linux-kernel - Re: [PATCH] Replace __get_free_page() + memset(0) with get_zeroed

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Date:	Wed, 03 Jan 2007 15:18:07 +0059
From:	Jiri Slaby <jirislaby@...il.com>
To:	"Robert P. J. Day" <rpjday@...dspring.com>
Cc:	Linux kernel mailing list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Replace __get_free_page() + memset(0) with get_zeroed_page()
 calls.

Robert P. J. Day wrote:
>   Replace the small number of combinations of __get_free_page() plus a
> call to memset(...,0,PAGE_SIZE) with a single call to
> get_zeroed_page().
> 
> Signed-off-by: Robert P. J. Day <rpjday@...dspring.com>
> 
> ---
> 
>   all of the following simplifications *look* valid, but i'm happy to
> be convinced otherwise.
> 
> 
>  arch/sparc/mm/sun4c.c           |    4 +---
>  arch/sparc64/kernel/pci_iommu.c |    3 +--
>  drivers/s390/net/qeth_eddp.c    |    3 +--
>  include/asm-m68k/sun3_pgalloc.h |    3 +--
>  include/asm-um/pgtable-3level.h |    5 +----
>  sound/oss/emu10k1/main.c        |    3 +--
>  sound/oss/emu10k1/mixer.c       |    3 +--
>  7 files changed, 7 insertions(+), 17 deletions(-)
[...]
> index fd82411..b3932e5 100644
> --- a/include/asm-m68k/sun3_pgalloc.h
> +++ b/include/asm-m68k/sun3_pgalloc.h
> @@ -36,12 +36,11 @@ static inline void pte_free(struct page *page)
>  static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm,
>  					  unsigned long address)
>  {
> -	unsigned long page = __get_free_page(GFP_KERNEL|__GFP_REPEAT);
> +	unsigned long page = get_zeroed_page(GFP_KERNEL|__GFP_REPEAT);
> 
>  	if (!page)
>  		return NULL;
> 
> -	memset((void *)page, 0, PAGE_SIZE);
>  	return (pte_t *) (page);
>  }

perhaps simply
return (pte_t *)get_zeroed_page(GFP_KERNEL|__GFP_REPEAT);

> diff --git a/include/asm-um/pgtable-3level.h b/include/asm-um/pgtable-3level.h
> index ca0c2a9..6f43b58 100644
> --- a/include/asm-um/pgtable-3level.h
> +++ b/include/asm-um/pgtable-3level.h
> @@ -61,10 +61,7 @@ static inline void pgd_mkuptodate(pgd_t pgd) { pgd_val(pgd) &= ~_PAGE_NEWPAGE; }
> 
>  static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
>  {
> -        pmd_t *pmd = (pmd_t *) __get_free_page(GFP_KERNEL);
> -
> -        if(pmd)
> -                memset(pmd, 0, PAGE_SIZE);
> +        pmd_t *pmd = (pmd_t *) get_zeroed_page(GFP_KERNEL);
> 
>          return pmd;
>  }

here too, but this is also good.

regards,
-- 
http://www.fi.muni.cz/~xslaby/            Jiri Slaby
faculty of informatics, masaryk university, brno, cz
e-mail: jirislaby gmail com, gpg pubkey fingerprint:
B674 9967 0407 CE62 ACC8  22A0 32CC 55C3 39D4 7A7E
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