> Subject: [EXTERNAL] Re: [PATCH] hv_netvsc: Set device flags for properly > indicating bonding > > On Wed, 27 Nov 2024 11:42:50 -0800 > longli@xxxxxxxxxxxxxxxxx wrote: > > > hv_netvsc uses a subset of bonding features in that the master always > > has only one active slave. But it never properly setup those flags. > > > > Other kernel APIs (e.g those in "include/linux/netdevice.h") check for > > IFF_MASTER, IFF_SLAVE and IFF_BONDING for determing if those are used > > in a master/slave setup. RDMA uses those APIs extensively when looking > > for master/slave devices. > > > > Make hv_netvsc properly setup those flags. > > > > Signed-off-by: Long Li <longli@xxxxxxxxxxxxx> > > Linux networking has evolved a patch work of flags to network devices but never > really standardized on a way to express linked relationships between network > devices. There are several drivers do this in slighlty different and overlapping > ways: bonding, team, failover, hyperv, bridge and others. > > The current convention is to mark the primary device as IFF_MASTER and each > secondary device with IFF_SLAVE. But not clear what the right combination is if > stacked more than one level. Also, not clear if userspace and other addressing > should use or not use nested devices. > > It would be ideal to deprecate and use different terms than the non-inclusive > terms master/slave but probably that would have to have been done years ago > (like 2.5). > > For now, it makes sense for all the nested devices to use IFF_MASTER and > IFF_SLAVE consistently. It is not a good idea to set the priv_flag for IFF_BONDING > (or any of the other bits) which should be reserved for one driver. > > If hyperv driver needs to it could add its own flag in netdev_priv_flags, but it looks > like that is running out of bits. May need to grow to 64 bits or do some more work > to add a new field for device type. I.e. there are combinations of flags that are > impossible and having one bit per type leads to a problem. Fixing that is non trivial > but not impossible level of effort. > > My thoughts, but I don't use or work on Hyper-v anymore. Thank you. I have sent v2. Long
