linux-kernel - [PATCH v8 5/8] entry: Add arch_irqentry_exit_need

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Message-ID: <20250815030633.448613-6-ruanjinjie@huawei.com>
Date: Fri, 15 Aug 2025 11:06:30 +0800
From: Jinjie Ruan <ruanjinjie@...wei.com>
To: <catalin.marinas@....com>, <will@...nel.org>, <oleg@...hat.com>,
	<sstabellini@...nel.org>, <mark.rutland@....com>, <ada.coupriediaz@....com>,
	<mbenes@...e.cz>, <broonie@...nel.org>, <anshuman.khandual@....com>,
	<ryan.roberts@....com>, <chenl311@...natelecom.cn>, <liaochang1@...wei.com>,
	<kristina.martsenko@....com>, <leitao@...ian.org>, <ardb@...nel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
	<xen-devel@...ts.xenproject.org>
CC: <ruanjinjie@...wei.com>
Subject: [PATCH v8 5/8] entry: Add arch_irqentry_exit_need_resched() for arm64

Compared to the generic entry code, ARM64 does additional checks
when deciding to reschedule on return from interrupt. So introduce
arch_irqentry_exit_need_resched() in the need_resched()
condition of the generic raw_irqentry_exit_cond_resched(), with
a NOP default. This will allow ARM64 to implement the architecture
specific version for switching over to the generic entry code.

Suggested-by: Ada Couprie Diaz <ada.coupriediaz@....com>
Suggested-by: Mark Rutland <mark.rutland@....com>
Suggested-by: Kevin Brodsky <kevin.brodsky@....com>
Suggested-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Jinjie Ruan <ruanjinjie@...wei.com>
---
 kernel/entry/common.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index 408d28b5179d..f62e1d1b2063 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -143,6 +143,20 @@ noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs)
 	return ret;
 }
 
+/**
+ * arch_irqentry_exit_need_resched - Architecture specific need resched function
+ *
+ * Invoked from raw_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.
+ */
+static inline bool arch_irqentry_exit_need_resched(void);
+
+#ifndef arch_irqentry_exit_need_resched
+static inline bool arch_irqentry_exit_need_resched(void) { return true; }
+#endif
+
 void raw_irqentry_exit_cond_resched(void)
 {
 	if (!preempt_count()) {
@@ -150,7 +164,7 @@ void raw_irqentry_exit_cond_resched(void)
 		rcu_irq_exit_check_preempt();
 		if (IS_ENABLED(CONFIG_DEBUG_ENTRY))
 			WARN_ON_ONCE(!on_thread_stack());
-		if (need_resched())
+		if (need_resched() && arch_irqentry_exit_need_resched())
 			preempt_schedule_irq();
 	}
 }
-- 
2.34.1