[NETLINK]: Kill CB only when socket is unused

Since we can still receive packets until all references to the
socket are gone, we don't need to kill the CB until that happens.
This also aligns ourselves with the receive queue purging which
happens at that point.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 42d2fb94eff1b6716f8a29bf760c3d58b20723ca..7fc6b4da4f0216394d170d2a229479da35988d9f 100644 (file)
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -140,6 +140,15 @@ static struct hlist_head *nl_pid_hashfn(struct nl_pid_hash *hash, u32 pid)
 
 static void netlink_sock_destruct(struct sock *sk)
 {
+       struct netlink_sock *nlk = nlk_sk(sk);
+
+       BUG_ON(mutex_is_locked(nlk_sk(sk)->cb_mutex));
+       if (nlk->cb) {
+               if (nlk->cb->done)
+                       nlk->cb->done(nlk->cb);
+               netlink_destroy_callback(nlk->cb);
+       }
+
        skb_queue_purge(&sk->sk_receive_queue);
 
        if (!sock_flag(sk, SOCK_DEAD)) {
@@ -148,7 +157,6 @@ static void netlink_sock_destruct(struct sock *sk)
        }
        BUG_TRAP(!atomic_read(&sk->sk_rmem_alloc));
        BUG_TRAP(!atomic_read(&sk->sk_wmem_alloc));
-       BUG_TRAP(!nlk_sk(sk)->cb);
        BUG_TRAP(!nlk_sk(sk)->groups);
 }
 
@@ -456,17 +464,10 @@ static int netlink_release(struct socket *sock)
        sock_orphan(sk);
        nlk = nlk_sk(sk);
 
-       mutex_lock(nlk->cb_mutex);
-       if (nlk->cb) {
-               if (nlk->cb->done)
-                       nlk->cb->done(nlk->cb);
-               netlink_destroy_callback(nlk->cb);
-               nlk->cb = NULL;
-       }
-       mutex_unlock(nlk->cb_mutex);
-
-       /* OK. Socket is unlinked, and, therefore,
-          no new packets will arrive */
+       /*
+        * OK. Socket is unlinked, any packets that arrive now
+        * will be purged.
+        */
 
        sock->sk = NULL;
        wake_up_interruptible_all(&nlk->wait);
@@ -1426,9 +1427,9 @@ int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
                return -ECONNREFUSED;
        }
        nlk = nlk_sk(sk);
-       /* A dump or destruction is in progress... */
+       /* A dump is in progress... */
        mutex_lock(nlk->cb_mutex);
-       if (nlk->cb || sock_flag(sk, SOCK_DEAD)) {
+       if (nlk->cb) {
                mutex_unlock(nlk->cb_mutex);
                netlink_destroy_callback(cb);
                sock_put(sk);