1 files changed, 70 insertions, 9 deletions

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index e18cd3628db4..657835f227d3 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -169,6 +169,11 @@ static inline int unix_may_send(struct sock *sk, struct sock *osk)
         return (unix_peer(osk) == NULL || unix_our_peer(sk, osk));
 }
 
+static inline int unix_recvq_full(struct sock const *sk)
+{
+        return skb_queue_len(&sk->sk_receive_queue) > sk->sk_max_ack_backlog;
+}
+
 static struct sock *unix_peer_get(struct sock *s)
 {
         struct sock *peer;
@@ -482,6 +487,8 @@ static int unix_socketpair(struct socket *, struct socket *);
 static int unix_accept(struct socket *, struct socket *, int);
 static int unix_getname(struct socket *, struct sockaddr *, int *, int);
 static unsigned int unix_poll(struct file *, struct socket *, poll_table *);
+static unsigned int unix_datagram_poll(struct file *, struct socket *,
+                                       poll_table *);
 static int unix_ioctl(struct socket *, unsigned int, unsigned long);
 static int unix_shutdown(struct socket *, int);
 static int unix_stream_sendmsg(struct kiocb *, struct socket *,
@@ -527,7 +534,7 @@ static const struct proto_ops unix_dgram_ops = {
         .socketpair =   unix_socketpair,
         .accept =       sock_no_accept,
         .getname =      unix_getname,
-        .poll =         datagram_poll,
+        .poll =         unix_datagram_poll,
         .ioctl =        unix_ioctl,
         .listen =       sock_no_listen,
         .shutdown =     unix_shutdown,
@@ -548,7 +555,7 @@ static const struct proto_ops unix_seqpacket_ops = {
         .socketpair =   unix_socketpair,
         .accept =       unix_accept,
         .getname =      unix_getname,
-        .poll =         datagram_poll,
+        .poll =         unix_datagram_poll,
         .ioctl =        unix_ioctl,
         .listen =       unix_listen,
         .shutdown =     unix_shutdown,
@@ -983,8 +990,7 @@ static long unix_wait_for_peer(struct sock *other, long timeo)
 
         sched = !sock_flag(other, SOCK_DEAD) &&
                 !(other->sk_shutdown & RCV_SHUTDOWN) &&
-                (skb_queue_len(&other->sk_receive_queue) >
-                 other->sk_max_ack_backlog);
+                unix_recvq_full(other);
 
         unix_state_unlock(other);
 
@@ -1058,8 +1064,7 @@ restart:
         if (other->sk_state != TCP_LISTEN)
                 goto out_unlock;
 
-        if (skb_queue_len(&other->sk_receive_queue) >
-            other->sk_max_ack_backlog) {
+        if (unix_recvq_full(other)) {
                 err = -EAGAIN;
                 if (!timeo)
                         goto out_unlock;
@@ -1428,9 +1433,7 @@ restart:
                         goto out_unlock;
         }
 
-        if (unix_peer(other) != sk &&
-            (skb_queue_len(&other->sk_receive_queue) >
-             other->sk_max_ack_backlog)) {
+        if (unix_peer(other) != sk && unix_recvq_full(other)) {
                 if (!timeo) {
                         err = -EAGAIN;
                         goto out_unlock;
@@ -1991,6 +1994,64 @@ static unsigned int unix_poll(struct file * file, struct socket *sock, poll_tabl
         return mask;
 }
 
+static unsigned int unix_datagram_poll(struct file *file, struct socket *sock,
+                                       poll_table *wait)
+{
+        struct sock *sk = sock->sk, *peer;
+        unsigned int mask;
+
+        poll_wait(file, sk->sk_sleep, wait);
+
+        peer = unix_peer_get(sk);
+        if (peer) {
+                if (peer != sk) {
+                        /*
+                         * Writability of a connected socket additionally
+                         * depends on the state of the receive queue of the
+                         * peer.
+                         */
+                        poll_wait(file, &unix_sk(peer)->peer_wait, wait);
+                } else {
+                        sock_put(peer);
+                        peer = NULL;
+                }
+        }
+
+        mask = 0;
+
+        /* exceptional events? */
+        if (sk->sk_err || !skb_queue_empty(&sk->sk_error_queue))
+                mask |= POLLERR;
+        if (sk->sk_shutdown & RCV_SHUTDOWN)
+                mask |= POLLRDHUP;
+        if (sk->sk_shutdown == SHUTDOWN_MASK)
+                mask |= POLLHUP;
+
+        /* readable? */
+        if (!skb_queue_empty(&sk->sk_receive_queue) ||
+            (sk->sk_shutdown & RCV_SHUTDOWN))
+                mask |= POLLIN | POLLRDNORM;
+
+        /* Connection-based need to check for termination and startup */
+        if (sk->sk_type == SOCK_SEQPACKET) {
+                if (sk->sk_state == TCP_CLOSE)
+                        mask |= POLLHUP;
+                /* connection hasn't started yet? */
+                if (sk->sk_state == TCP_SYN_SENT)
+                        return mask;
+        }
+
+        /* writable? */
+        if (unix_writable(sk) && !(peer && unix_recvq_full(peer)))
+                mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
+        else
+                set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
+
+        if (peer)
+                sock_put(peer);
+
+        return mask;
+}
 
 #ifdef CONFIG_PROC_FS
 static struct sock *first_unix_socket(int *i)