linux-kernel - [PATCH v1 2/3] arm: disable irq on cpu shutdown flow

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Date:   Fri, 27 Nov 2020 22:15:30 +0800
From:   Hanks Chen <hanks.chen@...iatek.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Marc Zyngier <maz@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Russell King <linux@...linux.org.uk>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>
CC:     <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>,
        CC Hwang <cc.hwang@...iatek.com>,
        Kuohong Wang <kuohong.wang@...iatek.com>,
        Loda Chou <loda.chou@...iatek.com>,
        Hanks Chen <hanks.chen@...iatek.com>
Subject: [PATCH v1 2/3] arm: disable irq on cpu shutdown flow

Disable irq on cpu shutdown flow to ensure interrupts
did not bother this cpu after status as offline.

To avoid suspicious RCU usage
[0:swapper/0]RCU used illegally from offline CPU! ...
[0:swapper/0]lockdep: [name:lockdep&]cpu_id = 0, cpu_is_offline = 1

Signed-off-by: Hanks Chen <hanks.chen@...iatek.com>
---
 arch/arm/kernel/smp.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 48099c6e1e4a..6b8f72490320 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -262,6 +262,12 @@ int __cpu_disable(void)
 	remove_cpu_topology(cpu);
 #endif
 
+	/*
+	 * we disable irq here to ensure interrupts
+	 * did not bother this cpu after status as offline.
+	 */
+	local_irq_disable();
+
 	/*
 	 * Take this CPU offline.  Once we clear this, we can't return,
 	 * and we must not schedule until we're ready to give up the cpu.
@@ -600,11 +606,11 @@ static void ipi_cpu_stop(unsigned int cpu)
 		raw_spin_unlock(&stop_lock);
 	}
 
-	set_cpu_online(cpu, false);
-
 	local_fiq_disable();
 	local_irq_disable();
 
+	set_cpu_online(cpu, false);
+
 	while (1) {
 		cpu_relax();
 		wfe();
-- 
2.18.0