[net-next,06/10] sctp: introduce stream scheduler foundations

diff --git a/include/net/sctp/stream_sched.h b/include/net/sctp/stream_sched.h
new file mode 100644
index 0000000000000000000000000000000000000000..c676550a4c7dd0ea27ac0e14437d0a2b451ef499
--- /dev/null
+++ b/include/net/sctp/stream_sched.h
@@ -0,0 +1,72 @@ 
+/* SCTP kernel implementation
+ * (C) Copyright Red Hat Inc. 2017
+ *
+ * These are definitions used by the stream schedulers, defined in RFC
+ * draft ndata (https://tools.ietf.org/html/draft-ietf-tsvwg-sctp-ndata-11)
+ *
+ * This SCTP implementation is free software;
+ * you can redistribute it and/or modify it under the terms of
+ * the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * This SCTP implementation  is distributed in the hope that it
+ * will be useful, but WITHOUT ANY WARRANTY; without even the implied
+ *                 ************************
+ * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GNU CC; see the file COPYING.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * Please send any bug reports or fixes you make to the
+ * email addresses:
+ *    lksctp developers <linux-sctp@vger.kernel.org>
+ *
+ * Written or modified by:
+ *   Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
+ */
+
+#ifndef __sctp_stream_sched_h__
+#define __sctp_stream_sched_h__
+
+struct sctp_sched_ops {
+	/* Property handling for a given stream */
+	int (*set)(struct sctp_stream *stream, __u16 sid, __u16 value,
+		   gfp_t gfp);
+	int (*get)(struct sctp_stream *stream, __u16 sid, __u16 *value);
+
+	/* Init the specific scheduler */
+	int (*init)(struct sctp_stream *stream);
+	/* Init a stream */
+	int (*init_sid)(struct sctp_stream *stream, __u16 sid, gfp_t gfp);
+	/* Frees the entire thing */
+	void (*free)(struct sctp_stream *stream);
+
+	/* Enqueue a chunk */
+	void (*enqueue)(struct sctp_outq *q, struct sctp_datamsg *msg);
+	/* Dequeue a chunk */
+	struct sctp_chunk *(*dequeue)(struct sctp_outq *q);
+	/* Called only if the chunk fit the packet */
+	void (*dequeue_done)(struct sctp_outq *q, struct sctp_chunk *chunk);
+	/* Sched all chunks already enqueued */
+	void (*sched_all)(struct sctp_stream *steam);
+	/* Unched all chunks already enqueued */
+	void (*unsched_all)(struct sctp_stream *steam);
+};
+
+int sctp_sched_set_sched(struct sctp_association *asoc,
+			 enum sctp_sched_type sched);
+int sctp_sched_get_sched(struct sctp_association *asoc);
+int sctp_sched_set_value(struct sctp_association *asoc, __u16 sid,
+			 __u16 value, gfp_t gfp);
+int sctp_sched_get_value(struct sctp_association *asoc, __u16 sid,
+			 __u16 *value);
+void sctp_sched_dequeue_done(struct sctp_outq *q, struct sctp_chunk *ch);
+
+void sctp_sched_dequeue_common(struct sctp_outq *q, struct sctp_chunk *ch);
+int sctp_sched_init_sid(struct sctp_stream *stream, __u16 sid, gfp_t gfp);
+struct sctp_sched_ops *sctp_sched_ops_from_stream(struct sctp_stream *stream);
+
+#endif /* __sctp_stream_sched_h__ */
diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index c48f7999fe9b80c5b5e41910a3608059b94140a7..3c22a30fd71b4ef87419a77cf69b00807a5986bb 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -84,7 +84,6 @@  struct sctp_ulpq;
 struct sctp_ep_common;
 struct crypto_shash;
 struct sctp_stream;
-struct sctp_stream_out;
 
 
 #include <net/sctp/tsnmap.h>
@@ -531,8 +530,12 @@  struct sctp_chunk {
 	/* How many times this chunk have been sent, for prsctp RTX policy */
 	int sent_count;
 
-	/* This is our link to the per-transport transmitted list.  */
-	struct list_head transmitted_list;
+	union {
+		/* This is our link to the per-transport transmitted list.  */
+		struct list_head transmitted_list;
+		/* List in specific stream outq */
+		struct list_head stream_list;
+	};
 
