ARM: localtimer: clean up local timer on hot unplug
When a CPU is hot unplugged, the generic tick code cleans up the
clock event device, but fails to call down to the device's set_mode
function to actually shut the device down.
To work around this, we've historically had a local_timer_stop()
callback out of the hotplug code. However, this adds needless
complexity when we have the clock event device itself available.
Explicitly call the clock event device's set_mode function with
CLOCK_EVT_MODE_UNUSED, so that the hardware can be cleanly shutdown
without any special external callbacks. When/if the generic code
is fixed, percpu_timer_stop() can be killed off.
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 6afaf6f7..4dc864e 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -189,6 +189,8 @@
}
#ifdef CONFIG_HOTPLUG_CPU
+static void percpu_timer_stop(void);
+
/*
* __cpu_disable runs on the processor to be shutdown.
*/
@@ -216,7 +218,7 @@
/*
* Stop the local timer for this CPU.
*/
- local_timer_stop();
+ percpu_timer_stop();
/*
* Flush user cache and TLB mappings, and then remove this CPU
@@ -539,6 +541,21 @@
local_timer_setup(evt);
}
+#ifdef CONFIG_HOTPLUG_CPU
+/*
+ * The generic clock events code purposely does not stop the local timer
+ * on CPU_DEAD/CPU_DEAD_FROZEN hotplug events, so we have to do it
+ * manually here.
+ */
+static void percpu_timer_stop(void)
+{
+ unsigned int cpu = smp_processor_id();
+ struct clock_event_device *evt = &per_cpu(percpu_clockevent, cpu);
+
+ evt->set_mode(CLOCK_EVT_MODE_UNUSED, evt);
+}
+#endif
+
static DEFINE_SPINLOCK(stop_lock);
/*