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

[Hanks Chen]

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 at mediatek.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