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authorLinus Torvalds <torvalds@linux-foundation.org>2021-11-01 18:49:25 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-11-01 18:49:25 -0700
commit4dee060625e1095c7065fead542e96ba9504c7eb (patch)
treeb7fde2e7ee714d769bb5e4f957ab9eea0e8ed5fe
parent73d21a3579818aa0e39de207474a39ca35c7d8cb (diff)
parent97b31c1f8eb865bc3aa5f4a08286a6406d782ea8 (diff)
downloadlinux-4dee060625e1095c7065fead542e96ba9504c7eb.tar.bz2
Merge tag 'leds-5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/pavel/linux-leds
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
-rw-r--r--drivers/leds/led-class-flash.c2
-rw-r--r--drivers/leds/led-triggers.c41
-rw-r--r--drivers/leds/trigger/Kconfig1
-rw-r--r--include/linux/leds.h2
4 files changed, 24 insertions, 22 deletions
diff --git a/drivers/leds/led-class-flash.c b/drivers/leds/led-class-flash.c
index 185e17055317..6fe9d700dfef 100644
--- 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 4e7b78a84149..072491d3e17b 100644
--- 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 1f1d57288085..dc6816d36d06 100644
--- 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 a0b730be40ad..ba4861ec73d3 100644
--- 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 */