[PATCH] RDMA/hns: Use dma_alloc_coherent() instead of kmalloc/dma_map_single()

[PATCH] RDMA/hns: Use dma_alloc_coherent() instead of kmalloc/dma_map_single()

[Cai Huoqing]

Replacing kmalloc/kfree/dma_map_single/dma_unmap_single()
with dma_alloc_coherent/dma_free_coherent() helps to reduce
code size, and simplify the code, and coherent DMA will not
clear the cache every time.

Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
---
 drivers/infiniband/hw/hns/hns_roce_hw_v2.c | 20 +++++---------------
 1 file changed, 5 insertions(+), 15 deletions(-)

diff --git a/drivers/infiniband/hw/hns/hns_roce_hw_v2.c b/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
index 5b9953105752..380445f98a49 100644
--- a/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
+++ b/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
@@ -1165,32 +1165,22 @@ static int hns_roce_alloc_cmq_desc(struct hns_roce_dev *hr_dev,
 {
 	int size = ring->desc_num * sizeof(struct hns_roce_cmq_desc);
 
-	ring->desc = kzalloc(size, GFP_KERNEL);
+	ring->desc = dma_alloc_coherent(hr_dev->dev, size,
+					&ring->desc_dma_addr, GFP_KERNEL);
 	if (!ring->desc)
 		return -ENOMEM;
 
-	ring->desc_dma_addr = dma_map_single(hr_dev->dev, ring->desc, size,
-					     DMA_BIDIRECTIONAL);
-	if (dma_mapping_error(hr_dev->dev, ring->desc_dma_addr)) {
-		ring->desc_dma_addr = 0;
-		kfree(ring->desc);
-		ring->desc = NULL;
-
-		return -ENOMEM;
-	}
-
 	return 0;
 }
 
 static void hns_roce_free_cmq_desc(struct hns_roce_dev *hr_dev,
 				   struct hns_roce_v2_cmq_ring *ring)
 {
-	dma_unmap_single(hr_dev->dev, ring->desc_dma_addr,
-			 ring->desc_num * sizeof(struct hns_roce_cmq_desc),
-			 DMA_BIDIRECTIONAL);
+	dma_free_coherent(hr_dev->dev,
+			  ring->desc_num * sizeof(struct hns_roce_cmq_desc),
+			  ring->desc, ring->desc_dma_addr);
 
 	ring->desc_dma_addr = 0;
-	kfree(ring->desc);
 }
 
 static int init_csq(struct hns_roce_dev *hr_dev,
-- 
2.25.1

Re: [PATCH] RDMA/hns: Use dma_alloc_coherent() instead of kmalloc/dma_map_single()

[Jason Gunthorpe]

On Sun, Sep 26, 2021 at 02:11:15PM +0800, Cai Huoqing wrote:
> Replacing kmalloc/kfree/dma_map_single/dma_unmap_single()
> with dma_alloc_coherent/dma_free_coherent() helps to reduce
> code size, and simplify the code, and coherent DMA will not
> clear the cache every time.
> 
> Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
> ---
>  drivers/infiniband/hw/hns/hns_roce_hw_v2.c | 20 +++++---------------
>  1 file changed, 5 insertions(+), 15 deletions(-)

Given I don't see any dma_sync_single calls for this mapping, isn't
this a correctness fix too?

Jason

Re: [PATCH] RDMA/hns: Use dma_alloc_coherent() instead of kmalloc/dma_map_single()

[Jason Gunthorpe]

On Mon, Sep 27, 2021 at 08:59:13AM -0300, Jason Gunthorpe wrote:
> On Sun, Sep 26, 2021 at 02:11:15PM +0800, Cai Huoqing wrote:
> > Replacing kmalloc/kfree/dma_map_single/dma_unmap_single()
> > with dma_alloc_coherent/dma_free_coherent() helps to reduce
> > code size, and simplify the code, and coherent DMA will not
> > clear the cache every time.
> > 
> > Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
> >  drivers/infiniband/hw/hns/hns_roce_hw_v2.c | 20 +++++---------------
> >  1 file changed, 5 insertions(+), 15 deletions(-)
> 
> Given I don't see any dma_sync_single calls for this mapping, isn't
> this a correctness fix too?

HNS folks?

Jason

Re: [PATCH] RDMA/hns: Use dma_alloc_coherent() instead of kmalloc/dma_map_single()

[Wenpeng Liang]

On 2021/10/5 3:52, Jason Gunthorpe wrote:
> On Mon, Sep 27, 2021 at 08:59:13AM -0300, Jason Gunthorpe wrote:
>> On Sun, Sep 26, 2021 at 02:11:15PM +0800, Cai Huoqing wrote:
>>> Replacing kmalloc/kfree/dma_map_single/dma_unmap_single()
>>> with dma_alloc_coherent/dma_free_coherent() helps to reduce
>>> code size, and simplify the code, and coherent DMA will not
>>> clear the cache every time.
>>>
>>> Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
>>>  drivers/infiniband/hw/hns/hns_roce_hw_v2.c | 20 +++++---------------
>>>  1 file changed, 5 insertions(+), 15 deletions(-)
>>
>> Given I don't see any dma_sync_single calls for this mapping, isn't
>> this a correctness fix too?
> 
> HNS folks?
> 
> Jason
> .
> 

Our SoC can keep cache coherent, so there is no exception even if
dma_sync_single* is not called, but the driver should not make
assumptions about SoC.

