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authorEric Dumazet2012-04-11 23:05:28 +0000
committerDavid S. Miller2012-04-13 13:39:37 -0400
commit447167bf565a474ff0cfb0f41d54936937479e97 (patch)
tree38b03cb4e23bec19939545575e36f7395c5b156e
parent77577bf93275b485cecb4f358a085949c32e9dcd (diff)
udp: intoduce udp_encap_needed static_key
Most machines dont use UDP encapsulation (L2TP) Adds a static_key so that udp_queue_rcv_skb() doesnt have to perform a test if L2TP never setup the encap_rcv on a socket. Idea of this patch came after Simon Horman proposal to add a hook on TCP as well. If static_key is not yet enabled, the fast path does a single JMP . When static_key is enabled, JMP destination is patched to reach the real encap_type/encap_rcv logic, possibly adding cache misses. Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Cc: Simon Horman <horms@verge.net.au> Cc: dev@openvswitch.org Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--include/net/udp.h1
-rw-r--r--net/ipv4/udp.c12
-rw-r--r--net/l2tp/l2tp_core.c1
3 files changed, 13 insertions, 1 deletions
diff --git a/include/net/udp.h b/include/net/udp.h
index 5d606d9da9e5..9671f5f1df9c 100644
--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -267,4 +267,5 @@ extern void udp_init(void);
extern int udp4_ufo_send_check(struct sk_buff *skb);
extern struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
netdev_features_t features);
+extern void udp_encap_enable(void);
#endif /* _UDP_H */
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index fe141052a1be..ad1e0dd4da48 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -107,6 +107,7 @@
#include <net/checksum.h>
#include <net/xfrm.h>
#include <trace/events/udp.h>
+#include <linux/static_key.h>
#include "udp_impl.h"
struct udp_table udp_table __read_mostly;
@@ -1379,6 +1380,14 @@ static int __udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
}
+static struct static_key udp_encap_needed __read_mostly;
+void udp_encap_enable(void)
+{
+ if (!static_key_enabled(&udp_encap_needed))
+ static_key_slow_inc(&udp_encap_needed);
+}
+EXPORT_SYMBOL(udp_encap_enable);
+
/* returns:
* -1: error
* 0: success
@@ -1400,7 +1409,7 @@ int udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
goto drop;
nf_reset(skb);
- if (up->encap_type) {
+ if (static_key_false(&udp_encap_needed) && up->encap_type) {
int (*encap_rcv)(struct sock *sk, struct sk_buff *skb);
/*
@@ -1760,6 +1769,7 @@ int udp_lib_setsockopt(struct sock *sk, int level, int optname,
/* FALLTHROUGH */
case UDP_ENCAP_L2TPINUDP:
up->encap_type = val;
+ udp_encap_enable();
break;
default:
err = -ENOPROTOOPT;
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index 89ff8c67943e..f6732b6c758b 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -1424,6 +1424,7 @@ int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32
/* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
udp_sk(sk)->encap_type = UDP_ENCAP_L2TPINUDP;
udp_sk(sk)->encap_rcv = l2tp_udp_encap_recv;
+ udp_encap_enable();
}
sk->sk_user_data = tunnel;