Date: Fri, 11 Aug 2023 22:51:24 GMT From: Kristof Provost <kp@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 5f11a33ceeb3 - main - if_vlan: do not enable LRO for bridge interaces Message-ID: <202308112251.37BMpOnC064624@gitrepo.freebsd.org>
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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
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