On Fri, Oct 18, 2024 at 01:29:30PM +0200, Toke Høiland-Jørgensen wrote: > Simon Horman <horms@xxxxxxxxxx> writes: > > > On Fri, Oct 18, 2024 at 12:46:18AM +0000, Hangbin Liu wrote: > >> On Thu, Oct 17, 2024 at 04:47:19PM +0200, Toke Høiland-Jørgensen wrote: > >> > > diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c > >> > > index f0f76b6ac8be..6887a867fe8b 100644 > >> > > --- a/drivers/net/bonding/bond_main.c > >> > > +++ b/drivers/net/bonding/bond_main.c > >> > > @@ -5699,7 +5699,7 @@ static int bond_xdp_set(struct net_device *dev, struct bpf_prog *prog, > >> > > if (dev_xdp_prog_count(slave_dev) > 0) { > >> > > SLAVE_NL_ERR(dev, slave_dev, extack, > >> > > "Slave has XDP program loaded, please unload before enslaving"); > >> > > - err = -EOPNOTSUPP; > >> > > + err = -EEXIST; > >> > > >> > Hmm, this has been UAPI since kernel 5.15, so can we really change it > >> > now? What's the purpose of changing it, anyway? > >> > >> I just think it should return EXIST when the error is "Slave has XDP program > >> loaded". No special reason. If all others think we should not change it, I > >> can drop this patch. > > > > Hi Toke, > > > > Could you add some colour to what extent user's might rely on this error code? > > > > Basically I think that if they do then we shouldn't change this. > > Well, that's the trouble with UAPI, we don't really know. In libxdp and > xdp-tools we look at the return code to provide a nicer error message, > like: > > https://github.com/xdp-project/xdp-tools/blob/master/lib/libxdp/libxdp.c#L615 > > and as a signal to fall back to loading the programme without a dispatcher: > > https://github.com/xdp-project/xdp-tools/blob/master/lib/libxdp/libxdp.c#L1824 > > Both of these cases would be unaffected (or even improved) by this > patch, so in that sense I don't have a concrete objection, just a > general "userspace may react to this". In other words, my concern is > more of a general "we don't know, so this seems risky". If any of you > have more information about how bonding XDP is generally used, that may > help get a better idea of this? Yes, that is the trouble with the UAPI. I was hoping you might be able to provide the clarity you ask for above. But alas, things are as clear as mud. In lieu of more information I suggest caution and dropping this change for now. -- pw-bot: cr