sctp: implement start_pd for sctp_stream_interleave

start_pd is added as a member of sctp_stream_interleave, used to
do partial_delivery for data or idata when datalen >= asoc->rwnd
in sctp_eat_data. The codes have been done in last patches, but
they need to be extracted into start_pd, so that it could be used
for SCTP_CMD_PART_DELIVER cmd as well.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sctp/stream_interleave.h

@@ -45,6 +45,7 @@ struct sctp_stream_interleave {
 				 struct sctp_ulpevent *event);
 	void	(*renege_events)(struct sctp_ulpq *ulpq,
 				 struct sctp_chunk *chunk, gfp_t gfp);
+	void	(*start_pd)(struct sctp_ulpq *ulpq, gfp_t gfp);
 };
 
 void sctp_stream_interleave_init(struct sctp_stream *stream);

net/sctp/sm_sideeffect.c

@@ -1731,7 +1731,7 @@ static int sctp_cmd_interpreter(enum sctp_event event_type,
 			break;
 
 		case SCTP_CMD_PART_DELIVER:
-			sctp_ulpq_partial_delivery(&asoc->ulpq, GFP_ATOMIC);
+			asoc->stream.si->start_pd(&asoc->ulpq, GFP_ATOMIC);
 			break;
 
 		case SCTP_CMD_RENEGE:

net/sctp/stream_interleave.c

@@ -661,6 +661,7 @@ static struct sctp_stream_interleave sctp_stream_interleave_0 = {
 	.ulpevent_data		= sctp_ulpq_tail_data,
 	.enqueue_event		= sctp_ulpq_tail_event,
 	.renege_events		= sctp_ulpq_renege,
+	.start_pd		= sctp_ulpq_partial_delivery,
 };
 
 static struct sctp_stream_interleave sctp_stream_interleave_1 = {
@@ -672,6 +673,7 @@ static struct sctp_stream_interleave sctp_stream_interleave_1 = {
 	.ulpevent_data		= sctp_ulpevent_idata,
 	.enqueue_event		= sctp_enqueue_event,
 	.renege_events		= sctp_renege_events,
+	.start_pd		= sctp_intl_start_pd,
 };
 
 void sctp_stream_interleave_init(struct sctp_stream *stream)