[DCCP]: Check if already in the CLOSING state in dccp_rcv_closereq

It is possible to receive more than one CLOSEREQ packet if the
CLOSE packet sent in response is somehow lost, change the state
to DCCP_CLOSING only on the first CLOSEREQ packet received.

Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>

net/dccp/input.c

diff --git a/net/dccp/input.c b/net/dccp/input.c
index c60bc34..f01d588 100644
--- a/net/dccp/input.c
+++ b/net/dccp/input.c
@@ -50,7 +50,8 @@
 		return;
 	}
 
-	dccp_set_state(sk, DCCP_CLOSING);
+	if (sk->sk_state != DCCP_CLOSING)
+		dccp_set_state(sk, DCCP_CLOSING);
 	dccp_send_close(sk, 0);
 }