[PATCH V2] amdgpu: optimization-- reduce noneed mutex_lock area

[PATCH V2] amdgpu: optimization-- reduce noneed mutex_lock area

[Bernard Zhao]

Maybe we could reduce the mutex_lock(&mem->lock)`s protected code area,
and noneed to protect pr_debug.

Signed-off-by: Bernard Zhao <bernard@vivo.com>

Changes since V1:
*commit message improve

Link for V1:
*https://lore.kernel.org/patchwork/patch/1226588/
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
index 327317c54f7c..3c3769e57174 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
@@ -1285,17 +1285,18 @@ int amdgpu_amdkfd_gpuvm_free_memory_of_gpu(
 	struct bo_vm_reservation_context ctx;
 	struct ttm_validate_buffer *bo_list_entry;
 	int ret;
+	unsigned int mapped_to_gpu_memory;
 
 	mutex_lock(&mem->lock);
+	mapped_to_gpu_memory = mem->mapped_to_gpu_memory;
+	mutex_unlock(&mem->lock);
 
-	if (mem->mapped_to_gpu_memory > 0) {
+	if (mapped_to_gpu_memory > 0) {
 		pr_debug("BO VA 0x%llx size 0x%lx is still mapped.\n",
 				mem->va, bo_size);
-		mutex_unlock(&mem->lock);
 		return -EBUSY;
 	}
 
-	mutex_unlock(&mem->lock);
 	/* lock is not needed after this, since mem is unused and will
 	 * be freed anyway
 	 */
-- 
2.26.2

Re: [PATCH V2] amdgpu: optimization-- reduce noneed mutex_lock area

[Felix Kuehling]

Hi Bernard,

Thank you for the patch. Please see some comments inline.

Am 2020-04-20 um 10:25 p.m. schrieb Bernard Zhao:
> Maybe we could reduce the mutex_lock(&mem->lock)`s protected code area,
> and noneed to protect pr_debug.

Typo: noneed -> no need


>
> Signed-off-by: Bernard Zhao <bernard@vivo.com>
>
> Changes since V1:
> *commit message improve
>
> Link for V1:
> *https://lore.kernel.org/patchwork/patch/1226588/
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> index 327317c54f7c..3c3769e57174 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> @@ -1285,17 +1285,18 @@ int amdgpu_amdkfd_gpuvm_free_memory_of_gpu(
>  	struct bo_vm_reservation_context ctx;
>  	struct ttm_validate_buffer *bo_list_entry;
>  	int ret;
> +	unsigned int mapped_to_gpu_memory;
>  
>  	mutex_lock(&mem->lock);
> +	mapped_to_gpu_memory = mem->mapped_to_gpu_memory;
> +	mutex_unlock(&mem->lock);
>  
> -	if (mem->mapped_to_gpu_memory > 0) {
> +	if (mapped_to_gpu_memory > 0) {
>  		pr_debug("BO VA 0x%llx size 0x%lx is still mapped.\n",
>  				mem->va, bo_size);
> -		mutex_unlock(&mem->lock);
>  		return -EBUSY;
>  	}
>  
> -	mutex_unlock(&mem->lock);
>  	/* lock is not needed after this, since mem is unused and will
>  	 * be freed anyway
>  	 */

Please move this comment along with the mutex_unlock.

Regards,
  Felix