linux-kernel - [PATCH] x86, olpc: Eliminate BUG_ON and memset after alloc

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Date:	Sat, 19 Jul 2014 17:06:37 +0530
From:	Himangi Saraogi <himangi774@...il.com>
To:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org
Cc:	Julia Lawall <julia.lawall@...6.fr>
Subject: [PATCH] x86, olpc: Eliminate BUG_ON and memset after alloc_bootmem

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@...il.com>
Acked-by: Julia Lawall <julia.lawall@...6.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

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