[PATCH 0/5] sched: address missing-prototype warnings

[PATCH 0/5] sched: address missing-prototype warnings

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

I sent out a lot of -Wmissing-prototype warnings already, but noticed that
I missed some of the patches I did for the scheduler.

Addressing this is mainly useful in order to allow turning the
warning on by default in the future, but I also tried to
improe the code where possible.

Arnd Bergmann (5):
  sched: hide unused sched_update_scaling()
  sched: add schedule_user() declaration
  sched: fair: hide unused init_cfs_bandwidth() stub
  sched: make task_vruntime_update() prototype visible
  sched: fair: move unused stub functions to header

 kernel/sched/core.c  |  2 --
 kernel/sched/fair.c  | 19 +++----------------
 kernel/sched/sched.h | 13 +++++++++++++
 3 files changed, 16 insertions(+), 18 deletions(-)

-- 
2.39.2

Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: linux-kernel@vger.kernel.org

[PATCH 1/5] sched: hide unused sched_update_scaling()

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

This function is only used when CONFIG_SMP is enabled, without that there
is no caller and no prototype:

kernel/sched/fair.c:688:5: error: no previous prototype for 'sched_update_scaling' [-Werror=missing-prototypes

Hide the definition in the same #ifdef check as the declaration.

Fixes: 8a99b6833c88 ("sched: Move SCHED_DEBUG sysctl to debugfs")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 kernel/sched/fair.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 48b6f0ca13ac..2c1b345c3b8d 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -684,7 +684,7 @@ struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
 /**************************************************************
  * Scheduling class statistics methods:
  */
-
+#ifdef CONFIG_SMP
 int sched_update_scaling(void)
 {
 	unsigned int factor = get_update_sysctl_factor();
@@ -702,6 +702,7 @@ int sched_update_scaling(void)
 	return 0;
 }
 #endif
+#endif
 
 /*
  * delta /= w
-- 
2.39.2

Re: [PATCH 1/5] sched: hide unused sched_update_scaling()

[Mukesh Ojha]

On 5/23/2023 1:20 AM, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> This function is only used when CONFIG_SMP is enabled, without that there
> is no caller and no prototype:
> 
> kernel/sched/fair.c:688:5: error: no previous prototype for 'sched_update_scaling' [-Werror=missing-prototypes
> 
> Hide the definition in the same #ifdef check as the declaration.
> 
> Fixes: 8a99b6833c88 ("sched: Move SCHED_DEBUG sysctl to debugfs")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

LGTM, thanks.
Reviewed-by: Mukesh Ojha <quic_mojha@quicinc.com>

-- Mukesh

> ---
>   kernel/sched/fair.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 48b6f0ca13ac..2c1b345c3b8d 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -684,7 +684,7 @@ struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
>   /**************************************************************
>    * Scheduling class statistics methods:
>    */
> -
> +#ifdef CONFIG_SMP
>   int sched_update_scaling(void)
>   {
>   	unsigned int factor = get_update_sysctl_factor();
> @@ -702,6 +702,7 @@ int sched_update_scaling(void)
>   	return 0;
>   }
>   #endif
> +#endif
>   
>   /*
>    * delta /= w

[tip: sched/core] sched: Hide unused sched_update_scaling()

[tip-bot2 for Arnd Bergmann]

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     d55ebae3f3122b07689cc4c34043114e09ce904c
Gitweb:        https://git.kernel.org/tip/d55ebae3f3122b07689cc4c34043114e09ce904c
Author:        Arnd Bergmann <arnd@arndb.de>
AuthorDate:    Mon, 22 May 2023 21:50:17 +02:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Tue, 30 May 2023 22:46:24 +02:00

sched: Hide unused sched_update_scaling()

This function is only used when CONFIG_SMP is enabled, without that there
is no caller and no prototype:

kernel/sched/fair.c:688:5: error: no previous prototype for 'sched_update_scaling' [-Werror=missing-prototypes

Hide the definition in the same #ifdef check as the declaration.

