| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.14 198/238] alarmtimer: Lock k_itimer during timer callback | Date | Fri, 3 Oct 2014 14:31:53 -0700 |
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3.14-stable review patch. If anyone has any objections, please let me know.
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From: Richard Larocque <rlarocque@google.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@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Sharvil Nanavati <sharvil@google.com> Signed-off-by: Richard Larocque <rlarocque@google.com> Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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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