watchdog: Drop pointer to watchdog device from struct watchdog_device

The lifetime of the watchdog device pointer is different from the lifetime
of its character device. Remove it entirely to avoid race conditions.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

Documentation/watchdog/watchdog-kernel-api.txt

@@ -44,7 +44,6 @@ The watchdog device structure looks like this:
 
 struct watchdog_device {
 	int id;
-	struct device *dev;
 	struct device *parent;
 	const struct attribute_group **groups;
 	const struct watchdog_info *info;
@@ -66,7 +65,6 @@ It contains following fields:
   /dev/watchdog0 cdev (dynamic major, minor 0) as well as the old
   /dev/watchdog miscdev. The id is set automatically when calling
   watchdog_register_device.
-* dev: device under the watchdog class (created by watchdog_register_device).
 * parent: set this to the parent device (or NULL) before calling
   watchdog_register_device.
 * groups: List of sysfs attribute groups to create when creating the watchdog

drivers/watchdog/watchdog_core.c

@@ -249,8 +249,8 @@ static int __watchdog_register_device(struct watchdog_device *wdd)
 
 		ret = register_reboot_notifier(&wdd->reboot_nb);
 		if (ret) {
-			dev_err(wdd->dev, "Cannot register reboot notifier (%d)\n",
-				ret);
+			pr_err("watchdog%d: Cannot register reboot notifier (%d)\n",
+			       wdd->id, ret);
 			watchdog_dev_unregister(wdd);
 			ida_simple_remove(&watchdog_ida, wdd->id);
 			return ret;
@@ -262,8 +262,8 @@ static int __watchdog_register_device(struct watchdog_device *wdd)
 
 		ret = register_restart_handler(&wdd->restart_nb);
 		if (ret)
-			dev_warn(wdd->dev, "Cannot register restart handler (%d)\n",
-				 ret);
+			pr_warn("watchog%d: Cannot register restart handler (%d)\n",
+				wdd->id, ret);
 	}
 
 	return 0;

drivers/watchdog/watchdog_dev.c

@@ -143,7 +143,8 @@ static int watchdog_stop(struct watchdog_device *wdd)
 		return 0;
 
 	if (test_bit(WDOG_NO_WAY_OUT, &wdd->status)) {
-		dev_info(wdd->dev, "nowayout prevents watchdog being stopped!\n");
+		pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n",
+			wdd->id);
 		return -EBUSY;
 	}
 
@@ -604,7 +605,7 @@ static int watchdog_release(struct inode *inode, struct file *file)
 
 	/* If the watchdog was not stopped, send a keepalive ping */
 	if (err < 0) {
-		dev_crit(wdd->dev, "watchdog did not stop!\n");
+		pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id);
 		watchdog_ping(wdd);
 	}
 
@@ -751,7 +752,6 @@ int watchdog_dev_register(struct watchdog_device *wdd)
 		watchdog_cdev_unregister(wdd);
 		return PTR_ERR(dev);
 	}
-	wdd->dev = dev;
 
 	return ret;
 }
@@ -766,8 +766,7 @@ int watchdog_dev_register(struct watchdog_device *wdd)
 
 void watchdog_dev_unregister(struct watchdog_device *wdd)
 {
-	device_destroy(&watchdog_class, wdd->dev->devt);
-	wdd->dev = NULL;
+	device_destroy(&watchdog_class, wdd->wd_data->cdev.dev);
 	watchdog_cdev_unregister(wdd);
 }
 

include/linux/watchdog.h

@@ -53,7 +53,6 @@ struct watchdog_ops {
 /** struct watchdog_device - The structure that defines a watchdog device
  *
  * @id:		The watchdog's ID. (Allocated by watchdog_register_device)
- * @dev:	The device for our watchdog
  * @parent:	The parent bus device
  * @groups:	List of sysfs attribute groups to create when creating the
  *		watchdog device.
@@ -82,7 +81,6 @@ struct watchdog_ops {
  */
 struct watchdog_device {
 	int id;
-	struct device *dev;
 	struct device *parent;
 	const struct attribute_group **groups;
 	const struct watchdog_info *info;