linux-kernel - [PATCH] gpiolib: cdev: Set lineevent_state::irq after IRQ register successfully

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Date:   Wed, 21 Sep 2022 11:20:20 +0800
From:   Meng Li <Meng.Li@...driver.com>
To:     linus.walleij@...aro.org, brgl@...ev.pl, warthog618@...il.com,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     meng.li@...driver.com
Subject: [PATCH] gpiolib: cdev: Set lineevent_state::irq after IRQ register successfully

When running gpio test on nxp-ls1028 platform with below command
gpiomon --num-events=3 --rising-edge gpiochip1 25
There will be a warning trace as below:
Call trace:
free_irq+0x204/0x360
lineevent_free+0x64/0x70
gpio_ioctl+0x598/0x6a0
__arm64_sys_ioctl+0xb4/0x100
invoke_syscall+0x5c/0x130
......
el0t_64_sync+0x1a0/0x1a4
The reason of this issue is that calling request_threaded_irq()
function failed, and then lineevent_free() is invoked to release
the resource. Since the lineevent_state::irq was already set, so
the subsequent invocation of free_irq() would trigger the above
warning call trace. To fix this issue, set the lineevent_state::irq
after the IRQ register successfully.

Fixes: 468242724143 ("gpiolib: cdev: refactor lineevent cleanup into lineevent_free")
Cc: stable@...r.kernel.org
Signed-off-by: Meng Li <Meng.Li@...driver.com>
---
 drivers/gpio/gpiolib-cdev.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index ffa0256cad5a..937e7a8dd8a9 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -1784,7 +1784,6 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
 		ret = -ENODEV;
 		goto out_free_le;
 	}
-	le->irq = irq;

 	if (eflags & GPIOEVENT_REQUEST_RISING_EDGE)
 		irqflags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
@@ -1798,7 +1797,7 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
 	init_waitqueue_head(&le->wait);

 	/* Request a thread to read the events */
-	ret = request_threaded_irq(le->irq,
+	ret = request_threaded_irq(irq,
 				   lineevent_irq_handler,
 				   lineevent_irq_thread,
 				   irqflags,
@@ -1807,6 +1806,8 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
 	if (ret)
 		goto out_free_le;

+	le->irq = irq;
+
 	fd = get_unused_fd_flags(O_RDONLY | O_CLOEXEC);
 	if (fd < 0) {
 		ret = fd;
-- 
2.36.1