4 files changed, 79 insertions, 6 deletions

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 7440c58b8e6f..65722deb8d28 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -40,17 +40,27 @@ static ssize_t brightness_store(struct device *dev,
 {
         struct led_classdev *led_cdev = dev_get_drvdata(dev);
         unsigned long state;
-        ssize_t ret = -EINVAL;
+        ssize_t ret;
+
+        mutex_lock(&led_cdev->led_access);
+
+        if (led_sysfs_is_disabled(led_cdev)) {
+                ret = -EBUSY;
+                goto unlock;
+        }
 
         ret = kstrtoul(buf, 10, &state);
         if (ret)
-                return ret;
+                goto unlock;
 
         if (state == LED_OFF)
                 led_trigger_remove(led_cdev);
         __led_set_brightness(led_cdev, state);
 
-        return size;
+        ret = size;
+unlock:
+        mutex_unlock(&led_cdev->led_access);
+        return ret;
 }
 static DEVICE_ATTR_RW(brightness);
 
@@ -214,6 +224,7 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
 #ifdef CONFIG_LEDS_TRIGGERS
         init_rwsem(&led_cdev->trigger_lock);
 #endif
+        mutex_init(&led_cdev->led_access);
         /* add to the list of leds */
         down_write(&leds_list_lock);
         list_add_tail(&led_cdev->node, &leds_list);
@@ -267,6 +278,8 @@ void led_classdev_unregister(struct led_classdev *led_cdev)
         down_write(&leds_list_lock);
         list_del(&led_cdev->node);
         up_write(&leds_list_lock);
+
+        mutex_destroy(&led_cdev->led_access);
 }
 EXPORT_SYMBOL_GPL(led_classdev_unregister);
 
diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
index aaa8eba9099f..be6d9fa5e971 100644
--- a/drivers/leds/led-core.c
+++ b/drivers/leds/led-core.c
@@ -143,3 +143,21 @@ int led_update_brightness(struct led_classdev *led_cdev)
         return ret;
 }
 EXPORT_SYMBOL(led_update_brightness);
+
+/* Caller must ensure led_cdev->led_access held */
+void led_sysfs_disable(struct led_classdev *led_cdev)
+{
+        lockdep_assert_held(&led_cdev->led_access);
+
+        led_cdev->flags |= LED_SYSFS_DISABLE;
+}
+EXPORT_SYMBOL_GPL(led_sysfs_disable);
+
+/* Caller must ensure led_cdev->led_access held */
+void led_sysfs_enable(struct led_classdev *led_cdev)
+{
+        lockdep_assert_held(&led_cdev->led_access);
+
+        led_cdev->flags &= ~LED_SYSFS_DISABLE;
+}
+EXPORT_SYMBOL_GPL(led_sysfs_enable);
diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
index c3734f10fdd5..e8b1120f486d 100644
--- a/drivers/leds/led-triggers.c
+++ b/drivers/leds/led-triggers.c
@@ -37,6 +37,14 @@ ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr,
         char trigger_name[TRIG_NAME_MAX];
         struct led_trigger *trig;
         size_t len;
+        int ret = count;
+
+        mutex_lock(&led_cdev->led_access);
+
+        if (led_sysfs_is_disabled(led_cdev)) {
+                ret = -EBUSY;
+                goto unlock;
+        }
 
         trigger_name[sizeof(trigger_name) - 1] = '\0';
         strncpy(trigger_name, buf, sizeof(trigger_name) - 1);
@@ -47,7 +55,7 @@ ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr,
 
         if (!strcmp(trigger_name, "none")) {
                 led_trigger_remove(led_cdev);
-                return count;
+                goto unlock;
         }
 
         down_read(&triggers_list_lock);
@@ -58,12 +66,14 @@ ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr,
                         up_write(&led_cdev->trigger_lock);
 
                         up_read(&triggers_list_lock);
-                        return count;
+                        goto unlock;
                 }
         }
         up_read(&triggers_list_lock);
 
-        return -EINVAL;
+unlock:
+        mutex_unlock(&led_cdev->led_access);
+        return ret;
 }
 EXPORT_SYMBOL_GPL(led_trigger_store);
 
diff --git a/include/linux/leds.h b/include/linux/leds.h
index a57611d0c94e..737f9b1051f2 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -13,6 +13,7 @@
 #define __LINUX_LEDS_H_INCLUDED
 
 #include <linux/list.h>
+#include <linux/mutex.h>
 #include <linux/rwsem.h>
 #include <linux/spinlock.h>
 #include <linux/timer.h>
@@ -42,6 +43,7 @@ struct led_classdev {
 #define LED_BLINK_ONESHOT       (1 << 17)
 #define LED_BLINK_ONESHOT_STOP  (1 << 18)
 #define LED_BLINK_INVERT        (1 << 19)
+#define LED_SYSFS_DISABLE       (1 << 20)
 
         /* Set LED brightness level */
         /* Must not sleep, use a workqueue if needed */
@@ -85,6 +87,9 @@ struct led_classdev {
         /* true if activated - deactivate routine uses it to do cleanup */
         bool                    activated;
 #endif
+
+        /* Ensures consistent access to the LED Flash Class device */
+        struct mutex            led_access;
 };
 
 extern int led_classdev_register(struct device *parent,
@@ -151,6 +156,33 @@ extern void led_set_brightness(struct led_classdev *led_cdev,
  */
 extern int led_update_brightness(struct led_classdev *led_cdev);
 
+/**
+ * led_sysfs_disable - disable LED sysfs interface
+ * @led_cdev: the LED to set
+ *
+ * Disable the led_cdev's sysfs interface.
+ */
+extern void led_sysfs_disable(struct led_classdev *led_cdev);
+
+/**
+ * led_sysfs_enable - enable LED sysfs interface
+ * @led_cdev: the LED to set
+ *
+ * Enable the led_cdev's sysfs interface.
+ */
+extern void led_sysfs_enable(struct led_classdev *led_cdev);
+
+/**
+ * led_sysfs_is_disabled - check if LED sysfs interface is disabled
+ * @led_cdev: the LED to query
+ *
+ * Returns: true if the led_cdev's sysfs interface is disabled.
+ */
+static inline bool led_sysfs_is_disabled(struct led_classdev *led_cdev)
+{
+        return led_cdev->flags & LED_SYSFS_DISABLE;
+}
+
 /*
  * LED Triggers
  */