1// SPDX-License-Identifier: GPL-2.0-or-later
  2/* SCTP kernel implementation
  3 * (C) Copyright Red Hat Inc. 2017
  4 *
  5 * This file is part of the SCTP kernel implementation
  6 *
  7 * These functions manipulate sctp stream queue/scheduling.
  8 *
  9 * Please send any bug reports or fixes you make to the
 10 * email addresched(es):
 11 *    lksctp developers <linux-sctp@vger.kernel.org>
 12 *
 13 * Written or modified by:
 14 *    Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
 15 */
 16
 17#include <linux/list.h>
 18#include <net/sctp/sctp.h>
 19#include <net/sctp/sm.h>
 20#include <net/sctp/stream_sched.h>
 21
 22/* Priority handling
 23 * RFC DRAFT ndata section 3.2
 24 */
 25static void sctp_sched_rr_unsched_all(struct sctp_stream *stream);
 26
 27static void sctp_sched_rr_next_stream(struct sctp_stream *stream)
 28{
 29	struct list_head *pos;
 30
 31	pos = stream->rr_next->rr_list.next;
 32	if (pos == &stream->rr_list)
 33		pos = pos->next;
 34	stream->rr_next = list_entry(pos, struct sctp_stream_out_ext, rr_list);
 35}
 36
 37static void sctp_sched_rr_unsched(struct sctp_stream *stream,
 38				  struct sctp_stream_out_ext *soute)
 39{
 40	if (stream->rr_next == soute)
 41		/* Try to move to the next stream */
 42		sctp_sched_rr_next_stream(stream);
 43
 44	list_del_init(&soute->rr_list);
 45
 46	/* If we have no other stream queued, clear next */
 47	if (list_empty(&stream->rr_list))
 48		stream->rr_next = NULL;
 49}
 50
 51static void sctp_sched_rr_sched(struct sctp_stream *stream,
 52				struct sctp_stream_out_ext *soute)
 53{
 54	if (!list_empty(&soute->rr_list))
 55		/* Already scheduled. */
 56		return;
 57
 58	/* Schedule the stream */
 59	list_add_tail(&soute->rr_list, &stream->rr_list);
 60
 61	if (!stream->rr_next)
 62		stream->rr_next = soute;
 63}
 64
 65static int sctp_sched_rr_set(struct sctp_stream *stream, __u16 sid,
 66			     __u16 prio, gfp_t gfp)
 67{
 68	return 0;
 69}
 70
 71static int sctp_sched_rr_get(struct sctp_stream *stream, __u16 sid,
 72			     __u16 *value)
 73{
 74	return 0;
 75}
 76
 77static int sctp_sched_rr_init(struct sctp_stream *stream)
 78{
 79	INIT_LIST_HEAD(&stream->rr_list);
 80	stream->rr_next = NULL;
 81
 82	return 0;
 83}
 84
 85static int sctp_sched_rr_init_sid(struct sctp_stream *stream, __u16 sid,
 86				  gfp_t gfp)
 87{
 88	INIT_LIST_HEAD(&SCTP_SO(stream, sid)->ext->rr_list);
 89
 90	return 0;
 91}
 92
 93static void sctp_sched_rr_free(struct sctp_stream *stream)
 94{
 95	sctp_sched_rr_unsched_all(stream);
 96}
 97
 98static void sctp_sched_rr_enqueue(struct sctp_outq *q,
 99				  struct sctp_datamsg *msg)
100{
101	struct sctp_stream *stream;
102	struct sctp_chunk *ch;
103	__u16 sid;
104
105	ch = list_first_entry(&msg->chunks, struct sctp_chunk, frag_list);
106	sid = sctp_chunk_stream_no(ch);
107	stream = &q->asoc->stream;
108	sctp_sched_rr_sched(stream, SCTP_SO(stream, sid)->ext);
109}
110
111static struct sctp_chunk *sctp_sched_rr_dequeue(struct sctp_outq *q)
112{
113	struct sctp_stream *stream = &q->asoc->stream;
114	struct sctp_stream_out_ext *soute;
115	struct sctp_chunk *ch = NULL;
116
117	/* Bail out quickly if queue is empty */
118	if (list_empty(&q->out_chunk_list))
119		goto out;
120
121	/* Find which chunk is next */
122	if (stream->out_curr)
123		soute = stream->out_curr->ext;
124	else
125		soute = stream->rr_next;
126	ch = list_entry(soute->outq.next, struct sctp_chunk, stream_list);
127
128	sctp_sched_dequeue_common(q, ch);
129
130out:
131	return ch;
132}
133
134static void sctp_sched_rr_dequeue_done(struct sctp_outq *q,
135				       struct sctp_chunk *ch)
136{
137	struct sctp_stream_out_ext *soute;
138	__u16 sid;
139
140	/* Last chunk on that msg, move to the next stream */
141	sid = sctp_chunk_stream_no(ch);
142	soute = SCTP_SO(&q->asoc->stream, sid)->ext;
143
144	sctp_sched_rr_next_stream(&q->asoc->stream);
145
146	if (list_empty(&soute->outq))
147		sctp_sched_rr_unsched(&q->asoc->stream, soute);
148}
149
150static void sctp_sched_rr_sched_all(struct sctp_stream *stream)
151{
152	struct sctp_association *asoc;
153	struct sctp_stream_out_ext *soute;
154	struct sctp_chunk *ch;
155
156	asoc = container_of(stream, struct sctp_association, stream);
157	list_for_each_entry(ch, &asoc->outqueue.out_chunk_list, list) {
158		__u16 sid;
159
160		sid = sctp_chunk_stream_no(ch);
161		soute = SCTP_SO(stream, sid)->ext;
162		if (soute)
163			sctp_sched_rr_sched(stream, soute);
164	}
165}
166
167static void sctp_sched_rr_unsched_all(struct sctp_stream *stream)
168{
169	struct sctp_stream_out_ext *soute, *tmp;
170
171	list_for_each_entry_safe(soute, tmp, &stream->rr_list, rr_list)
172		sctp_sched_rr_unsched(stream, soute);
173}
174
175static struct sctp_sched_ops sctp_sched_rr = {
176	.set = sctp_sched_rr_set,
177	.get = sctp_sched_rr_get,
178	.init = sctp_sched_rr_init,
179	.init_sid = sctp_sched_rr_init_sid,
180	.free = sctp_sched_rr_free,
181	.enqueue = sctp_sched_rr_enqueue,
182	.dequeue = sctp_sched_rr_dequeue,
183	.dequeue_done = sctp_sched_rr_dequeue_done,
184	.sched_all = sctp_sched_rr_sched_all,
185	.unsched_all = sctp_sched_rr_unsched_all,
186};
187
188void sctp_sched_ops_rr_init(void)
189{
190	sctp_sched_ops_register(SCTP_SS_RR, &sctp_sched_rr);
191}