[dpdk-dev] [PATCH] ethdev: fix wrong memset

[Ferruh Yigit]

On 1/23/2017 11:24 AM, Yuanhan Liu wrote:
> On Mon, Jan 23, 2017 at 11:05:25AM +0000, Ferruh Yigit wrote:
>>>>>>>>  lib/librte_ether/rte_ethdev.c | 2 +-
>>>>>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>>>>
>>>>>>>> diff --git a/lib/librte_ether/rte_ethdev.c b/lib/librte_ether/rte_ethdev.c
>>>>>>>> index 4790faf..61f44e2 100644
>>>>>>>> --- a/lib/librte_ether/rte_ethdev.c
>>>>>>>> +++ b/lib/librte_ether/rte_ethdev.c
>>>>>>>> @@ -225,7 +225,7 @@ struct rte_eth_dev *
>>>>>>>>  		return NULL;
>>>>>>>>  	}
>>>>>>>>  
>>>>>>>> -	memset(&rte_eth_devices[port_id], 0, sizeof(*eth_dev->data));
>>>>>>>> +	memset(&rte_eth_dev_data[port_id], 0, sizeof(struct rte_eth_dev_data));
>>>>>>>
>>>>>>> Not directly related to the this issue, but, after fix, this may have
>>>>>>> issues with secondary process.
>>>>>>>
>>>>>>> There were patches sent to fix this.
>>>>>>
>>>>>> I mean this one:
>>>>>> http://dpdk.org/ml/archives/dev/2017-January/054422.html
>>>>>
>>>>> d948f596fee2 ("ethdev: fix port data mismatched in multiple process
>>>>> model") should have fixed it.
>>>>
>>>> Think about case, where secondary process uses a virtual PMD, which does
>>>> a rte_eth_dev_allocate() call, shouldn't this corrupt primary process
>>>> device data?
>>>
>>> Yes, it may. However, I doubt that's the typical usage. 
>>
>> But this is a use case, and broken now,
> 
> I thought it was broken since the beginning?

No, memset(&rte_eth_dev_data[port_id], ...) breaks it.

> 
>> and fix is known.
> 
> And there is already a fix?

http://dpdk.org/ml/archives/dev/2017-January/054422.html

> 
>> Should be
>> fixed I think.
> 
> Sure.
> 
>>
>>> Besides that,
>>> most of virtual PMDs don't support Multipleprocess: git grep shows pcap
>>> is the only one that does claim Multipleprocess is supported.
>>
>> I guess you searched for NIC feature documentation for this.
> 
> Yes.
> 
>> But as far
>> as I know, all virtual drivers can be used in both primary and secondary
>> process.
> 
> Maybe. But it becomes very error-prone to me then when vdev are involved
> in both primary and secondary process. I don't think current code is (or
> designed to be) strong enough to support that.
> 
> I don't know it's allowed to use hotplug or not in the multiple process
> model. If yes, I think there would be many ways to break it.
> 
> Honestly, the multiple process doesn't look like a good/clean design to
> me, especially when some piece of code claim to support it while some
> other doesn't.
> 
> So my point was, yes, there is a bug, we should fix it. But it seems
> that there could be so many bugs if we hugely expand the test coverage
> of the multiple process feature.

Agreed.

> 
> 	--yliu
>