This is a note to let you know that I've just added the patch titled
regulator: core: Fix nested locking of supplies
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
regulator-core-fix-nested-locking-of-supplies.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 70a7fb80e85ae7f78f8e90cec3fbd862ea6a4d4b Mon Sep 17 00:00:00 2001
From: Thierry Reding <treding@xxxxxxxxxx>
Date: Wed, 2 Dec 2015 16:54:50 +0100
Subject: regulator: core: Fix nested locking of supplies
From: Thierry Reding <treding@xxxxxxxxxx>
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@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Fixes: fa731ac7ea04 ("regulator: core: avoid unused variable warning")
Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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);
}
Patches currently in stable-queue which might be from treding@xxxxxxxxxx are
queue-4.4/regulator-core-fix-nested-locking-of-supplies.patch
queue-4.4/revert-regulator-core-fix-nested-locking-of-supplies.patch
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