Input: gpio-keys - fix a sleep while atomic with PREEMPT_RT

When enabling PREEMPT_RT, the gpio_keys_irq_timer() callback runs in
hard irq context, but the input_event() takes a spin_lock, which isn't
allowed there as it is converted to a rt_spin_lock().

[ 4054.289999] BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48
[ 4054.290028] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 0, name: swapper/0
...
[ 4054.290195]  __might_resched+0x13c/0x1f4
[ 4054.290209]  rt_spin_lock+0x54/0x11c
[ 4054.290219]  input_event+0x48/0x80
[ 4054.290230]  gpio_keys_irq_timer+0x4c/0x78
[ 4054.290243]  __hrtimer_run_queues+0x1a4/0x438
[ 4054.290257]  hrtimer_interrupt+0xe4/0x240
[ 4054.290269]  arch_timer_handler_phys+0x2c/0x44
[ 4054.290283]  handle_percpu_devid_irq+0x8c/0x14c
[ 4054.290297]  handle_irq_desc+0x40/0x58
[ 4054.290307]  generic_handle_domain_irq+0x1c/0x28
[ 4054.290316]  gic_handle_irq+0x44/0xcc

Considering the gpio_keys_irq_isr() can run in any context, e.g. it can
be threaded, it seems there's no point in requesting the timer isr to
run in hard irq context.

Relax the hrtimer not to use the hard context.

Fixes: 019002f ("Input: gpio-keys - use hrtimer for release timer")
Suggested-by: Sebastian Andrzej Siewior <[email protected]>
Signed-off-by: Fabrice Gasnier <[email protected]>
Signed-off-by: Gatien Chevallier <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Cc: [email protected]
Signed-off-by: Dmitry Torokhov <[email protected]>

Author: Fabrice Gasnier

drivers/input/keyboard/gpio_keys.c

@@ -486,7 +486,7 @@ static irqreturn_t gpio_keys_irq_isr(int irq, void *dev_id)
 	if (bdata->release_delay)
 		hrtimer_start(&bdata->release_timer,
 			      ms_to_ktime(bdata->release_delay),
-			      HRTIMER_MODE_REL_HARD);
+			      HRTIMER_MODE_REL);
 out:
 	return IRQ_HANDLED;
 }
@@ -628,7 +628,7 @@ static int gpio_keys_setup_key(struct platform_device *pdev,
 
 		bdata->release_delay = button->debounce_interval;
 		hrtimer_setup(&bdata->release_timer, gpio_keys_irq_timer,
-			      CLOCK_REALTIME, HRTIMER_MODE_REL_HARD);
+			      CLOCK_REALTIME, HRTIMER_MODE_REL);
 
 		isr = gpio_keys_irq_isr;
 		irqflags = 0;