Applied "regulator: core: Fix nested locking of supplies" to the regulator tree

Applied "regulator: core: Fix nested locking of supplies" to the regulator tree

[Mark Brown]

The patch

   regulator: core: Fix nested locking of supplies

has been applied to the regulator tree at

   git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From 70a7fb80e85ae7f78f8e90cec3fbd862ea6a4d4b Mon Sep 17 00:00:00 2001
From: Thierry Reding <treding@nvidia.com>
Date: Wed, 2 Dec 2015 16:54:50 +0100
Subject: [PATCH] regulator: core: Fix nested locking of supplies

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: Fixes: fa731ac7ea04 ("regulator: core: avoid unused variable warning")
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 drivers/regulator/core.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index f71db02fcb71..732ac71b82cd 100644
--- 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 regulator_dev *rdev)
 {
 	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);
 }
 
-- 
2.6.2