FAILED: patch "[PATCH] Input: gpio-keys - fix a sleep while atomic with PREEMPT_RT" failed to apply to 6.6-stable tree

The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x f4a8f561d08e39f7833d4a278ebfb12a41eef15f
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2025062006-onshore-stool-de98@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From f4a8f561d08e39f7833d4a278ebfb12a41eef15f Mon Sep 17 00:00:00 2001
From: Fabrice Gasnier <[email protected]>
Date: Fri, 30 May 2025 15:36:43 -0700
Subject: [PATCH] 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.

index 5c39a217b94c..d884538107c9 100644
@@ -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;

From: Fabrice Gasnier <[email protected]>

[ Upstream commit f4a8f561d08e39f7833d4a278ebfb12a41eef15f ]

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.

---
 drivers/input/keyboard/gpio_keys.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

index c5f4207fddce9..a34b9533d8f18 100644
@@ -495,7 +495,7 @@ 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:
 	spin_unlock_irqrestore(&bdata->lock, flags);
 	return IRQ_HANDLED;

@@ -632,7 +632,7 @@ static int gpio_keys_setup_key(struct platform_device *pdev,
 
 		bdata->release_delay = button->debounce_interval;
 		hrtimer_init(&bdata->release_timer,
-			     CLOCK_REALTIME, HRTIMER_MODE_REL_HARD);
+			     CLOCK_REALTIME, HRTIMER_MODE_REL);
 		bdata->release_timer.function = gpio_keys_irq_timer;
 
 		isr = gpio_keys_irq_isr;

2.39.5