From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: "Tan, Jianfeng" <jianfeng.tan@intel.com>,
"Chen, Junjie J" <junjie.j.chen@intel.com>,
"mtetsuyah@gmail.com" <mtetsuyah@gmail.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH] net/vhost: fix segfault when creating vdev dynamically
Date: Thu, 29 Mar 2018 14:35:33 +0200 [thread overview]
Message-ID: <154a606b-a225-7926-f6c0-a29e4701d36e@redhat.com> (raw)
In-Reply-To: <45023f15-9ddd-ec64-8e06-bef74c2ca533@intel.com>
On 03/27/2018 04:01 PM, Tan, Jianfeng wrote:
>
>
> On 3/27/2018 7:28 PM, Maxime Coquelin wrote:
>>
>>
>> On 03/27/2018 11:42 AM, Tan, Jianfeng wrote:
>>>
>>>
>>> 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.
>>
>> FYI, I think I reproduced such an issue with the vdev statically created
>> in the past, while doing some experiments. I didn't went further into
>> the analysis at that time, but it looks like the issue Junjie is trying
>> to address with this patch for dynamically created vdev.
>
> Yes, I have noticed that this issue mostly happens at dynamic case. Just
> try to suggest a proper way to fix. Please check if my suggestion in
> another email makes sense.
Yes, it makes sense, that's the right thing to do I think.
Thanks,
Maxime
>
> Thanks,
> Jianfeng
>
>>
>> Cheers,
>> Maxime
>
next prev parent reply other threads:[~2018-03-29 12:35 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-27 16:05 Junjie Chen
2018-03-27 8:56 ` Tan, Jianfeng
2018-03-27 9:02 ` Chen, Junjie J
2018-03-27 9:10 ` Tan, Jianfeng
2018-03-27 9:24 ` Chen, Junjie J
2018-03-27 9:42 ` Tan, Jianfeng
2018-03-27 10:18 ` Chen, Junjie J
2018-03-27 13:54 ` Tan, Jianfeng
2018-03-27 11:28 ` Maxime Coquelin
2018-03-27 14:01 ` Tan, Jianfeng
2018-03-29 12:35 ` Maxime Coquelin [this message]
2018-03-29 15:35 ` [dpdk-dev] [PATCH v2] " Junjie Chen
2018-03-29 13:16 ` Maxime Coquelin
2018-03-30 6:58 ` [dpdk-dev] [PATCH v3] " Junjie Chen
2018-03-30 7:32 ` Yang, Zhiyong
2018-03-30 7:36 ` Maxime Coquelin
2018-03-30 7:35 ` Maxime Coquelin
2018-03-30 7:43 ` Maxime Coquelin
2018-04-09 12:37 ` Jens Freimann
2018-04-10 8:11 ` Chen, Junjie J
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