linux-kernel - [tip:x86/apic] x86/apic: Implement set_state_oneshot

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Message-ID: <tip-914122c389d091a02f7b5476209af715e77ccb73@git.kernel.org>
Date:   Mon, 9 Jan 2017 02:55:35 -0800
From:   tip-bot for Frederic Weisbecker <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     mingo@...nel.org, fweisbec@...il.com, linux-kernel@...r.kernel.org,
        bp@...en8.de, wanpeng.li@...mail.com, viresh.kumar@...aro.org,
        hpa@...or.com, tglx@...utronix.de
Subject: [tip:x86/apic] x86/apic: Implement set_state_oneshot_stopped()
 callback

Commit-ID:  914122c389d091a02f7b5476209af715e77ccb73
Gitweb:     http://git.kernel.org/tip/914122c389d091a02f7b5476209af715e77ccb73
Author:     Frederic Weisbecker <fweisbec@...il.com>
AuthorDate: Thu, 29 Dec 2016 17:45:49 +0100
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Mon, 9 Jan 2017 11:48:42 +0100

x86/apic: Implement set_state_oneshot_stopped() callback

When clock_event_device::set_state_oneshot_stopped() is not implemented,
hrtimer_cancel() can't stop the clock when there is no more timer in
the queue. So the ghost of the freshly cancelled hrtimer haunts us back
later with an extra interrupt:

          <idle>-0     [002] d..2  2248.557659: hrtimer_cancel: hrtimer=ffff88021fa92d80
          <idle>-0     [002] d.h1  2249.303659: local_timer_entry: vector=239

So let's implement this missing callback for the lapic clock. This
consist in calling its set_state_shutdown() callback. There don't seem
to be a lighter way to stop the clock. Simply writing 0 to APIC_TMICT
won't be enough to stop the clock and avoid the extra interrupt, as
opposed to what is specified in the specs. We must also mask the
timer interrupt in the device.

Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
Cc: Borislav Petkov <bp@...en8.de>
Reviewed-by: Wanpeng Li <wanpeng.li@...mail.com>
Reviewed-by: Viresh Kumar <viresh.kumar@...aro.org>
Link: http://lkml.kernel.org/r/1483029949-6925-1-git-send-email-fweisbec@gmail.com
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

---
 arch/x86/kernel/apic/apic.c | 25 +++++++++++++------------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 5c4fdcf..fdb9c46 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -529,18 +529,19 @@ static void lapic_timer_broadcast(const struct cpumask *mask)
  * The local apic timer can be used for any function which is CPU local.
  */
 static struct clock_event_device lapic_clockevent = {
-	.name			= "lapic",
-	.features		= CLOCK_EVT_FEAT_PERIODIC |
-				  CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_C3STOP
-				  | CLOCK_EVT_FEAT_DUMMY,
-	.shift			= 32,
-	.set_state_shutdown	= lapic_timer_shutdown,
-	.set_state_periodic	= lapic_timer_set_periodic,
-	.set_state_oneshot	= lapic_timer_set_oneshot,
-	.set_next_event		= lapic_next_event,
-	.broadcast		= lapic_timer_broadcast,
-	.rating			= 100,
-	.irq			= -1,
+	.name				= "lapic",
+	.features			= CLOCK_EVT_FEAT_PERIODIC |
+					  CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_C3STOP
+					  | CLOCK_EVT_FEAT_DUMMY,
+	.shift				= 32,
+	.set_state_shutdown		= lapic_timer_shutdown,
+	.set_state_periodic		= lapic_timer_set_periodic,
+	.set_state_oneshot		= lapic_timer_set_oneshot,
+	.set_state_oneshot_stopped	= lapic_timer_shutdown,
+	.set_next_event			= lapic_next_event,
+	.broadcast			= lapic_timer_broadcast,
+	.rating				= 100,
+	.irq				= -1,
 };
 static DEFINE_PER_CPU(struct clock_event_device, lapic_events);