Date: Fri, 11 Aug 2023 18:28:32 -0700 From: Kevin Bowling <kevin.bowling@kev009.com> To: Kristof Provost <kp@freebsd.org> Cc: src-committers@freebsd.org, dev-commits-src-all@freebsd.org, dev-commits-src-main@freebsd.org Subject: Re: git: 5f11a33ceeb3 - main - if_vlan: do not enable LRO for bridge interaces Message-ID: <CAK7dMtACaWTXnygA1e0-YzP7YXWrGHuzM-ixLuf17EsMduym%2Bg@mail.gmail.com> In-Reply-To: <CAK7dMtAYb1846-s6sVhLYe_UMjqZLTcUwc6ZVeZVbpEEj1dqtQ@mail.gmail.com> References: <202308112251.37BMpOnC064624@gitrepo.freebsd.org> <CAK7dMtAYb1846-s6sVhLYe_UMjqZLTcUwc6ZVeZVbpEEj1dqtQ@mail.gmail.com>
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I think this may be a better fix, currently untested
diff --git a/sys/net/if_vlan.c b/sys/net/if_vlan.c
index 6aa872a19364..51f0bc63ebda 100644
--- a/sys/net/if_vlan.c
+++ b/sys/net/if_vlan.c
@@ -2074,7 +2074,7 @@ vlan_capabilities(struct ifvlan *ifv)
if (p->if_capabilities & IFCAP_VLAN_HWCSUM)
cap |=3D p->if_capabilities & IFCAP_LRO;
if (p->if_capenable & IFCAP_VLAN_HWCSUM)
- ena |=3D p->if_capenable & IFCAP_LRO;
+ ena |=3D mena & IFCAP_LRO;
/*
* If the parent interface can offload TCP connections over VLANs th=
en
On Fri, Aug 11, 2023 at 5:07=E2=80=AFPM Kevin Bowling <kevin.bowling@kev009=
.com> wrote:
>
> I am wondering what is going on with this patch, it doesn't seem like
> a full fix. At the very least we should clean up the "can't disable
> some capabilities" message.
>
> I've been looking at this for a couple hours and am wondering what is
> going on in if_bridge.. it looks like it correctly loops over the
> interfaces and masks ifcaps it doesn't like using the interface's
> ioctl SIOCSIFCAP. A similar pattern is used in if_lagg. I don't see
> any issue there so far. I also don't see the SIOCSICAP ioctl failing
> nor did vixie's message report that.
>
> I checked on a cxgbe(9) bridged vlan setup I have and see this message
> "bridge0: can't disable some capabilities on vlan0: 0x400"
>
> So I am wondering if the bug is that if_vlan SIOCSIFCAP is
> disregarding the ioctl's request mask.. it is just blindly calling
> vlan_capabilities.
>
> Regards,
> Kevin
>
>
> On Fri, Aug 11, 2023 at 3:51=E2=80=AFPM Kristof Provost <kp@freebsd.org> =
wrote:
> >
> > The branch main has been updated by kp:
> >
> > URL: https://cgit.FreeBSD.org/src/commit/?id=3D5f11a33ceeb385477cb22d9a=
d5941061c5a26be9
> >
> > commit 5f11a33ceeb385477cb22d9ad5941061c5a26be9
> > Author: Paul Vixie <paul@redbarn.org>
> > AuthorDate: 2023-08-11 18:17:16 +0000
> > Commit: Kristof Provost <kp@FreeBSD.org>
> > CommitDate: 2023-08-11 22:50:37 +0000
> >
> > if_vlan: do not enable LRO for bridge interaces
> >
> > If the parent interface is not a bridge and can do LRO and
> > checksum offloading on VLANs, then guess it may do LRO on VLANs.
> > False positive here cost nothing, while false negative may lead
> > to some confusions. According to Wikipedia:
> >
> > "LRO should not operate on machines acting as routers, as it breaks
> > the end-to-end principle and can significantly impact performance."
> >
> > The same reasoning applies to machines acting as bridges.
> >
> > PR: 254596
> > MFC after: 3 weeks
> > ---
> > sys/net/if_vlan.c | 22 +++++++++++++++-------
> > 1 file changed, 15 insertions(+), 7 deletions(-)
> >
> > diff --git a/sys/net/if_vlan.c b/sys/net/if_vlan.c
> > index 6aa872a19364..92e4e4247e3d 100644
> > --- a/sys/net/if_vlan.c
> > +++ b/sys/net/if_vlan.c
> > @@ -2067,14 +2067,22 @@ vlan_capabilities(struct ifvlan *ifv)
> > }
> >
> > /*
> > - * If the parent interface can do LRO and checksum offloading o=
n
> > - * VLANs, then guess it may do LRO on VLANs. False positive he=
re
> > - * cost nothing, while false negative may lead to some confusio=
ns.
> > + * If the parent interface is not a bridge and can do LRO and
> > + * checksum offloading on VLANs, then guess it may do LRO on VLA=
Ns.
> > + * False positive here cost nothing, while false negative may le=
ad
> > + * to some confusions. According to Wikipedia:
> > + *
> > + * "LRO should not operate on machines acting as routers, as it =
breaks
> > + * the end-to-end principle and can significantly impact perform=
ance."
> > + *
> > + * The same reasoning applies to machines acting as bridges.
> > */
> > - if (p->if_capabilities & IFCAP_VLAN_HWCSUM)
> > - cap |=3D p->if_capabilities & IFCAP_LRO;
> > - if (p->if_capenable & IFCAP_VLAN_HWCSUM)
> > - ena |=3D p->if_capenable & IFCAP_LRO;
> > + if (ifp->if_bridge =3D=3D NULL) {
> > + if (p->if_capabilities & IFCAP_VLAN_HWCSUM)
> > + cap |=3D p->if_capabilities & IFCAP_LRO;
> > + if (p->if_capenable & IFCAP_VLAN_HWCSUM)
> > + ena |=3D p->if_capenable & IFCAP_LRO;
> > + }
> >
> > /*
> > * If the parent interface can offload TCP connections over VLA=
Ns then
> >
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