linux-kernel - [PATCH v2 1/2] Input: gpio-keys - fix a sleep while atomic with PREEMPT

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Message-ID: <20250528-gpio_keys_preempt_rt-v2-1-3fc55a9c3619@foss.st.com>
Date: Wed, 28 May 2025 10:50:21 +0200
From: Gatien Chevallier <gatien.chevallier@...s.st.com>
To: Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Sebastian Andrzej Siewior
	<bigeasy@...utronix.de>,
        Clark Williams <clrkwllms@...nel.org>,
        Steven
 Rostedt <rostedt@...dmis.org>,
        Paul Cercueil <paul@...pouillou.net>
CC: <linux-input@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-rt-devel@...ts.linux.dev>,
        Gatien Chevallier
	<gatien.chevallier@...s.st.com>,
        <fabrice.gasnier@...s.st.com>
Subject: [PATCH v2 1/2] Input: gpio-keys - fix a sleep while atomic with
 PREEMPT_RT

From: Fabrice Gasnier <fabrice.gasnier@...s.st.com>

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: 019002f20cb5 ("Input: gpio-keys - use hrtimer for release timer")
Suggested-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@...s.st.com>
Signed-off-by: Gatien Chevallier <gatien.chevallier@...s.st.com>
---
 drivers/input/keyboard/gpio_keys.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/input/keyboard/gpio_keys.c b/drivers/input/keyboard/gpio_keys.c
index 5c39a217b94c8ad03a8542380eed741fccdca5da..d884538107c9654d21e37fa20e0b3b6cd9a25ee4 100644
--- a/drivers/input/keyboard/gpio_keys.c
+++ b/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;

-- 
2.25.1