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[NET]: Replace skb_pull/skb_postpull_rcsum with skb_pull_rcsum 

We're now starting to have quite a number of places that do skb_pull
followed immediately by an skb_postpull_rcsum.  We can merge these two
operations into one function with skb_pull_rcsum.  This makes sense
since most pull operations on receive skb's need to update the
checksum.

I've decided to make this out-of-line since it is fairly big and the
fast path where hardware checksums are enabled need to call
csum_partial anyway.

Since this is a brand new function we get to add an extra check on the
len argument.  As it is most callers of skb_pull ignore its return
value which essentially means that there is no check on the len
argument.

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 2006-03-20 22:43:56 -08:00 committed by David S. Miller
parent ecba320f2e
commit cbb042f9e1
7 changed files with 32 additions and 15 deletions
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4
drivers/net/ppp_generic.c
View File

@ -1691,8 +1691,8 @@ ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
|| ppp->npmode[npi] != NPMODE_PASS) {
kfree_skb(skb);
} else {
skb_pull(skb, 2); /* chop off protocol */
skb_postpull_rcsum(skb, skb->data - 2, 2);
/* chop off protocol */
skb_pull_rcsum(skb, 2);
skb->dev = ppp->dev;
skb->protocol = htons(npindex_to_ethertype[npi]);
skb->mac.raw = skb->data;

3
drivers/net/pppoe.c
View File

@ -337,8 +337,7 @@ static int pppoe_rcv_core(struct sock *sk, struct sk_buff *skb)
if (sk->sk_state & PPPOX_BOUND) {
struct pppoe_hdr *ph = (struct pppoe_hdr *) skb->nh.raw;
int len = ntohs(ph->length);
skb_pull(skb, sizeof(struct pppoe_hdr));
skb_postpull_rcsum(skb, ph, sizeof(*ph));
skb_pull_rcsum(skb, sizeof(struct pppoe_hdr));
if (pskb_trim_rcsum(skb, len))
goto abort_kfree;

4
include/linux/skbuff.h
View File

@ -1159,12 +1159,14 @@ static inline int skb_linearize(struct sk_buff *skb, gfp_t gfp)
*/
static inline void skb_postpull_rcsum(struct sk_buff *skb,
const void *start, int len)
const void *start, unsigned int len)
{
if (skb->ip_summed == CHECKSUM_HW)
skb->csum = csum_sub(skb->csum, csum_partial(start, len, 0));
}
unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len);
/**
* pskb_trim_rcsum - trim received skb and update checksum
* @skb: buffer to trim

3
net/802/psnap.c
View File

@ -61,8 +61,7 @@ static int snap_rcv(struct sk_buff *skb, struct net_device *dev,
/* Pass the frame on. */
u8 *hdr = skb->data;
skb->h.raw += 5;
skb_pull(skb, 5);
skb_postpull_rcsum(skb, hdr, 5);
skb_pull_rcsum(skb, 5);
rc = proto->rcvfunc(skb, dev, &snap_packet_type, orig_dev);
} else {
skb->sk = NULL;

6
net/8021q/vlan_dev.c
View File

@ -163,10 +163,8 @@ int vlan_skb_recv(struct sk_buff *skb, struct net_device *dev,
stats->rx_packets++;
stats->rx_bytes += skb->len;
skb_pull(skb, VLAN_HLEN); /* take off the VLAN header (4 bytes currently) */
/* Need to correct hardware checksum */
skb_postpull_rcsum(skb, vhdr, VLAN_HLEN);
/* Take off the VLAN header (4 bytes currently) */
skb_pull_rcsum(skb, VLAN_HLEN);
/* Ok, lets check to make sure the device (dev) we
* came in on is what this VLAN is attached to.

6
net/bridge/br_netfilter.c
View File

@ -425,8 +425,7 @@ static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff **pskb,
if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
u8 *vhdr = skb->data;
skb_pull(skb, VLAN_HLEN);
skb_postpull_rcsum(skb, vhdr, VLAN_HLEN);
skb_pull_rcsum(skb, VLAN_HLEN);
skb->nh.raw += VLAN_HLEN;
}
return br_nf_pre_routing_ipv6(hook, skb, in, out, okfn);
@ -444,8 +443,7 @@ static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff **pskb,
if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
u8 *vhdr = skb->data;
skb_pull(skb, VLAN_HLEN);
skb_postpull_rcsum(skb, vhdr, VLAN_HLEN);
skb_pull_rcsum(skb, VLAN_HLEN);
skb->nh.raw += VLAN_HLEN;
}

21
net/core/skbuff.c
View File

@ -1795,6 +1795,27 @@ int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
return 0;
}
/**
* skb_pull_rcsum - pull skb and update receive checksum
* @skb: buffer to update
* @start: start of data before pull
* @len: length of data pulled
*
* This function performs an skb_pull on the packet and updates
* update the CHECKSUM_HW checksum. It should be used on receive
* path processing instead of skb_pull unless you know that the
* checksum difference is zero (e.g., a valid IP header) or you
* are setting ip_summed to CHECKSUM_NONE.
*/
unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len)
{
BUG_ON(len > skb->len);
skb->len -= len;
BUG_ON(skb->len < skb->data_len);
skb_postpull_rcsum(skb, skb->data, len);
return skb->data += len;
}
void __init skb_init(void)
{
skbuff_head_cache = kmem_cache_create("skbuff_head_cache",