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gro: Avoid unnecessary comparison after skb_gro_header

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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 <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Herbert Xu 2009-05-26 18:50:28 +00:00 committed by David S. Miller
parent 7489594cb2
commit a5b1cf288d
5 changed files with 63 additions and 27 deletions
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25
include/linux/netdevice.h
View File

@ -1132,20 +1132,25 @@ 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);
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;
}
return NAPI_GRO_CB(skb)->frag0 + offset;
}
static inline int skb_gro_header_hard(struct sk_buff *skb, unsigned int hlen)
{
return NAPI_GRO_CB(skb)->frag0_len < hlen;
}
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)
{
return NAPI_GRO_CB(skb)->frag0 ?: skb_mac_header(skb);

17
net/core/dev.c
View File

@ -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));

13
net/ipv4/af_inet.c
View File

@ -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);

22
net/ipv4/tcp.c
View File

@ -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);

13
net/ipv6/af_inet6.c
View File

@ -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));