Re: [PATCH] regulator: lock supply in regulator enable

[Mattias Wallin <mattias.wallin@stericsson.com>]

> Sorry, got a busy schedule atm. Can you give us your reasoning behind
> why you think we need a lock here ?
Yes, when we enter regulator_enable() we take the lock only for that specific regulator rdev->mutex
and calls the locked function _regulator_enable().
This locked function then checks if we have a supply and recursively calls the locked _regulator_enable() again but with the supply rdev as argument.
The supply rdev regulator is however not locked at this stage, only the "original" supplied regulator is locked.
So if we have two regulators with the same supply regulator trying to enable at approx. the same time they will both
enter the _regulator_enable without locks and we could get a race condition.
This would probably result in reference counting error and unbalanced regulator warnings.

In our system we make use the regulator hierarchy quite heavily.
> 
> Thanks
> 
> Liam

/Mattias Wallin