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_enqueue(struct sctp_outq *q,
54				    struct sctp_datamsg *msg)
55{
56}
57
58static struct sctp_chunk *sctp_sched_fcfs_dequeue(struct sctp_outq *q)
59{
60	struct sctp_stream *stream = &q->asoc->stream;
61	struct sctp_chunk *ch = NULL;
62	struct list_head *entry;
63
64	if (list_empty(&q->out_chunk_list))
65		goto out;
66
67	if (stream->out_curr) {
68		ch = list_entry(stream->out_curr->ext->outq.next,
69				struct sctp_chunk, stream_list);
70	} else {
71		entry = q->out_chunk_list.next;
72		ch = list_entry(entry, struct sctp_chunk, list);
73	}
74
75	sctp_sched_dequeue_common(q, ch);
76
77out:
78	return ch;
79}
80
81static void sctp_sched_fcfs_dequeue_done(struct sctp_outq *q,
82					 struct sctp_chunk *chunk)
83{
84}
85
86static void sctp_sched_fcfs_sched_all(struct sctp_stream *stream)
87{
88}
89
90static void sctp_sched_fcfs_unsched_all(struct sctp_stream *stream)
91{
92}
93
94static struct sctp_sched_ops sctp_sched_fcfs = {
95	.set = sctp_sched_fcfs_set,
96	.get = sctp_sched_fcfs_get,
97	.init = sctp_sched_fcfs_init,
98	.init_sid = sctp_sched_fcfs_init_sid,
99	.free_sid = sctp_sched_fcfs_free_sid,
100	.enqueue = sctp_sched_fcfs_enqueue,
101	.dequeue = sctp_sched_fcfs_dequeue,
102	.dequeue_done = sctp_sched_fcfs_dequeue_done,
103	.sched_all = sctp_sched_fcfs_sched_all,
104	.unsched_all = sctp_sched_fcfs_unsched_all,
105};
106
107static void sctp_sched_ops_fcfs_init(void)
108{
109	sctp_sched_ops_register(SCTP_SS_FCFS, &sctp_sched_fcfs);
110}
111
112/* API to other parts of the stack */
113
114static struct sctp_sched_ops *sctp_sched_ops[SCTP_SS_MAX + 1];
115
116void sctp_sched_ops_register(enum sctp_sched_type sched,
117			     struct sctp_sched_ops *sched_ops)
118{
119	sctp_sched_ops[sched] = sched_ops;
120}
121
122void sctp_sched_ops_init(void)
123{
124	sctp_sched_ops_fcfs_init();
125	sctp_sched_ops_prio_init();
126	sctp_sched_ops_rr_init();
127	sctp_sched_ops_fc_init();
128	sctp_sched_ops_wfq_init();
129}
130
131static void sctp_sched_free_sched(struct sctp_stream *stream)
132{
133	struct sctp_sched_ops *sched = sctp_sched_ops_from_stream(stream);
134	struct sctp_stream_out_ext *soute;
135	int i;
136
137	sched->unsched_all(stream);
138	for (i = 0; i < stream->outcnt; i++) {
139		soute = SCTP_SO(stream, i)->ext;
140		if (!soute)
141			continue;
142		sched->free_sid(stream, i);
143		/* Give the next scheduler a clean slate. */
144		memset_after(soute, 0, outq);
145	}
146}
147
148int sctp_sched_set_sched(struct sctp_association *asoc,
149			 enum sctp_sched_type sched)
150{
151	struct sctp_sched_ops *old = asoc->outqueue.sched;
152	struct sctp_datamsg *msg = NULL;
153	struct sctp_sched_ops *n;
154	struct sctp_chunk *ch;
155	int i, ret = 0;
156
157	if (sched > SCTP_SS_MAX)
158		return -EINVAL;
159
160	n = sctp_sched_ops[sched];
161	if (old == n)
162		return ret;
163
164	if (old)
165		sctp_sched_free_sched(&asoc->stream);
166
167	asoc->outqueue.sched = n;
