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Subject[PATCH 10/14] arch/um: Eliminate NULL test and memset after alloc_bootmem
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.

arch/um/drivers/net_kern.c | 4 ----
arch/um/kernel/initrd.c | 2 --
arch/um/kernel/physmem.c | 3 ---
3 files changed, 9 deletions(-)

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

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

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

@@
expression E,E1;
@@

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

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

diff -u -p a/arch/um/drivers/net_kern.c b/arch/um/drivers/net_kern.c
--- a/arch/um/drivers/net_kern.c
+++ b/arch/um/drivers/net_kern.c
@@ -668,10 +668,6 @@ static int __init eth_setup(char *str)
}

new = alloc_bootmem(sizeof(*new));
- if (new == NULL) {
- printk(KERN_ERR "eth_init : alloc_bootmem failed\n");
- return 1;
- }

INIT_LIST_HEAD(&new->list);
new->index = n;
diff -u -p a/arch/um/kernel/initrd.c b/arch/um/kernel/initrd.c
--- a/arch/um/kernel/initrd.c
+++ b/arch/um/kernel/initrd.c
@@ -37,8 +37,6 @@ static int __init read_initrd(void)
}

area = alloc_bootmem(size);
- if (area == NULL)
- return 0;

if (load_initrd(initrd, area, size) == -1)
return 0;
diff -u -p a/arch/um/kernel/physmem.c b/arch/um/kernel/physmem.c
--- a/arch/um/kernel/physmem.c
+++ b/arch/um/kernel/physmem.c
@@ -41,12 +41,9 @@ int __init init_maps(unsigned long physm
total_len = phys_len + iomem_len + highmem_len;

map = alloc_bootmem_low_pages(total_len);
- if (map == NULL)
- return -ENOMEM;

for (i = 0; i < total_pages; i++) {
p = &map[i];
- memset(p, 0, sizeof(struct page));
SetPageReserved(p);
INIT_LIST_HEAD(&p->lru);
}

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