Maybe we could reduce the mutex_lock(&mem->lock)`s protected code area,
and no need to protect pr_debug.
Signed-off-by: Bernard Zhao <[email protected]>
Changes since V1:
*commit message improve
Changes since V2:
*move comment along with the mutex_unlock
Changes since V3:
*lock protect the if check, there is some possibility of multi-threaded
racing modify.
Link for V1:
*https://lore.kernel.org/patchwork/patch/1226588/
---
drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
index 327317c54f7c..549bdb429883 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
@@ -1289,9 +1289,9 @@ int amdgpu_amdkfd_gpuvm_free_memory_of_gpu(
mutex_lock(&mem->lock);
if (mem->mapped_to_gpu_memory > 0) {
+ mutex_unlock(&mem->lock);
pr_debug("BO VA 0x%llx size 0x%lx is still mapped.\n",
mem->va, bo_size);
- mutex_unlock(&mem->lock);
return -EBUSY;
}
--
2.26.2
Am 21.04.20 um 09:36 schrieb Bernard Zhao:
> Maybe we could reduce the mutex_lock(&mem->lock)`s protected code area,
> and no need to protect pr_debug.
Well that change looks rather superfluous to me.
This is for freeing memory which by definition can only be done once and
so the should be exactly zero contention on the lock except in a case of
an error.
Regards,
Christian.
>
> Signed-off-by: Bernard Zhao <[email protected]>
>
> Changes since V1:
> *commit message improve
>
> Changes since V2:
> *move comment along with the mutex_unlock
>
> Changes since V3:
> *lock protect the if check, there is some possibility of multi-threaded
> racing modify.
>
> Link for V1:
> *https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Fpatchwork%2Fpatch%2F1226588%2F&data=02%7C01%7Cchristian.koenig%40amd.com%7C9f2b2080f4174c421e4f08d7e5c6b899%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637230513976133424&sdata=6wezM%2F%2FjM5uuLblJejS9XFlE9DjWQ5zSt5PsqrfvCVo%3D&reserved=0
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> index 327317c54f7c..549bdb429883 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> @@ -1289,9 +1289,9 @@ int amdgpu_amdkfd_gpuvm_free_memory_of_gpu(
> mutex_lock(&mem->lock);
>
> if (mem->mapped_to_gpu_memory > 0) {
> + mutex_unlock(&mem->lock);
> pr_debug("BO VA 0x%llx size 0x%lx is still mapped.\n",
> mem->va, bo_size);
> - mutex_unlock(&mem->lock);
> return -EBUSY;
> }
>
From: "Christian König" <[email protected]>
Date: 2020-04-21 15:41:27
To: [email protected],Felix Kuehling <[email protected]>,Alex Deucher <[email protected]>,"David (ChunMing) Zhou" <[email protected]>,David Airlie <[email protected]>,Daniel Vetter <[email protected]>,[email protected],[email protected],[email protected]
Cc: [email protected],Bernard Zhao <[email protected]>
Subject: Re: [PATCH V4] amdgpu: reduce no need mutex_lock area>Am 21.04.20 um 09:36 schrieb Bernard Zhao:
>> Maybe we could reduce the mutex_lock(&mem->lock)`s protected code area,
>> and no need to protect pr_debug.
>
>Well that change looks rather superfluous to me.
>
>This is for freeing memory which by definition can only be done once and
>so the should be exactly zero contention on the lock except in a case of
>an error.
>
>Regards,
>Christian.
>
>>
>> Signed-off-by: Bernard Zhao <[email protected]>
>>
>> Changes since V1:
>> *commit message improve
>>
>> Changes since V2:
>> *move comment along with the mutex_unlock
>>
>> Changes since V3:
>> *lock protect the if check, there is some possibility of multi-threaded
>> racing modify.
>>
>> Link for V1:
>> *https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Fpatchwork%2Fpatch%2F1226588%2F&data=02%7C01%7Cchristian.koenig%40amd.com%7C9f2b2080f4174c421e4f08d7e5c6b899%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637230513976133424&sdata=6wezM%2F%2FjM5uuLblJejS9XFlE9DjWQ5zSt5PsqrfvCVo%3D&reserved=0
>> ---
>> drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>> index 327317c54f7c..549bdb429883 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>> @@ -1289,9 +1289,9 @@ int amdgpu_amdkfd_gpuvm_free_memory_of_gpu(
>> mutex_lock(&mem->lock);
>>
>> if (mem->mapped_to_gpu_memory > 0) {
>> + mutex_unlock(&mem->lock);
>> pr_debug("BO VA 0x%llx size 0x%lx is still mapped.\n",
>> mem->va, bo_size);
>> - mutex_unlock(&mem->lock);
>> return -EBUSY;
>> }
>>
>
add Markus.Elfring in mail list
Regards,
Bernard