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authorDavid Howells <dhowells@redhat.com>2010-01-15 17:01:33 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2010-01-16 12:15:40 -0800
commit1e2ae599d37e60958c03ca5e46b1f657619a30cd (patch)
tree0a0c9ff0370fbefd4eb8fe3a44106880c1aae8cb /mm
parented5e5894b234ce4793d78078c026915b853e0678 (diff)
downloadlinux-linaro-stable-1e2ae599d37e60958c03ca5e46b1f657619a30cd.tar.gz
nommu: struct vm_region's vm_usage count need not be atomic
The vm_usage count field in struct vm_region does not need to be atomic as it's only even modified whilst nommu_region_sem is write locked. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Cc: Greg Ungerer <gerg@snapgear.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/nommu.c14
1 files changed, 7 insertions, 7 deletions
diff --git a/mm/nommu.c b/mm/nommu.c
index 17773862619b..5e39294f8ea8 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -552,11 +552,11 @@ static void free_page_series(unsigned long from, unsigned long to)
static void __put_nommu_region(struct vm_region *region)
__releases(nommu_region_sem)
{
- kenter("%p{%d}", region, atomic_read(&region->vm_usage));
+ kenter("%p{%d}", region, region->vm_usage);
BUG_ON(!nommu_region_tree.rb_node);
- if (atomic_dec_and_test(&region->vm_usage)) {
+ if (--region->vm_usage == 0) {
if (region->vm_top > region->vm_start)
delete_nommu_region(region);
up_write(&nommu_region_sem);
@@ -1205,7 +1205,7 @@ unsigned long do_mmap_pgoff(struct file *file,
if (!vma)
goto error_getting_vma;
- atomic_set(&region->vm_usage, 1);
+ region->vm_usage = 1;
region->vm_flags = vm_flags;
region->vm_pgoff = pgoff;
@@ -1272,7 +1272,7 @@ unsigned long do_mmap_pgoff(struct file *file,
}
/* we've found a region we can share */
- atomic_inc(&pregion->vm_usage);
+ pregion->vm_usage++;
vma->vm_region = pregion;
start = pregion->vm_start;
start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT;
@@ -1289,7 +1289,7 @@ unsigned long do_mmap_pgoff(struct file *file,
vma->vm_region = NULL;
vma->vm_start = 0;
vma->vm_end = 0;
- atomic_dec(&pregion->vm_usage);
+ pregion->vm_usage--;
pregion = NULL;
goto error_just_free;
}
@@ -1444,7 +1444,7 @@ int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
/* we're only permitted to split anonymous regions that have a single
* owner */
if (vma->vm_file ||
- atomic_read(&vma->vm_region->vm_usage) != 1)
+ vma->vm_region->vm_usage != 1)
return -ENOMEM;
if (mm->map_count >= sysctl_max_map_count)
@@ -1518,7 +1518,7 @@ static int shrink_vma(struct mm_struct *mm,
/* cut the backing region down to size */
region = vma->vm_region;
- BUG_ON(atomic_read(&region->vm_usage) != 1);
+ BUG_ON(region->vm_usage != 1);
down_write(&nommu_region_sem);
delete_nommu_region(region);