Date: Sat, 12 Aug 2023 10:45:35 +0200 From: Kristof Provost <kp@FreeBSD.org> To: Kevin Bowling <kevin.bowling@kev009.com> 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: <F71B697E-9D8C-4518-A730-6794EAFD6495@FreeBSD.org> In-Reply-To: <CAK7dMtACaWTXnygA1e0-YzP7YXWrGHuzM-ixLuf17EsMduym%2Bg@mail.gmail.com> References: <202308112251.37BMpOnC064624@gitrepo.freebsd.org> <CAK7dMtAYb1846-s6sVhLYe_UMjqZLTcUwc6ZVeZVbpEEj1dqtQ@mail.gmail.com> <CAK7dMtACaWTXnygA1e0-YzP7YXWrGHuzM-ixLuf17EsMduym%2Bg@mail.gmail.com>
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I also don=E2=80=99t have a setup to reproduce the issues Paul reported. Given the discussion in the PR I assumed everyone was happy with the fix = he posted. Best regards, Kristof On 12 Aug 2023, at 3:28, Kevin Bowling wrote: > 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 VLAN= s then > > On Fri, Aug 11, 2023 at 5:07=E2=80=AFPM Kevin Bowling <kevin.bowling@ke= v009.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.or= g> wrote: >>> >>> The branch main has been updated by kp: >>> >>> URL: https://cgit.FreeBSD.org/src/commit/?id=3D5f11a33ceeb385477cb22d= 9ad5941061c5a26be9 >>> >>> 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 brea= ks >>> the end-to-end principle and can significantly impact performance= =2E" >>> >>> 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= on >>> - * VLANs, then guess it may do LRO on VLANs. False positive = here >>> - * cost nothing, while false negative may lead to some confus= ions. >>> + * If the parent interface is not a bridge and can do LRO and >>> + * checksum offloading on VLANs, then guess it may do LRO on V= LANs. >>> + * 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 i= t breaks >>> + * the end-to-end principle and can significantly impact perfo= rmance." >>> + * >>> + * 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 V= LANs then >>>
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