UBUNTU: Ubuntu-4.15.0-96.97

[mirror_ubuntu-bionic-kernel.git] / net / core / sock_reuseport.c

diff --git a/net/core/sock_reuseport.c b/net/core/sock_reuseport.c
index 5eeb1d20cc388732c1a58d5a5e13db3b872e7ddd..676092d7bd8129917b1931054f4bc7634f71d198 100644 (file)
--- a/net/core/sock_reuseport.c
+++ b/net/core/sock_reuseport.c
@@ -94,6 +94,16 @@ static struct sock_reuseport *reuseport_grow(struct sock_reuseport *reuse)
        return more_reuse;
 }
 
+static void reuseport_free_rcu(struct rcu_head *head)
+{
+       struct sock_reuseport *reuse;
+
+       reuse = container_of(head, struct sock_reuseport, rcu);
+       if (reuse->prog)
+               bpf_prog_destroy(reuse->prog);
+       kfree(reuse);
+}
+
 /**
  *  reuseport_add_sock - Add a socket to the reuseport group of another.
  *  @sk:  New socket to add to the group.
@@ -102,7 +112,7 @@ static struct sock_reuseport *reuseport_grow(struct sock_reuseport *reuse)
  */
 int reuseport_add_sock(struct sock *sk, struct sock *sk2)
 {
-       struct sock_reuseport *reuse;
+       struct sock_reuseport *old_reuse, *reuse;
 
        if (!rcu_access_pointer(sk2->sk_reuseport_cb)) {
                int err = reuseport_alloc(sk2);
@@ -113,10 +123,13 @@ int reuseport_add_sock(struct sock *sk, struct sock *sk2)
 
        spin_lock_bh(&reuseport_lock);
        reuse = rcu_dereference_protected(sk2->sk_reuseport_cb,
-                                         lockdep_is_held(&reuseport_lock)),
-       WARN_ONCE(rcu_dereference_protected(sk->sk_reuseport_cb,
-                                           lockdep_is_held(&reuseport_lock)),
-                 "socket already in reuseport group");
+                                         lockdep_is_held(&reuseport_lock));
+       old_reuse = rcu_dereference_protected(sk->sk_reuseport_cb,
+                                            lockdep_is_held(&reuseport_lock));
+       if (old_reuse && old_reuse->num_socks != 1) {
+               spin_unlock_bh(&reuseport_lock);
+               return -EBUSY;
+       }
 
        if (reuse->num_socks == reuse->max_socks) {
                reuse = reuseport_grow(reuse);
@@ -134,19 +147,11 @@ int reuseport_add_sock(struct sock *sk, struct sock *sk2)
 
        spin_unlock_bh(&reuseport_lock);
 
+       if (old_reuse)
+               call_rcu(&old_reuse->rcu, reuseport_free_rcu);
        return 0;
 }
 
-static void reuseport_free_rcu(struct rcu_head *head)
-{
-       struct sock_reuseport *reuse;
-
-       reuse = container_of(head, struct sock_reuseport, rcu);
-       if (reuse->prog)
-               bpf_prog_destroy(reuse->prog);
-       kfree(reuse);
-}
-
 void reuseport_detach_sock(struct sock *sk)
 {
        struct sock_reuseport *reuse;