[PATCH v1 3/3] arm64: 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)[0:swapper/0]RCU used illegally from offline CPU! ...
(0)[0:swapper/0]lockdep: [name:lockdep&]cpu_id = 0, cpu_is_offline = 1

Signed-off-by: Hanks Chen <hanks.chen@xxxxxxxxxxxx>
---
 arch/arm64/kernel/smp.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 82e75fc2c903..27a6553fa86f 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -308,6 +308,12 @@ int __cpu_disable(void)
 	remove_cpu_topology(cpu);
 	numa_remove_cpu(cpu);
 
+	/*
+	 * 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.
@@ -842,9 +848,10 @@ void arch_irq_work_raise(void)
 
 static void local_cpu_stop(void)
 {
+	local_daif_mask();
+
 	set_cpu_online(smp_processor_id(), false);
 
-	local_daif_mask();
 	sdei_mask_local_cpu();
 	cpu_park_loop();
 }
-- 
2.18.0