 	/* This field is used by chunks that hold fragmented data.
 	 * For the first fragment this is the list that holds the rest of
@@ -1019,6 +1022,9 @@  struct sctp_outq {
 	/* Data pending that has never been transmitted.  */
 	struct list_head out_chunk_list;
 
+	/* Stream scheduler being used */
+	struct sctp_sched_ops *sched;
+
 	unsigned int out_qlen;	/* Total length of queued data chunks. */
 
 	/* Error of send failed, may used in SCTP_SEND_FAILED event. */
@@ -1325,6 +1331,7 @@  struct sctp_inithdr_host {
 struct sctp_stream_out_ext {
 	__u64 abandoned_unsent[SCTP_PR_INDEX(MAX) + 1];
 	__u64 abandoned_sent[SCTP_PR_INDEX(MAX) + 1];
+	struct list_head outq; /* chunks enqueued by this stream */
 };
 
 struct sctp_stream_out {
@@ -1342,6 +1349,8 @@  struct sctp_stream {
 	struct sctp_stream_in *in;
 	__u16 outcnt;
 	__u16 incnt;
+	/* Current stream being sent, if any */
+	struct sctp_stream_out *out_curr;
 };
 
 #define SCTP_STREAM_CLOSED		0x00
diff --git a/include/uapi/linux/sctp.h b/include/uapi/linux/sctp.h
index 6217ff8500a1d818fd1002fbd6f81c0c11974665..4487e7625ddbd48be1868a8292a807ecd0a314bc 100644
--- a/include/uapi/linux/sctp.h
+++ b/include/uapi/linux/sctp.h
@@ -1088,4 +1088,10 @@  struct sctp_add_streams {
 	uint16_t sas_outstrms;
 };
 
+/* SCTP Stream schedulers */
+enum sctp_sched_type {
+	SCTP_SS_FCFS,
+	SCTP_SS_MAX = SCTP_SS_FCFS
+};
+
 #endif /* _UAPI_SCTP_H */
diff --git a/net/sctp/Makefile b/net/sctp/Makefile
index 70f1b570bab9764d692f1c2e605d76d056cda2cd..0f6e6d1d69fd336b4a99f896851b0120f9a0d1e0 100644
--- a/net/sctp/Makefile
+++ b/net/sctp/Makefile
@@ -12,7 +12,7 @@  sctp-y := sm_statetable.o sm_statefuns.o sm_sideeffect.o \
 	  inqueue.o outqueue.o ulpqueue.o \
 	  tsnmap.o bind_addr.o socket.o primitive.o \
 	  output.o input.o debug.o stream.o auth.o \
-	  offload.o
+	  offload.o stream_sched.o
 
 sctp_probe-y := probe.o
 
diff --git a/net/sctp/outqueue.c b/net/sctp/outqueue.c
index 746b07b7937d8730824b9e09917d947aa7863ec6..4db012aa25f7a042f063bc17b56270effebc6cc6 100644
--- a/net/sctp/outqueue.c
+++ b/net/sctp/outqueue.c
@@ -50,6 +50,7 @@ 
 
 #include <net/sctp/sctp.h>
 #include <net/sctp/sm.h>
+#include <net/sctp/stream_sched.h>
 
 /* Declare internal functions here.  */
 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn);
@@ -72,32 +73,38 @@  static void sctp_outq_flush(struct sctp_outq *q, int rtx_timeout, gfp_t gfp);
 
 /* Add data to the front of the queue. */
 static inline void sctp_outq_head_data(struct sctp_outq *q,
-					struct sctp_chunk *ch)
+				       struct sctp_chunk *ch)
 {
+	struct sctp_stream_out_ext *oute;
+	__u16 stream;
+
 	list_add(&ch->list, &q->out_chunk_list);
 	q->out_qlen += ch->skb->len;
+
+	stream = sctp_chunk_stream_no(ch);
+	oute = q->asoc->stream.out[stream].ext;
+	list_add(&ch->stream_list, &oute->outq);
 }
 
