Re: [dpdk-dev] [PATCH] net/vhost: fix segfault when creating vdev dynamically

["Tan, Jianfeng" <jianfeng.tan@intel.com>]

On 3/27/2018 5:24 PM, Chen, Junjie J wrote:
>>>> On 3/28/2018 12:05 AM, Junjie Chen wrote:
>>>>> when creating vdev dynamically, vhost pmd driver start directly
>>>>> without checking TX/RX queues ready or not, and thus cause
>>>>> segmentation fault when vhost library accessing queues. This patch
>>>>> add flag to check whether queues setup or not, and add driver start
>>>>> call into dev_start to allow user start it after setting up queue.
>>>> The issue is clear now. But this patch just puts the situation before below
>> fix:
>>>> "it doesn't create the actual datagram socket until you call .dev_start()."
>>> No, if the queue exist, the datagram socket still get created in vhost_create
>> API, since the vhost_driver_register still exist in vhost_create.
>>
>> The queue can never be created, as it's still not probed.
> I think we need to separate this into two cases:
> 	Statically create vdev, the datagram recreate logical is still there since queues are exist already, this patch doesn't change anything.
> 	Dynamic create vdev, as you pointed out, queue can never be created, while this should be not valid since In normal process of creating vdev dynamically, we always need to config queues. Correct me if I'm wrong.

My point is, either vdev is created statically or dynamically, when 
probe(), queues are not setup yet definitely, then *the unix socket will 
not be created* until we set up the queues and do dev_start(). If the 
unix socket is not created, then VM cannot connect to it.

> In summary, I think the previously commit fixes the static code path and this patch fixes the dynamic code path (we need to at least setup queue once).