regulator: core: Add locking to debugfs regulator_summary

Most functions that access the rdev lock the rdev mutex before looking
at data.  ...but not the code that implements the debugfs
regulator_summary.  It probably should though, so let's do it.

Note: this fixes no known issues.  The problem was found only by code
inspection.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/core.c

@@ -3475,21 +3475,23 @@ int regulator_set_current_limit(struct regulator *regulator,
 }
 EXPORT_SYMBOL_GPL(regulator_set_current_limit);
 
+static int _regulator_get_current_limit_unlocked(struct regulator_dev *rdev)
+{
+	/* sanity check */
+	if (!rdev->desc->ops->get_current_limit)
+		return -EINVAL;
+
+	return rdev->desc->ops->get_current_limit(rdev);
+}
+
 static int _regulator_get_current_limit(struct regulator_dev *rdev)
 {
 	int ret;
 
 	regulator_lock(rdev);
-
-	/* sanity check */
-	if (!rdev->desc->ops->get_current_limit) {
-		ret = -EINVAL;
-		goto out;
-	}
-
-	ret = rdev->desc->ops->get_current_limit(rdev);
-out:
+	ret = _regulator_get_current_limit_unlocked(rdev);
 	regulator_unlock(rdev);
+
 	return ret;
 }
 
@@ -3554,21 +3556,23 @@ int regulator_set_mode(struct regulator *regulator, unsigned int mode)
 }
 EXPORT_SYMBOL_GPL(regulator_set_mode);
 
+static unsigned int _regulator_get_mode_unlocked(struct regulator_dev *rdev)
+{
+	/* sanity check */
+	if (!rdev->desc->ops->get_mode)
+		return -EINVAL;
+
+	return rdev->desc->ops->get_mode(rdev);
+}
+
 static unsigned int _regulator_get_mode(struct regulator_dev *rdev)
 {
 	int ret;
 
 	regulator_lock(rdev);
-
-	/* sanity check */
-	if (!rdev->desc->ops->get_mode) {
-		ret = -EINVAL;
-		goto out;
-	}
-
-	ret = rdev->desc->ops->get_mode(rdev);
-out:
+	ret = _regulator_get_mode_unlocked(rdev);
 	regulator_unlock(rdev);
+
 	return ret;
 }
 
@@ -4675,18 +4679,23 @@ static void regulator_summary_show_subtree(struct seq_file *s,
 	struct regulation_constraints *c;
 	struct regulator *consumer;
 	struct summary_data summary_data;
+	unsigned int opmode;
 
 	if (!rdev)
 		return;
 
+	regulator_lock_nested(rdev, level);
+
+	opmode = _regulator_get_mode_unlocked(rdev);
 	seq_printf(s, "%*s%-*s %3d %4d %6d %7s ",
 		   level * 3 + 1, "",
 		   30 - level * 3, rdev_get_name(rdev),
 		   rdev->use_count, rdev->open_count, rdev->bypass_count,
-		   regulator_opmode_to_str(_regulator_get_mode(rdev)));
+		   regulator_opmode_to_str(opmode));
 
 	seq_printf(s, "%5dmV ", _regulator_get_voltage(rdev) / 1000);
-	seq_printf(s, "%5dmA ", _regulator_get_current_limit(rdev) / 1000);
+	seq_printf(s, "%5dmA ",
+		   _regulator_get_current_limit_unlocked(rdev) / 1000);
 
 	c = rdev->constraints;
 	if (c) {
@@ -4733,6 +4742,8 @@ static void regulator_summary_show_subtree(struct seq_file *s,
 
 	class_for_each_device(&regulator_class, NULL, &summary_data,
 			      regulator_summary_show_children);
+
+	regulator_unlock(rdev);
 }
 
 static int regulator_summary_show_roots(struct device *dev, void *data)