[PATCH] swapoff atomic_inc_not_zero on mm_users

[Hugh Dickins]

Now that we have atomic_inc_not_zero, it's more elegant for try_to_unuse
to use that on mm_users: doesn't actually matter at present, but safer to
be sure that once mm_users has gone to 0, nothing raises it for an instant.

Signed-off-by: Hugh Dickins <hugh@xxxxxxxxxxx>
---
 mm/swapfile.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

--- 2.6.17-rc5/mm/swapfile.c	2006-05-25 03:43:37.000000000 +0100
+++ linux/mm/swapfile.c	2006-05-26 17:55:29.000000000 +0100
@@ -785,10 +785,8 @@ again:
 			while (*swap_map > 1 && !retval &&
 					(p = p->next) != &start_mm->mmlist) {
 				mm = list_entry(p, struct mm_struct, mmlist);
-				if (atomic_inc_return(&mm->mm_users) == 1) {
-					atomic_dec(&mm->mm_users);
+				if (!atomic_inc_not_zero(&mm->mm_users))
 					continue;
-				}
 				spin_unlock(&mmlist_lock);
 				mmput(prev_mm);
 				prev_mm = mm;
-
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