linux-kernel - Re: clockevents_shutdown vs pending interrupt

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Date:	Wed, 1 Jul 2015 16:57:43 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Andriy Gapon <avg@...eBSD.org>
cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: clockevents_shutdown vs pending interrupt

Andriy,

On Wed, 1 Jul 2015, Andriy Gapon wrote:
> I've caught a couple of boot logs with different stack traces from unsuccessful
> boot attempts and one from a successful attempt with exactly the same VM
> configuration.
> The logs are here:
> https://people.freebsd.org/~avg/linux-boot-hang/

I have to admit, that I'm thoroughly confused about that broadcast
check in the install path. Can you apply the debug patch below and
provide the output?

Thanks,

	tglx
---
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index d39f32cdd1b5..f1f921a49da9 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -100,6 +100,7 @@ void tick_install_broadcast_device(struct clock_event_device *dev)
 	if (cur)
 		cur->event_handler = clockevents_handle_noop;
 	tick_broadcast_device.evtdev = dev;
+	pr_err("Install broadcast device %p %s\n", dev, dev->name);
 	if (!cpumask_empty(tick_broadcast_mask))
 		tick_broadcast_start_periodic(dev);
 	/*
@@ -301,6 +302,13 @@ static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
 	bool bc_local;
 
 	raw_spin_lock(&tick_broadcast_lock);
+	/* Handle spurious interrupt */
+	if (clockevent_state_shutdown(dev)) {
+		pr_err("Spurious broadcast event %p %s\n", dev, dev->name);
+		raw_spin_unlock(&tick_broadcast_lock);
+		return;
+	}
+
 	bc_local = tick_do_periodic_broadcast();
 
 	if (clockevent_state_oneshot(dev)) {
diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index 76446cb5dfe1..ecd439b2de7e 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -321,6 +321,7 @@ void tick_check_new_device(struct clock_event_device *newdev)
 	if (!try_module_get(newdev->owner))
 		return;
 
+	pr_err("Install per cpu tick device %p %s\n", newdev, newdev->name);
 	/*
 	 * Replace the eventually existing device by the new
 	 * device. If the current device is the broadcast device, do


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