[PATCH 5/14] arch/m68k/mm/Sun3mmu.c: Eliminate NULL test and memset after alloc_bootmem

[PATCH 5/14] arch/m68k/mm/Sun3mmu.c: Eliminate NULL test and memset after alloc_bootmem

[Julia Lawall]

From: Julia Lawall <julia@diku.dk>

As noted by Akinobu Mita in patch b1fceac2b9e04d278316b2faddf276015fc06e3b,
alloc_bootmem and related functions never return NULL and always return a
zeroed region of memory.  Thus a NULL test or memset after calls to these
functions is unnecessary.

 arch/m68k/mm/sun3mmu.c |    1 -
 1 file changed, 1 deletion(-)

This was fixed using the following semantic patch.
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@@
expression E;
statement S;
@@

E = \(alloc_bootmem\|alloc_bootmem_low\|alloc_bootmem_pages\|alloc_bootmem_low_pages\)(...)
... when != E
(
- BUG_ON (E == NULL);
|
- if (E == NULL) S
)

@@
expression E,E1;
@@

E = \(alloc_bootmem\|alloc_bootmem_low\|alloc_bootmem_pages\|alloc_bootmem_low_pages\)(...)
... when != E
- memset(E,0,E1);
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
---

diff -u -p a/arch/m68k/mm/sun3mmu.c b/arch/m68k/mm/sun3mmu.c
--- a/arch/m68k/mm/sun3mmu.c
+++ b/arch/m68k/mm/sun3mmu.c
@@ -53,7 +53,6 @@ void __init paging_init(void)
 	wp_works_ok = 0;
 #endif
 	empty_zero_page = alloc_bootmem_pages(PAGE_SIZE);
-	memset(empty_zero_page, 0, PAGE_SIZE);
 
 	address = PAGE_OFFSET;
 	pg_dir = swapper_pg_dir;

Re: [PATCH 5/14] arch/m68k/mm/Sun3mmu.c: Eliminate NULL test and memset after alloc_bootmem

[Geert Uytterhoeven]

On Tue, 24 Jun 2008, Julia Lawall wrote:
> From: Julia Lawall <julia@diku.dk>
> 
> As noted by Akinobu Mita in patch b1fceac2b9e04d278316b2faddf276015fc06e3b,
> alloc_bootmem and related functions never return NULL and always return a
> zeroed region of memory.  Thus a NULL test or memset after calls to these
> functions is unnecessary.
> 
>  arch/m68k/mm/sun3mmu.c |    1 -
>  1 file changed, 1 deletion(-)
> 
> This was fixed using the following semantic patch.
> (http://www.emn.fr/x-info/coccinelle/)
> 
> // <smpl>
> @@
> expression E;
> statement S;
> @@
> 
> E = \(alloc_bootmem\|alloc_bootmem_low\|alloc_bootmem_pages\|alloc_bootmem_low_pages\)(...)
> ... when != E
> (
> - BUG_ON (E == NULL);
> |
> - if (E == NULL) S
> )
> 
> @@
> expression E,E1;
> @@
> 
> E = \(alloc_bootmem\|alloc_bootmem_low\|alloc_bootmem_pages\|alloc_bootmem_low_pages\)(...)
> ... when != E
> - memset(E,0,E1);
> // </smpl>
> 
> Signed-off-by: Julia Lawall <julia@diku.dk>

Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>

(queued for 2.6.27)

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds