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/* First Come First Serve (a.k.a. FIFO)
23 * RFC DRAFT ndata Section 3.1
24 */
25static int sctp_sched_fcfs_set(struct sctp_stream *stream, __u16 sid,
26			       __u16 value, gfp_t gfp)
27{
28	return 0;
29}
30
31static int sctp_sched_fcfs_get(struct sctp_stream *stream, __u16 sid,
32			       __u16 *value)
33{
34	*value = 0;
35	return 0;
36}
37
38static int sctp_sched_fcfs_init(struct sctp_stream *stream)
39{
40	return 0;
41}
42
43static int sctp_sched_fcfs_init_sid(struct sctp_stream *stream, __u16 sid,
44				    gfp_t gfp)
45{
46	return 0;
47}
48
49static void sctp_sched_fcfs_free_sid(struct sctp_stream *stream, __u16 sid)
50{
51}
52
53static void sctp_sched_fcfs_free(struct sctp_stream *stream)
54{
55}
56
57static void sctp_sched_fcfs_enqueue(struct sctp_outq *q,
58				    struct sctp_datamsg *msg)
59{
60}
61
62static struct sctp_chunk *sctp_sched_fcfs_dequeue(struct sctp_outq *q)
63{
64	struct sctp_stream *stream = &q->asoc->stream;
65	struct sctp_chunk *ch = NULL;
66	struct list_head *entry;
67
68	if (list_empty(&q->out_chunk_list))
69		goto out;
70
71	if (stream->out_curr) {
72		ch = list_entry(stream->out_curr->ext->outq.next,
73				struct sctp_chunk, stream_list);
74	} else {
75		entry = q->out_chunk_list.next;
76		ch = list_entry(entry, struct sctp_chunk, list);
77	}
78
79	sctp_sched_dequeue_common(q, ch);
80
81out:
82	return ch;
83}
84
85static void sctp_sched_fcfs_dequeue_done(struct sctp_outq *q,
86					 struct sctp_chunk *chunk)
87{
88}
89
90static void sctp_sched_fcfs_sched_all(struct sctp_stream *stream)
91{
92}
93
94static void sctp_sched_fcfs_unsched_all(struct sctp_stream *stream)
95{
96}
97
98static struct sctp_sched_ops sctp_sched_fcfs = {
99	.set = sctp_sched_fcfs_set,
100	.get = sctp_sched_fcfs_get,
101	.init = sctp_sched_fcfs_init,
102	.init_sid = sctp_sched_fcfs_init_sid,
103	.free_sid = sctp_sched_fcfs_free_sid,
104	.free = sctp_sched_fcfs_free,
105	.enqueue = sctp_sched_fcfs_enqueue,
106	.dequeue = sctp_sched_fcfs_dequeue,
107	.dequeue_done = sctp_sched_fcfs_dequeue_done,
108	.sched_all = sctp_sched_fcfs_sched_all,
109	.unsched_all = sctp_sched_fcfs_unsched_all,
110};
111
112static void sctp_sched_ops_fcfs_init(void)
113{
114	sctp_sched_ops_register(SCTP_SS_FCFS, &sctp_sched_fcfs);
115}
116
117/* API to other parts of the stack */
118
119static struct sctp_sched_ops *sctp_sched_ops[SCTP_SS_MAX + 1];
120
121void sctp_sched_ops_register(enum sctp_sched_type sched,
122			     struct sctp_sched_ops *sched_ops)
123{
124	sctp_sched_ops[sched] = sched_ops;
125}
126
127void sctp_sched_ops_init(void)
128{
129	sctp_sched_ops_fcfs_init();
130	sctp_sched_ops_prio_init();
131	sctp_sched_ops_rr_init();
132}
133
134int sctp_sched_set_sched(struct sctp_association *asoc,
135			 enum sctp_sched_type sched)
136{
137	struct sctp_sched_ops *n = sctp_sched_ops[sched];
138	struct sctp_sched_ops *old = asoc->outqueue.sched;
139	struct sctp_datamsg *msg = NULL;
140	struct sctp_chunk *ch;
141	int i, ret = 0;
142
143	if (old == n)
144		return ret;
145
146	if (sched > SCTP_SS_MAX)
147		return -EINVAL;
148
149	if (old) {
150		old->free(&asoc->stream);
151
152		/* Give the next scheduler a clean slate. */
153		for (i = 0; i < asoc->stream.outcnt; i++) {
154			void *p = SCTP_SO(&asoc->stream, i)->ext;
155
156			if (!p)
157				continue;
158
159			p += offsetofend(struct sctp_stream_out_ext, outq);
160			memset(p, 0, sizeof(struct sctp_stream_out_ext) -
161				     offsetofend(struct sctp_stream_out_ext, outq));
162		}
163	}
164
165	asoc->outqueue.sched = n;
166	n->init(&asoc->stream);
167	for (i = 0; i < asoc->stream.outcnt; i++) {
168		if (!SCTP_SO(&asoc->stream, i)->ext)
169			continue;
170
171		ret = n->init_sid(&asoc->stream, i, GFP_ATOMIC);
172		if (ret)
173			goto err;
174	}
175
176	/* We have to requeue all chunks already queued. */
177	list_for_each_entry(ch, &asoc->outqueue.out_chunk_list, list) {
178		if (ch->msg == msg)
179			continue;
180		msg = ch->msg;
181		n->enqueue(&asoc->outqueue, msg);
182	}
183
184	return ret;
185
186err:
187	n->free(&asoc->stream);
188	asoc->outqueue.sched = &sctp_sched_fcfs; /* Always safe */
189
190	return ret;
191}
192
193int sctp_sched_get_sched(struct sctp_association *asoc)
194{
195	int i;
196
197	for (i = 0; i <= SCTP_SS_MAX; i++)
198		if (asoc->outqueue.sched == sctp_sched_ops[i])
199			return i;
200
201	return 0;
202}
203
204int sctp_sched_set_value(struct sctp_association *asoc, __u16 sid,
205			 __u16 value, gfp_t gfp)
206{
207	if (sid >= asoc->stream.outcnt)
208		return -EINVAL;
209
210	if (!SCTP_SO(&asoc->stream, sid)->ext) {
211		int ret;
212
213		ret = sctp_stream_init_ext(&asoc->stream, sid);
214		if (ret)
215			return ret;
216	}
217
218	return asoc->outqueue.sched->set(&asoc->stream, sid, value, gfp);
219}
220
221int sctp_sched_get_value(struct sctp_association *asoc, __u16 sid,
222			 __u16 *value)
223{
224	if (sid >= asoc->stream.outcnt)
225		return -EINVAL;
226
227	if (!SCTP_SO(&asoc->stream, sid)->ext)
228		return 0;
229
230	return asoc->outqueue.sched->get(&asoc->stream, sid, value);
231}
232
233void sctp_sched_dequeue_done(struct sctp_outq *q, struct sctp_chunk *ch)
234{
235	if (!list_is_last(&ch->frag_list, &ch->msg->chunks) &&
236	    !q->asoc->peer.intl_capable) {
237		struct sctp_stream_out *sout;
238		__u16 sid;
239
240		/* datamsg is not finish, so save it as current one,
241		 * in case application switch scheduler or a higher
242		 * priority stream comes in.
243		 */
244		sid = sctp_chunk_stream_no(ch);
245		sout = SCTP_SO(&q->asoc->stream, sid);
246		q->asoc->stream.out_curr = sout;
247		return;
248	}
249
250	q->asoc->stream.out_curr = NULL;
251	q->sched->dequeue_done(q, ch);
252}
253
254/* Auxiliary functions for the schedulers */
255void sctp_sched_dequeue_common(struct sctp_outq *q, struct sctp_chunk *ch)
256{
257	list_del_init(&ch->list);
258	list_del_init(&ch->stream_list);
259	q->out_qlen -= ch->skb->len;
260}
261
262int sctp_sched_init_sid(struct sctp_stream *stream, __u16 sid, gfp_t gfp)
263{
264	struct sctp_sched_ops *sched = sctp_sched_ops_from_stream(stream);
265	struct sctp_stream_out_ext *ext = SCTP_SO(stream, sid)->ext;
266
267	INIT_LIST_HEAD(&ext->outq);
268	return sched->init_sid(stream, sid, gfp);
269}
270
271struct sctp_sched_ops *sctp_sched_ops_from_stream(struct sctp_stream *stream)
272{
273	struct sctp_association *asoc;
274
275	asoc = container_of(stream, struct sctp_association, stream);
276
277	return asoc->outqueue.sched;
278}
279