thr_setschedparam.c revision 44963 
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 */
33#include <errno.h>
34#include <sys/param.h>
35#ifdef _THREAD_SAFE
36#include <pthread.h>
37#include "pthread_private.h"
38
39int
40pthread_setschedparam(pthread_t pthread, int policy, struct sched_param *param)
41{
42	int old_prio, in_readyq = 0, ret = 0;
43
44	if ((param == NULL) || (param->sched_priority < PTHREAD_MIN_PRIORITY) ||
45	    (param->sched_priority > PTHREAD_MAX_PRIORITY) ||
46	    (policy < SCHED_FIFO) || (policy > SCHED_RR))
47		/* Return an invalid argument error: */
48		ret = EINVAL;
49
50	/* Find the thread in the list of active threads: */
51	else if ((ret = _find_thread(pthread)) == 0) {
52		/*
53		 * Guard against being preempted by a scheduling
54		 * signal:
55		 */
56		_thread_kern_sched_defer();
57
58		if (param->sched_priority != pthread->base_priority) {
59			/*
60			 * Remove the thread from its current priority
61			 * queue before any adjustments are made to its
62			 * active priority:
63			 */
64			if ((pthread != _thread_run) &&
65			   (pthread->state == PS_RUNNING)) {
66				in_readyq = 1;
67				old_prio = pthread->active_priority;
68				PTHREAD_PRIOQ_REMOVE(pthread);
69			}
70
71			/* Set the thread base priority: */
72			pthread->base_priority = param->sched_priority;
73
74			/* Recalculate the active priority: */
75			pthread->active_priority = MAX(pthread->base_priority,
76			    pthread->inherited_priority);
77
78			if (in_readyq) {
79				if ((pthread->priority_mutex_count > 0) &&
80				    (old_prio > pthread->active_priority)) {
81					/*
82					 * POSIX states that if the priority is
83					 * being lowered, the thread must be
84					 * inserted at the head of the queue for
85					 * its priority if it owns any priority
86					 * protection or inheritence mutexes.
87					 */
88					PTHREAD_PRIOQ_INSERT_HEAD(pthread);
89				}
90				else
91					PTHREAD_PRIOQ_INSERT_TAIL(pthread);
92			}
93
94			/*
95			 * Check for any mutex priority adjustments.  This
96			 * includes checking for a priority mutex on which
97			 * this thread is waiting.
98			 */
99			_mutex_notify_priochange(pthread);
100		}
101
102		/* Set the scheduling policy: */
103		pthread->attr.sched_policy = policy;
104
105		/*
106		 * Renable preemption and yield if a scheduling signal
107		 * arrived while in the critical region:
108		 */
109		_thread_kern_sched_undefer();
110	}
111	return(ret);
112}
113#endif
114