linux-kernel - [PATCH -next v4 08/19] arm64: entry: Rework arm64_preempt_schedule

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Message-ID: <20241025100700.3714552-9-ruanjinjie@huawei.com>
Date: Fri, 25 Oct 2024 18:06:49 +0800
From: Jinjie Ruan <ruanjinjie@...wei.com>
To: <oleg@...hat.com>, <linux@...linux.org.uk>, <will@...nel.org>,
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Subject: [PATCH -next v4 08/19] arm64: entry: Rework arm64_preempt_schedule_irq()

Rework arm64_preempt_schedule_irq() to check whether it need
resched in a check function arm64_irqentry_exit_need_resched().

No functional changes.

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 b57f6dc66115..a3414fb599fa 100644
--- a/arch/arm64/kernel/entry-common.c
+++ b/arch/arm64/kernel/entry-common.c
@@ -69,10 +69,10 @@ 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_irqentry_exit_need_resched(void)
 {
 	if (!need_irq_preemption())
-		return;
+		return false;
 
 	/*
 	 * Note: thread_info::preempt_count includes both thread_info::count
@@ -80,7 +80,7 @@ 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
@@ -89,7 +89,7 @@ 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
@@ -99,8 +99,10 @@ 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;
 }
 
 /*
@@ -127,7 +129,8 @@ static void noinstr exit_to_kernel_mode(struct pt_regs *regs,
 			return;
 		}
 
-		arm64_preempt_schedule_irq();
+		if (arm64_irqentry_exit_need_resched())
+			preempt_schedule_irq();
 
 		trace_hardirqs_on();
 	} else {
-- 
2.34.1