Fixes: 8a99b6833c88 ("sched: Move SCHED_DEBUG sysctl to debugfs")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230522195021.3456768-2-arnd@kernel.org
---
 kernel/sched/fair.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 48b6f0c..2c1b345 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -684,7 +684,7 @@ struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
 /**************************************************************
  * Scheduling class statistics methods:
  */
-
+#ifdef CONFIG_SMP
 int sched_update_scaling(void)
 {
 	unsigned int factor = get_update_sysctl_factor();
@@ -702,6 +702,7 @@ int sched_update_scaling(void)
 	return 0;
 }
 #endif
+#endif
 
 /*
  * delta /= w

[PATCH 2/5] sched: add schedule_user() declaration

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

The schedule_user() function is used on powerpc and sparc architectures, but
only ever called from assembler, so it has no prototype, causing a harmless W=1
warning:

kernel/sched/core.c:6730:35: error: no previous prototype for 'schedule_user' [-Werror=missing-prototypes]

Add a prototype in sched/sched.h to shut up the warning.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 kernel/sched/sched.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 1704763897d0..44b34836bb60 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2376,6 +2376,7 @@ static inline struct cpuidle_state *idle_get_state(struct rq *rq)
 #endif
 
 extern void schedule_idle(void);
+asmlinkage void schedule_user(void);
 
 extern void sysrq_sched_debug_show(void);
 extern void sched_init_granularity(void);
-- 
2.39.2

[tip: sched/core] sched: Add schedule_user() declaration

[tip-bot2 for Arnd Bergmann]

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     378be384e01f13fc44d0adc70873de525586ad74
Gitweb:        https://git.kernel.org/tip/378be384e01f13fc44d0adc70873de525586ad74
Author:        Arnd Bergmann <arnd@arndb.de>
AuthorDate:    Mon, 22 May 2023 21:50:18 +02:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Tue, 30 May 2023 22:46:25 +02:00

sched: Add schedule_user() declaration

The schedule_user() function is used on powerpc and sparc architectures, but
only ever called from assembler, so it has no prototype, causing a harmless W=1
warning:

kernel/sched/core.c:6730:35: error: no previous prototype for 'schedule_user' [-Werror=missing-prototypes]

Add a prototype in sched/sched.h to shut up the warning.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230522195021.3456768-3-arnd@kernel.org
---
 kernel/sched/sched.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 6784462..192e781 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2376,6 +2376,7 @@ static inline struct cpuidle_state *idle_get_state(struct rq *rq)
 #endif
 
 extern void schedule_idle(void);
+asmlinkage void schedule_user(void);
 
 extern void sysrq_sched_debug_show(void);
 extern void sched_init_granularity(void);

[PATCH 3/5] sched: fair: hide unused init_cfs_bandwidth() stub

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

init_cfs_bandwidth() is only used when CONFIG_FAIR_GROUP_SCHED is
enabled, and without this causes a W=1 warning for the missing prototype:

kernel/sched/fair.c:6131:6: error: no previous prototype for 'init_cfs_bandwidth'

The normal implementation is only defined for CONFIG_CFS_BANDWIDTH,
so the stub exists when CFS_BANDWIDTH is disabled but FAIR_GROUP_SCHED
is enabled.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 kernel/sched/fair.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 2c1b345c3b8d..a7a8ccde3bd7 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6169,9 +6169,8 @@ static inline int throttled_lb_pair(struct task_group *tg,
 	return 0;
 }
 
-void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
-
 #ifdef CONFIG_FAIR_GROUP_SCHED
+void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
 static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
 #endif
 
-- 
2.39.2

Re: [PATCH 3/5] sched: fair: hide unused init_cfs_bandwidth() stub

[Mukesh Ojha]

On 5/23/2023 1:20 AM, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> init_cfs_bandwidth() is only used when CONFIG_FAIR_GROUP_SCHED is
> enabled, and without this causes a W=1 warning for the missing prototype:
> 
> kernel/sched/fair.c:6131:6: error: no previous prototype for 'init_cfs_bandwidth'
> 
> The normal implementation is only defined for CONFIG_CFS_BANDWIDTH,
> so the stub exists when CFS_BANDWIDTH is disabled but FAIR_GROUP_SCHED
> is enabled.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>


