Re: git: 5f11a33ceeb3 - main - if_vlan: do not enable LRO for bridge interaces
Date: Sat, 12 Aug 2023 08:45:35 UTC
I also don’t 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 |= p->if_capabilities & IFCAP_LRO; > if (p->if_capenable & IFCAP_VLAN_HWCSUM) > - ena |= p->if_capenable & IFCAP_LRO; > + ena |= mena & IFCAP_LRO; > > /* > * If the parent interface can offload TCP connections over VLANs then > > On Fri, Aug 11, 2023 at 5:07 PM 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 PM Kristof Provost <kp@freebsd.org> wrote: >>> >>> The branch main has been updated by kp: >>> >>> URL: https://cgit.FreeBSD.org/src/commit/?id=5f11a33ceeb385477cb22d9ad5941061c5a26be9 >>> >>> 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 on >>> - * VLANs, then guess it may do LRO on VLANs. False positive here >>> - * cost nothing, while false negative may lead to some confusions. >>> + * 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. >>> */ >>> - if (p->if_capabilities & IFCAP_VLAN_HWCSUM) >>> - cap |= p->if_capabilities & IFCAP_LRO; >>> - if (p->if_capenable & IFCAP_VLAN_HWCSUM) >>> - ena |= p->if_capenable & IFCAP_LRO; >>> + if (ifp->if_bridge == NULL) { >>> + if (p->if_capabilities & IFCAP_VLAN_HWCSUM) >>> + cap |= p->if_capabilities & IFCAP_LRO; >>> + if (p->if_capenable & IFCAP_VLAN_HWCSUM) >>> + ena |= p->if_capenable & IFCAP_LRO; >>> + } >>> >>> /* >>> * If the parent interface can offload TCP connections over VLANs then >>>