Merge tag 'leds-5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/pavel...

Pull LED updates from Pavel Machek:
 "Johannes pointed out that locking is still problematic with triggers
  list, attempt to solve that by using RCU"

* tag 'leds-5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/pavel/linux-leds:
  leds: trigger: Disable CPU trigger on PREEMPT_RT
  leds: trigger: use RCU to protect the led_cdevs list
  led-class-flash: fix -Wrestrict warning

diff --git a/drivers/leds/led-class-flash.c b/drivers/leds/led-class-flash.c
index 185e170..6fe9d70 100644 (file)
--- a/drivers/leds/led-class-flash.c
+++ b/drivers/leds/led-class-flash.c
@@ -207,7 +207,7 @@ static ssize_t flash_fault_show(struct device *dev,
                mask <<= 1;
        }
 
-       return sprintf(buf, "%s\n", buf);
+       return strlen(strcat(buf, "\n"));
 }
 static DEVICE_ATTR_RO(flash_fault);
 

diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
index 4e7b78a..072491d 100644 (file)
--- a/drivers/leds/led-triggers.c
+++ b/drivers/leds/led-triggers.c
@@ -157,7 +157,6 @@ EXPORT_SYMBOL_GPL(led_trigger_read);
 /* Caller must ensure led_cdev->trigger_lock held */
 int led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig)
 {
-       unsigned long flags;
        char *event = NULL;
        char *envp[2];
        const char *name;
@@ -171,10 +170,13 @@ int led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig)
 
        /* Remove any existing trigger */
        if (led_cdev->trigger) {
-               write_lock_irqsave(&led_cdev->trigger->leddev_list_lock, flags);
-               list_del(&led_cdev->trig_list);
-               write_unlock_irqrestore(&led_cdev->trigger->leddev_list_lock,
-                       flags);
+               spin_lock(&led_cdev->trigger->leddev_list_lock);
+               list_del_rcu(&led_cdev->trig_list);
+               spin_unlock(&led_cdev->trigger->leddev_list_lock);
+
+               /* ensure it's no longer visible on the led_cdevs list */
+               synchronize_rcu();
+
                cancel_work_sync(&led_cdev->set_brightness_work);
                led_stop_software_blink(led_cdev);
                if (led_cdev->trigger->deactivate)
@@ -186,9 +188,9 @@ int led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig)
                led_set_brightness(led_cdev, LED_OFF);
        }
        if (trig) {
-               write_lock_irqsave(&trig->leddev_list_lock, flags);
-               list_add_tail(&led_cdev->trig_list, &trig->led_cdevs);
-               write_unlock_irqrestore(&trig->leddev_list_lock, flags);
+               spin_lock(&trig->leddev_list_lock);
+               list_add_tail_rcu(&led_cdev->trig_list, &trig->led_cdevs);
+               spin_unlock(&trig->leddev_list_lock);
                led_cdev->trigger = trig;
 
                if (trig->activate)
@@ -223,9 +225,10 @@ err_add_groups:
                trig->deactivate(led_cdev);
 err_activate:
 
-       write_lock_irqsave(&led_cdev->trigger->leddev_list_lock, flags);
-       list_del(&led_cdev->trig_list);
-       write_unlock_irqrestore(&led_cdev->trigger->leddev_list_lock, flags);
+       spin_lock(&led_cdev->trigger->leddev_list_lock);
+       list_del_rcu(&led_cdev->trig_list);
+       spin_unlock(&led_cdev->trigger->leddev_list_lock);
+       synchronize_rcu();
        led_cdev->trigger = NULL;
        led_cdev->trigger_data = NULL;
        led_set_brightness(led_cdev, LED_OFF);
@@ -285,7 +288,7 @@ int led_trigger_register(struct led_trigger *trig)
        struct led_classdev *led_cdev;
        struct led_trigger *_trig;
 
-       rwlock_init(&trig->leddev_list_lock);
+       spin_lock_init(&trig->leddev_list_lock);
        INIT_LIST_HEAD(&trig->led_cdevs);
 
        down_write(&triggers_list_lock);
@@ -378,15 +381,14 @@ void led_trigger_event(struct led_trigger *trig,
                        enum led_brightness brightness)
 {
        struct led_classdev *led_cdev;
-       unsigned long flags;
 
        if (!trig)
                return;
 
-       read_lock_irqsave(&trig->leddev_list_lock, flags);
-       list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list)
+       rcu_read_lock();
+       list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list)
                led_set_brightness(led_cdev, brightness);
-       read_unlock_irqrestore(&trig->leddev_list_lock, flags);
+       rcu_read_unlock();
 }
 EXPORT_SYMBOL_GPL(led_trigger_event);
 
@@ -397,20 +399,19 @@ static void led_trigger_blink_setup(struct led_trigger *trig,
                             int invert)
 {
        struct led_classdev *led_cdev;
-       unsigned long flags;
 
        if (!trig)
                return;
 
-       read_lock_irqsave(&trig->leddev_list_lock, flags);
-       list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list) {
+       rcu_read_lock();
+       list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list) {
                if (oneshot)
                        led_blink_set_oneshot(led_cdev, delay_on, delay_off,
                                              invert);
                else
                        led_blink_set(led_cdev, delay_on, delay_off);
        }
-       read_unlock_irqrestore(&trig->leddev_list_lock, flags);
+       rcu_read_unlock();
 }
 
 void led_trigger_blink(struct led_trigger *trig,

diff --git a/drivers/leds/trigger/Kconfig b/drivers/leds/trigger/Kconfig
index 1f1d572..dc6816d 100644 (file)
--- a/drivers/leds/trigger/Kconfig
+++ b/drivers/leds/trigger/Kconfig
@@ -64,6 +64,7 @@ config LEDS_TRIGGER_BACKLIGHT
 
 config LEDS_TRIGGER_CPU
        bool "LED CPU Trigger"
+       depends on !PREEMPT_RT
        help
          This allows LEDs to be controlled by active CPUs. This shows
          the active CPUs across an array of LEDs so you can see which

diff --git a/include/linux/leds.h b/include/linux/leds.h
index a0b730b..ba4861e 100644 (file)
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -360,7 +360,7 @@ struct led_trigger {
        struct led_hw_trigger_type *trigger_type;
 
        /* LEDs under control by this trigger (for simple triggers) */
-       rwlock_t          leddev_list_lock;
+       spinlock_t        leddev_list_lock;
        struct list_head  led_cdevs;
 
        /* Link to next registered trigger */