[PATCH 4.2.y-ckt 37/53] net: use skb_postpush_rcsum instead of own implementations

From: Kamal Mostafa
Date: Tue May 24 2016 - 14:02:38 EST


4.2.8-ckt11 -stable review patch. If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Daniel Borkmann <daniel@xxxxxxxxxxxxx>

[ Upstream commit 6b83d28a55a891a9d70fc61ccb1c138e47dcbe74,
skb_postpush_rcsum() added from commit
f8ffad69c9f8b8dfb0b633425d4ef4d2493ba61a ]

Replace individual implementations with the recently introduced
skb_postpush_rcsum() helper.

Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Acked-by: Tom Herbert <tom@xxxxxxxxxxxxxxx>
Acked-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
include/linux/skbuff.h | 17 +++++++++++++++++
net/core/skbuff.c | 4 +---
net/ipv6/reassembly.c | 6 ++----
net/openvswitch/actions.c | 6 ++----
net/openvswitch/vport-netdev.c | 2 +-
net/openvswitch/vport.h | 7 -------
6 files changed, 23 insertions(+), 19 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 365a771..30616d5 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2633,6 +2633,23 @@ static inline void skb_postpull_rcsum(struct sk_buff *skb,

unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len);

+static inline void skb_postpush_rcsum(struct sk_buff *skb,
+ const void *start, unsigned int len)
+{
+ /* For performing the reverse operation to skb_postpull_rcsum(),
+ * we can instead of ...
+ *
+ * skb->csum = csum_add(skb->csum, csum_partial(start, len, 0));
+ *
+ * ... just use this equivalent version here to save a few
+ * instructions. Feeding csum of 0 in csum_partial() and later
+ * on adding skb->csum is equivalent to feed skb->csum in the
+ * first place.
+ */
+ if (skb->ip_summed == CHECKSUM_COMPLETE)
+ skb->csum = csum_partial(start, len, skb->csum);
+}
+
/**
* pskb_trim_rcsum - trim received skb and update checksum
* @skb: buffer to trim
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index ae0b23f..c412278 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -4415,9 +4415,7 @@ int skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci)
skb->mac_len += VLAN_HLEN;
__skb_pull(skb, offset);

- if (skb->ip_summed == CHECKSUM_COMPLETE)
- skb->csum = csum_add(skb->csum, csum_partial(skb->data
- + (2 * ETH_ALEN), VLAN_HLEN, 0));
+ skb_postpush_rcsum(skb, skb->data + (2 * ETH_ALEN), VLAN_HLEN);
}
__vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
return 0;
diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
index 45f5ae5..a234552 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -496,10 +496,8 @@ static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
IP6CB(head)->flags |= IP6SKB_FRAGMENTED;

/* Yes, and fold redundant checksum back. 8) */
- if (head->ip_summed == CHECKSUM_COMPLETE)
- head->csum = csum_partial(skb_network_header(head),
- skb_network_header_len(head),
- head->csum);
+ skb_postpush_rcsum(head, skb_network_header(head),
+ skb_network_header_len(head));

rcu_read_lock();
IP6_INC_STATS_BH(net, __in6_dev_get(dev), IPSTATS_MIB_REASMOKS);
diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index c97ddc8..791c261 100644
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -140,9 +140,7 @@ static int push_mpls(struct sk_buff *skb, struct sw_flow_key *key,
new_mpls_lse = (__be32 *)skb_mpls_header(skb);
*new_mpls_lse = mpls->mpls_lse;

- if (skb->ip_summed == CHECKSUM_COMPLETE)
- skb->csum = csum_add(skb->csum, csum_partial(new_mpls_lse,
- MPLS_HLEN, 0));
+ skb_postpush_rcsum(skb, new_mpls_lse, MPLS_HLEN);

hdr = eth_hdr(skb);
hdr->h_proto = mpls->mpls_ethertype;
@@ -266,7 +264,7 @@ static int set_eth_addr(struct sk_buff *skb, struct sw_flow_key *flow_key,
ether_addr_copy_masked(eth_hdr(skb)->h_dest, key->eth_dst,
mask->eth_dst);

- ovs_skb_postpush_rcsum(skb, eth_hdr(skb), ETH_ALEN * 2);
+ skb_postpush_rcsum(skb, eth_hdr(skb), ETH_ALEN * 2);

ether_addr_copy(flow_key->eth.src, eth_hdr(skb)->h_source);
ether_addr_copy(flow_key->eth.dst, eth_hdr(skb)->h_dest);
diff --git a/net/openvswitch/vport-netdev.c b/net/openvswitch/vport-netdev.c
index 33e6d6e..eece71d 100644
--- a/net/openvswitch/vport-netdev.c
+++ b/net/openvswitch/vport-netdev.c
@@ -52,7 +52,7 @@ static void netdev_port_receive(struct vport *vport, struct sk_buff *skb)
return;

skb_push(skb, ETH_HLEN);
- ovs_skb_postpush_rcsum(skb, skb->data, ETH_HLEN);
+ skb_postpush_rcsum(skb, skb->data, ETH_HLEN);

ovs_vport_receive(vport, skb, NULL);
return;
diff --git a/net/openvswitch/vport.h b/net/openvswitch/vport.h
index bc85331..cb4cd12 100644
--- a/net/openvswitch/vport.h
+++ b/net/openvswitch/vport.h
@@ -228,13 +228,6 @@ static inline struct vport *vport_from_priv(void *priv)
void ovs_vport_receive(struct vport *, struct sk_buff *,
const struct ovs_tunnel_info *);

-static inline void ovs_skb_postpush_rcsum(struct sk_buff *skb,
- const void *start, unsigned int len)
-{
- if (skb->ip_summed == CHECKSUM_COMPLETE)
- skb->csum = csum_add(skb->csum, csum_partial(start, len, 0));
-}
-
int ovs_vport_ops_register(struct vport_ops *ops);
void ovs_vport_ops_unregister(struct vport_ops *ops);

--
2.7.4