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Date: Tue, 7 Jul 2015 10:15:13 -0700
From: tip-bot for Thomas Gleixner <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: hpa@...or.com, tglx@...utronix.de, avg@...eBSD.org,
preeti@...ux.vnet.ibm.com, mingo@...nel.org,
linux-kernel@...r.kernel.org, sudeep.holla@....com,
peterz@...radead.org
Subject: [tip:timers/urgent] tick/broadcast:
Handle spurious interrupts gracefully
Commit-ID: c4288334818c81c946acb23d2319881f58c3d497
Gitweb: http://git.kernel.org/tip/c4288334818c81c946acb23d2319881f58c3d497
Author: Thomas Gleixner <tglx@...utronix.de>
AuthorDate: Sun, 5 Jul 2015 20:53:17 +0000
Committer: Thomas Gleixner <tglx@...utronix.de>
CommitDate: Tue, 7 Jul 2015 18:46:48 +0200
tick/broadcast: Handle spurious interrupts gracefully
Andriy reported that on a virtual machine the warning about negative
expiry time in the clock events programming code triggered:
hpet: hpet0 irq 40 for MSI
hpet: hpet1 irq 41 for MSI
Switching to clocksource hpet
WARNING: at kernel/time/clockevents.c:239
[<ffffffff810ce6eb>] clockevents_program_event+0xdb/0xf0
[<ffffffff810cf211>] tick_handle_periodic_broadcast+0x41/0x50
[<ffffffff81016525>] timer_interrupt+0x15/0x20
When the second hpet is installed as a per cpu timer the broadcast
event is not longer required and stopped, which sets the next_evt of
the broadcast device to KTIME_MAX.
If after that a spurious interrupt happens on the broadcast device,
then the current code blindly handles it and tries to reprogram the
broadcast device afterwards, which adds the period to
next_evt. KTIME_MAX + period results in a negative expiry value
causing the WARN_ON in the clockevents code to trigger.
Add a proper check for the state of the broadcast device into the
interrupt handler and return if the interrupt is spurious.
[ Folded in pointer fix from Sudeep ]
Reported-by: Andriy Gapon <avg@...eBSD.org>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Sudeep Holla <sudeep.holla@....com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Preeti U Murthy <preeti@...ux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/20150705205221.802094647@linutronix.de
---
kernel/time/tick-broadcast.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index c8d731a..ee3cf94 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -316,6 +316,13 @@ static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
bool bc_local;
raw_spin_lock(&tick_broadcast_lock);
+
+ /* Handle spurious interrupts gracefully */
+ if (clockevent_state_shutdown(tick_broadcast_device.evtdev)) {
+ raw_spin_unlock(&tick_broadcast_lock);
+ return;
+ }
+
bc_local = tick_do_periodic_broadcast();
if (clockevent_state_oneshot(dev)) {
--
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