Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 7197e77a authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Thomas Gleixner
Browse files

clocksource: Remove kthread 



The clocksource watchdog uses a work to spawn a kthread to run the
watchdog. That is about as silly as it sounds, run the watchdog
directly from the work.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: len.brown@intel.com
Cc: rjw@rjwysocki.net
Cc: diego.viola@gmail.com
Cc: rui.zhang@intel.com
Link: https://lkml.kernel.org/r/20180430100344.713862818@infradead.org
parent 604a98f1

kernel/time/clocksource.c

+10 −21
Original line number Diff line number Diff line
@@ -129,31 +129,19 @@ static void inline clocksource_watchdog_unlock(unsigned long *flags) 
	spin_unlock_irqrestore(&watchdog_lock, *flags);

}



static int clocksource_watchdog_kthread(void *data);

static void __clocksource_change_rating(struct clocksource *cs, int rating);



/*

 * Interval: 0.5sec Threshold: 0.0625s

 */

#define WATCHDOG_INTERVAL (HZ >> 1)

#define WATCHDOG_THRESHOLD (NSEC_PER_SEC >> 4)



static void clocksource_watchdog_work(struct work_struct *work)

{

	/*

	 * If kthread_run fails the next watchdog scan over the

	 * watchdog_list will find the unstable clock again.

	 */

	kthread_run(clocksource_watchdog_kthread, NULL, "kwatchdog");

}



static void __clocksource_unstable(struct clocksource *cs)

{

	cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG);

	cs->flags |= CLOCK_SOURCE_UNSTABLE;



	/*

	 * If the clocksource is registered clocksource_watchdog_kthread() will

	 * If the clocksource is registered clocksource_watchdog_work() will

	 * re-rate and re-select.

	 */

	if (list_empty(&cs->list)) {
@@ -164,7 +152,7 @@ static void __clocksource_unstable(struct clocksource *cs) 
	if (cs->mark_unstable)

		cs->mark_unstable(cs);



	/* kick clocksource_watchdog_kthread() */

	/* kick clocksource_watchdog_work() */

	if (finished_booting)

		schedule_work(&watchdog_work);

}
@@ -174,7 +162,7 @@ static void __clocksource_unstable(struct clocksource *cs) 
 * @cs:		clocksource to be marked unstable

 *

 * This function is called by the x86 TSC code to mark clocksources as unstable;

 * it defers demotion and re-selection to a kthread.

 * it defers demotion and re-selection to a work.

 */

void clocksource_mark_unstable(struct clocksource *cs)

{
@@ -399,7 +387,9 @@ static void clocksource_dequeue_watchdog(struct clocksource *cs) 
	}

}



static int __clocksource_watchdog_kthread(void)

static void __clocksource_change_rating(struct clocksource *cs, int rating);



static int __clocksource_watchdog_work(void)

{

	struct clocksource *cs, *tmp;

	unsigned long flags;
@@ -424,13 +414,12 @@ static int __clocksource_watchdog_kthread(void) 
	return select;

}



static int clocksource_watchdog_kthread(void *data)

static void clocksource_watchdog_work(struct work_struct *work)

{

	mutex_lock(&clocksource_mutex);

	if (__clocksource_watchdog_kthread())

	if (__clocksource_watchdog_work())

		clocksource_select();

	mutex_unlock(&clocksource_mutex);

	return 0;

}



static bool clocksource_is_watchdog(struct clocksource *cs)
@@ -449,7 +438,7 @@ static void clocksource_enqueue_watchdog(struct clocksource *cs) 
static void clocksource_select_watchdog(bool fallback) { }

static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { }

static inline void clocksource_resume_watchdog(void) { }

static inline int __clocksource_watchdog_kthread(void) { return 0; }

static inline int __clocksource_watchdog_work(void) { return 0; }

static bool clocksource_is_watchdog(struct clocksource *cs) { return false; }

void clocksource_mark_unstable(struct clocksource *cs) { }
@@ -683,7 +672,7 @@ static int __init clocksource_done_booting(void) 
	/*

	 * Run the watchdog first to eliminate unstable clock sources

	 */

	__clocksource_watchdog_kthread();

	__clocksource_watchdog_work();

	clocksource_select();

	mutex_unlock(&clocksource_mutex);

	return 0;