[PATCH 3.2 092/152] regulator: core: fix race condition in regulator_put()

From: Ben Hutchings
Date: Mon Feb 16 2015 - 21:28:36 EST

3.2.67-rc1 review patch. If anyone has any objections, please let me know.


From: Ashay Jaiswal <ashayj@xxxxxxxxxxxxxx>

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>
[bwh: Backported to 3.2:
- Adjust context
- Don't touch the comment; __regulator_put() has not been split out of
regulator_put() here]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
drivers/regulator/core.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1314,12 +1314,14 @@ void regulator_put(struct regulator *reg
device_remove_file(regulator->dev, &regulator->dev_attr);
+ mutex_lock(&rdev->mutex);

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


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