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* [PATCH] mm/mmap.c: use while instead of if+goto
@ 2015-03-30 19:40 Rasmus Villemoes
  2015-03-30 20:54 ` Kirill A. Shutemov
  0 siblings, 1 reply; 4+ messages in thread
From: Rasmus Villemoes @ 2015-03-30 19:40 UTC (permalink / raw)
  To: Andrew Morton, Kirill A. Shutemov, Sasha Levin, Cyrill Gorcunov,
	Roman Gushchin
  Cc: Hugh Dickins, Rasmus Villemoes, linux-mm, linux-kernel

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@rasmusvillemoes.dk>
---
 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... */
-- 
2.1.3


^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH] mm/mmap.c: use while instead of if+goto
  2015-03-30 19:40 [PATCH] mm/mmap.c: use while instead of if+goto Rasmus Villemoes
@ 2015-03-30 20:54 ` Kirill A. Shutemov
  2015-03-30 21:58   ` Andrew Morton
  0 siblings, 1 reply; 4+ messages in thread
From: Kirill A. Shutemov @ 2015-03-30 20:54 UTC (permalink / raw)
  To: Rasmus Villemoes
  Cc: Andrew Morton, Kirill A. Shutemov, Sasha Levin, Cyrill Gorcunov,
	Roman Gushchin, Hugh Dickins, linux-mm, linux-kernel

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@rasmusvillemoes.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

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH] mm/mmap.c: use while instead of if+goto
  2015-03-30 20:54 ` Kirill A. Shutemov
@ 2015-03-30 21:58   ` Andrew Morton
  2015-03-31 10:01     ` Rasmus Villemoes
  0 siblings, 1 reply; 4+ messages in thread
From: Andrew Morton @ 2015-03-30 21:58 UTC (permalink / raw)
  To: Kirill A. Shutemov
  Cc: Rasmus Villemoes, Kirill A. Shutemov, Sasha Levin,
	Cyrill Gorcunov, Roman Gushchin, Hugh Dickins, linux-mm,
	linux-kernel

On Mon, 30 Mar 2015 23:54:13 +0300 "Kirill A. Shutemov" <kirill@shutemov.name> wrote:

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

--- a/mm/mmap.c~mm-mmapc-use-while-instead-of-ifgoto-fix
+++ a/mm/mmap.c
@@ -1551,7 +1551,8 @@ unsigned long mmap_region(struct file *f
 
 	/* Clear old maps */
 	error = -ENOMEM;
-	while (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;
 	}
@@ -1569,7 +1570,8 @@ unsigned long mmap_region(struct file *f
 	/*
 	 * Can we just expand an old mapping?
 	 */
-	vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL);
+	vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff,
+	                NULL);
 	if (vma)
 		goto out;
 
@@ -2737,7 +2739,8 @@ static unsigned long do_brk(unsigned lon
 	/*
 	 * Clear old maps.  this also does some error checking for us
 	 */
-	while (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;
 	}

I'm not sure it improves things a lot, but mmap.c has been pretty
careful about the 80-col thing...


^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH] mm/mmap.c: use while instead of if+goto
  2015-03-30 21:58   ` Andrew Morton
@ 2015-03-31 10:01     ` Rasmus Villemoes
  0 siblings, 0 replies; 4+ messages in thread
From: Rasmus Villemoes @ 2015-03-31 10:01 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Kirill A. Shutemov, Kirill A. Shutemov, Sasha Levin,
	Cyrill Gorcunov, Roman Gushchin, Hugh Dickins, linux-mm,
	linux-kernel

On Mon, Mar 30 2015, Andrew Morton <akpm@linux-foundation.org> wrote:

> On Mon, 30 Mar 2015 23:54:13 +0300 "Kirill A. Shutemov" <kirill@shutemov.name> wrote:
>
>> 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@rasmusvillemoes.dk>
>> 
>> 
>> Looks good, except both your plus-lines are over 80-characters long for no
>> reason.
>
> --- a/mm/mmap.c~mm-mmapc-use-while-instead-of-ifgoto-fix
> +++ a/mm/mmap.c
> @@ -1551,7 +1551,8 @@ unsigned long mmap_region(struct file *f
>
> I'm not sure it improves things a lot, but mmap.c has been pretty
> careful about the 80-col thing...

Yeah, I did run checkpatch and chose to ignore the 80-col warning, since
I think both the patch and the resulting code was more readable that
way. I don't really care either way, though.

Rasmus

^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2015-03-31 10:01 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2015-03-30 19:40 [PATCH] mm/mmap.c: use while instead of if+goto Rasmus Villemoes
2015-03-30 20:54 ` Kirill A. Shutemov
2015-03-30 21:58   ` Andrew Morton
2015-03-31 10:01     ` Rasmus Villemoes

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