Reviewed-by: Mukesh Ojha <quic_mojha@quicinc.com>

-- Mukesh

> ---
>   kernel/sched/fair.c | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 2c1b345c3b8d..a7a8ccde3bd7 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -6169,9 +6169,8 @@ static inline int throttled_lb_pair(struct task_group *tg,
>   	return 0;
>   }
>   
> -void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
> -
>   #ifdef CONFIG_FAIR_GROUP_SCHED
> +void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
>   static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
>   #endif
>   

[tip: sched/core] sched/fair: Hide unused init_cfs_bandwidth() stub

[tip-bot2 for Arnd Bergmann]

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     c0bdfd72fbfb7319581bd5bb09b4f10979385bac
Gitweb:        https://git.kernel.org/tip/c0bdfd72fbfb7319581bd5bb09b4f10979385bac
Author:        Arnd Bergmann <arnd@arndb.de>
AuthorDate:    Mon, 22 May 2023 21:50:19 +02:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Tue, 30 May 2023 22:46:25 +02:00

sched/fair: Hide unused init_cfs_bandwidth() stub

init_cfs_bandwidth() is only used when CONFIG_FAIR_GROUP_SCHED is
enabled, and without this causes a W=1 warning for the missing prototype:

kernel/sched/fair.c:6131:6: error: no previous prototype for 'init_cfs_bandwidth'

The normal implementation is only defined for CONFIG_CFS_BANDWIDTH,
so the stub exists when CFS_BANDWIDTH is disabled but FAIR_GROUP_SCHED
is enabled.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230522195021.3456768-4-arnd@kernel.org
---
 kernel/sched/fair.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 2c1b345..a7a8ccd 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6169,9 +6169,8 @@ static inline int throttled_lb_pair(struct task_group *tg,
 	return 0;
 }
 
-void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
-
 #ifdef CONFIG_FAIR_GROUP_SCHED
+void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
 static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
 #endif
 

[PATCH 4/5] sched: make task_vruntime_update() prototype visible

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

Having the prototype next to the caller but not visible to the callee causes
a W=1 warning:

kernel/sched/fair.c:11985:6: error: no previous prototype for 'task_vruntime_update' [-Werror=missing-prototypes]

Move this to a header, as we do for all other function declarations.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 kernel/sched/core.c  | 2 --
 kernel/sched/sched.h | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 044bcdf4181a..aae6ff717c55 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6030,8 +6030,6 @@ static inline struct task_struct *pick_task(struct rq *rq)
 	BUG(); /* The idle class should always have a runnable task. */
 }
 
-extern void task_vruntime_update(struct rq *rq, struct task_struct *p, bool in_fi);
-
 static void queue_core_balance(struct rq *rq);
 
 static struct task_struct *
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 44b34836bb60..d5ac0af1eede 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1245,6 +1245,7 @@ static inline raw_spinlock_t *__rq_lockp(struct rq *rq)
 
 bool cfs_prio_less(const struct task_struct *a, const struct task_struct *b,
 			bool fi);
+void task_vruntime_update(struct rq *rq, struct task_struct *p, bool in_fi);
 
 /*
  * Helpers to check if the CPU's core cookie matches with the task's cookie
-- 
2.39.2

Re: [PATCH 4/5] sched: make task_vruntime_update() prototype visible

[Mukesh Ojha]

On 5/23/2023 1:20 AM, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> Having the prototype next to the caller but not visible to the callee causes
> a W=1 warning:
> 
> kernel/sched/fair.c:11985:6: error: no previous prototype for 'task_vruntime_update' [-Werror=missing-prototypes]
> 
> Move this to a header, as we do for all other function declarations.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>


LGTM.
Reviewed-by: Mukesh Ojha <quic_mojha@quicinc.com>

-- Mukesh

> ---
>   kernel/sched/core.c  | 2 --
>   kernel/sched/sched.h | 1 +
>   2 files changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 044bcdf4181a..aae6ff717c55 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -6030,8 +6030,6 @@ static inline struct task_struct *pick_task(struct rq *rq)
>   	BUG(); /* The idle class should always have a runnable task. */
>   }
>   
> -extern void task_vruntime_update(struct rq *rq, struct task_struct *p, bool in_fi);
> -
>   static void queue_core_balance(struct rq *rq);
>   
>   static struct task_struct *
> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> index 44b34836bb60..d5ac0af1eede 100644
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h
> @@ -1245,6 +1245,7 @@ static inline raw_spinlock_t *__rq_lockp(struct rq *rq)
>   
>   bool cfs_prio_less(const struct task_struct *a, const struct task_struct *b,
>   			bool fi);
> +void task_vruntime_update(struct rq *rq, struct task_struct *p, bool in_fi);
>   
>   /*
>    * Helpers to check if the CPU's core cookie matches with the task's cookie

