Re: [PATCH v2] RDMA/hns: fix return value in hns_roce_map_mr_sg

[Zhu Yanjun <yanjun.zhu@linux.dev>]

在 2024/4/11 8:26, shaozhengchao 写道:
>
>
> On 2024/4/11 14:08, Zhu Yanjun wrote:
>> 在 2024/4/11 5:38, Zhengchao Shao 写道:
>>> As described in the ib_map_mr_sg function comment, it returns the 
>>> number
>>> of sg elements that were mapped to the memory region. However,
>>> hns_roce_map_mr_sg returns the number of pages required for mapping the
>>> DMA area. Fix it.
>>>
>>> Fixes: 9b2cf76c9f05 ("RDMA/hns: Optimize PBL buffer allocation 
>>> process")
>>> Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
>>> ---
>>> v2: fix the return value and coding format issues
>>> ---
>>>   drivers/infiniband/hw/hns/hns_roce_mr.c | 15 +++++++--------
>>>   1 file changed, 7 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/drivers/infiniband/hw/hns/hns_roce_mr.c 
>>> b/drivers/infiniband/hw/hns/hns_roce_mr.c
>>> index 9e05b57a2d67..80c050d7d0ea 100644
>>> --- a/drivers/infiniband/hw/hns/hns_roce_mr.c
>>> +++ b/drivers/infiniband/hw/hns/hns_roce_mr.c
>>> @@ -441,18 +441,18 @@ int hns_roce_map_mr_sg(struct ib_mr *ibmr, 
>>> struct scatterlist *sg, int sg_nents,
>>>       struct ib_device *ibdev = &hr_dev->ib_dev;
>>>       struct hns_roce_mr *mr = to_hr_mr(ibmr);
>>>       struct hns_roce_mtr *mtr = &mr->pbl_mtr;
>>> -    int ret = 0;
>>> +    int ret, sg_num = 0;
>>>       mr->npages = 0;
>>>       mr->page_list = kvcalloc(mr->pbl_mtr.hem_cfg.buf_pg_count,
>>>                    sizeof(dma_addr_t), GFP_KERNEL);
>>>       if (!mr->page_list)
>>> -        return ret;
>>> +        return sg_num;
>>> -    ret = ib_sg_to_pages(ibmr, sg, sg_nents, sg_offset, 
>>> hns_roce_set_page);
>>> -    if (ret < 1) {
>>> +    sg_num = ib_sg_to_pages(ibmr, sg, sg_nents, sg_offset, 
>>> hns_roce_set_page);
>>> +    if (sg_num < 1) {
>>>           ibdev_err(ibdev, "failed to store sg pages %u %u, cnt = 
>>> %d.\n",
>>> -              mr->npages, mr->pbl_mtr.hem_cfg.buf_pg_count, ret);
>>> +              mr->npages, mr->pbl_mtr.hem_cfg.buf_pg_count, sg_num);
>>>           goto err_page_list;
>>>       }
>>> @@ -463,17 +463,16 @@ int hns_roce_map_mr_sg(struct ib_mr *ibmr, 
>>> struct scatterlist *sg, int sg_nents,
>>>       ret = hns_roce_mtr_map(hr_dev, mtr, mr->page_list, mr->npages);
>>>       if (ret) {
>>>           ibdev_err(ibdev, "failed to map sg mtr, ret = %d.\n", ret);
>>> -        ret = 0;
>>> +        sg_num = 0;
>>>       } else {
>>>           mr->pbl_mtr.hem_cfg.buf_pg_shift = 
>>> (u32)ilog2(ibmr->page_size);
>>> -        ret = mr->npages;
>>>       }
>>
> Hi Yanjun:
>   Thank you for your review. The hns_roce_mtr_map function indicates
> whether the page is successfully mapped. If sg_num is used, there may be
> ambiguity. Maybe what do I missed?

Sure. From my perspective, I just want to remove a local variable. You 
consideration also makes sense.

Zhu Yanjun

>
> Zhengchao Shao
>> In the above, can we replace the local variable ret with sg_num? So 
>> the local variable ret can be removed.
>> A trivial problem.
>>
>> @@ -433,7 +433,7 @@ int hns_roce_map_mr_sg(struct ib_mr *ibmr, struct 
>> scatterlist *sg, int sg_nents,
>>          struct ib_device *ibdev = &hr_dev->ib_dev;
>>          struct hns_roce_mr *mr = to_hr_mr(ibmr);
>>          struct hns_roce_mtr *mtr = &mr->pbl_mtr;
>> -       int ret, sg_num = 0;
>> +       int sg_num = 0;
>>
>>          mr->npages = 0;
>>          mr->page_list = kvcalloc(mr->pbl_mtr.hem_cfg.buf_pg_count,
>> @@ -452,9 +452,9 @@ int hns_roce_map_mr_sg(struct ib_mr *ibmr, struct 
>> scatterlist *sg, int sg_nents,
>>          mtr->hem_cfg.region[0].count = mr->npages;
>>          mtr->hem_cfg.region[0].hopnum = mr->pbl_hop_num;
>>          mtr->hem_cfg.region_count = 1;
>> -       ret = hns_roce_mtr_map(hr_dev, mtr, mr->page_list, mr->npages);
>> -       if (ret) {
>> -               ibdev_err(ibdev, "failed to map sg mtr, ret = %d.\n", 
>> ret);
>> +       sg_num = hns_roce_mtr_map(hr_dev, mtr, mr->page_list, 
>> mr->npages);
>> +       if (sg_num) {
>> +               ibdev_err(ibdev, "failed to map sg mtr, ret = %d.\n", 
>> sg_num);
>>                  sg_num = 0;
>>          } else {
>>                  mr->pbl_mtr.hem_cfg.buf_pg_shift = 
>> (u32)ilog2(ibmr->page_size);
>>
>> Zhu Yanjun
>>
>>>   err_page_list:
>>>       kvfree(mr->page_list);
>>>       mr->page_list = NULL;
>>> -    return ret;
>>> +    return sg_num;
>>>   }
>>>   static void hns_roce_mw_free(struct hns_roce_dev *hr_dev,
>>