From cbb042f9e1292434e3cacb90e67d8d381aeac5a9 Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Mon, 20 Mar 2006 22:43:56 -0800 Subject: [PATCH] [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 Signed-off-by: David S. Miller --- drivers/net/ppp_generic.c | 4 ++-- drivers/net/pppoe.c | 3 +-- include/linux/skbuff.h | 4 +++- net/802/psnap.c | 3 +-- net/8021q/vlan_dev.c | 6 ++---- net/bridge/br_netfilter.c | 6 ++---- net/core/skbuff.c | 21 +++++++++++++++++++++ 7 files changed, 32 insertions(+), 15 deletions(-) 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_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; 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 @@ 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; 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 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 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 @@ 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; diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c index 0f604d2..da9cfe9 100644 --- a/net/8021q/vlan_dev.c +++ b/net/8021q/vlan_dev.c @@ -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. 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 @@ 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; } 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 @@ 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", -- 2.7.4