linux-kernel - Re: [PATCH] mm/mmap.c: use while instead of if+goto

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Message-ID: <20150330205413.GA4458@node.dhcp.inet.fi>
Date:	Mon, 30 Mar 2015 23:54:13 +0300
From:	"Kirill A. Shutemov" <kirill@...temov.name>
To:	Rasmus Villemoes <linux@...musvillemoes.dk>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Sasha Levin <sasha.levin@...cle.com>,
	Cyrill Gorcunov <gorcunov@...nvz.org>,
	Roman Gushchin <klamm@...dex-team.ru>,
	Hugh Dickins <hughd@...gle.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/mmap.c: use while instead of if+goto

On Mon, Mar 30, 2015 at 09:40:35PM +0200, Rasmus Villemoes wrote:
> The creators of the C language gave us the while keyword. Let's use
> that instead of synthesizing it from if+goto.
> 
> Made possible by 6597d783397a ("mm/mmap.c: replace find_vma_prepare()
> with clearer find_vma_links()").
> 
> Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>


Looks good, except both your plus-lines are over 80-characters long for no
reason.

> ---
>  mm/mmap.c | 8 ++------
>  1 file changed, 2 insertions(+), 6 deletions(-)
> 
> diff --git a/mm/mmap.c b/mm/mmap.c
> index da9990acc08b..e1ae629b1e9c 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -1553,11 +1553,9 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
>  
>  	/* Clear old maps */
>  	error = -ENOMEM;
> -munmap_back:
> -	if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) {
> +	while (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) {
>  		if (do_munmap(mm, addr, len))
>  			return -ENOMEM;
> -		goto munmap_back;
>  	}
>  
>  	/*
> @@ -2741,11 +2739,9 @@ static unsigned long do_brk(unsigned long addr, unsigned long len)
>  	/*
>  	 * Clear old maps.  this also does some error checking for us
>  	 */
> - munmap_back:
> -	if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) {
> +	while (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) {
>  		if (do_munmap(mm, addr, len))
>  			return -ENOMEM;
> -		goto munmap_back;
>  	}
>  
>  	/* Check against address space limits *after* clearing old maps... */
-- 
 Kirill A. Shutemov
--
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