clocksource/i8253: Use raw_spinlock_irqsave() in clockevent_i8253_dis…

…able()

On x86 during boot, clockevent_i8253_disable() can be invoked via
x86_late_time_init -> hpet_time_init() -> pit_timer_init() which happens
with enabled interrupts.

If some of the old i8253 hardware is actually used then lockdep will notice
that i8253_lock is used in hard interrupt context. This causes lockdep to
complain because it observed the lock being acquired with interrupts
enabled and in hard interrupt context.

Make clockevent_i8253_disable() acquire the lock with
raw_spinlock_irqsave() to cure this.

[ tglx: Massage change log and use guard() ]

Fixes: c8c4076 ("x86/timer: Skip PIT initialization on modern chipsets")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20250404133116.p-XRWJXf@linutronix.de

drivers/clocksource/i8253.c

@@ -103,7 +103,7 @@ int __init clocksource_i8253_init(void)
 #ifdef CONFIG_CLKEVT_I8253
 void clockevent_i8253_disable(void)
 {
-	raw_spin_lock(&i8253_lock);
+	guard(raw_spinlock_irqsave)(&i8253_lock);
 
 	/*
 	 * Writing the MODE register should stop the counter, according to
@@ -132,8 +132,6 @@ void clockevent_i8253_disable(void)
 	outb_p(0, PIT_CH0);
 
 	outb_p(0x30, PIT_MODE);
-
-	raw_spin_unlock(&i8253_lock);
 }
 
 static int pit_shutdown(struct clock_event_device *evt)