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authorJeffrey Carlyle <jeff.carlyle@motorola.com>2010-10-08 14:49:19 -0500
committerLiam Girdwood <lrg@slimlogic.co.uk>2010-10-28 22:40:31 +0100
commit8cbf811dfd027bde8504e541d0009c5722b98be5 (patch)
tree0f7190a0c3680485ad7893a36d37967ae8f3c526 /drivers
parent688fe99a439f7c9dfcc52fbf7cb347f140a2dc8b (diff)
regulator: avoid deadlock when disabling regulator with supply
I have a regulator A that sets regulator B as its supply. When I call set_supply to add B as the supply for A, regulator A gets added to the supply_list for regulator B. When I call regulator_disable(A), I end up with a call chain like this: regulator_disable(A) > mutex_lock(A) > _regulator_disable(A) >> _regulator_disable(B) >>> _notifier_call_chain(B) >>>> mutex_lock(A) Which results in dead lock since we are trying to acquire the mutex lock for regulator A which we already hold. This patch addresses this issue by moving the call to disable regulator B outside of the lock aquired inside the initial call to regulator_disable. This change also addresses the issue of not acquiring the mutex for regulator B before calling _regulator_disable(B). Signed-off-by: Jeffrey Carlyle <jeff.carlyle@motorola.com> Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com> Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/regulator/core.c35
1 files changed, 26 insertions, 9 deletions
diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 4fa08c85f3c..f1d10c974cd 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -64,7 +64,8 @@ struct regulator {
};
static int _regulator_is_enabled(struct regulator_dev *rdev);
-static int _regulator_disable(struct regulator_dev *rdev);
+static int _regulator_disable(struct regulator_dev *rdev,
+ struct regulator_dev **supply_rdev_ptr);
static int _regulator_get_voltage(struct regulator_dev *rdev);
static int _regulator_get_current_limit(struct regulator_dev *rdev);
static unsigned int _regulator_get_mode(struct regulator_dev *rdev);
@@ -1354,7 +1355,8 @@ int regulator_enable(struct regulator *regulator)
EXPORT_SYMBOL_GPL(regulator_enable);
/* locks held by regulator_disable() */
-static int _regulator_disable(struct regulator_dev *rdev)
+static int _regulator_disable(struct regulator_dev *rdev,
+ struct regulator_dev **supply_rdev_ptr)
{
int ret = 0;
@@ -1382,8 +1384,7 @@ static int _regulator_disable(struct regulator_dev *rdev)
}
/* decrease our supplies ref count and disable if required */
- if (rdev->supply)
- _regulator_disable(rdev->supply);
+ *supply_rdev_ptr = rdev->supply;
rdev->use_count = 0;
} else if (rdev->use_count > 1) {
@@ -1413,17 +1414,29 @@ static int _regulator_disable(struct regulator_dev *rdev)
int regulator_disable(struct regulator *regulator)
{
struct regulator_dev *rdev = regulator->rdev;
+ struct regulator_dev *supply_rdev = NULL;
int ret = 0;
mutex_lock(&rdev->mutex);
- ret = _regulator_disable(rdev);
+ ret = _regulator_disable(rdev, &supply_rdev);
mutex_unlock(&rdev->mutex);
+
+ /* decrease our supplies ref count and disable if required */
+ while (supply_rdev != NULL) {
+ rdev = supply_rdev;
+
+ mutex_lock(&rdev->mutex);
+ _regulator_disable(rdev, &supply_rdev);
+ mutex_unlock(&rdev->mutex);
+ }
+
return ret;
}
EXPORT_SYMBOL_GPL(regulator_disable);
/* locks held by regulator_force_disable() */
-static int _regulator_force_disable(struct regulator_dev *rdev)
+static int _regulator_force_disable(struct regulator_dev *rdev,
+ struct regulator_dev **supply_rdev_ptr)
{
int ret = 0;
@@ -1442,8 +1455,7 @@ static int _regulator_force_disable(struct regulator_dev *rdev)
}
/* decrease our supplies ref count and disable if required */
- if (rdev->supply)
- _regulator_disable(rdev->supply);
+ *supply_rdev_ptr = rdev->supply;
rdev->use_count = 0;
return ret;
@@ -1460,12 +1472,17 @@ static int _regulator_force_disable(struct regulator_dev *rdev)
*/
int regulator_force_disable(struct regulator *regulator)
{
+ struct regulator_dev *supply_rdev = NULL;
int ret;
mutex_lock(&regulator->rdev->mutex);
regulator->uA_load = 0;
- ret = _regulator_force_disable(regulator->rdev);
+ ret = _regulator_force_disable(regulator->rdev, &supply_rdev);
mutex_unlock(&regulator->rdev->mutex);
+
+ if (supply_rdev)
+ regulator_disable(get_device_regulator(rdev_get_dev(supply_rdev)));
+
return ret;
}
EXPORT_SYMBOL_GPL(regulator_force_disable);