[PATCH 3.12 048/122] regulator: core: fix race condition in regulator_put()

From: Jiri Slaby
Date: Tue Feb 17 2015 - 07:01:41 EST

From: Ashay Jaiswal <ashayj@xxxxxxxxxxxxxx>

3.12-stable review patch. If anyone has any objections, please let me know.


commit 83b0302d347a49f951e904184afe57ac3723476e upstream.

The regulator framework maintains a list of consumer regulators
for a regulator device and protects it from concurrent access using
the regulator device's mutex lock.

In the case of regulator_put() the consumer is removed and regulator
device's parameters are updated without holding the regulator device's
mutex. This would lead to a race condition between the regulator_put()
and any function which traverses the consumer list or modifies regulator
device's parameters.
Fix this race condition by holding the regulator device's mutex in case
of regulator_put.

Signed-off-by: Ashay Jaiswal <ashayj@xxxxxxxxxxxxxx>
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
drivers/regulator/core.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index ea83084cb7d9..a2ce8e86ced7 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1474,7 +1474,7 @@ struct regulator *devm_regulator_get_optional(struct device *dev,

-/* Locks held by regulator_put() */
+/* regulator_list_mutex lock held by regulator_put() */
static void _regulator_put(struct regulator *regulator)
struct regulator_dev *rdev;
@@ -1489,12 +1489,14 @@ static void _regulator_put(struct regulator *regulator)
/* remove any sysfs entries */
if (regulator->dev)
sysfs_remove_link(&rdev->dev.kobj, regulator->supply_name);
+ mutex_lock(&rdev->mutex);

rdev->exclusive = 0;
+ mutex_unlock(&rdev->mutex);


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