[PATCH 2/5] sched: dynamic: Simplify {cond,might}_resched()
From: Mark Rutland
Date: Fri Jul 03 2026 - 09:34:42 EST
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>
Cc: Frederic Weisbecker <frederic@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: John Stultz <jstultz@xxxxxxxxxx>
Cc: Juri Lelli <juri.lelli@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Valentin Schneider <vschneid@xxxxxxxxxx>
Cc: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
---
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 e5570a16cbb1a..533ee1e6e1cb7 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 373bcc0598d10..1a44c5261c2dd 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2119,44 +2119,19 @@ 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 2db78826a484b..84ec93694d718 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7733,7 +7733,7 @@ void rt_mutex_setprio(struct task_struct *p, struct task_struct *pi_task)
}
#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()) {
@@ -7761,38 +7761,6 @@ 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.
@@ -7862,8 +7830,6 @@ 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
@@ -7876,16 +7842,12 @@ 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
@@ -7932,8 +7894,6 @@ 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);
@@ -7943,8 +7903,6 @@ 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);
--
2.30.2