linux-kernel - Re: [PATCH rdma-next 4/5] RDMA/hns: Add reset process for RoCE in hip08

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Date:   Wed, 23 May 2018 10:54:54 +0800
From:   "Wei Hu (Xavier)" <xavier.huwei@...wei.com>
To:     Jason Gunthorpe <jgg@...pe.ca>
CC:     <dledford@...hat.com>, <linux-rdma@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <xavier.huwei@....com>,
        <lijun_nudt@....com>
Subject: Re: [PATCH rdma-next 4/5] RDMA/hns: Add reset process for RoCE in
 hip08



On 2018/5/23 4:26, Jason Gunthorpe wrote:
> On Fri, May 18, 2018 at 03:23:00PM +0800, Wei Hu (Xavier) wrote:
>>
>> On 2018/5/18 12:15, Jason Gunthorpe wrote:
>>> On Fri, May 18, 2018 at 11:28:11AM +0800, Wei Hu (Xavier) wrote:
>>>> On 2018/5/17 23:14, Jason Gunthorpe wrote:
>>>>> On Thu, May 17, 2018 at 04:02:52PM +0800, Wei Hu (Xavier) wrote:
>>>>>> diff --git a/drivers/infiniband/hw/hns/hns_roce_hw_v2.c b/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
>>>>>> index 86ef15f..e1c44a6 100644
>>>>>> +++ b/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
>>>>>> @@ -774,6 +774,9 @@ static int hns_roce_cmq_send(struct hns_roce_dev *hr_dev,
>>>>>>  	int ret = 0;
>>>>>>  	int ntc;
>>>>>>  
>>>>>> +	if (hr_dev->is_reset)
>>>>>> +		return 0;
>>>>>> +
>>>>>>  	spin_lock_bh(&csq->lock);
>>>>>>  
>>>>>>  	if (num > hns_roce_cmq_space(csq)) {
>>>>>> @@ -4790,6 +4793,7 @@ static int hns_roce_hw_v2_init_instance(struct hnae3_handle *handle)
>>>>>>  	return 0;
>>>>>>  
>>>>>>  error_failed_get_cfg:
>>>>>> +	handle->priv = NULL;
>>>>>>  	kfree(hr_dev->priv);
>>>>>>  
>>>>>>  error_failed_kzalloc:
>>>>>> @@ -4803,14 +4807,70 @@ static void hns_roce_hw_v2_uninit_instance(struct hnae3_handle *handle,
>>>>>>  {
>>>>>>  	struct hns_roce_dev *hr_dev = (struct hns_roce_dev *)handle->priv;
>>>>>>  
>>>>>> +	if (!hr_dev)
>>>>>> +		return;
>>>>>> +
>>>>>>  	hns_roce_exit(hr_dev);
>>>>>> +	handle->priv = NULL;
>>>>>>  	kfree(hr_dev->priv);
>>>>>>  	ib_dealloc_device(&hr_dev->ib_dev);
>>>>>>  }
>>>>> Why are these hunks here? If init fails then uninit should not be
>>>>> called, so why meddle with priv?
>>>> In hns_roce_hw_v2_init_instance function, we evaluate handle->priv with 
>>>> hr_dev,
>>>> We want clear the value in hns_roce_hw_v2_uninit_instance function.
>>>> So we can ensure no problem in RoCE driver.
>>> What problem could happen?
>>>
>>> I keep removing unnecessary sets to null and checks of null, so please
>>> don't add them if they cannot happen.
>>>
>>> Eg uninit should never be called with a null priv, that is a serious
>>> logic mis-design someplace if it happens.
>>>
>>> Jason
>> NIC driver call the registered reset_notify() function to finish the
>> part of RoCE reset process.
>> In RoCE driver,  when hnae3_reset_notify_type is HNAE3_UNINIT_CLIENT,
>> we call hns_roce_hw_v2_uninit_instance(handle, false) to release the
>> resources.
>> when hnae3_reset_notify_type is HNAE3_INIT_CLIENT, we call
>> hns_roce_hw_v2_init_instance.
>> if hns_roce_hw_v2_init_instance failed, we should ensure no problem in
>> the other callback
>> function registered by RoCE driver.
> Don't design things like this.
>
> init/uninit are paired - do not call something uninit if it can be
> called after init fails, or better, arrange to prevent that so things
> are sane.
>
> Jason
>
> .
The current RoCE driver registered 3 callback function to NIC driver as
belows:
1.init_instance/uninit_instance are paired.
2.In reset_notify function,  RoCE dirver still call
init_instance/uninit_instance function.
but NIC driver does not perceive the behavior.  We need to judge in RoCE
driver.

static const struct hnae3_client_ops hns_roce_hw_v2_ops = {
    .init_instance = hns_roce_hw_v2_init_instance,
    .uninit_instance = hns_roce_hw_v2_uninit_instance,
    .reset_notify = hns_roce_hw_v2_reset_notify,
};

Wei Hu
>