kernel: make ledtrig-netdev use a work queue for updates

This fixes hangs in igb that happen if the update call interrupts an
already existing dev_get_stats call. In that case the calling CPU
deadlocks because it's trying to acquire the same spinlock recursively.

Signed-off-by: Felix Fietkau <nbd@nbd.name>

diff --git a/target/linux/generic/files/drivers/leds/ledtrig-netdev.c b/target/linux/generic/files/drivers/leds/ledtrig-netdev.c
index cfa4dc0758dcc37224a08ef726b7225dbb55822b..2181a262509c9f37b321db52904485e76860d666 100644 (file)
--- a/target/linux/generic/files/drivers/leds/ledtrig-netdev.c
+++ b/target/linux/generic/files/drivers/leds/ledtrig-netdev.c
@@ -70,7 +70,7 @@
 struct led_netdev_data {
        spinlock_t lock;
 
-       struct timer_list timer;
+       struct delayed_work work;
        struct notifier_block notifier;
 
        struct led_classdev *led_cdev;
@@ -91,7 +91,7 @@ static void set_baseline_state(struct led_netdev_data *trigger_data)
                led_set_brightness(trigger_data->led_cdev, LED_OFF);
 
        if ((trigger_data->mode & (MODE_TX | MODE_RX)) != 0 && trigger_data->link_up)
-               mod_timer(&trigger_data->timer, jiffies + trigger_data->interval);
+               schedule_delayed_work(&trigger_data->work, trigger_data->interval);
 }
 
 static ssize_t led_device_name_show(struct device *dev,
@@ -116,8 +116,9 @@ static ssize_t led_device_name_store(struct device *dev,
        if (size < 0 || size >= IFNAMSIZ)
                return -EINVAL;
 
+       cancel_delayed_work_sync(&trigger_data->work);
+
        spin_lock_bh(&trigger_data->lock);
-       del_timer_sync(&trigger_data->timer);
 
        strcpy(trigger_data->device_name, buf);
        if (size > 0 && trigger_data->device_name[size-1] == '\n')
@@ -201,11 +202,10 @@ static ssize_t led_mode_store(struct device *dev,
        if (new_mode == -1)
                return -EINVAL;
 
-       spin_lock_bh(&trigger_data->lock);
-       del_timer_sync(&trigger_data->timer);
+       cancel_delayed_work_sync(&trigger_data->work);
 
+       spin_lock_bh(&trigger_data->lock);
        trigger_data->mode = new_mode;
-
        set_baseline_state(trigger_data);
        spin_unlock_bh(&trigger_data->lock);
 
@@ -242,11 +242,10 @@ static ssize_t led_interval_store(struct device *dev,
 
        /* impose some basic bounds on the timer interval */
        if (count == size && value >= 5 && value <= 10000) {
-               spin_lock_bh(&trigger_data->lock);
-               del_timer_sync(&trigger_data->timer);
+               cancel_delayed_work_sync(&trigger_data->work);
 
+               spin_lock_bh(&trigger_data->lock);
                trigger_data->interval = msecs_to_jiffies(value);
-
                set_baseline_state(trigger_data); /* resets timer */
                spin_unlock_bh(&trigger_data->lock);
 
@@ -268,13 +267,13 @@ static int netdev_trig_notify(struct notifier_block *nb,
        if (evt != NETDEV_UP && evt != NETDEV_DOWN && evt != NETDEV_CHANGE && evt != NETDEV_REGISTER && evt != NETDEV_UNREGISTER && evt != NETDEV_CHANGENAME)
                return NOTIFY_DONE;
 
+       cancel_delayed_work_sync(&trigger_data->work);
+
        spin_lock_bh(&trigger_data->lock);
 
        if (strcmp(dev->name, trigger_data->device_name))
                goto done;
 
-       del_timer_sync(&trigger_data->timer);
-
        if (evt == NETDEV_REGISTER || evt == NETDEV_CHANGENAME) {
                if (trigger_data->net_dev != NULL)
                        dev_put(trigger_data->net_dev);
@@ -302,9 +301,9 @@ done:
 }
 
 /* here's the real work! */
-static void netdev_trig_timer(unsigned long arg)
+static void netdev_trig_work(struct work_struct *work)
 {
-       struct led_netdev_data *trigger_data = (struct led_netdev_data *)arg;
+       struct led_netdev_data *trigger_data = container_of(work, struct led_netdev_data, work.work);
        struct rtnl_link_stats64 *dev_stats;
        unsigned new_activity;
        struct rtnl_link_stats64 temp;
@@ -343,7 +342,7 @@ static void netdev_trig_timer(unsigned long arg)
        }
 
        trigger_data->last_activity = new_activity;
-       mod_timer(&trigger_data->timer, jiffies + trigger_data->interval);
+       schedule_delayed_work(&trigger_data->work, trigger_data->interval);
 }
 
 static void netdev_trig_activate(struct led_classdev *led_cdev)
@@ -360,7 +359,7 @@ static void netdev_trig_activate(struct led_classdev *led_cdev)
        trigger_data->notifier.notifier_call = netdev_trig_notify;
        trigger_data->notifier.priority = 10;
 
-       setup_timer(&trigger_data->timer, netdev_trig_timer, (unsigned long) trigger_data);
+       INIT_DELAYED_WORK(&trigger_data->work, netdev_trig_work);
 
        trigger_data->led_cdev = led_cdev;
        trigger_data->net_dev = NULL;
@@ -406,8 +405,9 @@ static void netdev_trig_deactivate(struct led_classdev *led_cdev)
                device_remove_file(led_cdev->dev, &dev_attr_mode);
                device_remove_file(led_cdev->dev, &dev_attr_interval);
 
+               cancel_delayed_work_sync(&trigger_data->work);
+
                spin_lock_bh(&trigger_data->lock);
-               del_timer_sync(&trigger_data->timer);
 
                if (trigger_data->net_dev) {
                        dev_put(trigger_data->net_dev);