 /* Take data from the front of the queue. */
 static inline struct sctp_chunk *sctp_outq_dequeue_data(struct sctp_outq *q)
 {
-	struct sctp_chunk *ch = NULL;
-
-	if (!list_empty(&q->out_chunk_list)) {
-		struct list_head *entry = q->out_chunk_list.next;
-
-		ch = list_entry(entry, struct sctp_chunk, list);
-		list_del_init(entry);
-		q->out_qlen -= ch->skb->len;
-	}
-	return ch;
+	return q->sched->dequeue(q);
 }
+
 /* Add data chunk to the end of the queue. */
 static inline void sctp_outq_tail_data(struct sctp_outq *q,
 				       struct sctp_chunk *ch)
 {
+	struct sctp_stream_out_ext *oute;
+	__u16 stream;
+
 	list_add_tail(&ch->list, &q->out_chunk_list);
 	q->out_qlen += ch->skb->len;
+
+	stream = sctp_chunk_stream_no(ch);
+	oute = q->asoc->stream.out[stream].ext;
+	list_add_tail(&ch->stream_list, &oute->outq);
 }
 
 /*
@@ -207,6 +214,7 @@  void sctp_outq_init(struct sctp_association *asoc, struct sctp_outq *q)
 	INIT_LIST_HEAD(&q->retransmit);
 	INIT_LIST_HEAD(&q->sacked);
 	INIT_LIST_HEAD(&q->abandoned);
+	sctp_sched_set_sched(asoc, SCTP_SS_FCFS);
 }
 
 /* Free the outqueue structure and any related pending chunks.
@@ -258,6 +266,7 @@  static void __sctp_outq_teardown(struct sctp_outq *q)
 
 	/* Throw away any leftover data chunks. */
 	while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
+		sctp_sched_dequeue_done(q, chunk);
 
 		/* Mark as send failure. */
 		sctp_chunk_fail(chunk, q->error);
@@ -391,13 +400,14 @@  static int sctp_prsctp_prune_unsent(struct sctp_association *asoc,
 	struct sctp_outq *q = &asoc->outqueue;
 	struct sctp_chunk *chk, *temp;
 
+	q->sched->unsched_all(&asoc->stream);
+
 	list_for_each_entry_safe(chk, temp, &q->out_chunk_list, list) {
 		if (!SCTP_PR_PRIO_ENABLED(chk->sinfo.sinfo_flags) ||
 		    chk->sinfo.sinfo_timetolive <= sinfo->sinfo_timetolive)
 			continue;
 
-		list_del_init(&chk->list);
-		q->out_qlen -= chk->skb->len;
+		sctp_sched_dequeue_common(q, chk);
 		asoc->sent_cnt_removable--;
 		asoc->abandoned_unsent[SCTP_PR_INDEX(PRIO)]++;
 		if (chk->sinfo.sinfo_stream < asoc->stream.outcnt) {
@@ -415,6 +425,8 @@  static int sctp_prsctp_prune_unsent(struct sctp_association *asoc,
 			break;
 	}
 
+	q->sched->sched_all(&asoc->stream);
+
 	return msg_len;
 }
 
@@ -1033,22 +1045,9 @@  static void sctp_outq_flush(struct sctp_outq *q, int rtx_timeout, gfp_t gfp)
 		while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
 			__u32 sid = ntohs(chunk->subh.data_hdr->stream);
 
-			/* RFC 2960 6.5 Every DATA chunk MUST carry a valid
-			 * stream identifier.
-			 */
-			if (chunk->sinfo.sinfo_stream >= asoc->stream.outcnt) {
-
-				/* Mark as failed send. */
-				sctp_chunk_fail(chunk, SCTP_ERROR_INV_STRM);
-				if (asoc->peer.prsctp_capable &&
-				    SCTP_PR_PRIO_ENABLED(chunk->sinfo.sinfo_flags))
-					asoc->sent_cnt_removable--;
-				sctp_chunk_free(chunk);
-				continue;
-			}
-
 			/* Has this chunk expired? */
 			if (sctp_chunk_abandoned(chunk)) {
+				sctp_sched_dequeue_done(q, chunk);
 				sctp_chunk_fail(chunk, 0);
 				sctp_chunk_free(chunk);
 				continue;
@@ -1070,6 +1069,7 @@  static void sctp_outq_flush(struct sctp_outq *q, int rtx_timeout, gfp_t gfp)
 				new_transport = asoc->peer.active_path;
 			if (new_transport->state == SCTP_UNCONFIRMED) {
 				WARN_ONCE(1, "Attempt to send packet on unconfirmed path.");
+				sctp_sched_dequeue_done(q, chunk);
 				sctp_chunk_fail(chunk, 0);
 				sctp_chunk_free(chunk);
 				continue;
@@ -1133,6 +1133,11 @@  static void sctp_outq_flush(struct sctp_outq *q, int rtx_timeout, gfp_t gfp)
 				else
 					asoc->stats.oodchunks++;
 
