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 11:49:13 +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 10:54, Wei Hu (Xavier) wrote:
>
> 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,
> };
struct hnae3_handle is defined in NIC driver, and handle->priv is used
for RoCE driver,
NIC driver will not use this member handle->priv.

struct hnae3_handle {
    struct hnae3_client *client;
    struct pci_dev *pdev;
    void *priv;
    struct hnae3_ae_algo *ae_algo;  /* the class who provides this handle */
    u64 flags; /* Indicate the capabilities for this handle*/

    unsigned long last_reset_time;
    enum hnae3_reset_type reset_level;

    union {
        struct net_device *netdev; /* first member */
        struct hnae3_knic_private_info kinfo;
        struct hnae3_unic_private_info uinfo;
        struct hnae3_roce_private_info rinfo;
    };

    u32 numa_node_mask;    /* for multi-chip support */
};
> Wei Hu
>
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> .
>