[PATCH] swapoff: use atomic_inc_not_zero() on mm_users

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@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/mm/swapfile.c b/mm/swapfile.c
index fbceed67a075336146a8653a9fc234e7ea54503a..f2824c3c31b428053e4b77c602b357417421dd2d 100644 (file)
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -772,10 +772,8 @@ static int try_to_unuse(unsigned int type)
                        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;