[PATCH 1/1] net-next: add dev_loopback_xmit() to avoid duplicate code

Michel Machado
2012-06-12T20:16:49Z

Add dev_loopback_xmit() in order to deduplicate functions
ip_dev_loopback_xmit() (in net/ipv4/ip_output.c) and
ip6_dev_loopback_xmit() (in net/ipv6/ip6_output.c).

I was about to reinvent the wheel when I noticed that
ip_dev_loopback_xmit() and ip6_dev_loopback_xmit() do exactly what I
need and are not IP-only functions, but they were not available to reuse
elsewhere.

ip6_dev_loopback_xmit() does not have line "skb_dst_force(skb);", but I
understand that this is harmless, and should be in dev_loopback_xmit().

Signed-off-by: Michel Machado <michel@digirati.com.br>
CC: "David S. Miller" <davem@davemloft.net>
CC: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
CC: James Morris <jmorris@namei.org>
CC: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
CC: Patrick McHardy <kaber@trash.net>
CC: Eric Dumazet <edumazet@google.com>
CC: Jiri Pirko <jpirko@redhat.com>
CC: "Michał Mirosław" <mirq-linux@rere.qmqm.pl>
CC: Ben Hutchings <bhutchings@solarflare.com>
---

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index e7fd468..1c49c21 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1626,6 +1626,7 @@ extern int dev_alloc_name(struct net_device *dev, const char *name);
extern int dev_open(struct net_device *dev);
extern int dev_close(struct net_device *dev);
extern void dev_disable_lro(struct net_device *dev);
+extern int dev_loopback_xmit(struct sk_buff *newskb);
extern int dev_queue_xmit(struct sk_buff *skb);
extern int register_netdevice(struct net_device *dev);
extern void unregister_netdevice_queue(struct net_device *dev,
diff --git a/net/core/dev.c b/net/core/dev.c
index cd09819..c6e29ea6 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2476,6 +2476,23 @@ static DEFINE_PER_CPU(int, xmit_recursion);
#define RECURSION_LIMIT 10

/**
+ * dev_loopback_xmit - loop back @skb
+ * @skb: buffer to transmit
+ */
+int dev_loopback_xmit(struct sk_buff *skb)
+{
+ skb_reset_mac_header(skb);
+ __skb_pull(skb, skb_network_offset(skb));
+ skb->pkt_type = PACKET_LOOPBACK;
+ skb->ip_summed = CHECKSUM_UNNECESSARY;
+ WARN_ON(!skb_dst(skb));
+ skb_dst_force(skb);
+ netif_rx_ni(skb);
+ return 0;
+}
+EXPORT_SYMBOL(dev_loopback_xmit);
+
+/**
* dev_queue_xmit - transmit a buffer
* @skb: buffer to transmit
*
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 451f97c..d34ddde 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -113,19 +113,6 @@ int ip_local_out(struct sk_buff *skb)
}
EXPORT_SYMBOL_GPL(ip_local_out);

-/* dev_loopback_xmit for use with netfilter. */
-static int ip_dev_loopback_xmit(struct sk_buff *newskb)
-{
- skb_reset_mac_header(newskb);
- __skb_pull(newskb, skb_network_offset(newskb));
- newskb->pkt_type = PACKET_LOOPBACK;
- newskb->ip_summed = CHECKSUM_UNNECESSARY;
- WARN_ON(!skb_dst(newskb));
- skb_dst_force(newskb);
- netif_rx_ni(newskb);
- return 0;
-}
-
static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst)
{
int ttl = inet->uc_ttl;
@@ -281,7 +268,7 @@ int ip_mc_output(struct sk_buff *skb)
if (newskb)
NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
newskb, NULL, newskb->dev,
- ip_dev_loopback_xmit);
+ dev_loopback_xmit);
}

/* Multicasts with ttl 0 must not go beyond the host */
@@ -296,7 +283,7 @@ int ip_mc_output(struct sk_buff *skb)
struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
if (newskb)
NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, newskb,
- NULL, newskb->dev, ip_dev_loopback_xmit);
+ NULL, newskb->dev, dev_loopback_xmit);
}

return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL,
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index d99fdc6..8443c00 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -83,19 +83,6 @@ int ip6_local_out(struct sk_buff *skb)
}
EXPORT_SYMBOL_GPL(ip6_local_out);

-/* dev_loopback_xmit for use with netfilter. */
-static int ip6_dev_loopback_xmit(struct sk_buff *newskb)
-{
- skb_reset_mac_header(newskb);
- __skb_pull(newskb, skb_network_offset(newskb));
- newskb->pkt_type = PACKET_LOOPBACK;
- newskb->ip_summed = CHECKSUM_UNNECESSARY;
- WARN_ON(!skb_dst(newskb));
-
- netif_rx_ni(newskb);
- return 0;
-}
-
static int ip6_finish_output2(struct sk_buff *skb)
{
struct dst_entry *dst = skb_dst(skb);
@@ -121,7 +108,7 @@ static int ip6_finish_output2(struct sk_buff *skb)
if (newskb)
NF_HOOK(NFPROTO_IPV6, NF_INET_POST_ROUTING,
newskb, NULL, newskb->dev,
- ip6_dev_loopback_xmit);
+ dev_loopback_xmit);

if (ipv6_hdr(skb)->hop_limit == 0) {
IP6_INC_STATS(dev_net(dev), idev,