ARM: CPU hotplug: ensure correct ordering of unplug

Don't call idle_task_exit() with interrupts disabled, and ensure
that we have a memory barrier after interrupts are disabled but
before signalling that this CPU has shut down.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 8c81ff9..1a1c5e2 100644 (file)
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -269,9 +269,11 @@ void __ref cpu_die(void)
 {
        unsigned int cpu = smp_processor_id();
 
-       local_irq_disable();
        idle_task_exit();
 
+       local_irq_disable();
+       mb();
+
        /* Tell __cpu_die() that this CPU is now safe to dispose of */
        complete(&cpu_died);