regulator: core: Move regulator release to avoid deadlock

PATCH Applied Charles Keepax 3 participants 4 messages Oct 29, 2012 – Oct 31, 2012 Voltage and current regulator framework

lore

Share & tools

lore

Charles Keepax

author

2012-10-29 09:33 UTC #0 lore raw

PATCH 1/1 regulator: core: Move regulator release to avoid deadlock

regulator_put function was called whilst holding the regulator_list_mutex, which is also locked from regulator_put. This causes deadlock when failing to register a regulator.

This patch adds a second exit point for the regulator_register function which releases the mutex and then cleans up the supply.

Signed-off-by Charles Keepax <[email protected]>

---
 drivers/regulator/core.c |    9 ++++++---
 1 files changed, 6 insertions(+), 3 deletions(-)

drivers/regulator/core.c +6 -3

index 5c4829c..e68754c 100644
@@ -3444,15 +3444,18 @@ unset_supplies:
 	unset_regulator_supplies(rdev);
 
 scrub:
-	if (rdev->supply)
-		regulator_put(rdev->supply);
 	if (rdev->ena_gpio)
 		gpio_free(rdev->ena_gpio);
 	kfree(rdev->constraints);
 	device_unregister(&rdev->dev);
+
+	mutex_unlock(&regulator_list_mutex);
+	if (rdev->supply)
+		regulator_put(rdev->supply);
+
 	/* device core frees rdev */
 	rdev = ERR_PTR(ret);
-	goto out;
+	return rdev;
 
 clean:
 	kfree(rdev);

Signature · 1 line

1.7.2.5

Mark Brown

Applied

2012-10-29 16:14 UTC #1 lore raw

Quoted 3 lines · Charles Keepax

regulator_put function was called whilst holding the regulator_list_mutex, which is also locked from regulator_put. This causes deadlock when failing to register a regulator.

Applied, thanks.

Laxman Dewangan

2012-10-31 10:35 UTC #2 lore raw

Quoted 7 lines · Mark Brown

* PGP Signed by an unknown key
Quoted 3 lines · Charles Keepax
regulator_put function was called whilst holding the regulator_list_mutex, which is also locked from regulator_put. This causes deadlock when failing to register a regulator.
Applied, thanks.

This patch create the crash in following case:
- If there is of rail supply and supply does not found. In this case it goes to scrub and rdev->supply at this point shows NULL but when call the function device_unregister(&rdev->dev), the rdev->supply becomes random pointer.

What happen if we do the device_unregister() outside the mutex lock?

Charles Keepax

author

2012-10-31 12:01 UTC #3 lore raw

Quoted 7 lines · Laxman Dewangan

Quoted 6 lines · Mark Brown
* PGP Signed by an unknown key
Quoted 3 lines · Charles Keepax
regulator_put function was called whilst holding the regulator_list_mutex, which is also locked from regulator_put. This causes deadlock when failing to register a regulator.

Quoted 7 lines

Quoted 1 line
Applied, thanks.
This patch create the crash in following case:
- If there is of rail supply and supply does not found. In this case it goes to scrub and rdev->supply at this point shows NULL but when call the function device_unregister(&rdev->dev), the rdev->supply becomes random pointer.

Yeah that is a problem, sorry for missing this.

Quoted 2 lines

What happen if we do the device_unregister() outside the mutex lock?

It would look reasonable to me, but I think it is going to make more sense for someone with more experience than myself to have a closer look at what can be done.