linux-kernel - Re: [PATCH rdma-next 2/5] RDMA/hns: Modify uar allocation algorithm to avoid bitmap exhaust

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Date:   Wed, 23 May 2018 10:00:55 +0300
From:   Leon Romanovsky <leon@...nel.org>
To:     "Wei Hu (Xavier)" <xavier.huwei@...wei.com>
Cc:     dledford@...hat.com, jgg@...pe.ca, linux-rdma@...r.kernel.org,
        linux-kernel@...r.kernel.org, xavier.huwei@....com,
        lijun_nudt@....com
Subject: Re: [PATCH rdma-next 2/5] RDMA/hns: Modify uar allocation algorithm
 to avoid bitmap exhaust

On Wed, May 23, 2018 at 02:49:35PM +0800, Wei Hu (Xavier) wrote:
>
>
> On 2018/5/23 14:05, Leon Romanovsky wrote:
> > On Thu, May 17, 2018 at 04:02:50PM +0800, Wei Hu (Xavier) wrote:
> >> This patch modified uar allocation algorithm in hns_roce_uar_alloc
> >> function to avoid bitmap exhaust.
> >>
> >> Signed-off-by: Wei Hu (Xavier) <xavier.huwei@...wei.com>
> >> ---
> >>  drivers/infiniband/hw/hns/hns_roce_device.h |  1 +
> >>  drivers/infiniband/hw/hns/hns_roce_pd.c     | 10 ++++++----
> >>  2 files changed, 7 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/drivers/infiniband/hw/hns/hns_roce_device.h b/drivers/infiniband/hw/hns/hns_roce_device.h
> >> index 53c2f1b..412297d4 100644
> >> --- a/drivers/infiniband/hw/hns/hns_roce_device.h
> >> +++ b/drivers/infiniband/hw/hns/hns_roce_device.h
> >> @@ -214,6 +214,7 @@ enum {
> >>  struct hns_roce_uar {
> >>  	u64		pfn;
> >>  	unsigned long	index;
> >> +	unsigned long	logic_idx;
> >>  };
> >>
> >>  struct hns_roce_ucontext {
> >> diff --git a/drivers/infiniband/hw/hns/hns_roce_pd.c b/drivers/infiniband/hw/hns/hns_roce_pd.c
> >> index 4b41e04..b9f2c87 100644
> >> --- a/drivers/infiniband/hw/hns/hns_roce_pd.c
> >> +++ b/drivers/infiniband/hw/hns/hns_roce_pd.c
> >> @@ -107,13 +107,15 @@ int hns_roce_uar_alloc(struct hns_roce_dev *hr_dev, struct hns_roce_uar *uar)
> >>  	int ret = 0;
> >>
> >>  	/* Using bitmap to manager UAR index */
> >> -	ret = hns_roce_bitmap_alloc(&hr_dev->uar_table.bitmap, &uar->index);
> >> +	ret = hns_roce_bitmap_alloc(&hr_dev->uar_table.bitmap, &uar->logic_idx);
> >>  	if (ret == -1)
> >>  		return -ENOMEM;
> >>
> >> -	if (uar->index > 0)
> >> -		uar->index = (uar->index - 1) %
> >> +	if (uar->logic_idx > 0 && hr_dev->caps.phy_num_uars > 1)
> >> +		uar->index = (uar->logic_idx - 1) %
> >>  			     (hr_dev->caps.phy_num_uars - 1) + 1;
> >> +	else
> >> +		uar->index = 0;
> >>
> > Sorry, but maybe I didn't understand this change fully, but logic_idx is
> > not initialized at all and one of two (needs to check your uar
> > allocation): the logic_idx is always zero -> index will be zero too,
> > or logic_idx is random variable -> index will be random too.
> >
> > What did you want to do?
> >
> Hi, Leon
>
>     The prototype of hns_roce_bitmap_alloc as belows:
>         int hns_roce_bitmap_alloc(struct hns_roce_bitmap *bitmap,
> unsigned long *obj);
>     In this statement,  we evaluate uar->logic_idx.
>         ret = hns_roce_bitmap_alloc(&hr_dev->uar_table.bitmap,
> &uar->logic_idx);
>
>     In hip06,  hr_dev->caps.phy_num_uars equals 8,
>         if (uar->logic_idx > 0)
>              uar-> index = 0;
>        else
>              uar-> index =(uar->logic_idx - 1) %
> (hr_dev->caps.phy_num_uars - 1) + 1;
>     In hip08,  hr_dev->caps.phy_num_uars equals 1,  uar-> index = 0;
>
>    Regards

Where did you change/set logic_idx?

Thanks


> Wei Hu
> >>  	if (!dev_is_pci(hr_dev->dev)) {
> >>  		res = platform_get_resource(hr_dev->pdev, IORESOURCE_MEM, 0);
> >> @@ -132,7 +134,7 @@ int hns_roce_uar_alloc(struct hns_roce_dev *hr_dev, struct hns_roce_uar *uar)
> >>
> >>  void hns_roce_uar_free(struct hns_roce_dev *hr_dev, struct hns_roce_uar *uar)
> >>  {
> >> -	hns_roce_bitmap_free(&hr_dev->uar_table.bitmap, uar->index,
> >> +	hns_roce_bitmap_free(&hr_dev->uar_table.bitmap, uar->logic_idx,
> >>  			     BITMAP_NO_RR);
> >>  }
> >>
> >> --
> >> 1.9.1
> >>
>
>
> --
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