[PATCH 5.10 083/290] gpio: fix gpio-device list corruption

[gregkh]

From: Greg Kroah-Hartman <gre...@linuxfoundation.org>

From: Johan Hovold <jo...@kernel.org>

commit cf25ef6b631c6fc6c0435fc91eba8734cca20511 upstream.

Make sure to hold the gpio_lock when removing the gpio device from the
gpio_devices list (when dropping the last reference) to avoid corrupting
the list when there are concurrent accesses.

Fixes: ff2b13592299 ("gpio: make the gpiochip a real device")
Cc: sta...@vger.kernel.org      # 4.6
Reviewed-by: Saravana Kannan <sarava...@google.com>
Signed-off-by: Johan Hovold <jo...@kernel.org>
Signed-off-by: Bartosz Golaszewski <bgolaszew...@baylibre.com>
[ johan: adjust context to 5.11 ]
Signed-off-by: Johan Hovold <jo...@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 drivers/gpio/gpiolib.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -468,8 +468,12 @@ EXPORT_SYMBOL_GPL(gpiochip_line_is_valid
 static void gpiodevice_release(struct device *dev)
 {
        struct gpio_device *gdev = dev_get_drvdata(dev);
+       unsigned long flags;
 
+       spin_lock_irqsave(&gpio_lock, flags);
        list_del(&gdev->list);
+       spin_unlock_irqrestore(&gpio_lock, flags);
+
        ida_free(&gpio_ida, gdev->id);
        kfree_const(gdev->label);
        kfree(gdev->descs);