[PATCH v2 libdrm] amdgpu: Eliminate void* arithmetic in amdgpu_find_bo_by_cpu_mapping

[Christian König]

Am 16.08.2018 um 15:54 schrieb Michel Dänzer:
> From: Michel Dänzer <michel.daenzer at amd.com>
>
> Arithmetic using void* pointers isn't defined by the C standard, only as
> a GCC extension. Avoids compiler warnings:
>
> ../../amdgpu/amdgpu_bo.c: In function ‘amdgpu_find_bo_by_cpu_mapping’:
> ../../amdgpu/amdgpu_bo.c:554:48: warning: pointer of type ‘void *’ used in arithmetic [-Wpointer-arith]
>     if (cpu >= bo->cpu_ptr && cpu < (bo->cpu_ptr + bo->alloc_size))
>                                                  ^
> ../../amdgpu/amdgpu_bo.c:561:23: warning: pointer of type ‘void *’ used in subtraction [-Wpointer-arith]
>     *offset_in_bo = cpu - bo->cpu_ptr;
>                         ^
>
> v2: Use uintptr_t instead of char*, don't change function signature
>      (Junwei Zhang)
>
> Fixes: 4d454424e1f2 ("amdgpu: add a function to find bo by cpu mapping
>                       (v2)")
> Signed-off-by: Michel Dänzer <michel.daenzer at amd.com>

Reviewed-by: Christian König <christian.koenig at amd.com>

> ---
>   amdgpu/amdgpu_bo.c | 5 +++--
>   1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/amdgpu/amdgpu_bo.c b/amdgpu/amdgpu_bo.c
> index 86d1c143..8efd014e 100644
> --- a/amdgpu/amdgpu_bo.c
> +++ b/amdgpu/amdgpu_bo.c
> @@ -551,14 +551,15 @@ int amdgpu_find_bo_by_cpu_mapping(amdgpu_device_handle dev,
>   		bo = handle_table_lookup(&dev->bo_handles, i);
>   		if (!bo || !bo->cpu_ptr || size > bo->alloc_size)
>   			continue;
> -		if (cpu >= bo->cpu_ptr && cpu < (bo->cpu_ptr + bo->alloc_size))
> +		if (cpu >= bo->cpu_ptr &&
> +		    cpu < (void*)((uintptr_t)bo->cpu_ptr + bo->alloc_size))
>   			break;
>   	}
>   
>   	if (i < dev->bo_handles.max_key) {
>   		atomic_inc(&bo->refcount);
>   		*buf_handle = bo;
> -		*offset_in_bo = cpu - bo->cpu_ptr;
> +		*offset_in_bo = (uintptr_t)cpu - (uintptr_t)bo->cpu_ptr;
>   	} else {
>   		*buf_handle = NULL;
>   		*offset_in_bo = 0;