[tip: timers/urgent] clocksource/i8253: Use raw_spinlock_irqsave() in clockevent_i8253_disable()

["tip-bot2 for Sebastian Andrzej Siewior" <tip-bot2@linutronix.de>]

The following commit has been merged into the timers/urgent branch of tip:

Commit-ID:     94cff94634e506a4a44684bee1875d2dbf782722
Gitweb:        https://git.kernel.org/tip/94cff94634e506a4a44684bee1875d2dbf782722
Author:        Sebastian Andrzej Siewior <bigeasy@linutronix.de>
AuthorDate:    Fri, 04 Apr 2025 15:31:16 +02:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Mon, 05 May 2025 15:34:49 +02:00

clocksource/i8253: Use raw_spinlock_irqsave() in clockevent_i8253_disable()

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: c8c4076723dac ("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 | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/clocksource/i8253.c b/drivers/clocksource/i8253.c
index 39f7c2d..b603c25 100644
--- a/drivers/clocksource/i8253.c
+++ b/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)