linux-kernel - [PATCH -next v4 15/19] entry: Add arch irqentry_exit_need

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Message-ID: <20241025100700.3714552-16-ruanjinjie@huawei.com>
Date: Fri, 25 Oct 2024 18:06:56 +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 15/19] entry: Add arch irqentry_exit_need_resched() for arm64

As the front patch 6 ~ 13 did, the arm64_preempt_schedule_irq() is
same with the irq preempt schedule code of generic entry besides those
architecture-related logic called arm64_irqentry_exit_need_resched().

So add arch irqentry_exit_need_resched() to support architecture-related
need_resched() check logic, which do not affect existing architectures
that use generic entry, but support arm64 to use generic irq entry.

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 2ad132c7be05..0cc117b658b8 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 need resched.
+ * Defaults return true.
+ *
+ * The main purpose is to permit arch to skip preempt 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