linux-kernel - [PATCH -next v4 09/19] arm64: entry: Use preempt_count() and need

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Message-ID: <20241025100700.3714552-10-ruanjinjie@huawei.com>
Date: Fri, 25 Oct 2024 18:06:50 +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 09/19] arm64: entry: Use preempt_count() and need_resched() helper

The "READ_ONCE(current_thread_info()->preempt_count = 0" is equivalent
to "preempt_count() == 0 && need_resched()", so use these helpers to
replace it, which will make it more clear when switch to generic entry.

No functional changes.

Signed-off-by: Jinjie Ruan <ruanjinjie@...wei.com>
---
 arch/arm64/kernel/entry-common.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c
index a3414fb599fa..3ea3ab32d232 100644
--- a/arch/arm64/kernel/entry-common.c
+++ b/arch/arm64/kernel/entry-common.c
@@ -74,14 +74,6 @@ static inline bool arm64_irqentry_exit_need_resched(void)
 	if (!need_irq_preemption())
 		return false;
 
-	/*
-	 * Note: thread_info::preempt_count includes both thread_info::count
-	 * and thread_info::need_resched, and is not equivalent to
-	 * preempt_count().
-	 */
-	if (READ_ONCE(current_thread_info()->preempt_count) != 0)
-		return false;
-
 	/*
 	 * DAIF.DA are cleared at the start of IRQ/FIQ handling, and when GIC
 	 * priority masking is used the GIC irqchip driver will clear DAIF.IF
@@ -129,8 +121,10 @@ static void noinstr exit_to_kernel_mode(struct pt_regs *regs,
 			return;
 		}
 
-		if (arm64_irqentry_exit_need_resched())
-			preempt_schedule_irq();
+		if (!preempt_count()) {
+			if (need_resched() && arm64_irqentry_exit_need_resched())
+				preempt_schedule_irq();
+		}
 
 		trace_hardirqs_on();
 	} else {
-- 
2.34.1