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

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Date:   Thu, 17 May 2018 22:15:02 -0600
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     "Wei Hu (Xavier)" <xavier.huwei@...wei.com>
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 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