Subject: Re: [RFC PATCH v2 1/4] powerpc: Move the setting of rflags out of loop in __hash_page_huge

From: Michael Ellerman <[email-masked]>
Date: Mon, 15 Apr 2013 16:32:58 +1000

On Fri, Apr 12, 2013 at 10:16:57AM +0800, Li Zhong wrote:
> It seems that rflags don't get changed in  the repeating loop, so move
> it out of the loop.

You've also changed the way new_pte is handled on repeat, but I think
that's OK too.

cheers

> diff --git a/arch/powerpc/mm/hugetlbpage-hash64.c b/arch/powerpc/mm/hugetlbpage-hash64.c
> index cecad34..edb4129 100644
> --- a/arch/powerpc/mm/hugetlbpage-hash64.c
> +++ b/arch/powerpc/mm/hugetlbpage-hash64.c
> @@ -87,10 +87,6 @@ int __hash_page_huge(unsigned long ea, unsigned long access, unsigned long vsid,
>  
>  		pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
>  
> -repeat:
> -		hpte_group = ((hash & htab_hash_mask) *
> -			      HPTES_PER_GROUP) & ~0x7UL;
> -
>  		/* clear HPTE slot informations in new PTE */
>  #ifdef CONFIG_PPC_64K_PAGES
>  		new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | _PAGE_HPTE_SUB0;

ie. here new_pte was updated on repeat, but now it's not.

> @@ -101,6 +97,10 @@ repeat:
>  		rflags |= (new_pte & (_PAGE_WRITETHRU | _PAGE_NO_CACHE |
>  				      _PAGE_COHERENT | _PAGE_GUARDED));
>  
> +repeat:
> +		hpte_group = ((hash & htab_hash_mask) *
> +			      HPTES_PER_GROUP) & ~0x7UL;
> +
>  		/* Insert into the hash table, primary slot */
>  		slot = ppc_md.hpte_insert(hpte_group, vpn, pa, rflags, 0,
>  					  mmu_psize, ssize);