[ARM] eliminate NULL test and memset after alloc_bootmem

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>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 2ab5f962a0533c0131ab8f9cfaf73b53abaf5d49..9b36c5cb5e9f68306c017cf63f94ab55ccc1ce3f 100644 (file)
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -827,7 +827,6 @@ static void __init devicemaps_init(struct machine_desc *mdesc)
         * Allocate the vector page early.
         */
        vectors = alloc_bootmem_low_pages(PAGE_SIZE);
-       BUG_ON(!vectors);
 
        for (addr = VMALLOC_END; addr; addr += PGDIR_SIZE)
                pmd_clear(pmd_off_k(addr));
@@ -912,10 +911,10 @@ void __init paging_init(struct machine_desc *mdesc)
        top_pmd = pmd_off_k(0xffff0000);
 
        /*
-        * allocate the zero page.  Note that we count on this going ok.
+        * allocate the zero page.  Note that this always succeeds and
+        * returns a zeroed result.
         */
        zero_page = alloc_bootmem_low_pages(PAGE_SIZE);
-       memset(zero_page, 0, PAGE_SIZE);
        empty_zero_page = virt_to_page(zero_page);
        flush_dcache_page(empty_zero_page);
 }