linux-kernel - Re: [PATCH] mm/mmap.c: Remove redundant local variables for may_expand

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <20151110013945.GA24497@hori1.linux.bs1.fc.nec.co.jp>
Date:	Tue, 10 Nov 2015 01:39:46 +0000
From:	Naoya Horiguchi <n-horiguchi@...jp.nec.com>
To:	Chen Gang <xili_gchen_5257@...mail.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	"oleg@...hat.com" <oleg@...hat.com>,
	"kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>,
	"dave@...olabs.net" <dave@...olabs.net>,
	"aarcange@...hat.com" <aarcange@...hat.com>,
	Linux Memory <linux-mm@...ck.org>,
	kernel mailing list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm/mmap.c: Remove redundant local variables for
 may_expand_vm()

On Tue, Nov 10, 2015 at 05:41:08AM +0800, Chen Gang wrote:
> From 7050c267d8dda220226067039d815593d2f9a874 Mon Sep 17 00:00:00 2001
> From: Chen Gang <gang.chen.5i5j@...il.com>
> Date: Tue, 10 Nov 2015 05:32:38 +0800
> Subject: [PATCH] mm/mmap.c: Remove redundant local variables for may_expand_vm()
> 
> After merge the related code into one line, the code is still simple and
> meaningful enough.
> 
> Signed-off-by: Chen Gang <gang.chen.5i5j@...il.com>

I agree that this function can be cleaned up.

> ---
>  mm/mmap.c | 7 +------
>  1 file changed, 1 insertion(+), 6 deletions(-)
> 
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 2ce04a6..a515260 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -2988,12 +2988,7 @@ out:
>   */
>  int may_expand_vm(struct mm_struct *mm, unsigned long npages)

marking inline? 

>  {
> -	unsigned long cur = mm->total_vm;	/* pages */
> -	unsigned long lim;
> -
> -	lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT;
> -
> -	if (cur + npages > lim)
> +	if (mm->total_vm + npages > (rlimit(RLIMIT_AS) >> PAGE_SHIFT))
>  		return 0;
>  	return 1;

How about doing simply

	return mm->total_vm + npages <= (rlimit(RLIMIT_AS) >> PAGE_SHIFT);

? These changes save some bytes :)

   text    data     bss     dec     hex filename 
  20566    2250      40   22856    5948 mm/mmap.o (before)

   text    data     bss     dec     hex filename 
  20542    2250      40   22832    5930 mm/mmap.o (after)

Thanks,
Naoya Horiguchi--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/