udp: inuse checks can quit early for reuseport

UDP lib inuse checks will walk the entire hash bucket to check if the
portaddr is in use. In the case of reuseport we can stop searching when
we find a matching reuseport.

On a 16-core VM a test program that spawns 16 threads that each bind to
1024 sockets (one per 10ms) takes 1m45s. With this change it takes 11s.

Also add a cond_resched() when the port is not specified.

Signed-off-by: Eric Garver <e@erig.me>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 1307a7c2e5445d37d1d1c4f5fbfd5bf7c29040d7..4318d72e0248ddf0f1ce5990fb3df60471088dc0 100644 (file)
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -153,13 +153,18 @@ static int udp_lib_lport_inuse(struct net *net, __u16 num,
                    (!sk2->sk_reuse || !sk->sk_reuse) &&
                    (!sk2->sk_bound_dev_if || !sk->sk_bound_dev_if ||
                     sk2->sk_bound_dev_if == sk->sk_bound_dev_if) &&
-                   (!sk2->sk_reuseport || !sk->sk_reuseport ||
-                    rcu_access_pointer(sk->sk_reuseport_cb) ||
-                    !uid_eq(uid, sock_i_uid(sk2))) &&
                    saddr_comp(sk, sk2, true)) {
-                       if (!bitmap)
-                               return 1;
-                       __set_bit(udp_sk(sk2)->udp_port_hash >> log, bitmap);
+                       if (sk2->sk_reuseport && sk->sk_reuseport &&
+                           !rcu_access_pointer(sk->sk_reuseport_cb) &&
+                           uid_eq(uid, sock_i_uid(sk2))) {
+                               if (!bitmap)
+                                       return 0;
+                       } else {
+                               if (!bitmap)
+                                       return 1;
+                               __set_bit(udp_sk(sk2)->udp_port_hash >> log,
+                                         bitmap);
+                       }
                }
        }
        return 0;
@@ -188,11 +193,14 @@ static int udp_lib_lport_inuse2(struct net *net, __u16 num,
                    (!sk2->sk_reuse || !sk->sk_reuse) &&
                    (!sk2->sk_bound_dev_if || !sk->sk_bound_dev_if ||
                     sk2->sk_bound_dev_if == sk->sk_bound_dev_if) &&
-                   (!sk2->sk_reuseport || !sk->sk_reuseport ||
-                    rcu_access_pointer(sk->sk_reuseport_cb) ||
-                    !uid_eq(uid, sock_i_uid(sk2))) &&
                    saddr_comp(sk, sk2, true)) {
-                       res = 1;
+                       if (sk2->sk_reuseport && sk->sk_reuseport &&
+                           !rcu_access_pointer(sk->sk_reuseport_cb) &&
+                           uid_eq(uid, sock_i_uid(sk2))) {
+                               res = 0;
+                       } else {
+                               res = 1;
+                       }
                        break;
                }
        }
@@ -285,6 +293,7 @@ int udp_lib_get_port(struct sock *sk, unsigned short snum,
                                snum += rand;
                        } while (snum != first);
                        spin_unlock_bh(&hslot->lock);
+                       cond_resched();
                } while (++first != last);
                goto fail;
        } else {