Messages in this thread | | | Date | Tue, 17 Nov 2015 10:30:36 -0800 | From | Brian Norris <> | Subject | Re: [PATCH 1/7] phy: brcmstb-sata: add missing of_node_put |
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On Tue, Nov 17, 2015 at 06:48:39PM +0100, Julia Lawall wrote: > On Tue, 17 Nov 2015, Brian Norris wrote: > > On Tue, Nov 17, 2015 at 07:12:22AM +0100, Julia Lawall wrote: > > > On Mon, 16 Nov 2015, Brian Norris wrote: > > > > diff --git a/drivers/phy/phy-core.c b/drivers/phy/phy-core.c > > > > index fc48fac003a6..8df29caeeef9 100644 > > > > --- a/drivers/phy/phy-core.c > > > > +++ b/drivers/phy/phy-core.c > > > > @@ -697,6 +697,7 @@ struct phy *phy_create(struct device *dev, struct device_node *node, > > > > phy->dev.class = phy_class; > > > > phy->dev.parent = dev; > > > > phy->dev.of_node = node ?: dev->of_node; > > > > + of_node_get(phy->dev.of_node); > > > > > > Why not put of_node_get around dev->of_node? > > > > Like this? > > > > phy->dev.of_node = node ?: of_node_get(dev->of_node); > > > > Or this? > > > > phy->dev.of_node = of_node_get(node ?: dev->of_node); > > > > The former wouldn't do what I proposed; if this PHY device is created > > with a sub-node of 'dev' rather than dev->of_node, then the caller will > > pass it in as the 2nd argument to phy_create (i.e., 'node'), and then I > > expect it's the PHY core's responsibility to refcount it. > > > > I'd be fine with the latter. Looks a little better, I suppose. > > I proposed it because I was worried that the of_node field could end up > containing something that had been freed. But probably this is not > possible?
AIUI, the caller of phy_create() should already have a refcount on both 'dev->of_node' and 'node' (if applicable), so nobody should be freeing it from underneath us right here. But *after* phy_create() returns, there's no guarantee the caller will hold a reference for us.
So even if it's ever possible, I'd consider it a bug in the caller, not in phy_create().
> If it is not possible, then the ?: in the function argument is > probably a bit ugly...
OK, then I'll go with my first proposal.
> Is this something that should be checked for elsewhere?
I expect the same sort of problem shows up plenty of other places. I don't think many people use CONFIG_OF_DYNAMIC, so the effects of these failures probably aren't felt by many.
Brian
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