From a5b1cf288d4200506ab62fbb86cc81ace948a306 Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Tue, 26 May 2009 18:50:28 +0000 Subject: [PATCH] gro: Avoid unnecessary comparison after skb_gro_header For the overwhelming majority of cases, skb_gro_header's return value cannot be NULL. Yet we must check it because of its current form. This patch splits it up into multiple functions in order to avoid this. Signed-off-by: Herbert Xu Signed-off-by: David S. Miller --- include/linux/netdevice.h | 23 ++++++++++++++--------- net/core/dev.c | 17 ++++++++++++----- net/ipv4/af_inet.c | 13 ++++++++++--- net/ipv4/tcp.c | 22 ++++++++++++++++------ net/ipv6/af_inet6.c | 13 ++++++++++--- 5 files changed, 62 insertions(+), 26 deletions(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 2e44a049be0f..371ece521e58 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -1132,18 +1132,23 @@ static inline void skb_gro_pull(struct sk_buff *skb, unsigned int len) NAPI_GRO_CB(skb)->data_offset += len; } -static inline void *skb_gro_header(struct sk_buff *skb, unsigned int hlen) +static inline void *skb_gro_header_fast(struct sk_buff *skb, + unsigned int offset) { - unsigned int offset = skb_gro_offset(skb); + return NAPI_GRO_CB(skb)->frag0 + offset; +} - hlen += offset; - if (NAPI_GRO_CB(skb)->frag0_len < hlen) { - NAPI_GRO_CB(skb)->frag0 = NULL; - NAPI_GRO_CB(skb)->frag0_len = 0; - return pskb_may_pull(skb, hlen) ? skb->data + offset : NULL; - } +static inline int skb_gro_header_hard(struct sk_buff *skb, unsigned int hlen) +{ + return NAPI_GRO_CB(skb)->frag0_len < hlen; +} - return NAPI_GRO_CB(skb)->frag0 + offset; +static inline void *skb_gro_header_slow(struct sk_buff *skb, unsigned int hlen, + unsigned int offset) +{ + NAPI_GRO_CB(skb)->frag0 = NULL; + NAPI_GRO_CB(skb)->frag0_len = 0; + return pskb_may_pull(skb, hlen) ? skb->data + offset : NULL; } static inline void *skb_gro_mac_header(struct sk_buff *skb) diff --git a/net/core/dev.c b/net/core/dev.c index b1722a2d1fbe..cd29e613bc5a 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -2590,17 +2590,24 @@ struct sk_buff *napi_frags_skb(struct napi_struct *napi) { struct sk_buff *skb = napi->skb; struct ethhdr *eth; + unsigned int hlen; + unsigned int off; napi->skb = NULL; skb_reset_mac_header(skb); skb_gro_reset_offset(skb); - eth = skb_gro_header(skb, sizeof(*eth)); - if (!eth) { - napi_reuse_skb(napi, skb); - skb = NULL; - goto out; + off = skb_gro_offset(skb); + hlen = off + sizeof(*eth); + eth = skb_gro_header_fast(skb, off); + if (skb_gro_header_hard(skb, hlen)) { + eth = skb_gro_header_slow(skb, hlen, off); + if (unlikely(!eth)) { + napi_reuse_skb(napi, skb); + skb = NULL; + goto out; + } } skb_gro_pull(skb, sizeof(*eth)); diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c index 170689681aa2..644cc5535319 100644 --- a/net/ipv4/af_inet.c +++ b/net/ipv4/af_inet.c @@ -1246,13 +1246,20 @@ static struct sk_buff **inet_gro_receive(struct sk_buff **head, struct sk_buff **pp = NULL; struct sk_buff *p; struct iphdr *iph; + unsigned int hlen; + unsigned int off; int flush = 1; int proto; int id; - iph = skb_gro_header(skb, sizeof(*iph)); - if (unlikely(!iph)) - goto out; + off = skb_gro_offset(skb); + hlen = off + sizeof(*iph); + iph = skb_gro_header_fast(skb, off); + if (skb_gro_header_hard(skb, hlen)) { + iph = skb_gro_header_slow(skb, hlen, off); + if (unlikely(!iph)) + goto out; + } proto = iph->protocol & (MAX_INET_PROTOS - 1); diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 68342d431896..c3dcec5efea5 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2518,20 +2518,30 @@ struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb) unsigned int thlen; unsigned int flags; unsigned int mss = 1; + unsigned int hlen; + unsigned int off; int flush = 1; int i; - th = skb_gro_header(skb, sizeof(*th)); - if (unlikely(!th)) - goto out; + off = skb_gro_offset(skb); + hlen = off + sizeof(*th); + th = skb_gro_header_fast(skb, off); + if (skb_gro_header_hard(skb, hlen)) { + th = skb_gro_header_slow(skb, hlen, off); + if (unlikely(!th)) + goto out; + } thlen = th->doff * 4; if (thlen < sizeof(*th)) goto out; - th = skb_gro_header(skb, thlen); - if (unlikely(!th)) - goto out; + hlen = off + thlen; + if (skb_gro_header_hard(skb, hlen)) { + th = skb_gro_header_slow(skb, hlen, off); + if (unlikely(!th)) + goto out; + } skb_gro_pull(skb, thlen); diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c index 61f55386a236..b6215be0963f 100644 --- a/net/ipv6/af_inet6.c +++ b/net/ipv6/af_inet6.c @@ -817,13 +817,20 @@ static struct sk_buff **ipv6_gro_receive(struct sk_buff **head, struct sk_buff *p; struct ipv6hdr *iph; unsigned int nlen; + unsigned int hlen; + unsigned int off; int flush = 1; int proto; __wsum csum; - iph = skb_gro_header(skb, sizeof(*iph)); - if (unlikely(!iph)) - goto out; + off = skb_gro_offset(skb); + hlen = off + sizeof(*iph); + iph = skb_gro_header_fast(skb, off); + if (skb_gro_header_hard(skb, hlen)) { + iph = skb_gro_header_slow(skb, hlen, off); + if (unlikely(!iph)) + goto out; + } skb_gro_pull(skb, sizeof(*iph)); skb_set_transport_header(skb, skb_gro_offset(skb)); -- 2.30.2