1/*-
2 * SPDX-License-Identifier: BSD-4-Clause
3 *
4 * Copyright (c) 1996, 1997
5 *	HD Associates, Inc.  All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. All advertising materials mentioning features or use of this software
16 *    must display the following acknowledgement:
17 *	This product includes software developed by HD Associates, Inc
18 * 4. Neither the name of the author nor the names of any co-contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY HD ASSOCIATES AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL HD ASSOCIATES OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35/* ksched: Soft real time scheduling based on "rtprio". */
36
37#include <sys/cdefs.h>
38__FBSDID("$FreeBSD$");
39
40#include "opt_posix.h"
41
42#include <sys/param.h>
43#include <sys/systm.h>
44#include <sys/lock.h>
45#include <sys/sysctl.h>
46#include <sys/kernel.h>
47#include <sys/mutex.h>
48#include <sys/proc.h>
49#include <sys/posix4.h>
50#include <sys/resource.h>
51#include <sys/sched.h>
52
53FEATURE(kposix_priority_scheduling, "POSIX P1003.1B realtime extensions");
54
55/* ksched: Real-time extension to support POSIX priority scheduling. */
56
57struct ksched {
58	struct timespec rr_interval;
59};
60
61int
62ksched_attach(struct ksched **p)
63{
64	struct ksched *ksched;
65
66	ksched = malloc(sizeof(*ksched), M_P31B, M_WAITOK);
67	ksched->rr_interval.tv_sec = 0;
68	ksched->rr_interval.tv_nsec = 1000000000L / hz * sched_rr_interval();
69	*p = ksched;
70	return (0);
71}
72
73int
74ksched_detach(struct ksched *ks)
75{
76
77	free(ks, M_P31B);
78	return (0);
79}
80
81/*
82 * XXX About priorities
83 *
84 *	POSIX 1003.1b requires that numerically higher priorities be of
85 *	higher priority.  It also permits sched_setparam to be
86 *	implementation defined for SCHED_OTHER.  I don't like
87 *	the notion of inverted priorites for normal processes when
88 *      you can use "setpriority" for that.
89 *
90 */
91
92/* Macros to convert between the unix (lower numerically is higher priority)
93 * and POSIX 1003.1b (higher numerically is higher priority)
94 */
95
96#define p4prio_to_rtpprio(P) (RTP_PRIO_MAX - (P))
97#define rtpprio_to_p4prio(P) (RTP_PRIO_MAX - (P))
98
99#define p4prio_to_tsprio(P) ((PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE) - (P))
100#define tsprio_to_p4prio(P) ((PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE) - (P))
101
102/* These improve readability a bit for me:
103 */
104#define P1B_PRIO_MIN rtpprio_to_p4prio(RTP_PRIO_MAX)
105#define P1B_PRIO_MAX rtpprio_to_p4prio(RTP_PRIO_MIN)
106
107static __inline int
108getscheduler(struct ksched *ksched, struct thread *td, int *policy)
109{
110	struct rtprio rtp;
111	int e;
112
113	e = 0;
114	pri_to_rtp(td, &rtp);
115	switch (rtp.type) {
116	case RTP_PRIO_FIFO:
117		*policy = SCHED_FIFO;
118		break;
119	case RTP_PRIO_REALTIME:
120		*policy = SCHED_RR;
121		break;
122	default:
123		*policy = SCHED_OTHER;
124		break;
125	}
126	return (e);
127}
128
129int
130ksched_setparam(struct ksched *ksched,
131    struct thread *td, const struct sched_param *param)
132{
133	int e, policy;
134
135	e = getscheduler(ksched, td, &policy);
136	if (e == 0)
137		e = ksched_setscheduler(ksched, td, policy, param);
138	return (e);
139}
140
141int
142ksched_getparam(struct ksched *ksched, struct thread *td,
143    struct sched_param *param)
144{
145	struct rtprio rtp;
146
147	pri_to_rtp(td, &rtp);
148	if (RTP_PRIO_IS_REALTIME(rtp.type))
149		param->sched_priority = rtpprio_to_p4prio(rtp.prio);
150	else {
151		if (PRI_MIN_TIMESHARE < rtp.prio)
152			/*
153		 	 * The interactive score has it to min realtime
154			 * so we must show max (64 most likely).
155			 */
156			param->sched_priority = PRI_MAX_TIMESHARE -
157			    PRI_MIN_TIMESHARE;
158		else
159			param->sched_priority = tsprio_to_p4prio(rtp.prio);
160	}
161	return (0);
162}
163
164/*
165 * XXX The priority and scheduler modifications should
166 *     be moved into published interfaces in kern/kern_sync.
167 *
168 * The permissions to modify process p were checked in "p31b_proc()".
169 *
170 */
171int
172ksched_setscheduler(struct ksched *ksched, struct thread *td, int policy,
173    const struct sched_param *param)
174{
175	struct rtprio rtp;
176	int e;
177
178	e = 0;
179	switch(policy) {
180	case SCHED_RR:
181	case SCHED_FIFO:
182		if (param->sched_priority >= P1B_PRIO_MIN &&
183		    param->sched_priority <= P1B_PRIO_MAX) {
184			rtp.prio = p4prio_to_rtpprio(param->sched_priority);
185			rtp.type = (policy == SCHED_FIFO) ? RTP_PRIO_FIFO :
186			    RTP_PRIO_REALTIME;
187			rtp_to_pri(&rtp, td);
188		} else {
189			e = EPERM;
190		}
191		break;
192	case SCHED_OTHER:
193		if (param->sched_priority >= 0 && param->sched_priority <=
194		    (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE)) {
195			rtp.type = RTP_PRIO_NORMAL;
196			rtp.prio = p4prio_to_tsprio(param->sched_priority);
197			rtp_to_pri(&rtp, td);
198		} else {
199			e = EINVAL;
200		}
201		break;
202	default:
203		e = EINVAL;
204		break;
205	}
206	return (e);
207}
208
209int
210ksched_getscheduler(struct ksched *ksched, struct thread *td, int *policy)
211{
212
213	return (getscheduler(ksched, td, policy));
214}
215
216/* ksched_yield: Yield the CPU. */
217int
218ksched_yield(struct ksched *ksched)
219{
220
221	sched_relinquish(curthread);
222	return (0);
223}
224
225int
226ksched_get_priority_max(struct ksched *ksched, int policy, int *prio)
227{
228	int e;
229
230	e = 0;
231	switch (policy)	{
232	case SCHED_FIFO:
233	case SCHED_RR:
234		*prio = P1B_PRIO_MAX;
235		break;
236	case SCHED_OTHER:
237		*prio = PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE;
238		break;
239	default:
240		e = EINVAL;
241		break;
242	}
243	return (e);
244}
245
246int
247ksched_get_priority_min(struct ksched *ksched, int policy, int *prio)
248{
249	int e;
250
251	e = 0;
252	switch (policy)	{
253	case SCHED_FIFO:
254	case SCHED_RR:
255		*prio = P1B_PRIO_MIN;
256		break;
257	case SCHED_OTHER:
258		*prio = 0;
259		break;
260	default:
261		e = EINVAL;
262		break;
263	}
264	return (e);
265}
266
267int
268ksched_rr_get_interval(struct ksched *ksched, struct thread *td,
269    struct timespec *timespec)
270{
271
272	*timespec = ksched->rr_interval;
273	return (0);
274}
275