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Date: Fri, 10 Jun 2016 15:59:22 -0400 From: Vivien Didelot <vivien.didelot@...oirfairelinux.com> To: Andrew Lunn <andrew@...n.ch> Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org, kernel@...oirfairelinux.com, "David S. Miller" <davem@...emloft.net>, Florian Fainelli <f.fainelli@...il.com> Subject: Re: [PATCH net-next 4/8] net: dsa: mv88e6xxx: do not increment bus refcount Hi, Andrew Lunn <andrew@...n.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). Thanks, Vivien
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