hwmon: (lm90) Use worker for alarm notifications

Reporting alarms using hwmon_notify_event() may result in a callback
from the thermal subsystem. This means that such notifications must
not hold the update lock to avoid a deadlock. To avoid this situation,
use a worker to handle notifications.

Reported-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Fixes: f6d0775119fb ("hwmon: (lm90) Rework alarm/status handling")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c
index 9d878163a1f23b47294269d3235d8f528ca101ea..03d07da8c2dcf3f4a2d7b3d0e3ef5abc71a92cb0 100644 (file)
--- a/drivers/hwmon/lm90.c
+++ b/drivers/hwmon/lm90.c
@@ -693,6 +693,7 @@ struct lm90_data {
        struct hwmon_chip_info chip;
        struct mutex update_lock;
        struct delayed_work alert_work;
+       struct work_struct report_work;
        bool valid;             /* true if register values are valid */
        bool alarms_valid;      /* true if status register values are valid */
        unsigned long last_updated; /* in jiffies */
@@ -1043,13 +1044,18 @@ static int lm90_update_limits(struct device *dev)
        return 0;
 }
 
-static void lm90_report_alarms(struct device *dev, struct lm90_data *data)
+static void lm90_report_alarms(struct work_struct *work)
 {
-       u16 cleared_alarms = data->reported_alarms & ~data->current_alarms;
-       u16 new_alarms = data->current_alarms & ~data->reported_alarms;
+       struct lm90_data *data = container_of(work, struct lm90_data, report_work);
+       u16 cleared_alarms, new_alarms, current_alarms;
        struct device *hwmon_dev = data->hwmon_dev;
+       struct device *dev = &data->client->dev;
        int st, st2;
 
+       current_alarms = data->current_alarms;
+       cleared_alarms = data->reported_alarms & ~current_alarms;
+       new_alarms = current_alarms & ~data->reported_alarms;
+
        if (!cleared_alarms && !new_alarms)
                return;
 
@@ -1101,7 +1107,7 @@ static void lm90_report_alarms(struct device *dev, struct lm90_data *data)
        if (st2 & MAX6696_STATUS2_R2OT2)
                hwmon_notify_event(hwmon_dev, hwmon_temp, hwmon_temp_emergency_alarm, 2);
 
-       data->reported_alarms = data->current_alarms;
+       data->reported_alarms = current_alarms;
 }
 
 static int lm90_update_alarms_locked(struct lm90_data *data, bool force)
@@ -1143,7 +1149,7 @@ static int lm90_update_alarms_locked(struct lm90_data *data, bool force)
                        (data->config & 0x80);
 
                if (force || check_enable)
-                       lm90_report_alarms(&client->dev, data);
+                       schedule_work(&data->report_work);
 
                /*
                 * Re-enable ALERT# output if it was originally enabled, relevant
@@ -2552,6 +2558,7 @@ static void lm90_restore_conf(void *_data)
        struct i2c_client *client = data->client;
 
        cancel_delayed_work_sync(&data->alert_work);
+       cancel_work_sync(&data->report_work);
 
        /* Restore initial configuration */
        if (data->flags & LM90_HAVE_CONVRATE)
@@ -2769,6 +2776,7 @@ static int lm90_probe(struct i2c_client *client)
        i2c_set_clientdata(client, data);
        mutex_init(&data->update_lock);
        INIT_DELAYED_WORK(&data->alert_work, lm90_alert_work);
+       INIT_WORK(&data->report_work, lm90_report_alarms);
 
        /* Set the device type */
        if (client->dev.of_node)