Subject: [PATCH 07/22] [RESEND] sched: fair: move unused stub functions to header

From: Arnd Bergmann <[email-masked]>
Date: Wed, 8 Nov 2023 13:58:28 +0100

From: Arnd Bergmann <[email-masked]>

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.

[A different patch with the same description got applied by accident
 and was later reverted, but the original patch is still missing]

Fixes: 7aa55f2a5902 ("sched/fair: Move unused stub functions to header")
Signed-off-by: Arnd Bergmann <[email-masked]>
---
A patch with the same commit log has
---
 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 2048138ce54b..82b82fa1d81b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -12927,19 +12927,6 @@ 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 2e5a95486a42..8f5df5250b8d 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -436,10 +436,21 @@ 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