regulator: core: Don't try to remove device links if add failed

device_link_add() might not always succeed depending on the type of
device link and the rest of the dependencies in the system. If
device_link_add() didn't succeed, then we shouldn't try to remove the
link later on as it might remove a link someone else created.
Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20191115000438.45970-1-saravanak@google.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/core.c

@@ -1844,6 +1844,7 @@ struct regulator *_regulator_get(struct device *dev, const char *id,
 	struct regulator_dev *rdev;
 	struct regulator *regulator;
 	const char *devname = dev ? dev_name(dev) : "deviceless";
+	struct device_link *link;
 	int ret;
 
 	if (get_type >= MAX_GET_TYPE) {
@@ -1951,7 +1952,9 @@ struct regulator *_regulator_get(struct device *dev, const char *id,
 			rdev->use_count = 0;
 	}
 
-	device_link_add(dev, &rdev->dev, DL_FLAG_STATELESS);
+	link = device_link_add(dev, &rdev->dev, DL_FLAG_STATELESS);
+	if (!IS_ERR_OR_NULL(link))
+		regulator->device_link = true;
 
 	return regulator;
 }
@@ -2046,7 +2049,8 @@ static void _regulator_put(struct regulator *regulator)
 	debugfs_remove_recursive(regulator->debugfs);
 
 	if (regulator->dev) {
-		device_link_remove(regulator->dev, &rdev->dev);
+		if (regulator->device_link)
+			device_link_remove(regulator->dev, &rdev->dev);
 
 		/* remove any sysfs entries */
 		sysfs_remove_link(&rdev->dev.kobj, regulator->supply_name);

drivers/regulator/internal.h

@@ -36,6 +36,7 @@ struct regulator {
 	struct list_head list;
 	unsigned int always_on:1;
 	unsigned int bypass:1;
+	unsigned int device_link:1;
 	int uA_load;
 	unsigned int enable_count;
 	unsigned int deferred_disables;