linux-kernel - Re: [PATCH] amdgpu/uvd: use kmemdup

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Date:	Thu, 19 May 2016 13:18:10 +0200
From:	Christian König <christian.koenig@....com>
To:	Muhammad Falak R Wani <falakreyaz@...il.com>,
	David Airlie <airlied@...ux.ie>
CC:	Alex Deucher <alexander.deucher@....com>,
	Chunming Zhou <David1.Zhou@....com>,
	Jammy Zhou <Jammy.Zhou@....com>, Leo Liu <leo.liu@....com>,
	Sonny Jiang <sonny.jiang@....com>,
	<dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] amdgpu/uvd: use kmemdup

Am 19.05.2016 um 13:11 schrieb Muhammad Falak R Wani:
> Use kmemdup when some other buffer is immediately copied into allocated
> region. It replaces call to allocation followed by memcpy, by a single
> call to kmemdup.
>
> Signed-off-by: Muhammad Falak R Wani <falakreyaz@...il.com>

NAK, actually using memcpy() is wrong in the first place.

The UVD BO is in VRAM so the pointer is pointing to IO memory here, so 
this should be memcpy_fromio() instead of memcpy().

Christian.

> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c | 4 +---
>   1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c
> index 01abfc2..c977ab6 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c
> @@ -295,12 +295,10 @@ int amdgpu_uvd_suspend(struct amdgpu_device *adev)
>   	size = amdgpu_bo_size(adev->uvd.vcpu_bo);
>   	ptr = adev->uvd.cpu_addr;
>   
> -	adev->uvd.saved_bo = kmalloc(size, GFP_KERNEL);
> +	adev->uvd.saved_bo = kmemdup(ptr, size, GFP_KERNEL);
>   	if (!adev->uvd.saved_bo)
>   		return -ENOMEM;
>   
> -	memcpy(adev->uvd.saved_bo, ptr, size);
> -
>   	return 0;
>   }
>