From: Simon Horman <horms@kernel•org>
To: "Toke Høiland-Jørgensen" <toke@redhat•com>
Cc: Hangbin Liu <liuhangbin@gmail•com>,
netdev@vger•kernel.org, "David S. Miller" <davem@davemloft•net>,
Eric Dumazet <edumazet@google•com>,
Jakub Kicinski <kuba@kernel•org>, Paolo Abeni <pabeni@redhat•com>,
Alexei Starovoitov <ast@kernel•org>,
Daniel Borkmann <daniel@iogearbox•net>,
Jesper Dangaard Brouer <hawk@kernel•org>,
John Fastabend <john.fastabend@gmail•com>,
Jiri Pirko <jiri@resnulli•us>,
Sebastian Andrzej Siewior <bigeasy@linutronix•de>,
Lorenzo Bianconi <lorenzo@kernel•org>,
Andrii Nakryiko <andriin@fb•com>, Jussi Maki <joamaki@gmail•com>,
Jay Vosburgh <jv@jvosburgh•net>,
Andy Gospodarek <andy@greyhouse•net>,
Jonathan Corbet <corbet@lwn•net>,
Andrew Lunn <andrew+netdev@lunn•ch>,
linux-doc@vger•kernel.org, linux-kernel@vger•kernel.org,
bpf@vger•kernel.org, Nikolay Aleksandrov <razor@blackwall•org>
Subject: Re: [PATCHv2 net-next 2/3] bonding: use correct return value
Date: Fri, 18 Oct 2024 15:21:04 +0100 [thread overview]
Message-ID: <20241018142104.GP1697@kernel.org> (raw)
In-Reply-To: <87o73hy7hh.fsf@toke.dk>
On Fri, Oct 18, 2024 at 01:29:30PM +0200, Toke Høiland-Jørgensen wrote:
> Simon Horman <horms@kernel•org> 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
next prev parent reply other threads:[~2024-10-18 14:21 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-17 2:06 [PATCHv2 net-next 0/3] Bonding: returns detailed error about XDP failures Hangbin Liu
2024-10-17 2:06 ` [PATCHv2 net-next 1/3] bonding: return detailed error when loading native XDP fails Hangbin Liu
2024-10-17 14:45 ` Toke Høiland-Jørgensen
2024-10-17 2:06 ` [PATCHv2 net-next 2/3] bonding: use correct return value Hangbin Liu
2024-10-17 14:47 ` Toke Høiland-Jørgensen
2024-10-18 0:46 ` Hangbin Liu
2024-10-18 9:41 ` Simon Horman
2024-10-18 11:29 ` Toke Høiland-Jørgensen
2024-10-18 14:21 ` Simon Horman [this message]
2024-10-19 0:51 ` Hangbin Liu
2024-10-19 9:19 ` Simon Horman
2024-10-17 2:06 ` [PATCHv2 net-next 3/3] Documentation: bonding: add XDP support explanation Hangbin Liu
2024-10-17 8:42 ` Nikolay Aleksandrov
2024-10-17 8:40 ` [PATCHv2 net-next 0/3] Bonding: returns detailed error about XDP failures Nikolay Aleksandrov
2024-10-17 9:26 ` Hangbin Liu
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