+				/* Only now it's safe to consider this
+				 * chunk as sent, sched-wise.
+				 */
+				sctp_sched_dequeue_done(q, chunk);
+
 				break;
 
 			default:
diff --git a/net/sctp/sm_sideeffect.c b/net/sctp/sm_sideeffect.c
index e6a2974e020e1a4232d94e6c2933eebff5f8acb4..402bfbb888cda53248dd192d3756a2f4db1d2a7f 100644
--- a/net/sctp/sm_sideeffect.c
+++ b/net/sctp/sm_sideeffect.c
@@ -50,6 +50,7 @@ 
 #include <net/sock.h>
 #include <net/sctp/sctp.h>
 #include <net/sctp/sm.h>
+#include <net/sctp/stream_sched.h>
 
 static int sctp_cmd_interpreter(enum sctp_event event_type,
 				union sctp_subtype subtype,
@@ -1089,6 +1090,8 @@  static void sctp_cmd_send_msg(struct sctp_association *asoc,
 
 	list_for_each_entry(chunk, &msg->chunks, frag_list)
 		sctp_outq_tail(&asoc->outqueue, chunk, gfp);
+
+	asoc->outqueue.sched->enqueue(&asoc->outqueue, msg);
 }
 
 
diff --git a/net/sctp/stream.c b/net/sctp/stream.c
index 055ca25bbc91bf932db8048c72a1b11cc2214942..5ea33a2c453b4272c5c22fa61e8e8bec06001f8b 100644
--- a/net/sctp/stream.c
+++ b/net/sctp/stream.c
@@ -32,8 +32,61 @@ 
  *    Xin Long <lucien.xin@gmail.com>
  */
 
+#include <linux/list.h>
 #include <net/sctp/sctp.h>
 #include <net/sctp/sm.h>
+#include <net/sctp/stream_sched.h>
+
+/* Migrates chunks from stream queues to new stream queues if needed,
+ * but not across associations. Also, removes those chunks to streams
+ * higher than the new max.
+ */
+static void sctp_stream_outq_migrate(struct sctp_stream *stream,
+				     struct sctp_stream *new, __u16 outcnt)
+{
+	struct sctp_association *asoc;
+	struct sctp_chunk *ch, *temp;
+	struct sctp_outq *outq;
+	int i;
+
+	asoc = container_of(stream, struct sctp_association, stream);
+	outq = &asoc->outqueue;
+
+	list_for_each_entry_safe(ch, temp, &outq->out_chunk_list, list) {
+		__u16 sid = sctp_chunk_stream_no(ch);
+
+		if (sid < outcnt)
+			continue;
+
+		sctp_sched_dequeue_common(outq, ch);
+		/* No need to call dequeue_done here because
+		 * the chunks are not scheduled by now.
+		 */
+
+		/* Mark as failed send. */
+		sctp_chunk_fail(ch, SCTP_ERROR_INV_STRM);
+		if (asoc->peer.prsctp_capable &&
+		    SCTP_PR_PRIO_ENABLED(ch->sinfo.sinfo_flags))
+			asoc->sent_cnt_removable--;
+
+		sctp_chunk_free(ch);
+	}
+
+	if (new) {
+		/* Here we actually move the old ext stuff into the new
+		 * buffer, because we want to keep it. Then
+		 * sctp_stream_update will swap ->out pointers.
+		 */
+		for (i = 0; i < outcnt; i++) {
+			kfree(new->out[i].ext);
+			new->out[i].ext = stream->out[i].ext;
+			stream->out[i].ext = NULL;
+		}
+	}
+
+	for (i = outcnt; i < stream->outcnt; i++)
+		kfree(stream->out[i].ext);
+}
 
