linux-kernel - [PATCH 4/5] arch/powerpc: Eliminate NULL test and memset after alloc

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Message-ID: <Pine.LNX.4.64.0811231148170.28343@ask.diku.dk>
Date:	Sun, 23 Nov 2008 11:48:56 +0100 (CET)
From:	Julia Lawall <julia@...u.dk>
To:	paulus@...ba.org, benh@...nel.crashing.org,
	linuxppc-dev@...abs.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: [PATCH 4/5] arch/powerpc: Eliminate NULL test and memset after
 alloc_bootmem

From: Julia Lawall <julia@...u.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.

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

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

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

@@
expression E,E1;
@@

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

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

 arch/powerpc/kernel/setup_64.c      |    2 --
 1 files changed, 0 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 9dca8cf..261c1b0 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -606,8 +606,6 @@ void __init setup_per_cpu_areas(void)
 
 	for_each_possible_cpu(i) {
 		ptr = alloc_bootmem_pages_node(NODE_DATA(cpu_to_node(i)), size);
-		if (!ptr)
-			panic("Cannot allocate cpu data for CPU %d\n", i);
 
 		paca[i].data_offset = ptr - __per_cpu_start;
 		memcpy(ptr, __per_cpu_start, __per_cpu_end - __per_cpu_start);
--
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