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timekeeping: Update auxiliary timekeepers on clocksource change

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

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20250625183757.803890875@linutronix.de
This commit is contained in:
Thomas Gleixner
2025-06-25 20:38:29 +02:00
parent 180d8b4ce9
commit 9f7729480a
1 changed files with 33 additions and 0 deletions
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33
kernel/time/timekeeping.c
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@@ -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++)