Commit 9f772948 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

timekeeping: Update auxiliary timekeepers on clocksource change 



Propagate a system clocksource change to the auxiliary timekeepers so that
they can pick up the new clocksource.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarJohn Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20250625183757.803890875@linutronix.de
parent 180d8b4c

kernel/time/timekeeping.c

+33 −0
Original line number Diff line number Diff line
@@ -119,8 +119,10 @@ static struct tk_fast tk_fast_raw ____cacheline_aligned = { 


#ifdef CONFIG_POSIX_AUX_CLOCKS

static __init void tk_aux_setup(void);

static void tk_aux_update_clocksource(void);

#else

static inline void tk_aux_setup(void) { }

static inline void tk_aux_update_clocksource(void) { }

#endif



unsigned long timekeeper_lock_irqsave(void)
@@ -1548,6 +1550,8 @@ static int change_clocksource(void *data) 
		timekeeping_update_from_shadow(&tk_core, TK_UPDATE_ALL);

	}



	tk_aux_update_clocksource();



	if (old) {

		if (old->disable)

			old->disable(old);
@@ -2651,6 +2655,35 @@ EXPORT_SYMBOL(hardpps); 
#endif /* CONFIG_NTP_PPS */



#ifdef CONFIG_POSIX_AUX_CLOCKS



/*

 * Bitmap for the activated auxiliary timekeepers to allow lockless quick

 * checks in the hot paths without touching extra cache lines. If set, then

 * the state of the corresponding timekeeper has to be re-checked under

 * timekeeper::lock.

 */

static unsigned long aux_timekeepers;



/* Invoked from timekeeping after a clocksource change */

static void tk_aux_update_clocksource(void)

{

	unsigned long active = READ_ONCE(aux_timekeepers);

	unsigned int id;



	for_each_set_bit(id, &active, BITS_PER_LONG) {

		struct tk_data *tkd = &timekeeper_data[id + TIMEKEEPER_AUX_FIRST];

		struct timekeeper *tks = &tkd->shadow_timekeeper;



		guard(raw_spinlock_irqsave)(&tkd->lock);

		if (!tks->clock_valid)

			continue;



		timekeeping_forward_now(tks);

		tk_setup_internals(tks, tk_core.timekeeper.tkr_mono.clock);

		timekeeping_update_from_shadow(tkd, TK_UPDATE_ALL);

	}

}



static __init void tk_aux_setup(void)

{

	for (int i = TIMEKEEPER_AUX_FIRST; i <= TIMEKEEPER_AUX_LAST; i++)