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

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  [PATCH] mm: memcontrol: Use int for event/state parameter in several functions Matthias Kaehlcke <mka@chromium.org> - 2017-07-27 23:20 +0200
    Re: [PATCH] mm: memcontrol: Use int for event/state parameter in  several functions Michal Hocko <mhocko@kernel.org> - 2017-07-28 09:00 +0200
    Re: [PATCH] mm: memcontrol: Use int for event/state parameter in  several functions Matthias Kaehlcke <mka@chromium.org> - 2017-07-28 20:30 +0200
      Re: [PATCH] mm: memcontrol: Use int for event/state parameter in  several functions Johannes Weiner <hannes@cmpxchg.org> - 2017-07-28 22:00 +0200

#1698327 — [PATCH] mm: memcontrol: Use int for event/state parameter in several functions

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.

Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
---
 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;
-- 
2.14.0.rc0.400.g1c36432dff-goog

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#1698522 — Re: [PATCH] mm: memcontrol: Use int for event/state parameter in several functions

On Thu 27-07-17 14:10:04, Matthias Kaehlcke wrote:
> 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.

enums are mostly for documentation purposes. Using defines would be
possible but less elegant. If for anything else then things like
MEMCG_NR_STAT.

> This fixes a ton of enum-conversion warnings that are generated when
> building the kernel with clang.
> 
> Signed-off-by: Matthias Kaehlcke <mka@chromium.org>

Acked-by: Michal Hocko <mhocko@suse.com>

Thanks!
> ---
>  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;
> -- 
> 2.14.0.rc0.400.g1c36432dff-goog

-- 
Michal Hocko
SUSE Labs

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#1698998 — Re: [PATCH] mm: memcontrol: Use int for event/state parameter in several functions

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;

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#1699049 — Re: [PATCH] mm: memcontrol: Use int for event/state parameter in several functions

On Fri, Jul 28, 2017 at 11:23:54AM -0700, Matthias Kaehlcke wrote:
> 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.

Thanks for fixing this, Matthias.

Acked-by: Johannes Weiner <hannes@cmpxchg.org>

> 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).

Since it's the exact same rationale for the other functions, it would
make sense to me to do a v3 that includes the remaining sites.

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