On 2019/1/26 5:50, Jason Gunthorpe wrote:
> On Fri, Jan 25, 2019 at 10:15:40AM +0800, Wei Hu (Xavier) wrote:
>>
>> On 2019/1/25 2:31, Jason Gunthorpe wrote:
>>> On Thu, Jan 24, 2019 at 11:13:29AM +0800, Wei Hu (Xavier) wrote:
>>>> On 2019/1/24 6:40, Jason Gunthorpe wrote:
>>>>> On Sat, Jan 19, 2019 at 11:36:06AM +0800, Wei Hu (Xavier) wrote:
>>>>>
>>>>>> +static int hns_roce_v2_cmd_hw_resetting(struct hns_roce_dev *hr_dev,
>>>>>> + unsigned long instance_stage,
>>>>>> + unsigned long reset_stage)
>>>>>> +{
>>>>>> + struct hns_roce_v2_priv *priv = (struct hns_roce_v2_priv *)hr_dev->priv;
>>>>>> + struct hnae3_handle *handle = priv->handle;
>>>>>> + const struct hnae3_ae_ops *ops = handle->ae_algo->ops;
>>>>>> + unsigned long end;
>>>>>> +
>>>>>> + /* When hardware reset is detected, we should stop sending mailbox&cmq
>>>>>> + * to hardware, and wait until hardware reset finished. If now
>>>>>> + * in .init_instance() function, we should exit with error. If now at
>>>>>> + * HNAE3_INIT_CLIENT stage of soft reset process, we should exit with
>>>>>> + * error, and then HNAE3_INIT_CLIENT related process can rollback the
>>>>>> + * operation like notifing hardware to free resources, HNAE3_INIT_CLIENT
>>>>>> + * related process will exit with error to notify NIC driver to
>>>>>> + * reschedule soft reset process once again.
>>>>>> + */
>>>>>> + end = msecs_to_jiffies(HNS_ROCE_V2_HW_RST_TIMEOUT) + jiffies;
>>>>>> + while (ops->get_hw_reset_stat(handle) && time_before(jiffies, end))
>>>>>> + udelay(1);
>>>>> I thought you were getting rid of these loops?
>>>> Hi, Jason
>>>>
>>>> Upper applications maybe notify driver to issue mailbox or CMD
>>>> commands to hardware, some commands used to cancel resources,
>>>> destory bt/destory cq/unreg mr/destory qp etc. when such
>>>> commands are executed successfully, the hardware engine will
>>>> no longer access some memory registered by the driver.
>>>>
>>>> When reset occurs, it is possible for upper applications notify driver
>>>> to issue mailbox or CMD commands, we need to wait until hardware
>>>> reset finished to ensure that hardware no longer accesses related
>>>> memory.
>>> You should not wait for things using loops like the above.
>> Hi, Jason
>>
>> Are your comments foucsing on udelay? If not, thanks for your detail
>> information.
>> In hns3 RoCE driver, some CMQ/mailbox operation are called inside
>> the lock,
>> we can't use msleep in the lock, otherwise it will cause deadlock.
>> When reset occurs, RDMA service cannot be provided normally, I think
>> in this
>> case using udelay will not have a great impact.
> You should not use any kind of sleep call in a loop like this.
Hi, Jason
OK, I got your opinion and will modify it in v3 patch as below:
end = msecs_to_jiffies(HNS_ROCE_V2_HW_RST_TIMEOUT) + jiffies;
while (time_before(jiffies, end))
if (!ops->get_hw_reset_stat(handle))
break;
Regards
Xavier
> Jason
>
> .
>
