udp: Extract helper for selecting socket from reuseport group

Prepare for calling into reuseport from __udp4_lib_lookup as well.

Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200717103536.397595-8-jakub@cloudflare.com

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 073d346..9296fae 100644 (file)
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -408,6 +408,25 @@ static u32 udp_ehashfn(const struct net *net, const __be32 laddr,
                              udp_ehash_secret + net_hash_mix(net));
 }
 
+static inline struct sock *lookup_reuseport(struct net *net, struct sock *sk,
+                                           struct sk_buff *skb,
+                                           __be32 saddr, __be16 sport,
+                                           __be32 daddr, unsigned short hnum)
+{
+       struct sock *reuse_sk = NULL;
+       u32 hash;
+
+       if (sk->sk_reuseport && sk->sk_state != TCP_ESTABLISHED) {
+               hash = udp_ehashfn(net, daddr, hnum, saddr, sport);
+               reuse_sk = reuseport_select_sock(sk, hash, skb,
+                                                sizeof(struct udphdr));
+               /* Fall back to scoring if group has connections */
+               if (reuseport_has_conns(sk, false))
+                       return NULL;
+       }
+       return reuse_sk;
+}
+
 /* called with rcu_read_lock() */
 static struct sock *udp4_lib_lookup2(struct net *net,
                                     __be32 saddr, __be16 sport,
@@ -418,7 +437,6 @@ static struct sock *udp4_lib_lookup2(struct net *net,
 {
        struct sock *sk, *result;
        int score, badness;
-       u32 hash = 0;
 
        result = NULL;
        badness = 0;
@@ -426,15 +444,11 @@ static struct sock *udp4_lib_lookup2(struct net *net,
                score = compute_score(sk, net, saddr, sport,
                                      daddr, hnum, dif, sdif);
                if (score > badness) {
-                       if (sk->sk_reuseport &&
-                           sk->sk_state != TCP_ESTABLISHED) {
-                               hash = udp_ehashfn(net, daddr, hnum,
-                                                  saddr, sport);
-                               result = reuseport_select_sock(sk, hash, skb,
-                                                       sizeof(struct udphdr));
-                               if (result && !reuseport_has_conns(sk, false))
-                                       return result;
-                       }
+                       result = lookup_reuseport(net, sk, skb,
+                                                 saddr, sport, daddr, hnum);
+                       if (result)
+                               return result;
+
                        badness = score;
                        result = sk;
                }