From a0ca153f98db8cf25298565a09e11fe9d82846ad Mon Sep 17 00:00:00 2001 From: Alexander Duyck Date: Tue, 5 Apr 2016 09:13:39 -0700 Subject: [PATCH] GRE: Disable segmentation offloads w/ CSUM and we are encapsulated via FOU This patch fixes an issue I found in which we were dropping frames if we had enabled checksums on GRE headers that were encapsulated by either FOU or GUE. Without this patch I was barely able to get 1 Gb/s of throughput. With this patch applied I am now at least getting around 6 Gb/s. The issue is due to the fact that with FOU or GUE applied we do not provide a transport offset pointing to the GRE header, nor do we offload it in software as the GRE header is completely skipped by GSO and treated like a VXLAN or GENEVE type header. As such we need to prevent the stack from generating it and also prevent GRE from generating it via any interface we create. Fixes: c3483384ee511 ("gro: Allow tunnel stacking in the case of FOU/GUE") Signed-off-by: Alexander Duyck Signed-off-by: David S. Miller --- include/linux/netdevice.h | 5 ++++- net/core/dev.c | 1 + net/ipv4/fou.c | 6 ++++++ net/ipv4/gre_offload.c | 8 ++++++++ net/ipv4/ip_gre.c | 13 ++++++++++--- 5 files changed, 29 insertions(+), 4 deletions(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index cb0d5d09c2e4..8395308a2445 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -2120,7 +2120,10 @@ struct napi_gro_cb { /* Used in foo-over-udp, set in udp[46]_gro_receive */ u8 is_ipv6:1; - /* 7 bit hole */ + /* Used in GRE, set in fou/gue_gro_receive */ + u8 is_fou:1; + + /* 6 bit hole */ /* used to support CHECKSUM_COMPLETE for tunneling protocols */ __wsum csum; diff --git a/net/core/dev.c b/net/core/dev.c index b9bcbe77d913..77a71cd68535 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4439,6 +4439,7 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff NAPI_GRO_CB(skb)->flush = 0; NAPI_GRO_CB(skb)->free = 0; NAPI_GRO_CB(skb)->encap_mark = 0; + NAPI_GRO_CB(skb)->is_fou = 0; NAPI_GRO_CB(skb)->gro_remcsum_start = 0; /* Setup for GRO checksum validation */ diff --git a/net/ipv4/fou.c b/net/ipv4/fou.c index 5a94aea280d3..a39068b4a4d9 100644 --- a/net/ipv4/fou.c +++ b/net/ipv4/fou.c @@ -203,6 +203,9 @@ static struct sk_buff **fou_gro_receive(struct sk_buff **head, */ NAPI_GRO_CB(skb)->encap_mark = 0; + /* Flag this frame as already having an outer encap header */ + NAPI_GRO_CB(skb)->is_fou = 1; + rcu_read_lock(); offloads = NAPI_GRO_CB(skb)->is_ipv6 ? inet6_offloads : inet_offloads; ops = rcu_dereference(offloads[proto]); @@ -368,6 +371,9 @@ static struct sk_buff **gue_gro_receive(struct sk_buff **head, */ NAPI_GRO_CB(skb)->encap_mark = 0; + /* Flag this frame as already having an outer encap header */ + NAPI_GRO_CB(skb)->is_fou = 1; + rcu_read_lock(); offloads = NAPI_GRO_CB(skb)->is_ipv6 ? inet6_offloads : inet_offloads; ops = rcu_dereference(offloads[guehdr->proto_ctype]); diff --git a/net/ipv4/gre_offload.c b/net/ipv4/gre_offload.c index c47539d04b88..6a5bd4317866 100644 --- a/net/ipv4/gre_offload.c +++ b/net/ipv4/gre_offload.c @@ -150,6 +150,14 @@ static struct sk_buff **gre_gro_receive(struct sk_buff **head, if ((greh->flags & ~(GRE_KEY|GRE_CSUM)) != 0) goto out; + /* We can only support GRE_CSUM if we can track the location of + * the GRE header. In the case of FOU/GUE we cannot because the + * outer UDP header displaces the GRE header leaving us in a state + * of limbo. + */ + if ((greh->flags & GRE_CSUM) && NAPI_GRO_CB(skb)->is_fou) + goto out; + type = greh->protocol; rcu_read_lock(); diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c index 31936d387cfd..af5d1f38217f 100644 --- a/net/ipv4/ip_gre.c +++ b/net/ipv4/ip_gre.c @@ -862,9 +862,16 @@ static void __gre_tunnel_init(struct net_device *dev) dev->hw_features |= GRE_FEATURES; if (!(tunnel->parms.o_flags & TUNNEL_SEQ)) { - /* TCP offload with GRE SEQ is not supported. */ - dev->features |= NETIF_F_GSO_SOFTWARE; - dev->hw_features |= NETIF_F_GSO_SOFTWARE; + /* TCP offload with GRE SEQ is not supported, nor + * can we support 2 levels of outer headers requiring + * an update. + */ + if (!(tunnel->parms.o_flags & TUNNEL_CSUM) || + (tunnel->encap.type == TUNNEL_ENCAP_NONE)) { + dev->features |= NETIF_F_GSO_SOFTWARE; + dev->hw_features |= NETIF_F_GSO_SOFTWARE; + } + /* Can use a lockless transmit, unless we generate * output sequences */ -- 2.30.2