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

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
...@@ -129,31 +129,19 @@ static void inline clocksource_watchdog_unlock(unsigned long *flags) ...@@ -129,31 +129,19 @@ static void inline clocksource_watchdog_unlock(unsigned long *flags)
spin_unlock_irqrestore(&watchdog_lock, *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 * Interval: 0.5sec Threshold: 0.0625s
*/ */
#define WATCHDOG_INTERVAL (HZ >> 1) #define WATCHDOG_INTERVAL (HZ >> 1)
#define WATCHDOG_THRESHOLD (NSEC_PER_SEC >> 4) #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) static void __clocksource_unstable(struct clocksource *cs)
{ {
cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG); cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG);
cs->flags |= CLOCK_SOURCE_UNSTABLE; 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. * re-rate and re-select.
*/ */
if (list_empty(&cs->list)) { if (list_empty(&cs->list)) {
...@@ -164,7 +152,7 @@ static void __clocksource_unstable(struct clocksource *cs) ...@@ -164,7 +152,7 @@ static void __clocksource_unstable(struct clocksource *cs)
if (cs->mark_unstable) if (cs->mark_unstable)
cs->mark_unstable(cs); cs->mark_unstable(cs);
/* kick clocksource_watchdog_kthread() */ /* kick clocksource_watchdog_work() */
if (finished_booting) if (finished_booting)
schedule_work(&watchdog_work); schedule_work(&watchdog_work);
} }
...@@ -174,7 +162,7 @@ static void __clocksource_unstable(struct clocksource *cs) ...@@ -174,7 +162,7 @@ static void __clocksource_unstable(struct clocksource *cs)
* @cs: clocksource to be marked unstable * @cs: clocksource to be marked unstable
* *
* This function is called by the x86 TSC code to mark clocksources as 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) void clocksource_mark_unstable(struct clocksource *cs)
{ {
...@@ -399,7 +387,9 @@ static void clocksource_dequeue_watchdog(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; struct clocksource *cs, *tmp;
unsigned long flags; unsigned long flags;
...@@ -424,13 +414,12 @@ static int __clocksource_watchdog_kthread(void) ...@@ -424,13 +414,12 @@ static int __clocksource_watchdog_kthread(void)
return select; return select;
} }
static int clocksource_watchdog_kthread(void *data) static void clocksource_watchdog_work(struct work_struct *work)
{ {
mutex_lock(&clocksource_mutex); mutex_lock(&clocksource_mutex);
if (__clocksource_watchdog_kthread()) if (__clocksource_watchdog_work())
clocksource_select(); clocksource_select();
mutex_unlock(&clocksource_mutex); mutex_unlock(&clocksource_mutex);
return 0;
} }
static bool clocksource_is_watchdog(struct clocksource *cs) static bool clocksource_is_watchdog(struct clocksource *cs)
...@@ -449,7 +438,7 @@ static void clocksource_enqueue_watchdog(struct clocksource *cs) ...@@ -449,7 +438,7 @@ static void clocksource_enqueue_watchdog(struct clocksource *cs)
static void clocksource_select_watchdog(bool fallback) { } static void clocksource_select_watchdog(bool fallback) { }
static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { } static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { }
static inline void clocksource_resume_watchdog(void) { } 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; } static bool clocksource_is_watchdog(struct clocksource *cs) { return false; }
void clocksource_mark_unstable(struct clocksource *cs) { } void clocksource_mark_unstable(struct clocksource *cs) { }
...@@ -683,7 +672,7 @@ static int __init clocksource_done_booting(void) ...@@ -683,7 +672,7 @@ static int __init clocksource_done_booting(void)
/* /*
* Run the watchdog first to eliminate unstable clock sources * Run the watchdog first to eliminate unstable clock sources
*/ */
__clocksource_watchdog_kthread(); __clocksource_watchdog_work();
clocksource_select(); clocksource_select();
mutex_unlock(&clocksource_mutex); mutex_unlock(&clocksource_mutex);
return 0; return 0;
......
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