Re: [net-next PATCH v6 0/3] net: dummy: Introduce dummy virtual functions

On Wed, Jan 11, 2017 at 02:38:57PM +0100, Phil Sutter wrote:

On Fri, Jan 06, 2017 at 08:38:04PM -0500, David Miller wrote:

quoted

From: Phil Sutter <phil@nwl.cc>
Date: Thu,  5 Jan 2017 20:09:10 +0100

quoted

This series adds VF support to dummy device driver after adding the
necessary infrastructure changes:

Patch 1 adds a netdevice callback for device-specific VF count
retrieval. Patch 2 then changes dev_num_vf() implementation to make use
of that new callback (if implemented), falling back to the old
behaviour. Patch 3 then implements VF support in dummy, without the fake
PCI parent device hack from v5.

Please don't make this a netdev specific method and interface.

Put the method in "struct bus_device", thereby making it a generic
"device" layer thing.

So the pci BUS type will implement pci_bus_type.num_vf().  And you'll
make a bus type for the dummy device to attach to which will implement
it's own.

Following your approach, I'm running into a weird issue with conflicting
sysfs symlink names after calling register_netdevice for the dummy
device which has dev->dev.bus set to the dummy bus type I introduced:

In netdev_register_kobject, dev->class is set to &net_class. This means
that later in device_add, the call to device_add_class_symlinks will
create symlink to the class named devices/virtual/net/dummy0/subsystem.

The following call to bus_add_device by device_add though tries to
create a symlink to the bus with identical name.

Ah, nevermind - it's actually the netdev's parent which should have the
bus type set. At first I assumed this would be a PCI specific thing.

Thanks, Phil