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udp: implement complete book-keeping for encap_needed

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The *encap_needed static keys are enabled by UDP tunnels
and several UDP encapsulations type, but they are never
turned off. This can cause unneeded overall performance
degradation for systems where such features are used
transiently.

This patch introduces complete book-keeping for such keys,
decreasing the usage at socket destruction time, if needed,
and avoiding that the same socket could increase the key
usage multiple times.

rfc v3 -> v1:
 - add socket lock around udp_tunnel_encap_enable()

rfc v2 -> rfc v3:
 - use udp_tunnel_encap_enable() in setsockopt()

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Paolo Abeni
2018-11-07 12:38:28 +01:00
committed by David S. Miller
parent 7e225619e8
commit 60fb9567bf
4 changed files with 34 additions and 12 deletions
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19
net/ipv4/udp.c
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@@ -115,6 +115,7 @@
#include "udp_impl.h"
#include <net/sock_reuseport.h>
#include <net/addrconf.h>
#include <net/udp_tunnel.h>
struct udp_table udp_table __read_mostly;
EXPORT_SYMBOL(udp_table);
@@ -2395,11 +2396,15 @@ void udp_destroy_sock(struct sock *sk)
bool slow = lock_sock_fast(sk);
udp_flush_pending_frames(sk);
unlock_sock_fast(sk, slow);
if (static_branch_unlikely(&udp_encap_needed_key) && up->encap_type) {
void (*encap_destroy)(struct sock *sk);
encap_destroy = READ_ONCE(up->encap_destroy);
if (encap_destroy)
encap_destroy(sk);
if (static_branch_unlikely(&udp_encap_needed_key)) {
if (up->encap_type) {
void (*encap_destroy)(struct sock *sk);
encap_destroy = READ_ONCE(up->encap_destroy);
if (encap_destroy)
encap_destroy(sk);
}
if (up->encap_enabled)
static_branch_disable(&udp_encap_needed_key);
}
}
@@ -2444,7 +2449,9 @@ int udp_lib_setsockopt(struct sock *sk, int level, int optname,
/* FALLTHROUGH */
case UDP_ENCAP_L2TPINUDP:
up->encap_type = val;
udp_encap_enable();
lock_sock(sk);
udp_tunnel_encap_enable(sk->sk_socket);
release_sock(sk);
break;
default:
err = -ENOPROTOOPT;