linux-kernel - [PATCH] counter: interrupt-cnt: Drop IRQF_NO

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Message-ID: <20251118083603.778626-1-alexander.sverdlin@siemens.com>
Date: Tue, 18 Nov 2025 09:35:48 +0100
From: "A. Sverdlin" <alexander.sverdlin@...mens.com>
To: Oleksij Rempel <o.rempel@...gutronix.de>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	linux-iio@...r.kernel.org
Cc: Alexander Sverdlin <alexander.sverdlin@...mens.com>,
	William Breathitt Gray <wbg@...nel.org>,
	Jonathan Cameron <Jonathan.Cameron@...wei.com>,
	Ahmad Fatoum <a.fatoum@...gutronix.de>,
	linux-kernel@...r.kernel.org,
	"Paul E . McKenney" <paulmck@...nel.org>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	stable@...r.kernel.org
Subject: [PATCH] counter: interrupt-cnt: Drop IRQF_NO_THREAD flag

From: Alexander Sverdlin <alexander.sverdlin@...mens.com>

An IRQ handler can either be IRQF_NO_THREAD or acquire spinlock_t, as
CONFIG_PROVE_RAW_LOCK_NESTING warns:
=============================
[ BUG: Invalid wait context ]
6.18.0-rc1+git... #1
-----------------------------
some-user-space-process/1251 is trying to lock:
(&counter->events_list_lock){....}-{3:3}, at: counter_push_event [counter]
other info that might help us debug this:
context-{2:2}
no locks held by some-user-space-process/....
stack backtrace:
CPU: 0 UID: 0 PID: 1251 Comm: some-user-space-process 6.18.0-rc1+git... #1 PREEMPT
Call trace:
 show_stack (C)
 dump_stack_lvl
 dump_stack
 __lock_acquire
 lock_acquire
 _raw_spin_lock_irqsave
 counter_push_event [counter]
 interrupt_cnt_isr [interrupt_cnt]
 __handle_irq_event_percpu
 handle_irq_event
 handle_simple_irq
 handle_irq_desc
 generic_handle_domain_irq
 gpio_irq_handler
 handle_irq_desc
 generic_handle_domain_irq
 gic_handle_irq
 call_on_irq_stack
 do_interrupt_handler
 el0_interrupt
 __el0_irq_handler_common
 el0t_64_irq_handler
 el0t_64_irq

... and Sebastian correctly points out. Remove IRQF_NO_THREAD as an
alternative to switching to raw_spinlock_t, because the latter would limit
all potential nested locks to raw_spinlock_t only.

Cc: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc: stable@...r.kernel.org
Link: https://lore.kernel.org/all/20251117151314.xwLAZrWY@linutronix.de/
Fixes: a55ebd47f21f ("counter: add IRQ or GPIO based counter")
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@...mens.com>
---
 drivers/counter/interrupt-cnt.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/counter/interrupt-cnt.c b/drivers/counter/interrupt-cnt.c
index 6c0c1d2d7027d..e6100b5fb082e 100644
--- a/drivers/counter/interrupt-cnt.c
+++ b/drivers/counter/interrupt-cnt.c
@@ -229,8 +229,7 @@ static int interrupt_cnt_probe(struct platform_device *pdev)
 
 	irq_set_status_flags(priv->irq, IRQ_NOAUTOEN);
 	ret = devm_request_irq(dev, priv->irq, interrupt_cnt_isr,
-			       IRQF_TRIGGER_RISING | IRQF_NO_THREAD,
-			       dev_name(dev), counter);
+			       IRQF_TRIGGER_RISING, dev_name(dev), counter);
 	if (ret)
 		return ret;
 
-- 
2.51.1