Re: [PATCH] drm/i915/gem: Remove unnecessary cast

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Wed, Aug 14, 2024 at 07:59:47PM +0200, Andi Shyti wrote:
> The cast from "long" to "unsigned long" is unnecessary. Remove
> it.

I don't believe we can be that bold in this statement.
Some static analyzer tools might not agree and tell that
if the start or end are negative values we could have
undefined behavior.

> 
> In this case, the variables "start" and "end" are of type long
> because they need to account for the possibility of negative
> values. However, they are subsequently moved to "unsigned long"
> since addresses are typically handled as unsigned values.

right, but the static analyzer tools won't agree and complain
and people will start try to add this back.

Do we really need this patch?

> 
> Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/gem/i915_gem_mman.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
> index e9b2424156f0..80528ba90a56 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
> @@ -323,8 +323,8 @@ static void set_address_limits(struct vm_area_struct *area,
>  	end = min_t(long, end, vm_end);
>  
>  	/* Let's move back into the "<< PAGE_SHIFT" domain */
> -	*start_vaddr = (unsigned long)start << PAGE_SHIFT;
> -	*end_vaddr = (unsigned long)end << PAGE_SHIFT;
> +	*start_vaddr = start << PAGE_SHIFT;
> +	*end_vaddr = end << PAGE_SHIFT;
>  
>  	*pfn = (gmadr_start + i915_ggtt_offset(vma)) >> PAGE_SHIFT;
>  	*pfn += (*start_vaddr - area->vm_start) >> PAGE_SHIFT;
> -- 
> 2.45.2
>