hugetlb_cgroup: use helper for_each_hstate and hstate_index

Use helper for_each_hstate and hstate_index to iterate the hstate and get
the hstate index. Minor readability improvement.

Link: https://lkml.kernel.org/r/20220729080106.12752-6-linmiaohe@huawei.comSigned-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Mina Almasry <almasrymina@google.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/hugetlb_cgroup.c

@@ -75,11 +75,11 @@ parent_hugetlb_cgroup(struct hugetlb_cgroup *h_cg)
 
 static inline bool hugetlb_cgroup_have_usage(struct hugetlb_cgroup *h_cg)
 {
-	int idx;
+	struct hstate *h;
 
-	for (idx = 0; idx < hugetlb_max_hstate; idx++) {
+	for_each_hstate(h) {
 		if (page_counter_read(
-				hugetlb_cgroup_counter_from_cgroup(h_cg, idx)))
+		    hugetlb_cgroup_counter_from_cgroup(h_cg, hstate_index(h))))
 			return true;
 	}
 	return false;
@@ -225,17 +225,14 @@ static void hugetlb_cgroup_css_offline(struct cgroup_subsys_state *css)
 	struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(css);
 	struct hstate *h;
 	struct page *page;
-	int idx;
 
 	do {
-		idx = 0;
 		for_each_hstate(h) {
 			spin_lock_irq(&hugetlb_lock);
 			list_for_each_entry(page, &h->hugepage_activelist, lru)
-				hugetlb_cgroup_move_parent(idx, h_cg, page);
+				hugetlb_cgroup_move_parent(hstate_index(h), h_cg, page);
 
 			spin_unlock_irq(&hugetlb_lock);
-			idx++;
 		}
 		cond_resched();
 	} while (hugetlb_cgroup_have_usage(h_cg));