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: 46824272 ("gpiolib: cdev: refactor lineevent cleanup into lineevent_free")
Cc: stable@vger.kernel.org
Signed-off-by: NMeng Li <Meng.Li@windriver.com>
Reviewed-by: NKent Gibson <warthog618@gmail.com>
Signed-off-by: NBartosz Golaszewski <brgl@bgdev.pl>

drivers/gpio/gpiolib-cdev.c

@@ -1986,7 +1986,6 @@ 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) ?
@@ -2000,7 +1999,7 @@ 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,
@@ -2009,6 +2008,8 @@ 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;