On Fri, Feb 03, 2006 at 10:01:17AM -0800, Stephen Hemminger wrote:
>
> static unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len)
> {
> if (unlikely(len > skb->len))
> return NULL;
> if (skb->ip_summed == CHECKSUM_HW)
> skb->csum = csum_sub(skb->csum, csum_partial(skb->data, len,
> 0));
> return __skb_pull(skb, len);
> }
Thanks Stephen. I've changed most of the places that call
skb_postpull_rcsum over to use this instead. The only places
left are IPv6 where it makes sense to separate the checksum
update since it wants to pull in bits and pieces and update
at the very end. The other place is GRE which is in fact
buggy with respect to the pulling (the bug was introduced
with the WCCP patch). I'll send a separate patch for that.
[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 <[EMAIL PROTECTED]>
Cheers
--
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <[EMAIL PROTECTED]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
diff --git a/drivers/net/ppp_generic.c b/drivers/net/ppp_generic.c
--- a/drivers/net/ppp_generic.c
+++ b/drivers/net/ppp_generic.c
@@ -1691,8 +1691,8 @@ ppp_receive_nonmp_frame(struct ppp *ppp,
|| 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;
diff --git a/drivers/net/pppoe.c b/drivers/net/pppoe.c
--- a/drivers/net/pppoe.c
+++ b/drivers/net/pppoe.c
@@ -337,8 +337,7 @@ static int pppoe_rcv_core(struct sock *s
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;
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1174,12 +1174,14 @@ static inline int skb_linearize(struct s
*/
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
diff --git a/net/802/psnap.c b/net/802/psnap.c
--- a/net/802/psnap.c
+++ b/net/802/psnap.c
@@ -61,8 +61,7 @@ static int snap_rcv(struct sk_buff *skb,
/* 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;
diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
--- a/net/8021q/vlan_dev.c
+++ b/net/8021q/vlan_dev.c
@@ -163,10 +163,8 @@ int vlan_skb_recv(struct sk_buff *skb, s
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.
diff --git a/net/bridge/br_netfilter.c b/net/bridge/br_netfilter.c
--- a/net/bridge/br_netfilter.c
+++ b/net/bridge/br_netfilter.c
@@ -414,8 +414,7 @@ static unsigned int br_nf_pre_routing(un
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);
@@ -433,8 +432,7 @@ static unsigned int br_nf_pre_routing(un
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;
}
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -1781,6 +1781,27 @@ int skb_append_datato_frags(struct sock
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",
