linux-kernel - [tip:timers/urgent] clockevents: tTack broadcast device mode change in tick_broadcast_switch_to

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Date:	Tue, 10 Apr 2012 02:49:36 -0700
From:	tip-bot for Suresh Siddha <suresh.b.siddha@...el.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
	santosh.shilimkar@...com, suresh.b.siddha@...el.com,
	tglx@...utronix.de
Subject: [tip:timers/urgent] clockevents:
  tTack broadcast device mode change in tick_broadcast_switch_to_oneshot()

Commit-ID:  fa4da365bc7772c2cd6d5405bdf151612455f957
Gitweb:     http://git.kernel.org/tip/fa4da365bc7772c2cd6d5405bdf151612455f957
Author:     Suresh Siddha <suresh.b.siddha@...el.com>
AuthorDate: Mon, 9 Apr 2012 15:41:44 -0700
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Tue, 10 Apr 2012 11:42:07 +0200

clockevents: tTack broadcast device mode change in tick_broadcast_switch_to_oneshot()

In the commit 77b0d60c5adf39c74039e2142a1d3cd1e4d53799,
"clockevents: Leave the broadcast device in shutdown mode when not needed",
we were bailing out too quickly in tick_broadcast_switch_to_oneshot(),
with out tracking the broadcast device mode change to 'TICKDEV_MODE_ONESHOT'.

This breaks the platforms which need broadcast device oneshot services during
deep idle states. tick_broadcast_oneshot_control() thinks that it is
in periodic mode and fails to take proper decisions based on the
CLOCK_EVT_NOTIFY_BROADCAST_[ENTER, EXIT] notifications during deep
idle entry/exit.

Fix this by tracking the broadcast device mode as 'TICKDEV_MODE_ONESHOT',
before leaving the broadcast HW device in shutdown mode if there are no active
requests for the moment.

Reported-and-tested-by: Santosh Shilimkar <santosh.shilimkar@...com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@...el.com>
Cc: johnstul@...ibm.com
Link: http://lkml.kernel.org/r/1334011304.12400.81.camel@sbsiddha-desk.sc.intel.com
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 kernel/time/tick-broadcast.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index e883f57..bf57abd 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -575,10 +575,12 @@ void tick_broadcast_switch_to_oneshot(void)
 	unsigned long flags;
 
 	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
+
+	tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
+
 	if (cpumask_empty(tick_get_broadcast_mask()))
 		goto end;
 
-	tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
 	bc = tick_broadcast_device.evtdev;
 	if (bc)
 		tick_broadcast_setup_oneshot(bc);
--
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