soreuseport: fast reuseport UDP socket selection

Include a struct sock_reuseport instance when a UDP socket binds to
a specific address for the first time with the reuseport flag set.
When selecting a socket for an incoming UDP packet, use the information
available in sock_reuseport if present.

This required adding an additional field to the UDP source address
equality function to differentiate between exact and wildcard matches.
The original use case allowed wildcard matches when checking for
existing port uses during bind.  The new use case of adding a socket
to a reuseport group requires exact address matching.

Performance test (using a machine with 2 CPU sockets and a total of
48 cores):  Create reuseport groups of varying size.  Use one socket
from this group per user thread (pinning each thread to a different
core) calling recvmmsg in a tight loop.  Record number of messages
received per second while saturating a 10G link.
  10 sockets: 18% increase (~2.8M -> 3.3M pkts/s)
  20 sockets: 14% increase (~2.9M -> 3.3M pkts/s)
  40 sockets: 13% increase (~3.0M -> 3.4M pkts/s)

This work is based off a similar implementation written by
Ying Cai <ycai@google.com> for implementing policy-based reuseport
selection.

Signed-off-by: Craig Gallek <kraig@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 39 insertions, 9 deletions

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 00775ee..6204b89 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -47,6 +47,7 @@
 #include <net/xfrm.h>
 #include <net/inet6_hashtables.h>
 #include <net/busy_poll.h>
+#include <net/sock_reuseport.h>
 
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
@@ -76,7 +77,14 @@ static u32 udp6_ehashfn(const struct net *net,
 			       udp_ipv6_hash_secret + net_hash_mix(net));
 }
 
-int ipv6_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2)
+/* match_wildcard == true:  IPV6_ADDR_ANY equals to any IPv6 addresses if IPv6
+ *                          only, and any IPv4 addresses if not IPv6 only
+ * match_wildcard == false: addresses must be exactly the same, i.e.
+ *                          IPV6_ADDR_ANY only equals to IPV6_ADDR_ANY,
+ *                          and 0.0.0.0 equals to 0.0.0.0 only
+ */
+int ipv6_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2,
+			 bool match_wildcard)
 {
 	const struct in6_addr *sk2_rcv_saddr6 = inet6_rcv_saddr(sk2);
 	int sk2_ipv6only = inet_v6_ipv6only(sk2);
@@ -84,16 +92,24 @@ int ipv6_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2)
 	int addr_type2 = sk2_rcv_saddr6 ? ipv6_addr_type(sk2_rcv_saddr6) : IPV6_ADDR_MAPPED;
 
 	/* if both are mapped, treat as IPv4 */
-	if (addr_type == IPV6_ADDR_MAPPED && addr_type2 == IPV6_ADDR_MAPPED)
-		return (!sk2_ipv6only &&
-			(!sk->sk_rcv_saddr || !sk2->sk_rcv_saddr ||
-			  sk->sk_rcv_saddr == sk2->sk_rcv_saddr));
+	if (addr_type == IPV6_ADDR_MAPPED && addr_type2 == IPV6_ADDR_MAPPED) {
+		if (!sk2_ipv6only) {
+			if (sk->sk_rcv_saddr == sk2->sk_rcv_saddr)
+				return 1;
+			if (!sk->sk_rcv_saddr || !sk2->sk_rcv_saddr)
+				return match_wildcard;
+		}
+		return 0;
+	}
+
+	if (addr_type == IPV6_ADDR_ANY && addr_type2 == IPV6_ADDR_ANY)
+		return 1;
 
-	if (addr_type2 == IPV6_ADDR_ANY &&
+	if (addr_type2 == IPV6_ADDR_ANY && match_wildcard &&
 	    !(sk2_ipv6only && addr_type == IPV6_ADDR_MAPPED))
 		return 1;
 
-	if (addr_type == IPV6_ADDR_ANY &&
+	if (addr_type == IPV6_ADDR_ANY && match_wildcard &&
 	    !(ipv6_only_sock(sk) && addr_type2 == IPV6_ADDR_MAPPED))
 		return 1;
 
@@ -253,8 +269,14 @@ begin:
 			badness = score;
 			reuseport = sk->sk_reuseport;
 			if (reuseport) {
+				struct sock *sk2;
 				hash = udp6_ehashfn(net, daddr, hnum,
 						    saddr, sport);
+				sk2 = reuseport_select_sock(sk, hash);
+				if (sk2) {
+					result = sk2;
+					goto found;
+				}
 				matches = 1;
 			}
 		} else if (score == badness && reuseport) {
@@ -273,6 +295,7 @@ begin:
 		goto begin;
 
 	if (result) {
+found:
 		if (unlikely(!atomic_inc_not_zero_hint(&result->sk_refcnt, 2)))
 			result = NULL;
 		else if (unlikely(compute_score2(result, net, saddr, sport,
@@ -332,8 +355,14 @@ begin:
 			badness = score;
 			reuseport = sk->sk_reuseport;
 			if (reuseport) {
+				struct sock *sk2;
 				hash = udp6_ehashfn(net, daddr, hnum,
 						    saddr, sport);
+				sk2 = reuseport_select_sock(sk, hash);
+				if (sk2) {
+					result = sk2;
+					goto found;
+				}
 				matches = 1;
 			}
 		} else if (score == badness && reuseport) {
@@ -352,6 +381,7 @@ begin:
 		goto begin;
 
 	if (result) {
+found:
 		if (unlikely(!atomic_inc_not_zero_hint(&result->sk_refcnt, 2)))
 			result = NULL;
 		else if (unlikely(compute_score(result, net, hnum, saddr, sport,
@@ -549,8 +579,8 @@ void __udp6_lib_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 	int err;
 	struct net *net = dev_net(skb->dev);
 
-	sk = __udp6_lib_lookup(net, daddr, uh->dest,
-			       saddr, uh->source, inet6_iif(skb), udptable);
+	sk = __udp6_lib_lookup(net, daddr, uh->dest, saddr, uh->source,
+			       inet6_iif(skb), udptable);
 	if (!sk) {
 		ICMP6_INC_STATS_BH(net, __in6_dev_get(skb->dev),
 				   ICMP6_MIB_INERRORS);