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

[shaozhengchao <shaozhengchao@huawei.com>]

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?

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,
>