[tip: sched/core] sched: Make task_vruntime_update() prototype visible

[tip-bot2 for Arnd Bergmann]

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     f7df852ad6dbb84644e75df7402d9a34f39f31bd
Gitweb:        https://git.kernel.org/tip/f7df852ad6dbb84644e75df7402d9a34f39f31bd
Author:        Arnd Bergmann <arnd@arndb.de>
AuthorDate:    Mon, 22 May 2023 21:50:20 +02:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Tue, 30 May 2023 22:46:26 +02:00

sched: Make task_vruntime_update() prototype visible

Having the prototype next to the caller but not visible to the callee causes
a W=1 warning:

kernel/sched/fair.c:11985:6: error: no previous prototype for 'task_vruntime_update' [-Werror=missing-prototypes]

Move this to a header, as we do for all other function declarations.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230522195021.3456768-5-arnd@kernel.org
---
 kernel/sched/sched.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 192e781..ce07782 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1245,6 +1245,7 @@ static inline raw_spinlock_t *__rq_lockp(struct rq *rq)
 
 bool cfs_prio_less(const struct task_struct *a, const struct task_struct *b,
 			bool fi);
+void task_vruntime_update(struct rq *rq, struct task_struct *p, bool in_fi);
 
 /*
  * Helpers to check if the CPU's core cookie matches with the task's cookie

[PATCH 5/5] sched: fair: move unused stub functions to header

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

These four functions have a normal definition for CONFIG_FAIR_GROUP_SCHED,
and empty one that is only referenced when FAIR_GROUP_SCHED is disabled
but CGROUP_SCHED is still enabled. If both are turned off, the functions
are still defined but the misisng prototype causes a W=1 warning:

kernel/sched/fair.c:12544:6: error: no previous prototype for 'free_fair_sched_group'
kernel/sched/fair.c:12546:5: error: no previous prototype for 'alloc_fair_sched_group'
kernel/sched/fair.c:12553:6: error: no previous prototype for 'online_fair_sched_group'
kernel/sched/fair.c:12555:6: error: no previous prototype for 'unregister_fair_sched_group'

Move the alternatives into the header as static inline functions with
the correct combination of #ifdef checks to avoid the warning without
adding even more complexity.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 kernel/sched/fair.c  | 13 -------------
 kernel/sched/sched.h | 11 +++++++++++
 2 files changed, 11 insertions(+), 13 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index a7a8ccde3bd7..bae8907c1635 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -12602,19 +12602,6 @@ int sched_group_set_idle(struct task_group *tg, long idle)
 	return 0;
 }
 
-#else /* CONFIG_FAIR_GROUP_SCHED */
-
-void free_fair_sched_group(struct task_group *tg) { }
-
-int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
-{
-	return 1;
-}
-
-void online_fair_sched_group(struct task_group *tg) { }
-
-void unregister_fair_sched_group(struct task_group *tg) { }
-
 #endif /* CONFIG_FAIR_GROUP_SCHED */
 
 
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index d5ac0af1eede..0584fa15ffeb 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -453,10 +453,21 @@ static inline int walk_tg_tree(tg_visitor down, tg_visitor up, void *data)
 
 extern int tg_nop(struct task_group *tg, void *data);
 
+#ifdef CONFIG_FAIR_GROUP_SCHED
 extern void free_fair_sched_group(struct task_group *tg);
 extern int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent);
 extern void online_fair_sched_group(struct task_group *tg);
 extern void unregister_fair_sched_group(struct task_group *tg);
+#else
+static inline void free_fair_sched_group(struct task_group *tg) { }
+static inline int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
+{
+       return 1;
+}
+static inline void online_fair_sched_group(struct task_group *tg) { }
+static inline void unregister_fair_sched_group(struct task_group *tg) { }
+#endif
+
 extern void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq,
 			struct sched_entity *se, int cpu,
 			struct sched_entity *parent);
-- 
2.39.2

