Re: [PATCH net-next 4/8] net: dsa: mv88e6xxx: do not increment bus refcount

Andrew Lunn
2016-06-10T20:06:48Z

On Fri, Jun 10, 2016 at 03:59:22PM -0400, Vivien Didelot wrote:
> Hi,
>
> Andrew Lunn <andrew@lunn.ch> writes:
>
> > On Wed, Jun 08, 2016 at 08:44:52PM -0400, Vivien Didelot wrote:
> >> The MDIO device probe and remove functions are respectively incrementing
> >> and decrementing the bus refcount themselves. Since these bus level
> >> actions are out of the device scope, remove them.
> >
> > I agree with the patch. But have you checked the mdio layer is doing
> > the right thing? If not, we should fix that first.
>
> So I added some printing after incrementing/decrementing the refcount in
> get_device/put_device to track &ps->bus->dev, which name is "0.1".
>
> Regardless having this patch or not, the refcount of the 0.1 mii_bus
> device is 5 before loading the mv88e6xxx module on vf610-zii-dev-rev-b.
>
> Below is a portion of dmesg:
>
> [ 8.921647] get_device: 400d1000.etherne refcount: 4
> [ 8.926225] get_device: 0.1 refcount: 2
> [ 8.929561] get_device: mdio-mux refcount: 5
> [ 8.934076] get_device: 0.1 refcount: 3
> [ 8.937446] get_device: 0.1 refcount: 4
> [ 8.940792] put_device: 0.1 refcount: 3
> [ 8.944181] libphy: mdio_mux: probed
> [ 8.947885] mdio_bus 0.1:00: mdio_device_register
> [ 8.952649] get_device: 0.1:00 refcount: 2
> [ 8.956283] get_device: 0.1 refcount: 4
> [ 8.959838] get_device: 0.1:00 refcount: 3
> [ 8.963991] get_device: 0.1:00 refcount: 4
> [ 8.967598] put_device: 0.1:00 refcount: 3
> [ 8.971298] get_device: 0.2 refcount: 2
> [ 8.974687] get_device: mdio-mux refcount: 7
>
> So it seems like of_ is managing the bus refcount on events such as a
> new child node (0.1:00).

Great, thanks for looking at this.

Acked-by: Andrew Lunn <andrew@lunn.ch>

Andrew