| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.4 113/163] regulator: core: fix regulator_lock_supply regression | Date | Mon, 2 May 2016 17:12:21 -0700 |
| |
4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Arnd Bergmann <arnd@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 <geert@linux-m68k.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Fixes: 716fec9d1965 ("[SUBMITTED] regulator: core: avoid unused variable warning") Signed-off-by: Mark Brown <broonie@kernel.org> Cc: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Greg Kroah-Hartman <gregkh@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); }
|