So using dma_alloc_coherent() instead of kmalloc/dma_map_single()
can simplify the code and achieve the same purpose.

Wenpeng Liang

Re: [PATCH] RDMA/hns: Use dma_alloc_coherent() instead of kmalloc/dma_map_single()

[Cai Huoqing]

On 09 10月 21 17:50:50, Wenpeng Liang wrote:
> 
> 
> On 2021/10/5 3:52, Jason Gunthorpe wrote:
> > On Mon, Sep 27, 2021 at 08:59:13AM -0300, Jason Gunthorpe wrote:
> >> On Sun, Sep 26, 2021 at 02:11:15PM +0800, Cai Huoqing wrote:
> >>> Replacing kmalloc/kfree/dma_map_single/dma_unmap_single()
> >>> with dma_alloc_coherent/dma_free_coherent() helps to reduce
> >>> code size, and simplify the code, and coherent DMA will not
> >>> clear the cache every time.
> >>>
> >>> Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
> >>>  drivers/infiniband/hw/hns/hns_roce_hw_v2.c | 20 +++++---------------
> >>>  1 file changed, 5 insertions(+), 15 deletions(-)
> >>
> >> Given I don't see any dma_sync_single calls for this mapping, isn't
> >> this a correctness fix too?
> > 
> > HNS folks?
> > 
> > Jason
> > .
> > 
> 
> Our SoC can keep cache coherent, so there is no exception even if
> dma_sync_single* is not called, but the driver should not make
> assumptions about SoC.
> 
> So using dma_alloc_coherent() instead of kmalloc/dma_map_single()
> can simplify the code and achieve the same purpose.
> 
> Wenpeng Liang


Hi Liang

Thanks for your feedback.

If you think my patch is correct, you can give a Reviewed-by: to it.
You can also give a Tested-by: to it, if the test on hardware was made.

Thanks
Cai

Re: [PATCH] RDMA/hns: Use dma_alloc_coherent() instead of kmalloc/dma_map_single()

[Wenpeng Liang]

On 2021/10/9 18:42, Cai Huoqing wrote:
> On 09 10月 21 17:50:50, Wenpeng Liang wrote:
>>
>>
>> On 2021/10/5 3:52, Jason Gunthorpe wrote:
>>> On Mon, Sep 27, 2021 at 08:59:13AM -0300, Jason Gunthorpe wrote:
>>>> On Sun, Sep 26, 2021 at 02:11:15PM +0800, Cai Huoqing wrote:
>>>>> Replacing kmalloc/kfree/dma_map_single/dma_unmap_single()
>>>>> with dma_alloc_coherent/dma_free_coherent() helps to reduce
>>>>> code size, and simplify the code, and coherent DMA will not
>>>>> clear the cache every time.
>>>>>
>>>>> Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
>>>>>  drivers/infiniband/hw/hns/hns_roce_hw_v2.c | 20 +++++---------------
>>>>>  1 file changed, 5 insertions(+), 15 deletions(-)
>>>>
>>>> Given I don't see any dma_sync_single calls for this mapping, isn't
>>>> this a correctness fix too?
>>>
>>> HNS folks?
>>>
>>> Jason
>>> .
>>>
>>
>> Our SoC can keep cache coherent, so there is no exception even if
>> dma_sync_single* is not called, but the driver should not make
>> assumptions about SoC.
>>
>> So using dma_alloc_coherent() instead of kmalloc/dma_map_single()
>> can simplify the code and achieve the same purpose.
>>
>> Wenpeng Liang
> 
> 
> Hi Liang
> 
> Thanks for your feedback.
> 
> If you think my patch is correct, you can give a Reviewed-by: to it.
> You can also give a Tested-by: to it, if the test on hardware was made.
> 
> Thanks
> Cai
> .
> 

Hi, Cai

After testing, it seems ok to me.

Reviewed-by: Wenpeng Liang <liangwenpeng@huawei.com>
Tested-by: Wenpeng Liang <liangwenpeng@huawei.com>

Thanks,
Wenpeng

Re: [PATCH] RDMA/hns: Use dma_alloc_coherent() instead of kmalloc/dma_map_single()

[Jason Gunthorpe]

On Sun, Sep 26, 2021 at 02:11:15PM +0800, Cai Huoqing wrote:
> Replacing kmalloc/kfree/dma_map_single/dma_unmap_single()
> with dma_alloc_coherent/dma_free_coherent() helps to reduce
> code size, and simplify the code, and coherent DMA will not
> clear the cache every time.
> 
> Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
> Reviewed-by: Wenpeng Liang <liangwenpeng@huawei.com>
> Tested-by: Wenpeng Liang <liangwenpeng@huawei.com>
> ---
>  drivers/infiniband/hw/hns/hns_roce_hw_v2.c | 20 +++++---------------
>  1 file changed, 5 insertions(+), 15 deletions(-)

Applied to for-next, thanks

Jason