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 <[email protected]> Cc: Simon Horman <[email protected]> Cc: [email protected] --- include/net/udp.h | 1 + net/ipv4/udp.c | 12 +++++++++++- net/l2tp/l2tp_core.c | 1 + 3 files changed, 13 insertions(+), 1 deletion(-) diff --git a/include/net/udp.h b/include/net/udp.h index 5d606d9..9671f5f 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 fe14105..ad1e0dd 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 89ff8c6..f6732b6 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; _______________________________________________ dev mailing list [email protected] http://openvswitch.org/mailman/listinfo/dev
