linux-kernel - [PATCH -next v7 3/7] arm64: entry: Rework arm64_preempt_schedule

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Message-ID: <20250729015456.3411143-4-ruanjinjie@huawei.com>
Date: Tue, 29 Jul 2025 09:54:52 +0800
From: Jinjie Ruan <ruanjinjie@...wei.com>
To: <catalin.marinas@....com>, <will@...nel.org>, <oleg@...hat.com>,
	<sstabellini@...nel.org>, <mark.rutland@....com>, <puranjay@...nel.org>,
	<broonie@...nel.org>, <mbenes@...e.cz>, <ryan.roberts@....com>,
	<akpm@...ux-foundation.org>, <chenl311@...natelecom.cn>,
	<ada.coupriediaz@....com>, <anshuman.khandual@....com>,
	<kristina.martsenko@....com>, <liaochang1@...wei.com>, <ardb@...nel.org>,
	<leitao@...ian.org>, <linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <xen-devel@...ts.xenproject.org>
CC: <ruanjinjie@...wei.com>
Subject: [PATCH -next v7 3/7] arm64: entry: Rework arm64_preempt_schedule_irq()

The generic entry code has the form:

| raw_irqentry_exit_cond_resched()
| {
| 	if (!preempt_count()) {
| 		...
| 		if (need_resched())
| 			preempt_schedule_irq();
| 	}
| }

In preparation for moving arm64 over to the generic entry code, align
the structure of the arm64 code with raw_irqentry_exit_cond_resched() from
the generic entry code.

Signed-off-by: Jinjie Ruan <ruanjinjie@...wei.com>
---
 arch/arm64/kernel/entry-common.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c
index 97e0741abde1..21a7d8bea814 100644
--- a/arch/arm64/kernel/entry-common.c
+++ b/arch/arm64/kernel/entry-common.c
@@ -293,10 +293,10 @@ DEFINE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched);
 #define need_irq_preemption()	(IS_ENABLED(CONFIG_PREEMPTION))
 #endif
 
-static void __sched arm64_preempt_schedule_irq(void)
+static inline bool arm64_preempt_schedule_irq(void)
 {
 	if (!need_irq_preemption())
-		return;
+		return false;
 
 	/*
 	 * Note: thread_info::preempt_count includes both thread_info::count
@@ -304,7 +304,7 @@ static void __sched arm64_preempt_schedule_irq(void)
 	 * preempt_count().
 	 */
 	if (READ_ONCE(current_thread_info()->preempt_count) != 0)
-		return;
+		return false;
 
 	/*
 	 * DAIF.DA are cleared at the start of IRQ/FIQ handling, and when GIC
@@ -313,7 +313,7 @@ static void __sched arm64_preempt_schedule_irq(void)
 	 * DAIF we must have handled an NMI, so skip preemption.
 	 */
 	if (system_uses_irq_prio_masking() && read_sysreg(daif))
-		return;
+		return false;
 
 	/*
 	 * Preempting a task from an IRQ means we leave copies of PSTATE
@@ -323,8 +323,10 @@ static void __sched arm64_preempt_schedule_irq(void)
 	 * Only allow a task to be preempted once cpufeatures have been
 	 * enabled.
 	 */
-	if (system_capabilities_finalized())
-		preempt_schedule_irq();
+	if (!system_capabilities_finalized())
+		return false;
+
+	return true;
 }
 
 static void do_interrupt_handler(struct pt_regs *regs,
@@ -687,7 +689,8 @@ static __always_inline void __el1_irq(struct pt_regs *regs,
 	do_interrupt_handler(regs, handler);
 	irq_exit_rcu();
 
-	arm64_preempt_schedule_irq();
+	if (arm64_preempt_schedule_irq())
+		preempt_schedule_irq();
 
 	exit_to_kernel_mode(regs, state);
 }
-- 
2.34.1