Re: [PATCH 06/13] mm: remove superflous arguments from hmm_range_register

["Kuehling, Felix" <Felix.Kuehling-5C7GfCeVMHo@public.gmane.org>]

On 2019-07-30 1:51 a.m., Christoph Hellwig wrote:
> The start, end and page_shift values are all saved in the range
> structure, so we might as well use that for argument passing.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>


> ---
>   Documentation/vm/hmm.rst                |  2 +-
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c |  7 +++++--
>   drivers/gpu/drm/nouveau/nouveau_svm.c   |  5 ++---
>   include/linux/hmm.h                     |  6 +-----
>   mm/hmm.c                                | 20 +++++---------------
>   5 files changed, 14 insertions(+), 26 deletions(-)
>
> diff --git a/Documentation/vm/hmm.rst b/Documentation/vm/hmm.rst
> index ddcb5ca8b296..e63c11f7e0e0 100644
> --- a/Documentation/vm/hmm.rst
> +++ b/Documentation/vm/hmm.rst
> @@ -222,7 +222,7 @@ The usage pattern is::
>         range.flags = ...;
>         range.values = ...;
>         range.pfn_shift = ...;
> -      hmm_range_register(&range);
> +      hmm_range_register(&range, mirror);
>   
>         /*
>          * Just wait for range to be valid, safe to ignore return value as we
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index f0821638bbc6..71d6e7087b0b 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -818,8 +818,11 @@ int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo *bo, struct page **pages)
>   				0 : range->flags[HMM_PFN_WRITE];
>   	range->pfn_flags_mask = 0;
>   	range->pfns = pfns;
> -	hmm_range_register(range, mirror, start,
> -			   start + ttm->num_pages * PAGE_SIZE, PAGE_SHIFT);
> +	range->page_shift = PAGE_SHIFT;
> +	range->start = start;
> +	range->end = start + ttm->num_pages * PAGE_SIZE;
> +
> +	hmm_range_register(range, mirror);
>   
>   	/*
>   	 * Just wait for range to be valid, safe to ignore return value as we
> diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.c b/drivers/gpu/drm/nouveau/nouveau_svm.c
> index b889d5ec4c7e..40e706234554 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_svm.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_svm.c
> @@ -492,9 +492,7 @@ nouveau_range_fault(struct nouveau_svmm *svmm, struct hmm_range *range)
>   	range->default_flags = 0;
>   	range->pfn_flags_mask = -1UL;
>   
> -	ret = hmm_range_register(range, &svmm->mirror,
> -				 range->start, range->end,
> -				 PAGE_SHIFT);
> +	ret = hmm_range_register(range, &svmm->mirror);
>   	if (ret) {
>   		up_read(&range->hmm->mm->mmap_sem);
>   		return (int)ret;
> @@ -682,6 +680,7 @@ nouveau_svm_fault(struct nvif_notify *notify)
>   			 args.i.p.addr + args.i.p.size, fn - fi);
>   
>   		/* Have HMM fault pages within the fault window to the GPU. */
> +		range.page_shift = PAGE_SHIFT;
>   		range.start = args.i.p.addr;
>   		range.end = args.i.p.addr + args.i.p.size;
>   		range.pfns = args.phys;
> diff --git a/include/linux/hmm.h b/include/linux/hmm.h
> index 59be0aa2476d..c5b51376b453 100644
> --- a/include/linux/hmm.h
> +++ b/include/linux/hmm.h
> @@ -400,11 +400,7 @@ void hmm_mirror_unregister(struct hmm_mirror *mirror);
>   /*
>    * Please see Documentation/vm/hmm.rst for how to use the range API.
>    */
> -int hmm_range_register(struct hmm_range *range,
> -		       struct hmm_mirror *mirror,
> -		       unsigned long start,
> -		       unsigned long end,
> -		       unsigned page_shift);
> +int hmm_range_register(struct hmm_range *range, struct hmm_mirror *mirror);
>   void hmm_range_unregister(struct hmm_range *range);
>   
>   /*
> diff --git a/mm/hmm.c b/mm/hmm.c
> index 3a3852660757..926735a3aef9 100644
> --- a/mm/hmm.c
> +++ b/mm/hmm.c
> @@ -843,35 +843,25 @@ static void hmm_pfns_clear(struct hmm_range *range,
>    * hmm_range_register() - start tracking change to CPU page table over a range
>    * @range: range
>    * @mm: the mm struct for the range of virtual address
> - * @start: start virtual address (inclusive)
> - * @end: end virtual address (exclusive)
> - * @page_shift: expect page shift for the range
> + *
>    * Return: 0 on success, -EFAULT if the address space is no longer valid
>    *
>    * Track updates to the CPU page table see include/linux/hmm.h
>    */
> -int hmm_range_register(struct hmm_range *range,
> -		       struct hmm_mirror *mirror,
> -		       unsigned long start,
> -		       unsigned long end,
> -		       unsigned page_shift)
> +int hmm_range_register(struct hmm_range *range, struct hmm_mirror *mirror)
>   {
> -	unsigned long mask = ((1UL << page_shift) - 1UL);
> +	unsigned long mask = ((1UL << range->page_shift) - 1UL);
>   	struct hmm *hmm = mirror->hmm;
>   	unsigned long flags;
>   
>   	range->valid = false;
>   	range->hmm = NULL;
>   
> -	if ((start & mask) || (end & mask))
> +	if ((range->start & mask) || (range->end & mask))
>   		return -EINVAL;
> -	if (start >= end)
> +	if (range->start >= range->end)
>   		return -EINVAL;
>   
> -	range->page_shift = page_shift;
> -	range->start = start;
> -	range->end = end;
> -
>   	/* Prevent hmm_release() from running while the range is valid */
>   	if (!mmget_not_zero(hmm->mm))
>   		return -EFAULT;
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