linux-kernel - Re: [PATCH for-next 3/9] RDMA/hns: Add return statement when kzalloc return NULL in hns_roce_v1_recreate_lp

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Date:   Fri, 29 Sep 2017 13:23:37 +0300
From:   Leon Romanovsky <leon@...nel.org>
To:     "Wei Hu (Xavier)" <xavier.huwei@...wei.com>
Cc:     dledford@...hat.com, linux-rdma@...r.kernel.org,
        lijun_nudt@....com, oulijun@...wei.com, charles.chenxin@...wei.com,
        liuyixian@...wei.com, xushaobo2@...wei.com,
        zhangxiping3@...wei.com, xavier.huwei@....com, linuxarm@...wei.com,
        linux-kernel@...r.kernel.org, shaobohsu@....com
Subject: Re: [PATCH for-next 3/9] RDMA/hns: Add return statement when kzalloc
 return NULL in hns_roce_v1_recreate_lp_qp

On Fri, Sep 29, 2017 at 02:07:22PM +0800, Wei Hu (Xavier) wrote:
>
>
> On 2017/9/28 20:59, Leon Romanovsky wrote:
> > On Thu, Sep 28, 2017 at 07:56:59PM +0800, Wei Hu (Xavier) wrote:
> > >
> > > On 2017/9/28 17:13, Leon Romanovsky wrote:
> > > > On Thu, Sep 28, 2017 at 12:57:28PM +0800, Wei Hu (Xavier) wrote:
> > > > > From: Lijun Ou <oulijun@...wei.com>
> > > > >
> > > > > When lp_qp_work is NULL, it should be returned ENOMEM. This patch
> > > > > mainly fixes it.
> > > > >
> > > > > Ihis patch fixes the smatch error as below:
> > > > > drivers/infiniband/hw/hns/hns_roce_hw_v1.c:918 hns_roce_v1_recreate_lp_qp()
> > > > > error: potential null dereference 'lp_qp_work'.  (kzalloc returns null)
> > > > >
> > > > > Signed-off-by: Lijun Ou <oulijun@...wei.com>
> > > > > Signed-off-by: Wei Hu (Xavier) <xavier.huwei@...wei.com>
> > > > > Signed-off-by: Shaobo Xu <xushaobo2@...wei.com>
> > > > > ---
> > > > >    drivers/infiniband/hw/hns/hns_roce_hw_v1.c | 2 ++
> > > > >    1 file changed, 2 insertions(+)
> > > > >
> > > > > diff --git a/drivers/infiniband/hw/hns/hns_roce_hw_v1.c b/drivers/infiniband/hw/hns/hns_roce_hw_v1.c
> > > > > index 95f5c88..1071fa2 100644
> > > > > --- a/drivers/infiniband/hw/hns/hns_roce_hw_v1.c
> > > > > +++ b/drivers/infiniband/hw/hns/hns_roce_hw_v1.c
> > > > > @@ -912,6 +912,8 @@ static int hns_roce_v1_recreate_lp_qp(struct hns_roce_dev *hr_dev)
> > > > >
> > > > >    	lp_qp_work = kzalloc(sizeof(struct hns_roce_recreate_lp_qp_work),
> > > > >    			     GFP_KERNEL);
> > > > > +	if (!lp_qp_work)
> > > > > +		return -ENOMEM;
> > > > >
> > > > You will treat this error in the same was as you will treat timeout,
> > > > which is wrong.
> > > Thanks,  Leon
> > > We will send v2 to fix the compatible warn info.
> > No, you missed the point.
> >  From the code flow below the behavior of hns_roce_v1_recreate_lp_qp
> > for ENOMEM and ETIMEOUT returns will be the same and it is wrong.
> >
> > For the ETIMEOUT, you can continue, for ENOMEM, you should properly
> > unfold the whole flow.
> >
> > Thanks
> >
> Hi, Leon
>     We prepare to modify the warn info as bleow:
>
>         if (hr_dev->hw->dereg_mr && hns_roce_v1_recreate_lp_qp(hr_dev))
>             dev_warn(&hr_dev->pdev->dev, "recreate lp qp failed!\n");
>
>     for -ETIMEDOUT,  there is a warn info as blow, but there isn't this one
> for -ENOMEM.
>         dev_warn(dev, "recreate lp qp failed 20s timeout and return
> failed!\n");
>
>         static int hns_roce_v1_recreate_lp_qp(struct hns_roce_dev *hr_dev)
>         {
>             <snip>
>             lp_qp_work = kzalloc(sizeof(struct
> hns_roce_recreate_lp_qp_work),
>                  GFP_KERNEL);
>             if (!lp_qp_work)
>                 return -ENOMEM;
>
>             <snip>
>             dev_warn(dev, "recreate lp qp failed 20s timeout and return
> failed!\n");
>             return -ETIMEDOUT;
>         }
>
>     Regards
> Wei Hu

Hi Wei,

It will be helpful, if you post your suggestions in git diff format.

My expectation is to see the following code:

diff --git a/drivers/infiniband/hw/hns/hns_roce_hw_v1.c b/drivers/infiniband/hw/hns/hns_roce_hw_v1.c
index 747efd1ae5a6..0b9ec7c24f2d 100644
--- a/drivers/infiniband/hw/hns/hns_roce_hw_v1.c
+++ b/drivers/infiniband/hw/hns/hns_roce_hw_v1.c
@@ -1648,14 +1648,18 @@ void hns_roce_v1_set_mac(struct hns_roce_dev *hr_dev, u8 phy_port, u8 *addr)
 	u16 *p_h;
 	u32 *p;
 	u32 val;

 	/*
 	 * When mac changed, loopback may fail
 	 * because of smac not equal to dmac.
 	 * We Need to release and create reserved qp again.
 	 */
-	if (hr_dev->hw->dereg_mr && hns_roce_v1_recreate_lp_qp(hr_dev))
-		dev_warn(&hr_dev->pdev->dev, "recreate lp qp timeout!\n");
+	if (hr_dev->hw->dereg_mr) {
+		int ret;
+		ret = hns_roce_v1_recreate_lp_qp(hr_dev);
+		if (ret && ret != -ETIMEDOUT)
+			return ret;
+	}

 	p = (u32 *)(&addr[0]);
 	reg_smac_l = *p;

Thanks

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