[SCTP]: Do not interleave non-fragments when in partial delivery

The way partial delivery is currently implemnted, it is possible to
intereleave a message (either from another steram, or unordered) that
is not part of partial delivery process.  The only way to this is for
a message to not be a fragment and be 'in order' or unorderd for a
given stream.  This will result in bypassing the reassembly/ordering
queues where things live duing partial delivery, and the
message will be delivered to the socket in the middle of partial delivery.

This is a two-fold problem, in that:
1.  the app now must check the stream-id and flags which it may not
be doing.
2.  this clearing partial delivery state from the association and results
in ulp hanging.

This patch is a band-aid over a much bigger problem in that we
don't do stream interleave.
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sctp/ulpqueue.c

@@ -190,7 +190,14 @@ int sctp_ulpq_tail_event(struct sctp_ulpq *ulpq, struct sctp_ulpevent *event)
 	if (!sctp_sk(sk)->pd_mode) {
 		queue = &sk->sk_receive_queue;
 	} else if (ulpq->pd_mode) {
-		if (event->msg_flags & MSG_NOTIFICATION)
+		/* If the association is in partial delivery, we
+		 * need to finish delivering the partially processed
+		 * packet before passing any other data.  This is
+		 * because we don't truly support stream interleaving.
+		 */
+		if ((event->msg_flags & MSG_NOTIFICATION) ||
+		    (SCTP_DATA_NOT_FRAG ==
+			    (event->msg_flags & SCTP_DATA_FRAG_MASK)))
 			queue = &sctp_sk(sk)->pd_lobby;
 		else {
 			clear_pd = event->msg_flags & MSG_EOR;