Mon, Apr 15, 2019 at 09:27:09PM CEST, jakub.kicin...@netronome.com wrote: >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
Care to define "atomically" here? It is done in a very similar way to how it is done in mlxsw for example. Same flows. >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... Same here. Not sure where do you see the differences. Also, I plan to implement port splitting in follow-up patchset. All flows are there as well. > >> 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.