168	n->init(&asoc->stream);
169	for (i = 0; i < asoc->stream.outcnt; i++) {
170		if (!SCTP_SO(&asoc->stream, i)->ext)
171			continue;
172
173		ret = n->init_sid(&asoc->stream, i, GFP_ATOMIC);
174		if (ret)
175			goto err;
176	}
177
178	/* We have to requeue all chunks already queued. */
179	list_for_each_entry(ch, &asoc->outqueue.out_chunk_list, list) {
180		if (ch->msg == msg)
181			continue;
182		msg = ch->msg;
183		n->enqueue(&asoc->outqueue, msg);
184	}
185
186	return ret;
187
188err:
189	sctp_sched_free_sched(&asoc->stream);
190	asoc->outqueue.sched = &sctp_sched_fcfs; /* Always safe */
191
192	return ret;
193}
194
195int sctp_sched_get_sched(struct sctp_association *asoc)
196{
197	int i;
198
199	for (i = 0; i <= SCTP_SS_MAX; i++)
200		if (asoc->outqueue.sched == sctp_sched_ops[i])
201			return i;
202
203	return 0;
204}
205
206int sctp_sched_set_value(struct sctp_association *asoc, __u16 sid,
207			 __u16 value, gfp_t gfp)
208{
209	if (sid >= asoc->stream.outcnt)
210		return -EINVAL;
211
212	if (!SCTP_SO(&asoc->stream, sid)->ext) {
213		int ret;
214
215		ret = sctp_stream_init_ext(&asoc->stream, sid);
216		if (ret)
217			return ret;
218	}
219
220	return asoc->outqueue.sched->set(&asoc->stream, sid, value, gfp);
221}
222
223int sctp_sched_get_value(struct sctp_association *asoc, __u16 sid,
224			 __u16 *value)
225{
226	if (sid >= asoc->stream.outcnt)
227		return -EINVAL;
228
229	if (!SCTP_SO(&asoc->stream, sid)->ext)
230		return 0;
231
232	return asoc->outqueue.sched->get(&asoc->stream, sid, value);
233}
234
235void sctp_sched_dequeue_done(struct sctp_outq *q, struct sctp_chunk *ch)
236{
237	if (!list_is_last(&ch->frag_list, &ch->msg->chunks) &&
238	    !q->asoc->peer.intl_capable) {
239		struct sctp_stream_out *sout;
240		__u16 sid;
241
242		/* datamsg is not finish, so save it as current one,
243		 * in case application switch scheduler or a higher
244		 * priority stream comes in.
245		 */
246		sid = sctp_chunk_stream_no(ch);
247		sout = SCTP_SO(&q->asoc->stream, sid);
248		q->asoc->stream.out_curr = sout;
249		return;
250	}
251
252	q->asoc->stream.out_curr = NULL;
253	q->sched->dequeue_done(q, ch);
254}
255
256/* Auxiliary functions for the schedulers */
257void sctp_sched_dequeue_common(struct sctp_outq *q, struct sctp_chunk *ch)
258{
259	list_del_init(&ch->list);
260	list_del_init(&ch->stream_list);
261	q->out_qlen -= ch->skb->len;
262}
263
264int sctp_sched_init_sid(struct sctp_stream *stream, __u16 sid, gfp_t gfp)
265{
266	struct sctp_sched_ops *sched = sctp_sched_ops_from_stream(stream);
267	struct sctp_stream_out_ext *ext = SCTP_SO(stream, sid)->ext;
268
269	INIT_LIST_HEAD(&ext->outq);
270	return sched->init_sid(stream, sid, gfp);
271}
272
273struct sctp_sched_ops *sctp_sched_ops_from_stream(struct sctp_stream *stream)
274{
275	struct sctp_association *asoc;
276
277	asoc = container_of(stream, struct sctp_association, stream);
278
279	return asoc->outqueue.sched;
280}
281