alarmtimers: Change alarmtimer functions to return alarmtimer_restart values
In order to properly fix the denial of service issue with high freq
periodic alarm timers, we need to push the re-arming logic into the
alarm timer handler, much as the hrtimer code does.
This patch introduces alarmtimer_restart enum and changes the
alarmtimer handler declarations to use it as a return value. Further,
to ease following changes, it extends the alarmtimer handler functions
to also take the time at expiration. No logic is yet modified.
CC: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index ea5e1a9..9e78605 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -196,7 +196,7 @@
}
spin_unlock_irqrestore(&base->lock, flags);
if (alarm->function)
- alarm->function(alarm);
+ alarm->function(alarm, now);
spin_lock_irqsave(&base->lock, flags);
}
@@ -299,7 +299,7 @@
* @function: callback that is run when the alarm fires
*/
void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
- void (*function)(struct alarm *))
+ enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
{
timerqueue_init(&alarm->node);
alarm->period = ktime_set(0, 0);
@@ -365,12 +365,15 @@
*
* Posix timer callback for expired alarm timers.
*/
-static void alarm_handle_timer(struct alarm *alarm)
+static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
+ ktime_t now)
{
struct k_itimer *ptr = container_of(alarm, struct k_itimer,
it.alarmtimer);
if (posix_timer_event(ptr, 0) != 0)
ptr->it_overrun++;
+
+ return ALARMTIMER_NORESTART;
}
/**
@@ -509,13 +512,15 @@
*
* Wakes up the task that set the alarmtimer
*/
-static void alarmtimer_nsleep_wakeup(struct alarm *alarm)
+static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
+ ktime_t now)
{
struct task_struct *task = (struct task_struct *)alarm->data;
alarm->data = NULL;
if (task)
wake_up_process(task);
+ return ALARMTIMER_NORESTART;
}
/**