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SubjectRe: [PATCH rdma-next 2/5] RDMA/hns: Modify uar allocation algorithm to avoid bitmap exhaust
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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@huawei.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
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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