[PATCH 3/4] memcg: use proper type for mod_memcg_state

[Shakeel Butt <shakeel.butt@linux.dev>]

The memcg stats update functions can take arbitrary integer but the
only input which make sense is enum memcg_stat_item and we don't
want these functions to be called with arbitrary integer, so replace
the parameter type with enum memcg_stat_item and compiler will be able
to warn if memcg stat update functions are called with incorrect index
value.

Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
---
 include/linux/memcontrol.h | 13 +++++++------
 mm/memcontrol.c            |  3 ++-
 2 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index d68db7a0e829..1b4a6201c78c 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -991,7 +991,8 @@ void mem_cgroup_print_oom_group(struct mem_cgroup *memcg);
 void folio_memcg_lock(struct folio *folio);
 void folio_memcg_unlock(struct folio *folio);
 
-void __mod_memcg_state(struct mem_cgroup *memcg, int idx, int val);
+void __mod_memcg_state(struct mem_cgroup *memcg, enum memcg_stat_item  idx,
+		       int val);
 
 /* try to stablize folio_memcg() for all the pages in a memcg */
 static inline bool mem_cgroup_trylock_pages(struct mem_cgroup *memcg)
@@ -1012,7 +1013,7 @@ static inline void mem_cgroup_unlock_pages(void)
 
 /* idx can be of type enum memcg_stat_item or node_stat_item */
 static inline void mod_memcg_state(struct mem_cgroup *memcg,
-				   int idx, int val)
+				   enum memcg_stat_item idx, int val)
 {
 	unsigned long flags;
 
@@ -1022,7 +1023,7 @@ static inline void mod_memcg_state(struct mem_cgroup *memcg,
 }
 
 static inline void mod_memcg_page_state(struct page *page,
-					int idx, int val)
+					enum memcg_stat_item idx, int val)
 {
 	struct mem_cgroup *memcg;
 
@@ -1541,19 +1542,19 @@ static inline void mem_cgroup_print_oom_group(struct mem_cgroup *memcg)
 }
 
 static inline void __mod_memcg_state(struct mem_cgroup *memcg,
-				     int idx,
+				     enum memcg_stat_item idx,
 				     int nr)
 {
 }
 
 static inline void mod_memcg_state(struct mem_cgroup *memcg,
-				   int idx,
+				   enum memcg_stat_item idx,
 				   int nr)
 {
 }
 
 static inline void mod_memcg_page_state(struct page *page,
-					int idx, int val)
+					enum memcg_stat_item idx, int val)
 {
 }
 
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index bb1bbf417a46..4e991e913393 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -816,7 +816,8 @@ static int memcg_state_val_in_pages(int idx, int val)
  * @idx: the stat item - can be enum memcg_stat_item or enum node_stat_item
  * @val: delta to add to the counter, can be negative
  */
-void __mod_memcg_state(struct mem_cgroup *memcg, int idx, int val)
+void __mod_memcg_state(struct mem_cgroup *memcg, enum memcg_stat_item idx,
+		       int val)
 {
 	if (mem_cgroup_disabled())
 		return;
-- 
2.43.0