linux-kernel - Re: 3.10-rc3: WARNING: at kernel/time/tick-broadcast.c:578

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Date:	Mon, 27 May 2013 18:44:34 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Meelis Roos <mroos@...ux.ee>
cc:	Borislav Petkov <bp@...en8.de>,
	Linux Kernel list <linux-kernel@...r.kernel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Len Brown <lenb@...nel.org>, "Rafael J. Wysocki" <rjw@...k.pl>
Subject: Re: 3.10-rc3: WARNING: at kernel/time/tick-broadcast.c:578

On Mon, 27 May 2013, Meelis Roos wrote:
> > So we need to move the WARN_ON into the section where we actually set
> > the broadcast stuff up.
> 
> Are you sure? This is a UP machine.

Ooops.
 
> Tested the patch - no effect, warning is still there :(

Found another possibility how we end up with the stale flag.

diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index 24938d5..0c73942 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -511,6 +511,12 @@ again:
 		}
 	}
 
+	/*
+	 * Remove the current cpu from the pending mask. The event is
+	 * delivered immediately in tick_do_broadcast() !
+	 */
+	cpumask_clear_cpu(smp_processor_id(), tick_broadcast_pending_mask);
+
 	/* Take care of enforced broadcast requests */
 	cpumask_or(tmpmask, tmpmask, tick_broadcast_force_mask);
 	cpumask_clear(tick_broadcast_force_mask);
@@ -575,8 +581,8 @@ void tick_broadcast_oneshot_control(unsigned long reason)
 
 	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
 	if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) {
-		WARN_ON_ONCE(cpumask_test_cpu(cpu, tick_broadcast_pending_mask));
 		if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_oneshot_mask)) {
+			WARN_ON_ONCE(cpumask_test_cpu(cpu, tick_broadcast_pending_mask));
 			clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
 			/*
 			 * We only reprogram the broadcast timer if we
--
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