On Wed, Sep 23, 2015 at 12:10:13PM -0500, atull wrote:
> On Tue, 22 Sep 2015, Josh Cartwright wrote:
[..]
> > > +struct fpga_manager *of_fpga_mgr_get(struct device_node *node)
> > > +{
> > > + struct fpga_manager *mgr;
> > > + struct device *dev;
> > > +
> > > + if (!node)
> > > + return ERR_PTR(-EINVAL);
> > > +
> > > + dev = class_find_device(fpga_mgr_class, NULL, node,
> > > + fpga_mgr_of_node_match);
> > > + if (!dev)
> > > + return ERR_PTR(-ENODEV);
> > > +
> > > + mgr = to_fpga_manager(dev);
> > > + put_device(dev);
> >
> > Who's ensuring the FPGA manager device's lifetime between _get and _put?
>
> Well... get_device and put_device are not sufficient?
Sorry if I was too opaque.
You've just put_device()'d the only reference to the device you had
here, so nothing is preventing from the device from being ripped away
while it's being used.
You should remove the put_device() call here, and add a corresponding
put_device() in fpga_mgr_put().
The module refcounting is also a bit strange, as you are
acquiring/releasing a reference to THIS_MODULE, but you also should care
about the lower-level driver's module refcount.
[..]
> > > + dt_label = of_get_property(mgr->dev.of_node, "label", NULL);
> > > + if (dt_label)
> > > + ret = dev_set_name(&mgr->dev, "%s", dt_label);
> > > + else
> > > + ret = dev_set_name(&mgr->dev, "fpga%d", id);
> >
> > I'm wondering if an alias {} node is better for this.
>
> I could look into that. Is there an example of that you particularly
> like for this?
Look at i2c's usage of the of_alias_*() functions.
Josh
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