The patch titled
mm/page_alloc.c: eliminate NULL test and memset after alloc_bootmem
has been added to the -mm tree. Its filename is
mm-page_allocc-eliminate-null-test-and-memset-after-alloc_bootmem.patch
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------------------------------------------------------
Subject: mm/page_alloc.c: eliminate NULL test and memset after alloc_bootmem
From: Julia Lawall <julia@xxxxxxx>
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@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff -puN mm/page_alloc.c~mm-page_allocc-eliminate-null-test-and-memset-after-alloc_bootmem mm/page_alloc.c
--- a/mm/page_alloc.c~mm-page_allocc-eliminate-null-test-and-memset-after-alloc_bootmem
+++ a/mm/page_alloc.c
@@ -3396,10 +3396,8 @@ static void __init setup_usemap(struct p
{
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,
_
Patches currently in -mm which might be from julia@xxxxxxx are
linux-next.patch
drivers-char-agp-add-missing-pci_dev_get.patch
drivers-mtd-maps-nettelc-use-array_size.patch
net-tipc-bcasth-use-array_size.patch
drivers-isdn-misdn-use-array_size.patch
drivers-pci-hotplug-add-missing-pci_dev_get.patch
drivers-message-fusion-use-array_size.patch
fs-namespacec-drop-code-after-return.patch
arch-arm-eliminate-null-test-and-memset-after-alloc_bootmem.patch
arch-avr32-eliminate-null-test-and-memset-after-alloc_bootmem.patch
arch-ia64-eliminate-null-test-and-memset-after-alloc_bootmem.patch
arch-powerpc-eliminate-null-test-and-memset-after-alloc_bootmem.patch
mm-page_allocc-eliminate-null-test-and-memset-after-alloc_bootmem.patch
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