte_pci_remove_t.
>>>>> For primary and secondary processes, their rte_pci_device is 
>>>>> independent.
>>>> Yes it requires to free on both primary and secondary.
>>>>
>>>>> Is this for a scenario where there are multiple representor ports 
>>>>> under
>>>>> the same PCI address in the same processe?
>>>> A PCI device can have multiple physical or representor ports.
>>> Got it.
>>>>>>> Would it be more appropriate to do this in rte_eal_cleanup() if it
>>>>>>> cann't be done in the API above?
>>>>>> rte_eal_cleanup is a last cleanup for what was not done earlier.
>>>>>> We could do that but first we should properly free devices when 
>>>>>> closed.
>>>>>>
>>>>> Totally, it is appropriate that rte_eal_cleanup is responsible for
>>>>> releasing devices under the pci bus.
>>>> Yes, but if a device is closed while the rest of the app keep running,
>>>> we should not wait to free it.
>>>   From this point of view, it seems to make sense. However, 
>>> according to
>>> the OVS-DPDK
>>>
>>> usage, it calls dev_close() first, and then check whether all ports
>>> under the PCI address are
>>>
>>> closed to free rte_pci_device by calling rte_dev_remove().
>>>
>>>
>>> If we do not want the user to be aware of this, and we want
>>> rte_pci_device to be freed
>>>
>>> in a timely manner. Can we add a code logic calculating the number of
>>> ports under a PCI address
>>>
>>> and calling rte_dev_remove() to rte_eth_dev_close() to free
>>> rte_pci_device and delete it from rte_pci_bus?
>>>
>>> If we do, we may need to make some extra work, otherwise some
>>> applications, such as OVS-DPDK, will
>>>
>>> fail due to a second call to rte_dev_remove().
>> I don't understand the proposal.
>> Please could explain again the code path?
>
> 1. This RFC patch intended to free rte_pci_device in DPDK app by calling
>
> rte_dev_remove() after calling dev_close().
>
> 2. For the above-mentioned usage in OVS-DPDK, please see function
>
> netdev_dpdk_destruct() in lib/netdev-dpdk.c.
>
> 3. Later, you suggest that the release of rte_pci_device should be done
>
> in the dev_close() API, not in the rte_eal_init() which is not real-time.
>
> To sum up, the above proposal comes out.
>
>> It may deserve a separate mail thread.
>>
>>
>> .
> .