[PATCH] regulator: core: grab supply info before unlocking

[PATCH] regulator: core: grab supply info before unlocking

[John Ogness]

It is necessary to check if there is a supply while still holding
the regulator lock. Otherwise a theoretical race can occur that
someone else can add a supply and then we incorrectly try to
unlock that newly added regulator.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
---
 patch against next-20160421

 drivers/regulator/core.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 9348c78..629f92f 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -161,10 +161,10 @@ static void regulator_unlock_supply(struct regulator_dev *rdev)
 	struct regulator *supply;
 
 	while (1) {
-		mutex_unlock(&rdev->mutex);
 		supply = rdev->supply;
+		mutex_unlock(&rdev->mutex);
 
-		if (!rdev->supply)
+		if (!supply)
 			return;
 
 		rdev = supply->rdev;
-- 
1.7.10.4

Re: [PATCH] regulator: core: grab supply info before unlocking

[Mark Brown]

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On Fri, Apr 22, 2016 at 04:33:51PM +0200, John Ogness wrote:
> It is necessary to check if there is a supply while still holding
> the regulator lock. Otherwise a theoretical race can occur that
> someone else can add a supply and then we incorrectly try to
> unlock that newly added regulator.

I don't understand this.  What do you mean by "add a supply"?

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