regulator: core: Avoid deadlock when regulator_register fails

When regulator_register fails and exits through the scrub path the
regulator_put function was called whilst holding the
regulator_list_mutex, causing deadlock.

This patch adds a private version of the regulator_put function which
can be safely called whilst holding the mutex, replacing the
aforementioned call.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

1 files changed, 17 insertions, 11 deletions

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 5c4829cba6a6..3ebc06b280ab 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1381,22 +1381,14 @@ struct regulator *regulator_get_exclusive(struct device *dev, const char *id)
 }
 EXPORT_SYMBOL_GPL(regulator_get_exclusive);
 
-/**
- * regulator_put - "free" the regulator source
- * @regulator: regulator source
- *
- * Note: drivers must ensure that all regulator_enable calls made on this
- * regulator source are balanced by regulator_disable calls prior to calling
- * this function.
- */
-void regulator_put(struct regulator *regulator)
+/* Locks held by regulator_put() */
+static void _regulator_put(struct regulator *regulator)
 {
         struct regulator_dev *rdev;
 
         if (regulator == NULL || IS_ERR(regulator))
                 return;
 
-        mutex_lock(&regulator_list_mutex);
         rdev = regulator->rdev;
 
         debugfs_remove_recursive(regulator->debugfs);
@@ -1412,6 +1404,20 @@ void regulator_put(struct regulator *regulator)
         rdev->exclusive = 0;
 
         module_put(rdev->owner);
+}
+
+/**
+ * regulator_put - "free" the regulator source
+ * @regulator: regulator source
+ *
+ * Note: drivers must ensure that all regulator_enable calls made on this
+ * regulator source are balanced by regulator_disable calls prior to calling
+ * this function.
+ */
+void regulator_put(struct regulator *regulator)
+{
+        mutex_lock(&regulator_list_mutex);
+        _regulator_put(regulator);
         mutex_unlock(&regulator_list_mutex);
 }
 EXPORT_SYMBOL_GPL(regulator_put);
@@ -3445,7 +3451,7 @@ unset_supplies:
 
 scrub:
         if (rdev->supply)
-                regulator_put(rdev->supply);
+                _regulator_put(rdev->supply);
         if (rdev->ena_gpio)
                 gpio_free(rdev->ena_gpio);
         kfree(rdev->constraints);