[PATCH 3.13.y-ckt 29/80] regulator: core: fix race condition in regulator_put()

Kamal Mostafa kamal at canonical.com
Thu Mar 19 22:35:17 UTC 2015

3.13.11-ckt17 -stable review patch.  If anyone has any objections, please let me know.


From: Ashay Jaiswal <ashayj at codeaurora.org>

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 at codeaurora.org>
Signed-off-by: Mark Brown <broonie at kernel.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
 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 7271299..1291043 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1479,7 +1479,7 @@ struct regulator *regulator_get_optional(struct device *dev, const char *id)
-/* Locks held by regulator_put() */
+/* regulator_list_mutex lock held by regulator_put() */
 static void _regulator_put(struct regulator *regulator)
 	struct regulator_dev *rdev;
@@ -1494,12 +1494,14 @@ 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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