 static int sctp_stream_alloc_out(struct sctp_stream *stream, __u16 outcnt,
 				 gfp_t gfp)
@@ -87,7 +140,8 @@  static int sctp_stream_alloc_in(struct sctp_stream *stream, __u16 incnt,
 int sctp_stream_init(struct sctp_stream *stream, __u16 outcnt, __u16 incnt,
 		     gfp_t gfp)
 {
-	int i;
+	struct sctp_sched_ops *sched = sctp_sched_ops_from_stream(stream);
+	int i, ret = 0;
 
 	gfp |= __GFP_NOWARN;
 
@@ -97,6 +151,11 @@  int sctp_stream_init(struct sctp_stream *stream, __u16 outcnt, __u16 incnt,
 	if (outcnt == stream->outcnt)
 		goto in;
 
+	/* Filter out chunks queued on streams that won't exist anymore */
+	sched->unsched_all(stream);
+	sctp_stream_outq_migrate(stream, NULL, outcnt);
+	sched->sched_all(stream);
+
 	i = sctp_stream_alloc_out(stream, outcnt, gfp);
 	if (i)
 		return i;
@@ -105,20 +164,27 @@  int sctp_stream_init(struct sctp_stream *stream, __u16 outcnt, __u16 incnt,
 	for (i = 0; i < stream->outcnt; i++)
 		stream->out[i].state = SCTP_STREAM_OPEN;
 
+	sched->init(stream);
+
 in:
 	if (!incnt)
-		return 0;
+		goto out;
 
 	i = sctp_stream_alloc_in(stream, incnt, gfp);
 	if (i) {
-		kfree(stream->out);
-		stream->out = NULL;
-		return -ENOMEM;
+		ret = -ENOMEM;
+		goto free;
 	}
 
 	stream->incnt = incnt;
+	goto out;
 
-	return 0;
+free:
+	sched->free(stream);
+	kfree(stream->out);
+	stream->out = NULL;
+out:
+	return ret;
 }
 
 int sctp_stream_init_ext(struct sctp_stream *stream, __u16 sid)
@@ -130,13 +196,15 @@  int sctp_stream_init_ext(struct sctp_stream *stream, __u16 sid)
 		return -ENOMEM;
 	stream->out[sid].ext = soute;
 
-	return 0;
+	return sctp_sched_init_sid(stream, sid, GFP_KERNEL);
 }
 
 void sctp_stream_free(struct sctp_stream *stream)
 {
+	struct sctp_sched_ops *sched = sctp_sched_ops_from_stream(stream);
 	int i;
 
+	sched->free(stream);
 	for (i = 0; i < stream->outcnt; i++)
 		kfree(stream->out[i].ext);
 	kfree(stream->out);
@@ -156,6 +224,10 @@  void sctp_stream_clear(struct sctp_stream *stream)
 
 void sctp_stream_update(struct sctp_stream *stream, struct sctp_stream *new)
 {
+	struct sctp_sched_ops *sched = sctp_sched_ops_from_stream(stream);
+
+	sched->unsched_all(stream);
+	sctp_stream_outq_migrate(stream, new, new->outcnt);
 	sctp_stream_free(stream);
 
 	stream->out = new->out;
@@ -163,6 +235,8 @@  void sctp_stream_update(struct sctp_stream *stream, struct sctp_stream *new)
 	stream->outcnt = new->outcnt;
 	stream->incnt  = new->incnt;
 
