Re: [PATCH 4/5] sched: dynamic: Simplify irqentry_exit_cond_resched()
From: Shrikanth Hegde
Date: Mon Jul 06 2026 - 00:43:01 EST
+cc Christophe.
On 7/3/26 7:03 PM, Mark Rutland wrote:
PREEMPT_DYNAMIC is now limited to the FULL and LAZY preemption models.
In either model, irqentry_exit_cond_resched() is always called and never
disabled.
Remove the unnecessary code for this 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>
---
arch/powerpc/include/asm/preempt.h | 7 -------
include/linux/irq-entry-common.h | 17 +----------------
kernel/entry/common.c | 17 ++---------------
kernel/sched/core.c | 7 -------
4 files changed, 3 insertions(+), 45 deletions(-)
diff --git a/arch/powerpc/include/asm/preempt.h b/arch/powerpc/include/asm/preempt.h
index 000e2b9681f30..79fc1f9df88d9 100644
--- a/arch/powerpc/include/asm/preempt.h
+++ b/arch/powerpc/include/asm/preempt.h
@@ -4,13 +4,6 @@
#include <asm-generic/preempt.h>
-#if defined(CONFIG_PREEMPT_DYNAMIC)
-#include <linux/jump_label.h>
-DECLARE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched);
-#define need_irq_preemption() \
- (static_branch_unlikely(&sk_dynamic_irqentry_exit_cond_resched))
-#else
#define need_irq_preemption() (IS_ENABLED(CONFIG_PREEMPTION))
-#endif
JFYI,
Christophe had sent this patch, I am sure you guys will sort out the
conflicts. (I don't see it merged yet, but likely might)
https://lore.kernel.org/all/2bf10a0afffefb6aca44bf2f864cc17471a80e31.1781870889.git.chleroy@xxxxxxxxxx/
#endif /* __ASM_POWERPC_PREEMPT_H */
diff --git a/include/linux/irq-entry-common.h b/include/linux/irq-entry-common.h
index 1fabf0f5ea8e7..de7e10de91d04 100644
--- a/include/linux/irq-entry-common.h
+++ b/include/linux/irq-entry-common.h
@@ -346,22 +346,7 @@ typedef struct irqentry_state {
*
* Conditional reschedule with additional sanity checks.
*/
-void raw_irqentry_exit_cond_resched(void);
-
-#ifdef CONFIG_PREEMPT_DYNAMIC
-#if defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL)
-#define irqentry_exit_cond_resched_dynamic_enabled raw_irqentry_exit_cond_resched
-#define irqentry_exit_cond_resched_dynamic_disabled NULL
-DECLARE_STATIC_CALL(irqentry_exit_cond_resched, raw_irqentry_exit_cond_resched);
-#define irqentry_exit_cond_resched() static_call(irqentry_exit_cond_resched)()
-#elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
-DECLARE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched);
-void dynamic_irqentry_exit_cond_resched(void);
-#define irqentry_exit_cond_resched() dynamic_irqentry_exit_cond_resched()
-#endif
-#else /* CONFIG_PREEMPT_DYNAMIC */
-#define irqentry_exit_cond_resched() raw_irqentry_exit_cond_resched()
-#endif /* CONFIG_PREEMPT_DYNAMIC */
+void irqentry_exit_cond_resched(void);
/**
* irqentry_enter_from_kernel_mode - Establish state before invoking the irq handler
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index e3d381fd3d251..e234b04373fea 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -123,7 +123,7 @@ noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs)
/**
* arch_irqentry_exit_need_resched - Architecture specific need resched function
*
- * Invoked from raw_irqentry_exit_cond_resched() to check if resched is needed.
+ * Invoked from irqentry_exit_cond_resched() to check if resched is needed.
* Defaults return true.
*
* The main purpose is to permit arch to avoid preemption of a task from an IRQ.
@@ -134,7 +134,7 @@ static inline bool arch_irqentry_exit_need_resched(void);
static inline bool arch_irqentry_exit_need_resched(void) { return true; }
#endif
-void raw_irqentry_exit_cond_resched(void)
+void irqentry_exit_cond_resched(void)
{
if (!preempt_count()) {
/* Sanity check RCU and thread stack */
@@ -145,19 +145,6 @@ void raw_irqentry_exit_cond_resched(void)
preempt_schedule_irq();
}
}
-#ifdef CONFIG_PREEMPT_DYNAMIC
-#if defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL)
-DEFINE_STATIC_CALL(irqentry_exit_cond_resched, raw_irqentry_exit_cond_resched);
-#elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
-DEFINE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched);
-void dynamic_irqentry_exit_cond_resched(void)
-{
- if (!static_branch_unlikely(&sk_dynamic_irqentry_exit_cond_resched))
- return;
- raw_irqentry_exit_cond_resched();
-}
-#endif
-#endif
noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state)
{
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index f88b9ef70a0dd..4f754f4a472f8 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7788,9 +7788,6 @@ EXPORT_SYMBOL(__cond_resched_rwlock_write);
# endif
/*
- * SC:irqentry_exit_cond_resched
- *
- *
* NONE:
* (unselectable)
*
@@ -7798,11 +7795,9 @@ EXPORT_SYMBOL(__cond_resched_rwlock_write);
* (unselectable)
*
* FULL:
- * irqentry_exit_cond_resched <- irqentry_exit_cond_resched
* dynamic_preempt_lazy <- false
*
* LAZY:
- * irqentry_exit_cond_resched <- irqentry_exit_cond_resched
* dynamic_preempt_lazy <- true
*/
@@ -7846,14 +7841,12 @@ static void __sched_dynamic_update(int mode)
{
switch (mode) {
case preempt_dynamic_full:
- preempt_dynamic_enable(irqentry_exit_cond_resched);
preempt_dynamic_key_disable(preempt_lazy);
if (mode != preempt_dynamic_mode)
pr_info("Dynamic Preempt: full\n");
break;
case preempt_dynamic_lazy:
- preempt_dynamic_enable(irqentry_exit_cond_resched);
preempt_dynamic_key_enable(preempt_lazy);
if (mode != preempt_dynamic_mode)
pr_info("Dynamic Preempt: lazy\n");
Change per se, looks good to me.
Reviewed-by: Shrikanth Hegde <sshegde@xxxxxxxxxxxxx>