Re: [PATCH] node_device: Use "udev" monitor source

On 11/17/20 1:51 PM, Daniel P. Berrangé wrote: > On Tue, Nov 17, 2020 at 01:29:47PM +0100, Michal Privoznik wrote: > > In v6.3.0-rc1~67 I've made a switch: instead of listening on udev > > events the nodedev driver started listening for kernel events. > > This was because when a device changes its name (e.g. NICs) we > > will get "move" event with DEVPATH_OLD property set, which we can > > then use to remove the old device and thus keep our internal list > > up to date. The switch to "kernel" source was made because if the > > old NICs naming (eth0, eth1, ...) is enabled (e.g. via > > net.ifnames=0 on the kernel cmd line) then udev overwrites the > > property with the new name making our internal list go out of > > sync. Interestingly, when the od NICs naming is not enabled then > > the DEVPATH_OLD contains the correct value. > > I don't see any difference in properties regardless of net.ifnames > is 0 or 1. In both cases, there is DEVPATH + DEVPAT_OLD, and > INTERFACE has the new NIC name. Can you actually reproduce the > original problem with net.ifnames=0 ? If so, which distro ? Have you tried renaming back and forth? for instance: # ip link set tunl0 name tunl1 # ip link set tunl1 name tunl0 The "kernel" source yields: KERNEL[778387.296879] move /devices/virtual/net/tunl1 (net) ACTION=move DEVPATH=/devices/virtual/net/tunl1 DEVPATH_OLD=/devices/virtual/net/tunl0 IFINDEX=5 INTERFACE=tunl1 SEQNUM=20701 SUBSYSTEM=net KERNEL[778400.944769] move /devices/virtual/net/tunl0 (net) ACTION=move DEVPATH=/devices/virtual/net/tunl0 DEVPATH_OLD=/devices/virtual/net/tunl1 IFINDEX=5 INTERFACE=tunl0 SEQNUM=20702 SUBSYSTEM=net But "udev" gets: UDEV [778387.297247] move /devices/virtual/net/tunl1 (net) ACTION=move DEVPATH=/devices/virtual/net/tunl1 DEVPATH_OLD=/devices/virtual/net/tunl0 IFINDEX=5 INTERFACE=tunl1 SEQNUM=20701 SUBSYSTEM=net USEC_INITIALIZED=5901449841 net.ifnames=0 UDEV [778400.945195] move /devices/virtual/net/tunl1 (net) ACTION=move DEVPATH=/devices/virtual/net/tunl1 DEVPATH_OLD=/devices/virtual/net/tunl1 IFINDEX=5 INTERFACE=tunl1 SEQNUM=20702 SUBSYSTEM=net USEC_INITIALIZED=5901449841 net.ifnames=0 In both cases the first rename (tunl0 -> tunl1) gets correct DEVPATH_OLD, but the second rename is problematic (tunl1 -> tunl0) and only "kernel" gets it right.