leds: Fix led trigger locking bugs

Convert part of the led trigger core from rw spinlocks to rw
semaphores. We're calling functions which can sleep from invalid
contexts otherwise. Fixes bug #9264.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 4211293..ba8b04b 100644 (file)
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -111,7 +111,7 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
        write_unlock(&leds_list_lock);
 
 #ifdef CONFIG_LEDS_TRIGGERS
-       rwlock_init(&led_cdev->trigger_lock);
+       init_rwsem(&led_cdev->trigger_lock);
 
        rc = device_create_file(led_cdev->dev, &dev_attr_trigger);
        if (rc)
@@ -147,10 +147,10 @@ void led_classdev_unregister(struct led_classdev *led_cdev)
        device_remove_file(led_cdev->dev, &dev_attr_brightness);
 #ifdef CONFIG_LEDS_TRIGGERS
        device_remove_file(led_cdev->dev, &dev_attr_trigger);
-       write_lock(&led_cdev->trigger_lock);
+       down_write(&led_cdev->trigger_lock);
        if (led_cdev->trigger)
                led_trigger_set(led_cdev, NULL);
-       write_unlock(&led_cdev->trigger_lock);
+       up_write(&led_cdev->trigger_lock);
 #endif
 
        device_unregister(led_cdev->dev);

diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
index 575368c..0bdb786 100644 (file)
--- a/drivers/leds/led-triggers.c
+++ b/drivers/leds/led-triggers.c
@@ -19,13 +19,14 @@
 #include <linux/device.h>
 #include <linux/sysdev.h>
 #include <linux/timer.h>
+#include <linux/rwsem.h>
 #include <linux/leds.h>
 #include "leds.h"
 
 /*
  * Nests outside led_cdev->trigger_lock
  */
-static DEFINE_RWLOCK(triggers_list_lock);
+static DECLARE_RWSEM(triggers_list_lock);
 static LIST_HEAD(trigger_list);
 
 ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr,
@@ -44,24 +45,24 @@ ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr,
                trigger_name[len - 1] = '\0';
 
        if (!strcmp(trigger_name, "none")) {
-               write_lock(&led_cdev->trigger_lock);
+               down_write(&led_cdev->trigger_lock);
                led_trigger_set(led_cdev, NULL);
-               write_unlock(&led_cdev->trigger_lock);
+               up_write(&led_cdev->trigger_lock);
                return count;
        }
 
-       read_lock(&triggers_list_lock);
+       down_read(&triggers_list_lock);
        list_for_each_entry(trig, &trigger_list, next_trig) {
                if (!strcmp(trigger_name, trig->name)) {
-                       write_lock(&led_cdev->trigger_lock);
+                       down_write(&led_cdev->trigger_lock);
                        led_trigger_set(led_cdev, trig);
-                       write_unlock(&led_cdev->trigger_lock);
+                       up_write(&led_cdev->trigger_lock);
 
-                       read_unlock(&triggers_list_lock);
+                       up_read(&triggers_list_lock);
                        return count;
                }
        }
-       read_unlock(&triggers_list_lock);
+       up_read(&triggers_list_lock);
 
        return -EINVAL;
 }
@@ -74,8 +75,8 @@ ssize_t led_trigger_show(struct device *dev, struct device_attribute *attr,
        struct led_trigger *trig;
        int len = 0;
 
-       read_lock(&triggers_list_lock);
-       read_lock(&led_cdev->trigger_lock);
+       down_read(&triggers_list_lock);
+       down_read(&led_cdev->trigger_lock);
 
        if (!led_cdev->trigger)
                len += sprintf(buf+len, "[none] ");
@@ -89,8 +90,8 @@ ssize_t led_trigger_show(struct device *dev, struct device_attribute *attr,
                else
                        len += sprintf(buf+len, "%s ", trig->name);
        }
-       read_unlock(&led_cdev->trigger_lock);
-       read_unlock(&triggers_list_lock);
+       up_read(&led_cdev->trigger_lock);
+       up_read(&triggers_list_lock);
 
        len += sprintf(len+buf, "\n");
        return len;
@@ -145,14 +146,14 @@ void led_trigger_set_default(struct led_classdev *led_cdev)
        if (!led_cdev->default_trigger)
                return;
 
-       read_lock(&triggers_list_lock);
-       write_lock(&led_cdev->trigger_lock);
+       down_read(&triggers_list_lock);
+       down_write(&led_cdev->trigger_lock);
        list_for_each_entry(trig, &trigger_list, next_trig) {
                if (!strcmp(led_cdev->default_trigger, trig->name))
                        led_trigger_set(led_cdev, trig);
        }
-       write_unlock(&led_cdev->trigger_lock);
-       read_unlock(&triggers_list_lock);
+       up_write(&led_cdev->trigger_lock);
+       up_read(&triggers_list_lock);
 }
 
 int led_trigger_register(struct led_trigger *trigger)
@@ -163,18 +164,18 @@ int led_trigger_register(struct led_trigger *trigger)
        INIT_LIST_HEAD(&trigger->led_cdevs);
 
        /* Add to the list of led triggers */
-       write_lock(&triggers_list_lock);
+       down_write(&triggers_list_lock);
        list_add_tail(&trigger->next_trig, &trigger_list);
-       write_unlock(&triggers_list_lock);
+       up_write(&triggers_list_lock);
 
        /* Register with any LEDs that have this as a default trigger */
        read_lock(&leds_list_lock);
        list_for_each_entry(led_cdev, &leds_list, node) {
-               write_lock(&led_cdev->trigger_lock);
+               down_write(&led_cdev->trigger_lock);
                if (!led_cdev->trigger && led_cdev->default_trigger &&
                            !strcmp(led_cdev->default_trigger, trigger->name))
                        led_trigger_set(led_cdev, trigger);
-               write_unlock(&led_cdev->trigger_lock);
+               up_write(&led_cdev->trigger_lock);
        }
        read_unlock(&leds_list_lock);
 
@@ -206,17 +207,17 @@ void led_trigger_unregister(struct led_trigger *trigger)
        struct led_classdev *led_cdev;
 
        /* Remove from the list of led triggers */
-       write_lock(&triggers_list_lock);
+       down_write(&triggers_list_lock);
        list_del(&trigger->next_trig);
-       write_unlock(&triggers_list_lock);
+       up_write(&triggers_list_lock);
 
        /* Remove anyone actively using this trigger */
        read_lock(&leds_list_lock);
        list_for_each_entry(led_cdev, &leds_list, node) {
-               write_lock(&led_cdev->trigger_lock);
+               down_write(&led_cdev->trigger_lock);
                if (led_cdev->trigger == trigger)
                        led_trigger_set(led_cdev, NULL);
-               write_unlock(&led_cdev->trigger_lock);
+               up_write(&led_cdev->trigger_lock);
        }
        read_unlock(&leds_list_lock);
 }

diff --git a/include/linux/leds.h b/include/linux/leds.h
index dc1178f..b4130ff 100644 (file)
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -14,6 +14,7 @@
 
 #include <linux/list.h>
 #include <linux/spinlock.h>
+#include <linux/rwsem.h>
 
 struct device;
 /*
@@ -43,7 +44,7 @@ struct led_classdev {
 
 #ifdef CONFIG_LEDS_TRIGGERS
        /* Protects the trigger data below */
-       rwlock_t                 trigger_lock;
+       struct rw_semaphore      trigger_lock;
 
        struct led_trigger      *trigger;
        struct list_head         trig_list;