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timekeeping: Abort clocksource change in case of failure

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There is no point to go through a full timekeeping update when acquiring a
module reference or enabling the new clocksource fails.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20241009-devel-anna-maria-b4-timers-ptp-timekeeping-v2-4-554456a44a15@linutronix.de
This commit is contained in:
Thomas Gleixner 2024-10-09 10:28:57 +02:00
parent 9fe7d9a984
commit 1f7226b1e7
1 changed files with 13 additions and 18 deletions
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25
kernel/time/timekeeping.c
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@ -1608,33 +1608,29 @@ static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset)
static int change_clocksource(void *data)
{
struct timekeeper *tk = &tk_core.timekeeper;
struct clocksource *new, *old = NULL;
struct clocksource *new = data, *old = NULL;
unsigned long flags;
bool change = false;
new = (struct clocksource *) data;
/*
* If the cs is in module, get a module reference. Succeeds
* for built-in code (owner == NULL) as well.
* If the clocksource is in a module, get a module reference.
* Succeeds for built-in code (owner == NULL) as well. Abort if the
* reference can't be acquired.
*/
if (try_module_get(new->owner)) {
if (!new->enable || new->enable(new) == 0)
change = true;
else
if (!try_module_get(new->owner))
return 0;
/* Abort if the device can't be enabled */
if (new->enable && new->enable(new) != 0) {
module_put(new->owner);
return 0;
}
raw_spin_lock_irqsave(&timekeeper_lock, flags);
write_seqcount_begin(&tk_core.seq);
timekeeping_forward_now(tk);
if (change) {
old = tk->tkr_mono.clock;
tk_setup_internals(tk, new);
}
timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
write_seqcount_end(&tk_core.seq);
@ -1643,7 +1639,6 @@ static int change_clocksource(void *data)
if (old) {
if (old->disable)
old->disable(old);
module_put(old->owner);
}