[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>
diff --git a/drivers/net/ppp_generic.c b/drivers/net/ppp_generic.c
index 0245e40..f608c12 100644
--- a/drivers/net/ppp_generic.c
+++ b/drivers/net/ppp_generic.c
@@ -1691,8 +1691,8 @@
|| 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
index 9369f81..475dc93 100644
--- a/drivers/net/pppoe.c
+++ b/drivers/net/pppoe.c
@@ -337,8 +337,7 @@
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
index 75c9631..613b951 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1159,12 +1159,14 @@
*/
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
index 34e4296..97c95ee 100644
--- a/net/802/psnap.c
+++ b/net/802/psnap.c
@@ -61,8 +61,7 @@
/* 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
index 0f604d22..da9cfe9 100644
--- a/net/8021q/vlan_dev.c
+++ b/net/8021q/vlan_dev.c
@@ -163,10 +163,8 @@
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
index e060aad..6787bc5 100644
--- a/net/bridge/br_netfilter.c
+++ b/net/bridge/br_netfilter.c
@@ -425,8 +425,7 @@
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 @@
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
index 01abf1e..2960c8b 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -1795,6 +1795,27 @@
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",
