On Sat, 13 Apr 2019 18:20:57 +0200, Jiri Pirko wrote: > From: Jiri Pirko <j...@mellanox.com> > > Currently the model of netdevsim is a bit odd in multiple ways. > 1) devlink instance is not in any way related with actual netdevsim > netdevices. Instead, it is created per-namespace. > 2) multi-port netdevsim device is done using "link" attribute. > 3) netdevsim bus is there only to have something to bind the netdev to, > it really does not act as a bus.
Nope, it's there to expose SR-IOV ops :) > 4) netdevsim instances are created by "ip link add" which is great for > soft devices with no hw backend. The rtnl core allocates netdev and > calls into driver holding rtnl mutex. For hw-backed devices, this > flow is wrong as it breaks order in which things are done. > > This patchset adjust netdevsim to fix all above. > > In order to support proper devlink and devlink port instances and to be > able to emulate real devices, there is need to implement bus probe and > instantiate everything from there. User can specify device id and port > count to be instantianted. For example: > > echo "10 4" > /sys/bus/netdevsim/new_device I really don't like the design where ID has to be allocated by user space. It's a step back. I also dislike declaring ports from the start. In real drivers ports are never "atomically" registered, they are crated and destroyed one by one, and a lot of races/UAFs/bugs lie in those small periods of time where one netdev got unregistered, but other are still around... > Then devlink shows this: > > $ devlink dev > netdevsim/netdevsim10 > > $ devlink port > netdevsim/netdevsim10/0: type eth netdev netdevsim10p1 flavour physical > netdevsim/netdevsim10/1: type eth netdev netdevsim10p2 flavour physical > netdevsim/netdevsim10/2: type eth netdev netdevsim10p3 flavour physical > netdevsim/netdevsim10/3: type eth netdev netdevsim10p4 flavour physical > > Debugfs topology is also adjusted a bit. The rest stays the same as > before. > > TODO: > - teach udev to rename netdevsim netdevices similarly to pci netdevices So we can test udev as well? > - fix tools/testing/selftests/bpf/test_offload.py to work with new iface That'd step 0 :) BTW are you testing all this with the various sysfs/kobject debug checks? I don't remember all the deets now, but there were certainly ordering considerations coming from there.
