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mm: fix build warning for uninitialized value

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do_wp_page() sets mmun_called if mmun_start and mmun_end were
initialized and, if so, may call mmu_notifier_invalidate_range_end()
with these values.  This doesn't prevent gcc from emitting a build
warning though:

  mm/memory.c: In function `do_wp_page':
  mm/memory.c:2530: warning: `mmun_start' may be used uninitialized in this function
  mm/memory.c:2531: warning: `mmun_end' may be used uninitialized in this function

It's much easier to initialize the variables to impossible values and do
a simple comparison to determine if they were initialized to remove the
bool entirely.

Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Rientjes 2012-11-16 14:14:48 -08:00 committed by Linus Torvalds
parent 63c3b902e5
commit 1756954c61
1 changed files with 4 additions and 6 deletions
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10
mm/memory.c
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@ -2527,9 +2527,8 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
int ret = 0;
int page_mkwrite = 0;
struct page *dirty_page = NULL;
unsigned long mmun_start; /* For mmu_notifiers */
unsigned long mmun_end; /* For mmu_notifiers */
bool mmun_called = false; /* For mmu_notifiers */
unsigned long mmun_start = 0; /* For mmu_notifiers */
unsigned long mmun_end = 0; /* For mmu_notifiers */
old_page = vm_normal_page(vma, address, orig_pte);
if (!old_page) {
@ -2708,8 +2707,7 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
goto oom_free_new;
mmun_start = address & PAGE_MASK;
mmun_end = (address & PAGE_MASK) + PAGE_SIZE;
mmun_called = true;
mmun_end = mmun_start + PAGE_SIZE;
mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
/*
@ -2778,7 +2776,7 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
page_cache_release(new_page);
unlock:
pte_unmap_unlock(page_table, ptl);
if (mmun_called)
if (mmun_end > mmun_start)
mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
if (old_page) {
/*