Re: [PATCH] mm: memcontrol: Use int for event/state parameter in several functions

From: Matthias Kaehlcke
Date: Fri Jul 28 2017 - 14:24:05 EST


El Thu, Jul 27, 2017 at 02:10:04PM -0700 Matthias Kaehlcke ha dit:

> Several functions use an enum type as parameter for an event/state,
> but are called in some locations with an argument of a different enum
> type. Adjust the interface of these functions to reality by changing the
> parameter to int.
>
> This fixes a ton of enum-conversion warnings that are generated when
> building the kernel with clang.

While building for another target with a different configuration I
noticed that inc/dec/mod_memcg_page_state() are also called with a
conflicting enum type. Changing the parameter type for these functions
also would make the API more consistent, with the current patch there
is a somewhat odd mix of related functions, with some receiving an
enum and others an int.

Depending on your preference I can send a v3 of this patch or a
separate patch to address the remaining functions (since this patch
has already been added to -mm).

> ---
> include/linux/memcontrol.h | 20 ++++++++++++--------
> mm/memcontrol.c | 4 +++-
> 2 files changed, 15 insertions(+), 9 deletions(-)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 3914e3dd6168..80edbc04361e 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -487,8 +487,9 @@ extern int do_swap_account;
> void lock_page_memcg(struct page *page);
> void unlock_page_memcg(struct page *page);
>
> +/* idx can be of type enum memcg_stat_item or node_stat_item */
> static inline unsigned long memcg_page_state(struct mem_cgroup *memcg,
> - enum memcg_stat_item idx)
> + int idx)
> {
> long val = 0;
> int cpu;
> @@ -502,15 +503,17 @@ static inline unsigned long memcg_page_state(struct mem_cgroup *memcg,
> return val;
> }
>
> +/* idx can be of type enum memcg_stat_item or node_stat_item */
> static inline void __mod_memcg_state(struct mem_cgroup *memcg,
> - enum memcg_stat_item idx, int val)
> + int idx, int val)
> {
> if (!mem_cgroup_disabled())
> __this_cpu_add(memcg->stat->count[idx], val);
> }
>
> +/* idx can be of type enum memcg_stat_item or node_stat_item */
> static inline void mod_memcg_state(struct mem_cgroup *memcg,
> - enum memcg_stat_item idx, int val)
> + int idx, int val)
> {
> if (!mem_cgroup_disabled())
> this_cpu_add(memcg->stat->count[idx], val);
> @@ -631,8 +634,9 @@ static inline void count_memcg_events(struct mem_cgroup *memcg,
> this_cpu_add(memcg->stat->events[idx], count);
> }
>
> +/* idx can be of type enum memcg_stat_item or node_stat_item */
> static inline void count_memcg_page_event(struct page *page,
> - enum memcg_stat_item idx)
> + int idx)
> {
> if (page->mem_cgroup)
> count_memcg_events(page->mem_cgroup, idx, 1);
> @@ -840,19 +844,19 @@ static inline bool mem_cgroup_oom_synchronize(bool wait)
> }
>
> static inline unsigned long memcg_page_state(struct mem_cgroup *memcg,
> - enum memcg_stat_item idx)
> + int idx)
> {
> return 0;
> }
>
> static inline void __mod_memcg_state(struct mem_cgroup *memcg,
> - enum memcg_stat_item idx,
> + int idx,
> int nr)
> {
> }
>
> static inline void mod_memcg_state(struct mem_cgroup *memcg,
> - enum memcg_stat_item idx,
> + int idx,
> int nr)
> {
> }
> @@ -918,7 +922,7 @@ static inline void count_memcg_events(struct mem_cgroup *memcg,
> }
>
> static inline void count_memcg_page_event(struct page *page,
> - enum memcg_stat_item idx)
> + int idx)
> {
> }
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 3df3c04d73ab..460130d2a796 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -550,10 +550,12 @@ mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_node *mctz)
> * value, and reading all cpu value can be performance bottleneck in some
> * common workload, threshold and synchronization as vmstat[] should be
> * implemented.
> + *
> + * The parameter idx can be of type enum memcg_event_item or vm_event_item.
> */
>
> static unsigned long memcg_sum_events(struct mem_cgroup *memcg,
> - enum memcg_event_item event)
> + int event)
> {
> unsigned long val = 0;
> int cpu;