[tip: sched/core] sched: dynamic: Simplify {cond,might}_resched()

[tip-bot2 for Mark Rutland]

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

Commit-ID:     88e0b3bb9930605ad7e5d3ddac7d9875325bebf0
Gitweb:        https://git.kernel.org/tip/88e0b3bb9930605ad7e5d3ddac7d9875325bebf0
Author:        Mark Rutland <mark.rutland@xxxxxxx>
AuthorDate:    Mon, 03 Aug 2026 20:17:27 +01:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Wed, 02 Sep 2026 09:37:22 +02:00

sched: dynamic: Simplify {cond,might}_resched()

PREEMPT_DYNAMIC is now limited to the FULL and LAZY preemption models.
In either model, both cond_resched() and might_resched() are always
disabled and do nothing.

Remove the unnecessary code for these when PREEMPT_DYNAMIC is selected.

Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Shrikanth Hegde <sshegde@xxxxxxxxxxxxx>
Reviewed-by: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>
Tested-by: Mete Durlu <meted@xxxxxxxxxxxxx>
Tested-by: Shrikanth Hegde <sshegde@xxxxxxxxxxxxx>
Tested-by: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>
Link: https://patch.msgid.link/20260803191731.3244294-3-mark.rutland@xxxxxxx
---
 include/linux/kernel.h | 20 +-------------------
 include/linux/sched.h  | 31 ++---------------------------
 kernel/sched/core.c    | 44 +-----------------------------------------
 3 files changed, 4 insertions(+), 91 deletions(-)

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 24414c7..4b11d1d 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -43,30 +43,10 @@ struct completion;
 struct user;
 
 #ifdef CONFIG_PREEMPT_VOLUNTARY_BUILD
-
 extern int __cond_resched(void);
 # define might_resched() __cond_resched()
-
-#elif defined(CONFIG_PREEMPT_DYNAMIC) && defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL)
-
-extern int __cond_resched(void);
-
-DECLARE_STATIC_CALL(might_resched, __cond_resched);
-
-static __always_inline void might_resched(void)
-{
-	static_call_mod(might_resched)();
-}
-
-#elif defined(CONFIG_PREEMPT_DYNAMIC) && defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
-
-extern int dynamic_might_resched(void);
-# define might_resched() dynamic_might_resched()
-
 #else
-
 # define might_resched() do { } while (0)
-
 #endif /* CONFIG_PREEMPT_* */
 
 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 8b3d47a..d7cc771 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2134,44 +2134,19 @@ static inline void set_need_resched_current(void)
  * value indicates whether a reschedule was done in fact.
  * cond_resched_lock() will drop the spinlock before scheduling,
  */
-#if !defined(CONFIG_PREEMPTION) || defined(CONFIG_PREEMPT_DYNAMIC)
+#if !defined(CONFIG_PREEMPTION)
 extern int __cond_resched(void);
 
-#if defined(CONFIG_PREEMPT_DYNAMIC) && defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL)
-
-DECLARE_STATIC_CALL(cond_resched, __cond_resched);
-
-static __always_inline int _cond_resched(void)
-{
-	return static_call_mod(cond_resched)();
-}
-
-#elif defined(CONFIG_PREEMPT_DYNAMIC) && defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
-
-extern int dynamic_cond_resched(void);
-
-static __always_inline int _cond_resched(void)
-{
-	return dynamic_cond_resched();
-}
-
-#else /* !CONFIG_PREEMPTION */
-
 static inline int _cond_resched(void)
 {
 	return __cond_resched();
 }
-
-#endif /* PREEMPT_DYNAMIC && CONFIG_HAVE_PREEMPT_DYNAMIC_CALL */
-
-#else /* CONFIG_PREEMPTION && !CONFIG_PREEMPT_DYNAMIC */
-
+#else
 static inline int _cond_resched(void)
 {
 	return 0;
 }
-
-#endif /* !CONFIG_PREEMPTION || CONFIG_PREEMPT_DYNAMIC */
+#endif
 
 #define cond_resched() ({			\
 	__might_resched(__FILE__, __LINE__, 0);	\
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 84e7685..0060efc 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7794,7 +7794,7 @@ out_unlock:
 }
 #endif /* CONFIG_RT_MUTEXES */
 
