linux-kernel - Re: [PATCH] vmalloc:Merge multiple if conditional sentences

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Date:   Thu, 23 Jun 2022 15:34:11 +0800
From:   Muchun Song <songmuchun@...edance.com>
To:     Lv qian <lvqian@...china.com>
Cc:     akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, kernel@...china.com
Subject: Re: [PATCH] vmalloc:Merge multiple if conditional sentences

On Thu, Jun 23, 2022 at 02:45:27PM +0800, Lv qian wrote:
> Merge multiple if statements to improve code readability
>

Hi Lv qian,

Why do you think it is more readable? For me, the original one
is more readable than yours.

Thanks.
 
> Signed-off-by: Lv qian <lvqian@...china.com>
> ---
>  mm/vmalloc.c | 66 ++++++++++++++--------------------------------------
>  1 file changed, 18 insertions(+), 48 deletions(-)
> 
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index effd1ff6a4b4..6902a180f8f7 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -135,22 +135,12 @@ static int vmap_try_huge_pmd(pmd_t *pmd, unsigned long addr, unsigned long end,
>  			phys_addr_t phys_addr, pgprot_t prot,
>  			unsigned int max_page_shift)
>  {
> -	if (max_page_shift < PMD_SHIFT)
> -		return 0;
> -
> -	if (!arch_vmap_pmd_supported(prot))
> -		return 0;
> -
> -	if ((end - addr) != PMD_SIZE)
> -		return 0;
> -
> -	if (!IS_ALIGNED(addr, PMD_SIZE))
> -		return 0;
> -
> -	if (!IS_ALIGNED(phys_addr, PMD_SIZE))
> -		return 0;
> -
> -	if (pmd_present(*pmd) && !pmd_free_pte_page(pmd, addr))
> +	if (max_page_shift < PMD_SHIFT ||
> +			!arch_vmap_pmd_supported(prot) ||
> +			(end - addr) != PMD_SIZE ||
> +			!IS_ALIGNED(addr, PMD_SIZE) ||
> +			!IS_ALIGNED(phys_addr, PMD_SIZE) ||
> +			(pmd_present(*pmd) && !pmd_free_pte_page(pmd, addr)))
>  		return 0;
>  
>  	return pmd_set_huge(pmd, phys_addr, prot);
> @@ -185,22 +175,12 @@ static int vmap_try_huge_pud(pud_t *pud, unsigned long addr, unsigned long end,
>  			phys_addr_t phys_addr, pgprot_t prot,
>  			unsigned int max_page_shift)
>  {
> -	if (max_page_shift < PUD_SHIFT)
> -		return 0;
> -
> -	if (!arch_vmap_pud_supported(prot))
> -		return 0;
> -
> -	if ((end - addr) != PUD_SIZE)
> -		return 0;
> -
> -	if (!IS_ALIGNED(addr, PUD_SIZE))
> -		return 0;
> -
> -	if (!IS_ALIGNED(phys_addr, PUD_SIZE))
> -		return 0;
> -
> -	if (pud_present(*pud) && !pud_free_pmd_page(pud, addr))
> +	if (max_page_shift < PUD_SHIFT ||
> +			!arch_vmap_pud_supported(prot) ||
> +			(end - addr) != PUD_SIZE ||
> +			!IS_ALIGNED(addr, PUD_SIZE) ||
> +			!IS_ALIGNED(phys_addr, PUD_SIZE) ||
> +			(pud_present(*pud) && !pud_free_pmd_page(pud, addr)))
>  		return 0;
>  
>  	return pud_set_huge(pud, phys_addr, prot);
> @@ -236,22 +216,12 @@ static int vmap_try_huge_p4d(p4d_t *p4d, unsigned long addr, unsigned long end,
>  			phys_addr_t phys_addr, pgprot_t prot,
>  			unsigned int max_page_shift)
>  {
> -	if (max_page_shift < P4D_SHIFT)
> -		return 0;
> -
> -	if (!arch_vmap_p4d_supported(prot))
> -		return 0;
> -
> -	if ((end - addr) != P4D_SIZE)
> -		return 0;
> -
> -	if (!IS_ALIGNED(addr, P4D_SIZE))
> -		return 0;
> -
> -	if (!IS_ALIGNED(phys_addr, P4D_SIZE))
> -		return 0;
> -
> -	if (p4d_present(*p4d) && !p4d_free_pud_page(p4d, addr))
> +	if (max_page_shift < P4D_SHIFT ||
> +			!arch_vmap_p4d_supported(prot) ||
> +			(end - addr) != P4D_SIZE ||
> +			!IS_ALIGNED(addr, P4D_SIZE) ||
> +			!IS_ALIGNED(phys_addr, P4D_SIZE) ||
> +			(p4d_present(*p4d) && !p4d_free_pud_page(p4d, addr)))
>  		return 0;
>  
>  	return p4d_set_huge(p4d, phys_addr, prot);
> -- 
> 2.18.2
> 
>