* [PATCH] x86, olpc: Eliminate BUG_ON and memset after alloc_bootmem
@ 2014-07-19 11:36 Himangi Saraogi
2014-07-21 22:56 ` David Rientjes
0 siblings, 1 reply; 2+ messages in thread
From: Himangi Saraogi @ 2014-07-19 11:36 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, H. Peter Anvin, x86, linux-kernel
Cc: Julia Lawall
alloc_bootmem and related functions never return NULL and always return
a zeroed region of memory. Thus a BUG_ON the NULL test or memset after
calls to these functions is unnecessary.
The following Coccinelle semantic patch was used for making the change:
@@
expression E;
statement S;
@@
E = \(alloc_bootmem\|alloc_bootmem_low\|alloc_bootmem_pages\|alloc_bootmem_low_pages\)(...)
... when != E
- BUG_ON (E == NULL);
@@
expression E,E1;
@@
E = \(alloc_bootmem\|alloc_bootmem_low\|alloc_bootmem_pages\|alloc_bootmem_low_pages\)(...)
... when != E
- memset(E,0,E1);
Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
---
arch/x86/platform/olpc/olpc_dt.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/arch/x86/platform/olpc/olpc_dt.c b/arch/x86/platform/olpc/olpc_dt.c
index d6ee929..280645d 100644
--- a/arch/x86/platform/olpc/olpc_dt.c
+++ b/arch/x86/platform/olpc/olpc_dt.c
@@ -142,9 +142,7 @@ void * __init prom_early_alloc(unsigned long size)
* wasted bootmem) and hand off chunks of it to callers.
*/
res = alloc_bootmem(chunk_size);
- BUG_ON(!res);
prom_early_allocated += chunk_size;
- memset(res, 0, chunk_size);
free_mem = chunk_size;
mem = res;
}
--
1.9.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] x86, olpc: Eliminate BUG_ON and memset after alloc_bootmem
2014-07-19 11:36 [PATCH] x86, olpc: Eliminate BUG_ON and memset after alloc_bootmem Himangi Saraogi
@ 2014-07-21 22:56 ` David Rientjes
0 siblings, 0 replies; 2+ messages in thread
From: David Rientjes @ 2014-07-21 22:56 UTC (permalink / raw)
To: Himangi Saraogi
Cc: Thomas Gleixner, Ingo Molnar, H. Peter Anvin, x86, linux-kernel,
Julia Lawall
On Sat, 19 Jul 2014, Himangi Saraogi wrote:
> alloc_bootmem and related functions never return NULL and always return
> a zeroed region of memory. Thus a BUG_ON the NULL test or memset after
> calls to these functions is unnecessary.
>
> The following Coccinelle semantic patch was used for making the change:
>
> @@
> expression E;
> statement S;
> @@
>
> E = \(alloc_bootmem\|alloc_bootmem_low\|alloc_bootmem_pages\|alloc_bootmem_low_pages\)(...)
> ... when != E
> - BUG_ON (E == NULL);
>
> @@
> expression E,E1;
> @@
>
> E = \(alloc_bootmem\|alloc_bootmem_low\|alloc_bootmem_pages\|alloc_bootmem_low_pages\)(...)
> ... when != E
> - memset(E,0,E1);
>
> Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
> Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Acked-by: David Rientjes <rientjes@google.com>
Many callers of alloc_bootmem() do not check for the return value because
of this, there's no fallback available at this part in bootstrap so
there's nothing else that can be done.
^ permalink raw reply [flat|nested] 2+ messages in thread
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2014-07-19 11:36 [PATCH] x86, olpc: Eliminate BUG_ON and memset after alloc_bootmem Himangi Saraogi
2014-07-21 22:56 ` David Rientjes
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