| Message ID | 20241017020638.6905-3-liuhangbin@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | Bonding: returns detailed error about XDP failures | expand |
Hangbin Liu <liuhangbin@gmail.com> writes: > When a slave already has an XDP program loaded, the correct return value > should be -EEXIST instead of -EOPNOTSUPP. > > Fixes: 9e2ee5c7e7c3 ("net, bonding: Add XDP support to the bonding driver") > Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org> > Signed-off-by: Hangbin Liu <liuhangbin@gmail.com> > --- > drivers/net/bonding/bond_main.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > 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? -Toke
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. Thanks Hangbin
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.
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? -Toke
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.
On Fri, Oct 18, 2024 at 03:21:04PM +0100, Simon Horman wrote: > 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. OK, I will drop this one. Thanks Hangbin
On Sat, Oct 19, 2024 at 12:51:00AM +0000, Hangbin Liu wrote: > On Fri, Oct 18, 2024 at 03:21:04PM +0100, Simon Horman wrote: > > 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. > > OK, I will drop this one. Thanks.
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; goto err; }
When a slave already has an XDP program loaded, the correct return value should be -EEXIST instead of -EOPNOTSUPP. Fixes: 9e2ee5c7e7c3 ("net, bonding: Add XDP support to the bonding driver") Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org> Signed-off-by: Hangbin Liu <liuhangbin@gmail.com> --- drivers/net/bonding/bond_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)