gpiolib: use a mutex to protect the list of GPIO devices

The global list of GPIO devices is never modified or accessed from
atomic context so it's fine to protect it using a mutex. Add a new
global lock dedicated to the gpio_devices list and use it whenever
accessing or modifying it.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
index 3ccacf3c1288..8142b5cbc395 100644
--- a/drivers/gpio/gpiolib.h
+++ b/drivers/gpio/gpiolib.h
@@ -15,6 +15,7 @@
 #include <linux/gpio/consumer.h> /* for enum gpiod_flags */
 #include <linux/gpio/driver.h>
 #include <linux/module.h>
+#include <linux/mutex.h>
 #include <linux/notifier.h>
 #include <linux/rwsem.h>
 
@@ -136,6 +137,7 @@ int gpiod_set_transitory(struct gpio_desc *desc, bool transitory);
 
 extern spinlock_t gpio_lock;
 extern struct list_head gpio_devices;
+extern struct mutex gpio_devices_lock;
 
 void gpiod_line_state_notify(struct gpio_desc *desc, unsigned long action);