thr_setschedparam.c revision 113658 
1/*
2 * Copyright (c) 1998 Daniel Eischen <eischen@vigrid.com>.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by Daniel Eischen.
16 * 4. Neither the name of the author nor the names of any co-contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY DANIEL EISCHEN AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
32 * $FreeBSD: head/lib/libkse/thread/thr_setschedparam.c 113658 2003-04-18 05:04:16Z deischen $
33 */
34#include <errno.h>
35#include <sys/param.h>
36#include <pthread.h>
37#include "thr_private.h"
38
39__weak_reference(_pthread_setschedparam, pthread_setschedparam);
40
41int
42_pthread_setschedparam(pthread_t pthread, int policy,
43	const struct sched_param *param)
44{
45	struct pthread *curthread = _get_curthread();
46	int	in_syncq;
47	int	in_readyq = 0;
48	int	old_prio;
49	int	ret = 0;
50
51	if ((param == NULL) || (policy < SCHED_FIFO) || (policy > SCHED_RR)) {
52		/* Return an invalid argument error: */
53		ret = EINVAL;
54	} else if ((param->sched_priority < THR_MIN_PRIORITY) ||
55	    (param->sched_priority > THR_MAX_PRIORITY)) {
56		/* Return an unsupported value error. */
57		ret = ENOTSUP;
58
59	/* Find the thread in the list of active threads: */
60	} else if ((ret = _thr_ref_add(curthread, pthread, /*include dead*/0))
61	    == 0) {
62		/*
63		 * Lock the threads scheduling queue while we change
64		 * its priority:
65		 */
66		THR_SCHED_LOCK(curthread, pthread);
67		in_syncq = pthread->flags & THR_FLAGS_IN_SYNCQ;
68
69		/* Set the scheduling policy: */
70		pthread->attr.sched_policy = policy;
71
72		if (param->sched_priority ==
73		    THR_BASE_PRIORITY(pthread->base_priority))
74			/*
75			 * There is nothing to do; unlock the threads
76			 * scheduling queue.
77			 */
78			THR_SCHED_UNLOCK(curthread, pthread);
79		else {
80			/*
81			 * Remove the thread from its current priority
82			 * queue before any adjustments are made to its
83			 * active priority:
84			 */
85			old_prio = pthread->active_priority;
86			if ((pthread->flags & THR_FLAGS_IN_RUNQ) != 0) {
87				in_readyq = 1;
88				THR_RUNQ_REMOVE(pthread);
89			}
90
91			/* Set the thread base priority: */
92			pthread->base_priority &=
93			    (THR_SIGNAL_PRIORITY | THR_RT_PRIORITY);
94			pthread->base_priority = param->sched_priority;
95
96			/* Recalculate the active priority: */
97			pthread->active_priority = MAX(pthread->base_priority,
98			    pthread->inherited_priority);
99
100			if (in_readyq) {
101				if ((pthread->priority_mutex_count > 0) &&
102				    (old_prio > pthread->active_priority)) {
103					/*
104					 * POSIX states that if the priority is
105					 * being lowered, the thread must be
106					 * inserted at the head of the queue for
107					 * its priority if it owns any priority
108					 * protection or inheritence mutexes.
109					 */
110					THR_RUNQ_INSERT_HEAD(pthread);
111				}
112				else
113					THR_RUNQ_INSERT_TAIL(pthread);
114			}
115
116			/* Unlock the threads scheduling queue: */
117			THR_SCHED_UNLOCK(curthread, pthread);
118
119			/*
120			 * Check for any mutex priority adjustments.  This
121			 * includes checking for a priority mutex on which
122			 * this thread is waiting.
123			 */
124			_mutex_notify_priochange(curthread, pthread, in_syncq);
125		}
126		_thr_ref_delete(curthread, pthread);
127	}
128	return (ret);
129}
130