Re: [PATCH 5/5] sched: fair: move unused stub functions to header

[Mukesh Ojha]

On 5/23/2023 1:20 AM, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> These four functions have a normal definition for CONFIG_FAIR_GROUP_SCHED,
> and empty one that is only referenced when FAIR_GROUP_SCHED is disabled
> but CGROUP_SCHED is still enabled. If both are turned off, the functions
> are still defined but the misisng prototype causes a W=1 warning:

missing ?

> 
> kernel/sched/fair.c:12544:6: error: no previous prototype for 'free_fair_sched_group'
> kernel/sched/fair.c:12546:5: error: no previous prototype for 'alloc_fair_sched_group'
> kernel/sched/fair.c:12553:6: error: no previous prototype for 'online_fair_sched_group'
> kernel/sched/fair.c:12555:6: error: no previous prototype for 'unregister_fair_sched_group'
> 
> Move the alternatives into the header as static inline functions with
> the correct combination of #ifdef checks to avoid the warning without
> adding even more complexity.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

LGTM.

Reviewed-by: Mukesh Ojha <quic_mojha@quicinc.com>

-- Mukesh

> ---
>   kernel/sched/fair.c  | 13 -------------
>   kernel/sched/sched.h | 11 +++++++++++
>   2 files changed, 11 insertions(+), 13 deletions(-)
> 
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index a7a8ccde3bd7..bae8907c1635 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -12602,19 +12602,6 @@ int sched_group_set_idle(struct task_group *tg, long idle)
>   	return 0;
>   }
>   
> -#else /* CONFIG_FAIR_GROUP_SCHED */
> -
> -void free_fair_sched_group(struct task_group *tg) { }
> -
> -int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
> -{
> -	return 1;
> -}
> -
> -void online_fair_sched_group(struct task_group *tg) { }
> -
> -void unregister_fair_sched_group(struct task_group *tg) { }
> -
>   #endif /* CONFIG_FAIR_GROUP_SCHED */
>   
>   
> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> index d5ac0af1eede..0584fa15ffeb 100644
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h
> @@ -453,10 +453,21 @@ static inline int walk_tg_tree(tg_visitor down, tg_visitor up, void *data)
>   
>   extern int tg_nop(struct task_group *tg, void *data);
>   
> +#ifdef CONFIG_FAIR_GROUP_SCHED
>   extern void free_fair_sched_group(struct task_group *tg);
>   extern int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent);
>   extern void online_fair_sched_group(struct task_group *tg);
>   extern void unregister_fair_sched_group(struct task_group *tg);
> +#else
> +static inline void free_fair_sched_group(struct task_group *tg) { }
> +static inline int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
> +{
> +       return 1;
> +}
> +static inline void online_fair_sched_group(struct task_group *tg) { }
> +static inline void unregister_fair_sched_group(struct task_group *tg) { }
> +#endif
> +
>   extern void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq,
>   			struct sched_entity *se, int cpu,
>   			struct sched_entity *parent);

[tip: sched/core] sched/fair: Move unused stub functions to header

[tip-bot2 for Arnd Bergmann]

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     7aa55f2a5902646a19db89dab9961867724b27b8
Gitweb:        https://git.kernel.org/tip/7aa55f2a5902646a19db89dab9961867724b27b8
Author:        Arnd Bergmann <arnd@arndb.de>
AuthorDate:    Mon, 22 May 2023 21:50:21 +02:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Tue, 30 May 2023 22:46:26 +02:00

sched/fair: Move unused stub functions to header

These four functions have a normal definition for CONFIG_FAIR_GROUP_SCHED,
and empty one that is only referenced when FAIR_GROUP_SCHED is disabled
but CGROUP_SCHED is still enabled. If both are turned off, the functions
are still defined but the misisng prototype causes a W=1 warning:

kernel/sched/fair.c:12544:6: error: no previous prototype for 'free_fair_sched_group'
kernel/sched/fair.c:12546:5: error: no previous prototype for 'alloc_fair_sched_group'
kernel/sched/fair.c:12553:6: error: no previous prototype for 'online_fair_sched_group'
kernel/sched/fair.c:12555:6: error: no previous prototype for 'unregister_fair_sched_group'

