Messages in this thread Patch in this message | | | Date | Sun, 23 Nov 2008 11:49:36 +0100 (CET) | From | Julia Lawall <> | Subject | [PATCH 5/5] mm/page_alloc.c: Eliminate NULL test and memset after alloc_bootmem |
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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.
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@diku.dk> ---
mm/page_alloc.c | 4 +--- 1 files changed, 1 insertions(+), 3 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index d8ac014..5040299 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3381,10 +3381,8 @@ static void __init setup_usemap(struct pglist_data *pgdat, { unsigned long usemapsize = usemap_size(zonesize); zone->pageblock_flags = NULL; - if (usemapsize) { + if (usemapsize) zone->pageblock_flags = alloc_bootmem_node(pgdat, usemapsize); - memset(zone->pageblock_flags, 0, usemapsize); - } } #else static void inline setup_usemap(struct pglist_data *pgdat,
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