+	sched->sched_all(stream);
+
 	new->out = NULL;
 	new->in  = NULL;
 }
diff --git a/net/sctp/stream_sched.c b/net/sctp/stream_sched.c
new file mode 100644
index 0000000000000000000000000000000000000000..40a9a9de2b98a56786a4c8585f5ad514be9189af
--- /dev/null
+++ b/net/sctp/stream_sched.c
@@ -0,0 +1,270 @@ 
+/* SCTP kernel implementation
+ * (C) Copyright Red Hat Inc. 2017
+ *
+ * This file is part of the SCTP kernel implementation
+ *
+ * These functions manipulate sctp stream queue/scheduling.
+ *
+ * This SCTP implementation is free software;
+ * you can redistribute it and/or modify it under the terms of
+ * the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * This SCTP implementation is distributed in the hope that it
+ * will be useful, but WITHOUT ANY WARRANTY; without even the implied
+ *                 ************************
+ * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GNU CC; see the file COPYING.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * Please send any bug reports or fixes you make to the
+ * email addresched(es):
+ *    lksctp developers <linux-sctp@vger.kernel.org>
+ *
+ * Written or modified by:
+ *    Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
+ */
+
+#include <linux/list.h>
+#include <net/sctp/sctp.h>
+#include <net/sctp/sm.h>
+#include <net/sctp/stream_sched.h>
+
+/* First Come First Serve (a.k.a. FIFO)
+ * RFC DRAFT ndata Section 3.1
+ */
+static int sctp_sched_fcfs_set(struct sctp_stream *stream, __u16 sid,
+			       __u16 value, gfp_t gfp)
+{
+	return 0;
+}
+
+static int sctp_sched_fcfs_get(struct sctp_stream *stream, __u16 sid,
+			       __u16 *value)
+{
+	*value = 0;
+	return 0;
+}
+
+static int sctp_sched_fcfs_init(struct sctp_stream *stream)
+{
+	return 0;
+}
+
+static int sctp_sched_fcfs_init_sid(struct sctp_stream *stream, __u16 sid,
+				    gfp_t gfp)
+{
+	return 0;
+}
+
+static void sctp_sched_fcfs_free(struct sctp_stream *stream)
+{
+}
+
+static void sctp_sched_fcfs_enqueue(struct sctp_outq *q,
+				    struct sctp_datamsg *msg)
+{
+}
+
+static struct sctp_chunk *sctp_sched_fcfs_dequeue(struct sctp_outq *q)
+{
+	struct sctp_stream *stream = &q->asoc->stream;
+	struct sctp_chunk *ch = NULL;
+	struct list_head *entry;
+
+	if (list_empty(&q->out_chunk_list))
+		goto out;
+
+	if (stream->out_curr) {
+		ch = list_entry(stream->out_curr->ext->outq.next,
+				struct sctp_chunk, stream_list);
+	} else {
+		entry = q->out_chunk_list.next;
+		ch = list_entry(entry, struct sctp_chunk, list);
+	}
+
+	sctp_sched_dequeue_common(q, ch);
+
+out:
+	return ch;
+}
+
+static void sctp_sched_fcfs_dequeue_done(struct sctp_outq *q,
+					 struct sctp_chunk *chunk)
+{
+}
+
+static void sctp_sched_fcfs_sched_all(struct sctp_stream *stream)
+{
+}
+
+static void sctp_sched_fcfs_unsched_all(struct sctp_stream *stream)
+{
+}
+
+static struct sctp_sched_ops sctp_sched_fcfs = {
+	.set = sctp_sched_fcfs_set,
+	.get = sctp_sched_fcfs_get,
+	.init = sctp_sched_fcfs_init,
+	.init_sid = sctp_sched_fcfs_init_sid,
+	.free = sctp_sched_fcfs_free,
+	.enqueue = sctp_sched_fcfs_enqueue,
+	.dequeue = sctp_sched_fcfs_dequeue,
+	.dequeue_done = sctp_sched_fcfs_dequeue_done,
+	.sched_all = sctp_sched_fcfs_sched_all,
+	.unsched_all = sctp_sched_fcfs_unsched_all,
+};
+
+/* API to other parts of the stack */
+
+struct sctp_sched_ops *sctp_sched_ops[] = {
+	&sctp_sched_fcfs,
+};
