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regulator: core: fix regulator_lock_supply regression 

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>
This commit is contained in:
Arnd Bergmann 2015-11-27 14:46:41 +01:00 committed by Mark Brown
parent fa731ac7ea
commit bb41897e38
1 changed files with 2 additions and 1 deletions
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3
drivers/regulator/core.c
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@ -140,7 +140,8 @@ static void regulator_lock_supply(struct regulator_dev *rdev)
{
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);
}