4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Arnd Bergmann <a...@arndb.de>
commit bb41897e38c53458a88b271f2fbcd905ee1f9584 upstream.
As noticed by Geert Uytterhoeven, my patch to avoid a harmless build warning
in regulator_lock_supply() was total crap and introduced a real bug:
> [ BUG: bad unlock balance detected! ]
> kworker/u4:0/6 is trying to release lock (&rdev->mutex) at:
> [<c0247b84>] regulator_set_voltage+0x38/0x50
we still lock the regulator supplies, but not the actual regulators,
so we are missing a lock, and the unlock is unbalanced.
This rectifies it by first locking the regulator device itself before
using the same loop as before to lock its supplies.
Reported-by: Geert Uytterhoeven <ge...@linux-m68k.org>
Signed-off-by: Arnd Bergmann <a...@arndb.de>
Fixes: 716fec9d1965 ("[SUBMITTED] regulator: core: avoid unused variable
warning")
Signed-off-by: Mark Brown <broo...@kernel.org>
Cc: Guenter Roeck <li...@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
drivers/regulator/core.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -140,7 +140,8 @@ static void regulator_lock_supply(struct
{
int i;
- for (i = 0; rdev->supply; rdev = rdev->supply->rdev, i++)
+ mutex_lock(&rdev->mutex);
+ for (i = 1; rdev->supply; rdev = rdev->supply->rdev, i++)
mutex_lock_nested(&rdev->mutex, i);
}