Move the alternatives into the header as static inline functions with
the correct combination of #ifdef checks to avoid the warning without
adding even more complexity.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230522195021.3456768-6-arnd@kernel.org
---
 kernel/sched/fair.c  | 6 +++---
 kernel/sched/sched.h | 2 --
 2 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index a7a8ccd..48b6f0c 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -684,7 +684,7 @@ struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
 /**************************************************************
  * Scheduling class statistics methods:
  */
-#ifdef CONFIG_SMP
+
 int sched_update_scaling(void)
 {
 	unsigned int factor = get_update_sysctl_factor();
@@ -702,7 +702,6 @@ int sched_update_scaling(void)
 	return 0;
 }
 #endif
-#endif
 
 /*
  * delta /= w
@@ -6169,8 +6168,9 @@ static inline int throttled_lb_pair(struct task_group *tg,
 	return 0;
 }
 
-#ifdef CONFIG_FAIR_GROUP_SCHED
 void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
 static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
 #endif
 
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index ce07782..6784462 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1245,7 +1245,6 @@ static inline raw_spinlock_t *__rq_lockp(struct rq *rq)
 
 bool cfs_prio_less(const struct task_struct *a, const struct task_struct *b,
 			bool fi);
-void task_vruntime_update(struct rq *rq, struct task_struct *p, bool in_fi);
 
 /*
  * Helpers to check if the CPU's core cookie matches with the task's cookie
@@ -2377,7 +2376,6 @@ static inline struct cpuidle_state *idle_get_state(struct rq *rq)
 #endif
 
 extern void schedule_idle(void);
-asmlinkage void schedule_user(void);
 
 extern void sysrq_sched_debug_show(void);
 extern void sched_init_granularity(void);

Re: [PATCH 0/5] sched: address missing-prototype warnings

[Peter Zijlstra]

On Mon, May 22, 2023 at 09:50:16PM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> I sent out a lot of -Wmissing-prototype warnings already, but noticed that
> I missed some of the patches I did for the scheduler.
> 
> Addressing this is mainly useful in order to allow turning the
> warning on by default in the future, but I also tried to
> improe the code where possible.
> 
> Arnd Bergmann (5):
>   sched: hide unused sched_update_scaling()
>   sched: add schedule_user() declaration
>   sched: fair: hide unused init_cfs_bandwidth() stub
>   sched: make task_vruntime_update() prototype visible
>   sched: fair: move unused stub functions to header
> 

Thanks!

Re: [PATCH 0/5] sched: address missing-prototype warnings

[Vincent Guittot]

On Mon, 22 May 2023 at 21:50, Arnd Bergmann <arnd@kernel.org> wrote:
>
> From: Arnd Bergmann <arnd@arndb.de>
>
> I sent out a lot of -Wmissing-prototype warnings already, but noticed that
> I missed some of the patches I did for the scheduler.
>
> Addressing this is mainly useful in order to allow turning the
> warning on by default in the future, but I also tried to
> improe the code where possible.
>
> Arnd Bergmann (5):
>   sched: hide unused sched_update_scaling()
>   sched: add schedule_user() declaration
>   sched: fair: hide unused init_cfs_bandwidth() stub
>   sched: make task_vruntime_update() prototype visible
>   sched: fair: move unused stub functions to header

For the whole serie

Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>

>
>  kernel/sched/core.c  |  2 --
>  kernel/sched/fair.c  | 19 +++----------------
>  kernel/sched/sched.h | 13 +++++++++++++
>  3 files changed, 16 insertions(+), 18 deletions(-)
>
> --
> 2.39.2
>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Juri Lelli <juri.lelli@redhat.com>
> Cc: Vincent Guittot <vincent.guittot@linaro.org>
> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Ben Segall <bsegall@google.com>
> Cc: Mel Gorman <mgorman@suse.de>
> Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
> Cc: Valentin Schneider <vschneid@redhat.com>
> Cc: linux-kernel@vger.kernel.org
>