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Message-ID: <20250610075344.1379597-2-sshegde@linux.ibm.com>
Date: Tue, 10 Jun 2025 13:23:44 +0530
From: Shrikanth Hegde <sshegde@...ux.ibm.com>
To: mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
vincent.guittot@...aro.org, maddy@...ux.ibm.com
Cc: sshegde@...ux.ibm.com, tglx@...utronix.de, bigeasy@...utronix.de,
vschneid@...hat.com, dietmar.eggemann@....com, rostedt@...dmis.org,
linux-kernel@...r.kernel.org, catalin.marinas@....com, will@...nel.org,
linux-arm-kernel@...ts.infradead.org, mark.rutland@....com
Subject: [PATCH 1/1] sched: preempt: Move dynamic keys into kernel/sched
Dynamic preemption can be static key or static call based.
Static key is used to check kernel preemption depending on
the current preemption model. i.e enable for lazy, full.
Code is spread currently across entry/common.c, arm64 and latest being
powerpc. There is little arch specific to it. For example, arm64,
powerpc does the same thing. It is better to move it into kernel/sched
since preemption is more closely associated with scheduler.
Plus, Any new arch that wants dynamic preemption enabled need to have
only HAVE_PREEMPT_DYNAMIC_KEY.
This is more of code movement. No functional change.
Suggested-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Signed-off-by: Shrikanth Hegde <sshegde@...ux.ibm.com>
---
arch/arm64/include/asm/preempt.h | 1 -
arch/arm64/kernel/entry-common.c | 8 --------
arch/powerpc/include/asm/preempt.h | 16 ----------------
arch/powerpc/kernel/interrupt.c | 4 ----
include/linux/entry-common.h | 1 -
include/linux/sched.h | 8 ++++++++
kernel/entry/common.c | 1 -
kernel/sched/core.c | 4 ++++
8 files changed, 12 insertions(+), 31 deletions(-)
delete mode 100644 arch/powerpc/include/asm/preempt.h
diff --git a/arch/arm64/include/asm/preempt.h b/arch/arm64/include/asm/preempt.h
index 0159b625cc7f..a9348e65d75e 100644
--- a/arch/arm64/include/asm/preempt.h
+++ b/arch/arm64/include/asm/preempt.h
@@ -87,7 +87,6 @@ void preempt_schedule_notrace(void);
#ifdef CONFIG_PREEMPT_DYNAMIC
-DECLARE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched);
void dynamic_preempt_schedule(void);
#define __preempt_schedule() dynamic_preempt_schedule()
void dynamic_preempt_schedule_notrace(void);
diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c
index b260ddc4d3e9..b1c854fb4884 100644
--- a/arch/arm64/kernel/entry-common.c
+++ b/arch/arm64/kernel/entry-common.c
@@ -259,14 +259,6 @@ static void noinstr arm64_exit_el1_dbg(struct pt_regs *regs)
lockdep_hardirqs_on(CALLER_ADDR0);
}
-#ifdef CONFIG_PREEMPT_DYNAMIC
-DEFINE_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
-
static void __sched arm64_preempt_schedule_irq(void)
{
if (!need_irq_preemption())
diff --git a/arch/powerpc/include/asm/preempt.h b/arch/powerpc/include/asm/preempt.h
deleted file mode 100644
index 000e2b9681f3..000000000000
--- a/arch/powerpc/include/asm/preempt.h
+++ /dev/null
@@ -1,16 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef __ASM_POWERPC_PREEMPT_H
-#define __ASM_POWERPC_PREEMPT_H
-
-#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
-
-#endif /* __ASM_POWERPC_PREEMPT_H */
diff --git a/arch/powerpc/kernel/interrupt.c b/arch/powerpc/kernel/interrupt.c
index e0c681d0b076..4d62d785ad26 100644
--- a/arch/powerpc/kernel/interrupt.c
+++ b/arch/powerpc/kernel/interrupt.c
@@ -25,10 +25,6 @@
unsigned long global_dbcr0[NR_CPUS];
#endif
-#if defined(CONFIG_PREEMPT_DYNAMIC)
-DEFINE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched);
-#endif
-
#ifdef CONFIG_PPC_BOOK3S_64
DEFINE_STATIC_KEY_FALSE(interrupt_exit_not_reentrant);
static inline bool exit_must_hard_disable(void)
diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index f94f3fdf15fc..8624faa1f8b9 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -549,7 +549,6 @@ void raw_irqentry_exit_cond_resched(void);
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
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 45e5953b8f32..ebd230382027 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2115,6 +2115,14 @@ static inline int _cond_resched(void)
#endif /* !CONFIG_PREEMPTION || CONFIG_PREEMPT_DYNAMIC */
+#if defined(CONFIG_PREEMPT_DYNAMIC) && defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
+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
+
#define cond_resched() ({ \
__might_resched(__FILE__, __LINE__, 0); \
_cond_resched(); \
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index a8dd1f27417c..b8ffd7127338 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -268,7 +268,6 @@ void raw_irqentry_exit_cond_resched(void)
#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))
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 62b3416f5e43..6af2bab187cb 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7083,6 +7083,10 @@ EXPORT_SYMBOL(dynamic_preempt_schedule_notrace);
#endif /* CONFIG_PREEMPTION */
+#if defined(CONFIG_PREEMPT_DYNAMIC) && defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
+DEFINE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched);
+#endif
+
/*
* This is the entry point to schedule() from kernel preemption
* off of IRQ context.
--
2.43.0
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