+
+int sctp_sched_set_sched(struct sctp_association *asoc,
+			 enum sctp_sched_type sched)
+{
+	struct sctp_sched_ops *n = sctp_sched_ops[sched];
+	struct sctp_sched_ops *old = asoc->outqueue.sched;
+	struct sctp_datamsg *msg = NULL;
+	struct sctp_chunk *ch;
+	int i, ret = 0;
+
+	if (old == n)
+		return ret;
+
+	if (sched > SCTP_SS_MAX)
+		return -EINVAL;
+
+	if (old) {
+		old->free(&asoc->stream);
+
+		/* Give the next scheduler a clean slate. */
+		for (i = 0; i < asoc->stream.outcnt; i++) {
+			void *p = asoc->stream.out[i].ext;
+
+			if (!p)
+				continue;
+
+			p += offsetofend(struct sctp_stream_out_ext, outq);
+			memset(p, 0, sizeof(struct sctp_stream_out_ext) -
+				     offsetofend(struct sctp_stream_out_ext, outq));
+		}
+	}
+
+	asoc->outqueue.sched = n;
+	n->init(&asoc->stream);
+	for (i = 0; i < asoc->stream.outcnt; i++) {
+		if (!asoc->stream.out[i].ext)
+			continue;
+
+		ret = n->init_sid(&asoc->stream, i, GFP_KERNEL);
+		if (ret)
+			goto err;
+	}
+
+	/* We have to requeue all chunks already queued. */
+	list_for_each_entry(ch, &asoc->outqueue.out_chunk_list, list) {
+		if (ch->msg == msg)
+			continue;
+		msg = ch->msg;
+		n->enqueue(&asoc->outqueue, msg);
+	}
+
+	return ret;
+
+err:
+	n->free(&asoc->stream);
+	asoc->outqueue.sched = &sctp_sched_fcfs; /* Always safe */
+
+	return ret;
+}
+
+int sctp_sched_get_sched(struct sctp_association *asoc)
+{
+	int i;
+
+	for (i = 0; i <= SCTP_SS_MAX; i++)
+		if (asoc->outqueue.sched == sctp_sched_ops[i])
+			return i;
+
+	return 0;
+}
+
+int sctp_sched_set_value(struct sctp_association *asoc, __u16 sid,
+			 __u16 value, gfp_t gfp)
+{
+	if (sid >= asoc->stream.outcnt)
+		return -EINVAL;
+
+	if (!asoc->stream.out[sid].ext) {
+		int ret;
+
+		ret = sctp_stream_init_ext(&asoc->stream, sid);
+		if (ret)
+			return ret;
+	}
+
+	return asoc->outqueue.sched->set(&asoc->stream, sid, value, gfp);
+}
+
+int sctp_sched_get_value(struct sctp_association *asoc, __u16 sid,
+			 __u16 *value)
+{
+	if (sid >= asoc->stream.outcnt)
+		return -EINVAL;
+
+	if (!asoc->stream.out[sid].ext)
+		return 0;
+
+	return asoc->outqueue.sched->get(&asoc->stream, sid, value);
+}
+
+void sctp_sched_dequeue_done(struct sctp_outq *q, struct sctp_chunk *ch)
+{
+	if (!list_is_last(&ch->frag_list, &ch->msg->chunks)) {
+		struct sctp_stream_out *sout;
+		__u16 sid;
+
+		/* datamsg is not finish, so save it as current one,
+		 * in case application switch scheduler or a higher
+		 * priority stream comes in.
+		 */
+		sid = sctp_chunk_stream_no(ch);
+		sout = &q->asoc->stream.out[sid];
+		q->asoc->stream.out_curr = sout;
+		return;
+	}
+
+	q->asoc->stream.out_curr = NULL;
+	q->sched->dequeue_done(q, ch);
+}
+
+/* Auxiliary functions for the schedulers */
+void sctp_sched_dequeue_common(struct sctp_outq *q, struct sctp_chunk *ch)
+{
+	list_del_init(&ch->list);
+	list_del_init(&ch->stream_list);
+	q->out_qlen -= ch->skb->len;
+}
+
+int sctp_sched_init_sid(struct sctp_stream *stream, __u16 sid, gfp_t gfp)
+{
+	struct sctp_sched_ops *sched = sctp_sched_ops_from_stream(stream);
+
+	INIT_LIST_HEAD(&stream->out[sid].ext->outq);
+	return sched->init_sid(stream, sid, gfp);
+}
+
+struct sctp_sched_ops *sctp_sched_ops_from_stream(struct sctp_stream *stream)
+{
+	struct sctp_association *asoc;
+
+	asoc = container_of(stream, struct sctp_association, stream);
+
+	return asoc->outqueue.sched;
+}