[DCCP]: Initial dccp_poll implementation

Tested with a patched netcat, no horror stories so far 8)

Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 59 insertions, 1 deletions

diff --git a/net/dccp/input.c b/net/dccp/input.c
index 02af05ec23a2..ef29cef1dafe 100644
--- a/net/dccp/input.c
+++ b/net/dccp/input.c
@@ -34,6 +34,7 @@ static void dccp_rcv_close(struct sock *sk, struct sk_buff *skb)
         dccp_v4_send_reset(sk, DCCP_RESET_CODE_CLOSED);
         dccp_fin(sk, skb);
         dccp_set_state(sk, DCCP_CLOSED);
+        sk_wake_async(sk, 1, POLL_HUP);
 }
 
 static void dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb)
diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index 2b6db18e607f..600dda51d995 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -140,6 +140,62 @@ int dccp_disconnect(struct sock *sk, int flags)
         return err;
 }
 
+/*
+ *      Wait for a DCCP event.
+ *
+ *      Note that we don't need to lock the socket, as the upper poll layers
+ *      take care of normal races (between the test and the event) and we don't
+ *      go look at any of the socket buffers directly.
+ */
+static unsigned int dccp_poll(struct file *file, struct socket *sock,
+                              poll_table *wait)
+{
+        unsigned int mask;
+        struct sock *sk = sock->sk;
+
+        poll_wait(file, sk->sk_sleep, wait);
+        if (sk->sk_state == DCCP_LISTEN)
+                return inet_csk_listen_poll(sk);
+
+        /* Socket is not locked. We are protected from async events
+           by poll logic and correct handling of state changes
+           made by another threads is impossible in any case.
+         */
+
+        mask = 0;
+        if (sk->sk_err)
+                mask = POLLERR;
+
+        if (sk->sk_shutdown == SHUTDOWN_MASK || sk->sk_state == DCCP_CLOSED)
+                mask |= POLLHUP;
+        if (sk->sk_shutdown & RCV_SHUTDOWN)
+                mask |= POLLIN | POLLRDNORM;
+
+        /* Connected? */
+        if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_RESPOND)) {
+                if (atomic_read(&sk->sk_rmem_alloc) > 0)
+                        mask |= POLLIN | POLLRDNORM;
+
+                if (!(sk->sk_shutdown & SEND_SHUTDOWN)) {
+                        if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk)) {
+                                mask |= POLLOUT | POLLWRNORM;
+                        } else {  /* send SIGIO later */
+                                set_bit(SOCK_ASYNC_NOSPACE,
+                                        &sk->sk_socket->flags);
+                                set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
+
+                                /* Race breaker. If space is freed after
+                                 * wspace test but before the flags are set,
+                                 * IO signal will be lost.
+                                 */
+                                if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk))
+                                        mask |= POLLOUT | POLLWRNORM;
+                        }
+                }
+        }
+        return mask;
+}
+
 int dccp_ioctl(struct sock *sk, int cmd, unsigned long arg)
 {
         dccp_pr_debug("entry\n");
@@ -478,7 +534,8 @@ static struct proto_ops inet_dccp_ops = {
         .socketpair     = sock_no_socketpair,
         .accept         = inet_accept,
         .getname        = inet_getname,
-        .poll           = sock_no_poll,
+        /* FIXME: work on tcp_poll to rename it to inet_csk_poll */
+        .poll           = dccp_poll,
         .ioctl          = inet_ioctl,
         /* FIXME: work on inet_listen to rename it to sock_common_listen */
         .listen         = inet_dccp_listen,