On Mon, 6 Jul 2015, Sudeep Holla wrote:
> On 06/07/15 17:06, Thomas Gleixner wrote:
> 2. After boot I am seeing the below warning:
>
> ------------[ cut here ]------------
> WARNING: CPU: 1 PID: 0 at kernel/time/hrtimer.c:1247
> __hrtimer_run_queues+0x148/0x150()
> Modules linked in:
> CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.2.0-rc1 #573
> Hardware name: ARM Juno development board (r0) (DT)
> Call trace:
> [<ffffffc000089954>] dump_backtrace+0x0/0x124
> [<ffffffc000089a88>] show_stack+0x10/0x1c
> [<ffffffc0005d100c>] dump_stack+0x84/0xc8
> [<ffffffc0000b3f34>] warn_slowpath_common+0x98/0xd0
> [<ffffffc0000b402c>] warn_slowpath_null+0x14/0x20
> [<ffffffc000101eec>] __hrtimer_run_queues+0x144/0x150
> [<ffffffc0001028b4>] hrtimer_run_queues+0xb8/0xe8
> [<ffffffc000101714>] update_process_times+0x28/0x6c
> [<ffffffc00010d978>] tick_periodic+0x3c/0xb8
> [<ffffffc00010da1c>] tick_handle_periodic+0x28/0x94
> [<ffffffc0004d6154>] arch_timer_handler_phys+0x28/0x38
> [<ffffffc0000f5964>] handle_percpu_devid_irq+0x74/0x9c
> [<ffffffc0000f1668>] generic_handle_irq+0x30/0x4c
> [<ffffffc0000f1984>] __handle_domain_irq+0x5c/0xac
> [<ffffffc0000824a8>] gic_handle_irq+0x30/0x80
Bah. I fear Preeti's hrtimer-broadcast stuff recurses in the hrtimer
code.
tick_periodic()
expire broadcast timer()
handle_broadcast() {
tick_periodic()
expire_other_timer()
}
warning triggers
Crap. Patch below should cure that.
Thanks,
tglx
---
Index: tip/kernel/time/tick-broadcast.c
===================================================================
--- tip.orig/kernel/time/tick-broadcast.c
+++ tip/kernel/time/tick-broadcast.c
@@ -358,18 +358,21 @@ void tick_broadcast_control(enum tick_br
tick_broadcast_forced = 1;
case TICK_BROADCAST_ON:
cpumask_set_cpu(cpu, tick_broadcast_on);
- if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_mask)) {
- /*
- * Only shutdown the cpu local device, if the
- * broadcast device exists and is in periodic
- * mode. The latter check prevents a hickup
- * during the switch from periodic to oneshot
- * mode.
- */
- if (bc != NULL && tick_broadcast_device.mode ==
- TICKDEV_MODE_PERIODIC)
- clockevents_shutdown(dev);
- }
+
+ /*
+ * Only shutdown the cpu local device, if:
+ *
+ * - the broadcast device exists
+ * - the broadcast device is not a hrtimer based one
+ * - the broadcast device is in periodic mode to
+ * avoid a hickup during switch to oneshot mode
+ */
+ if (!bc || (bc->features & CLOCK_EVT_FEAT_HRTIMER) ||
+ tick_broadcast_device.mode != TICKDEV_MODE_PERIODIC)
+ break;
+
+ if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_mask))
+ clockevents_shutdown(dev);
break;
case TICK_BROADCAST_OFF:
@@ -697,14 +700,18 @@ int __tick_broadcast_oneshot_control(enu
* shutdown.
*/
ret = broadcast_needs_cpu(bc, cpu);
+ if (ret)
+ goto out;
/*
- * If the hrtimer broadcast check tells us that the
- * cpu cannot go deep idle, or if the broadcast device
- * is in periodic mode, we just return.
+ * If the broadcast device is in periodic mode, we
+ * return.
*/
- if (ret || tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
- goto out;
+ if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
+ /* If it is a hrtimer based broadcast, return busy */
+ if (bc->features & CLOCK_EVT_FEAT_HRTIMER)
+ ret = -EBUSY;
+ }
if (!cpumask_test_and_set_cpu(cpu,
tick_broadcast_oneshot_mask)) {
WARN_ON_ONCE(cpumask_test_cpu(cpu,
tick_broadcast_pending_mask));
--
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