[PATCH 4.4 115/163] regulator: core: Fix nested locking of supplies

Greg Kroah-Hartman
2016-05-03T00:26:41Z

From: Thierry Reding <treding@nvidia.com>

commit 70a7fb80e85ae7f78f8e90cec3fbd862ea6a4d4b upstream.

Commit fa731ac7ea04 ("regulator: core: avoid unused variable warning")
introduced a subtle change in how supplies are locked. Where previously
code was always locking the regulator of the current iteration, the new
implementation only locks the regulator if it has a supply. For any
given power tree that means that the root will never get locked.

On the other hand the regulator_unlock_supply() will still release all
the locks, which in turn causes the lock debugging code to warn about a
mutex being unlocked which wasn't locked.

Cc: Mark Brown <broonie@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Fixes: fa731ac7ea04 ("regulator: core: avoid unused variable warning")
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/regulator/core.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -132,6 +132,14 @@ static bool have_full_constraints(void)
return has_full_constraints || of_have_populated_dt();
}

+static inline struct regulator_dev *rdev_get_supply(struct regulator_dev *rdev)
+{
+ if (rdev && rdev->supply)
+ return rdev->supply->rdev;
+
+ return NULL;
+}
+
/**
* regulator_lock_supply - lock a regulator and its supplies
* @rdev: regulator source
@@ -140,8 +148,7 @@ static void regulator_lock_supply(struct
{
int i;

- mutex_lock(&rdev->mutex);
- for (i = 1; rdev; rdev = rdev->supply->rdev, i++)
+ for (i = 0; rdev; rdev = rdev_get_supply(rdev), i++)
mutex_lock_nested(&rdev->mutex, i);
}