Jarod Wilson <ja...@redhat.com> wrote: >On Wed, Dec 2, 2020 at 12:55 PM Jay Vosburgh <jay.vosbu...@canonical.com> >wrote: >> >> Jarod Wilson <ja...@redhat.com> wrote: >> >> >Don't try to adjust XFRM support flags if the bond device isn't yet >> >registered. Bad things can currently happen when netdev_change_features() >> >is called without having wanted_features fully filled in yet. Basically, >> >this code was racing against register_netdevice() filling in >> >wanted_features, and when it got there first, the empty wanted_features >> >led to features also getting emptied out, which was definitely not the >> >intended behavior, so prevent that from happening. >> >> Is this an actual race? Reading Ivan's prior message, it sounds >> like it's an ordering problem (in that bond_newlink calls >> register_netdevice after bond_changelink). > >Sorry, yeah, this is not actually a race condition, just an ordering >issue, bond_check_params() gets called at init time, which leads to >bond_option_mode_set() being called, and does so prior to >bond_create() running, which is where we actually call >register_netdevice().
So this only happens if there's a "mode" module parameter? That doesn't sound like the call path that Ivan described (coming in via bond_newlink). -J >> The change to bond_option_mode_set tests against reg_state, so >> presumably it wants to skip the first(?) time through, before the >> register_netdevice call; is that right? > >Correct. Later on, when the bonding driver is already loaded, and >parameter changes are made, bond_option_mode_set() gets called and if >the mode changes to or from active-backup, we do need/want this code >to run to update wanted and features flags properly. > > >-- >Jarod Wilson >ja...@redhat.com --- -Jay Vosburgh, jay.vosbu...@canonical.com