[PATCH] mm/mmap.c: Remove redundant local variables for may_expand_vm()

[PATCH] mm/mmap.c: Remove redundant local variables for may_expand_vm()

[Chen Gang]

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>From 7050c267d8dda220226067039d815593d2f9a874 Mon Sep 17 00:00:00 2001
From: Chen Gang <gang.chen.5i5j@gmail.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@gmail.com>
---
 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)
 {
-	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;
 }
-- 
1.9.3

 		 	   		  

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From 7050c267d8dda220226067039d815593d2f9a874 Mon Sep 17 00:00:00 2001
From: Chen Gang <gang.chen.5i5j@gmail.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@gmail.com>
---
 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)
 {
-	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;
 }
-- 
1.9.3

Re: [PATCH] mm/mmap.c: Remove redundant local variables for may_expand_vm()

[Naoya Horiguchi]

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@gmail.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@gmail.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
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Re: [PATCH] mm/mmap.c: Remove redundant local variables for may_expand_vm()

[Chen Gang]

On 11/10/15 09:39, Naoya Horiguchi wrote:
> On Tue, Nov 10, 2015 at 05:41:08AM +0800, Chen Gang wrote:
>> 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? 
> 

For me, inline is OK. But I guess, it depends on the members tastes: "It
is used at 5 areas within mm, inline will expand the binary size".

>>  {
>> -	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);
> 

For me, only one line is OK. But I guess, it also depends on the members
tastes: does it let code a little complex?

If we can use bool instead of int for may_epand_mm() return value, I
guess, one line implementation (your idea) will be OK to all members.

> ? 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
> 

Thanks.
-- 
Chen Gang (陈刚)

Open, share, and attitude like air, water, and life which God blessed

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Re: [PATCH] mm/mmap.c: Remove redundant local variables for may_expand_vm()

[Chen Gang]

Next, I shall read through another files.

I should not only send trivial patches to community, I should continue
learning mm. 

Until now, I did not spend enough time resources on mm. So next, I
should spend a little more my free time resources on mm.


Welcome any ideas, suggestions, and completions from any members.

Thanks.

On 11/10/15 05:41, Chen Gang wrote:
> From 7050c267d8dda220226067039d815593d2f9a874 Mon Sep 17 00:00:00 2001
> From: Chen Gang <gang.chen.5i5j@gmail.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@gmail.com>
> ---
>  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)
>  {
> -	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;
>  }
> -- 
> 1.9.3
> 
>  		 	   		  
> 

-- 
Chen Gang (陈刚)

Open, share, and attitude like air, water, and life which God blessed

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