Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.4 115/163] regulator: core: Fix nested locking of supplies | Date | Mon, 2 May 2016 17:12:23 -0700 |
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4.4-stable review patch. If anyone has any objections, please let me know.
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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); }
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