On Thu, Apr 03, 2014 at 11:58:04AM +0100, Charles Keepax wrote: > On Wed, Apr 02, 2014 at 05:53:54PM +0100, Mark Brown wrote:
> > To make this correct we need to at least ensure that the node passed > > into the regulator API is valid and referenced at that time so there > > should only be an issue for the core if the reference is dropped after > > that. In the above case the device model is holding a reference since > > this is the of_node for the device itself so taking the reference won't > > hurt but is redundant. In cases where we have more than one regulator > > and are using of_regulator_match() then things are more tricky. > > Something needs to drop the references it returns (which isn't happening > > at all at the minute). > From what I can see of_regulator_match isn't taking any > references at the minute? for_each_child_of_node will get a > reference but it will also put that when we process the next > child. We copy the pointer to the child into match->of_node > but don't manually increment the reference at all. So > of_regulator_match has no effect on the reference count of the > of_node. Right, so that needs fixing - like I say if there's no reference being taken we already have a problem and taking another reference later on isn't going to fix it. > > Doing it while doing the match and register > > seems simple and neat from an error handling point of view so having the > > core take an additional reference during the registration would join up > > with that. > The main issue I have is that devm_regualtor_register is a bit > awkward. With regulator_register you will always be calling > regulator_unregister so you can put the of_node there but with > devm there isn't really a good place to put the of_node. That's why I suggested it might be OK to take a reference in the core - this would allow the device probe to safely drop its reference before it returns. > Would perhaps a sensible thing here be to add an of_node_get to > of_regulator_match, since we seem to be expecting that to > increase the ref count. And then just add an of_node_put to > regulator_unregister. And for anything directly using > regulator_register/devm_regulator_register they should add a > manual of_node_get? That seems very ugly.
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