[PATCH V3] amdgpu:optimization-- reduce no need mutex_lock area

[Felix Kuehling]

Thanks again for the patch. I'm going to apply this with some minor 
fixes. The headline should start with "drm/amdgpu:".  I'll also change 
the wording of the headline and commit message:

    drm/amdgpu: shrink critical section in
    amdgpu_amdkfd_gpuvm_free_memory_of_gpu

    Reduce the mem->lock`s protected code area, no need to protect pr_debug.
    This also simplifies error handling.


There is one more cosmetic change I'm going to make, see inline. I'll 
apply your patch with those updates if you're OK with that.


On 2020-04-21 2:48, Bernard Zhao wrote:
> 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 <bernard at vivo.com>
>
> Changes since V1:
> *commit message improve
>
> Changes since V2:
> *move comment along with the mutex_unlock
>
> Link for V1:
> *https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Fpatchwork%2Fpatch%2F1226588%2F&data=02%7C01%7CFelix.Kuehling%40amd.com%7Cc715f5d02aae40846b8f08d7e5c001fd%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637230485152789682&sdata=4UdZiWMAbW8eR1BS2%2F6qMvs5K6cHWy5c8I32ReQ4uz0%3D&reserved=0
> Link for V2:
> *https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Fpatchwork%2Fpatch%2F1227907%2F&data=02%7C01%7CFelix.Kuehling%40amd.com%7Cc715f5d02aae40846b8f08d7e5c001fd%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637230485152799673&sdata=Wt%2Bk7k4MtSX4zIDgmLEOB6ZKzfuqAd6GJZ3Creqf1aY%3D&reserved=0
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 14 +++++++-------
>   1 file changed, 7 insertions(+), 7 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..f03d9843d723 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> @@ -1285,21 +1285,21 @@ 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;

I'll move this before the "int ret;" line. It makes the code more 
readable if long declarations come before short ones.

Regards,
   Felix


>   
>   	mutex_lock(&mem->lock);
> +	mapped_to_gpu_memory = mem->mapped_to_gpu_memory;
> +	mutex_unlock(&mem->lock);
> +	/* lock is not needed after this, since mem is unused and will
> +	 * be freed anyway
> +	 */
>   
> -	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
> -	 */
> -
>   	/* No more MMU notifiers */
>   	amdgpu_mn_unregister(mem->bo);
>   
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