[PATCH v8 03/14] ARM: smp_twd: add support for remapped PPI interrupts
From: Russell King - ARM Linux <hidden>
Date: 2011-07-08 19:27:34
On Tue, Jul 05, 2011 at 09:49:04AM +0100, Marc Zyngier wrote:
quoted hunk ↗ jump to hunk
@@ -43,6 +45,10 @@ static void twd_set_mode(enum clock_event_mode mode, ctrl = TWD_TIMER_CONTROL_IT_ENABLE | TWD_TIMER_CONTROL_ONESHOT; break; case CLOCK_EVT_MODE_UNUSED: +#ifdef CONFIG_ARM_GIC_PPI_MAP + disable_irq(clk->irq); + /* fall through */ +#endif
Eww, no. This is wrong. You can get an UNUSED event if the TWD clock
event device gets swapped out for some other clock event device (eg,
one with a higher preference.)
This is at best a hack around the problem. The existing code deals with
hot unplug via this in arch/arm/kernel/smp.c:
/*
* 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);
}
Maybe that needs a local_timer_stop() ->twd_timer_stop() call rather
than trying to be clever by doing this via the set_mode() method. That
would seem to be overall a cleaner solution.