-#if !defined(CONFIG_PREEMPTION) || defined(CONFIG_PREEMPT_DYNAMIC)
+#if !defined(CONFIG_PREEMPTION)
 int __sched __cond_resched(void)
 {
 	if (should_resched(0) && !irqs_disabled()) {
@@ -7822,38 +7822,6 @@ int __sched __cond_resched(void)
 EXPORT_SYMBOL(__cond_resched);
 #endif
 
-#ifdef CONFIG_PREEMPT_DYNAMIC
-# ifdef CONFIG_HAVE_PREEMPT_DYNAMIC_CALL
-#  define cond_resched_dynamic_enabled	__cond_resched
-#  define cond_resched_dynamic_disabled	((void *)&__static_call_return0)
-DEFINE_STATIC_CALL_RET0(cond_resched, __cond_resched);
-EXPORT_STATIC_CALL_TRAMP(cond_resched);
-
-#  define might_resched_dynamic_enabled	__cond_resched
-#  define might_resched_dynamic_disabled ((void *)&__static_call_return0)
-DEFINE_STATIC_CALL_RET0(might_resched, __cond_resched);
-EXPORT_STATIC_CALL_TRAMP(might_resched);
-# elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
-static DEFINE_STATIC_KEY_FALSE(sk_dynamic_cond_resched);
-int __sched dynamic_cond_resched(void)
-{
-	if (!static_branch_unlikely(&sk_dynamic_cond_resched))
-		return 0;
-	return __cond_resched();
-}
-EXPORT_SYMBOL(dynamic_cond_resched);
-
-static DEFINE_STATIC_KEY_FALSE(sk_dynamic_might_resched);
-int __sched dynamic_might_resched(void)
-{
-	if (!static_branch_unlikely(&sk_dynamic_might_resched))
-		return 0;
-	return __cond_resched();
-}
-EXPORT_SYMBOL(dynamic_might_resched);
-# endif
-#endif /* CONFIG_PREEMPT_DYNAMIC */
-
 /*
  * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
  * call schedule, and on return reacquire the lock.
@@ -7923,8 +7891,6 @@ EXPORT_SYMBOL(__cond_resched_rwlock_write);
 # endif
 
 /*
- * SC:cond_resched
- * SC:might_resched
  * SC:preempt_schedule
  * SC:preempt_schedule_notrace
  * SC:irqentry_exit_cond_resched
@@ -7937,16 +7903,12 @@ EXPORT_SYMBOL(__cond_resched_rwlock_write);
  *   (unselectable)
  *
  * FULL:
- *   cond_resched               <- RET0
- *   might_resched              <- RET0
  *   preempt_schedule           <- preempt_schedule
  *   preempt_schedule_notrace   <- preempt_schedule_notrace
  *   irqentry_exit_cond_resched <- irqentry_exit_cond_resched
  *   dynamic_preempt_lazy       <- false
  *
  * LAZY:
- *   cond_resched               <- RET0
- *   might_resched              <- RET0
  *   preempt_schedule           <- preempt_schedule
  *   preempt_schedule_notrace   <- preempt_schedule_notrace
  *   irqentry_exit_cond_resched <- irqentry_exit_cond_resched
@@ -7993,8 +7955,6 @@ static void __sched_dynamic_update(int mode)
 {
 	switch (mode) {
 	case preempt_dynamic_full:
-		preempt_dynamic_disable(cond_resched);
-		preempt_dynamic_disable(might_resched);
 		preempt_dynamic_enable(preempt_schedule);
 		preempt_dynamic_enable(preempt_schedule_notrace);
 		preempt_dynamic_enable(irqentry_exit_cond_resched);
@@ -8004,8 +7964,6 @@ static void __sched_dynamic_update(int mode)
 		break;
 
 	case preempt_dynamic_lazy:
-		preempt_dynamic_disable(cond_resched);
-		preempt_dynamic_disable(might_resched);
 		preempt_dynamic_enable(preempt_schedule);
 		preempt_dynamic_enable(preempt_schedule_notrace);
 		preempt_dynamic_enable(irqentry_exit_cond_resched);