Re: [PATCH] drm/i915/gt: Avoid redundant pointer validity check

[Tvrtko Ursulin]

Hi,

Adding Matt & Thomas as potential candidates to review.

Regards,

Tvrtko

On 03/02/2023 19:30, Deepak R Varma wrote:
> The macro definition of gen6_for_all_pdes() expands to a for loop such
> that it breaks when the page table is null. Hence there is no need to
> again test validity of the page table entry pointers in the pde list.
> This change is identified using itnull.cocci semantic patch.
>
> Signed-off-by: Deepak R Varma <drv@xxxxxxxxx>
> ---
> Please note: Proposed change is compile tested only.
>
>   drivers/gpu/drm/i915/gt/gen6_ppgtt.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/gen6_ppgtt.c b/drivers/gpu/drm/i915/gt/gen6_ppgtt.c
> index 5aaacc53fa4c..787b9e6d9f59 100644
> --- a/drivers/gpu/drm/i915/gt/gen6_ppgtt.c
> +++ b/drivers/gpu/drm/i915/gt/gen6_ppgtt.c
> @@ -258,8 +258,7 @@ static void gen6_ppgtt_free_pd(struct gen6_ppgtt *ppgtt)
>   	u32 pde;
>   
>   	gen6_for_all_pdes(pt, pd, pde)
> -		if (pt)
> -			free_pt(&ppgtt->base.vm, pt);
> +		free_pt(&ppgtt->base.vm, pt);
>   }
>   
>   static void gen6_ppgtt_cleanup(struct i915_address_space *vm)
> @@ -304,7 +303,7 @@ static void pd_vma_unbind(struct i915_address_space *vm,
>   
>   	/* Free all no longer used page tables */
>   	gen6_for_all_pdes(pt, ppgtt->base.pd, pde) {
> -		if (!pt || atomic_read(&pt->used))
> +		if (atomic_read(&pt->used))
>   			continue;
>   
>   		free_pt(&ppgtt->base.vm, pt);