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| author |   Eric Dumazet <eric.dumazet@gmail.com> | 2012-04-11 23:05:28 +0000 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2012-04-13 13:39:37 -0400 |
| commit | 447167bf565a474ff0cfb0f41d54936937479e97 (patch) | |
| tree | 38b03cb4e23bec19939545575e36f7395c5b156e /net/ipv4/udp.c | |
| parent | net: WIZnet drivers: fix possible NULL dereference (diff) | |
| download | linux-dev-447167bf565a474ff0cfb0f41d54936937479e97.tar.xz linux-dev-447167bf565a474ff0cfb0f41d54936937479e97.zip | |
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>
Diffstat (limited to 'net/ipv4/udp.c')
| -rw-r--r-- | net/ipv4/udp.c | 12 |
1 files changed, 11 insertions, 1 deletions
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; |