gpio: mockup: fix NULL pointer dereference when removing debugfs

stable inclusion
from stable-v5.10.146
commit bdea98b98f844bd8a983ca880893e509a8b4162f
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I6D0VX

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bdea98b98f844bd8a983ca880893e509a8b4162f

--------------------------------

commit b7df41a6 upstream.

We now remove the device's debugfs entries when unbinding the driver.
This now causes a NULL-pointer dereference on module exit because the
platform devices are unregistered *after* the global debugfs directory
has been recursively removed. Fix it by unregistering the devices first.

Fixes: 303e6da9 ("gpio: mockup: remove gpio debugfs when remove device")
Cc: Wei Yongjun <weiyongjun1@huawei.com>
Cc: stable@vger.kernel.org
Signed-off-by: NBartosz Golaszewski <brgl@bgdev.pl>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NJialin Zhang <zhangjialin11@huawei.com>
Reviewed-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/gpio/gpio-mockup.c

@@ -604,9 +604,9 @@ static int __init gpio_mockup_init(void)
 
 static void __exit gpio_mockup_exit(void)
 {
+	gpio_mockup_unregister_pdevs();
 	debugfs_remove_recursive(gpio_mockup_dbg_dir);
 	platform_driver_unregister(&gpio_mockup_driver);
-	gpio_mockup_unregister_pdevs();
 }
 
 module_init(gpio_mockup_init);