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Message-Id: <20141003212919.991895454@linuxfoundation.org>
Date: Fri, 3 Oct 2014 14:31:53 -0700
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...nel.org>,
Richard Cochran <richardcochran@...il.com>,
Prarit Bhargava <prarit@...hat.com>,
Sharvil Nanavati <sharvil@...gle.com>,
Richard Larocque <rlarocque@...gle.com>,
John Stultz <john.stultz@...aro.org>
Subject: [PATCH 3.14 198/238] alarmtimer: Lock k_itimer during timer callback
3.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Richard Larocque <rlarocque@...gle.com>
commit 474e941bed9262f5fa2394f9a4a67e24499e5926 upstream.
Locks the k_itimer's it_lock member when handling the alarm timer's
expiry callback.
The regular posix timers defined in posix-timers.c have this lock held
during timout processing because their callbacks are routed through
posix_timer_fn(). The alarm timers follow a different path, so they
ought to grab the lock somewhere else.
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Richard Cochran <richardcochran@...il.com>
Cc: Prarit Bhargava <prarit@...hat.com>
Cc: Sharvil Nanavati <sharvil@...gle.com>
Signed-off-by: Richard Larocque <rlarocque@...gle.com>
Signed-off-by: John Stultz <john.stultz@...aro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
kernel/time/alarmtimer.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -464,8 +464,12 @@ static enum alarmtimer_type clock2alarm(
static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
ktime_t now)
{
+ unsigned long flags;
struct k_itimer *ptr = container_of(alarm, struct k_itimer,
it.alarm.alarmtimer);
+ enum alarmtimer_restart result = ALARMTIMER_NORESTART;
+
+ spin_lock_irqsave(&ptr->it_lock, flags);
if ((ptr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) {
if (posix_timer_event(ptr, 0) != 0)
ptr->it_overrun++;
@@ -475,9 +479,11 @@ static enum alarmtimer_restart alarm_han
if (ptr->it.alarm.interval.tv64) {
ptr->it_overrun += alarm_forward(alarm, now,
ptr->it.alarm.interval);
- return ALARMTIMER_RESTART;
+ result = ALARMTIMER_RESTART;
}
- return ALARMTIMER_NORESTART;
+ spin_unlock_irqrestore(&ptr->it_lock, flags);
+
+ return result;
}
/**
--
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