thr_setschedparam.c revision 103388 
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 103388 2002-09-16 08:45:36Z mini $
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	int old_prio, in_readyq = 0, ret = 0;
46
47	if ((param == NULL) || (policy < SCHED_FIFO) || (policy > SCHED_RR)) {
48		/* Return an invalid argument error: */
49		ret = EINVAL;
50	} else if ((param->sched_priority < PTHREAD_MIN_PRIORITY) ||
51	    (param->sched_priority > PTHREAD_MAX_PRIORITY)) {
52		/* Return an unsupported value error. */
53		ret = ENOTSUP;
54
55	/* Find the thread in the list of active threads: */
56	} else if ((ret = _find_thread(pthread)) == 0) {
57		/*
58		 * Defer signals to protect the scheduling queues from
59		 * access by the signal handler:
60		 */
61		_thread_kern_sig_defer();
62
63		if (param->sched_priority !=
64		    PTHREAD_BASE_PRIORITY(pthread->base_priority)) {
65			/*
66			 * Remove the thread from its current priority
67			 * queue before any adjustments are made to its
68			 * active priority:
69			 */
70			old_prio = pthread->active_priority;
71			if ((pthread->flags & PTHREAD_FLAGS_IN_PRIOQ) != 0) {
72				in_readyq = 1;
73				PTHREAD_PRIOQ_REMOVE(pthread);
74			}
75
76			/* Set the thread base priority: */
77			pthread->base_priority &=
78			    (PTHREAD_SIGNAL_PRIORITY | PTHREAD_RT_PRIORITY);
79			pthread->base_priority = param->sched_priority;
80
81			/* Recalculate the active priority: */
82			pthread->active_priority = MAX(pthread->base_priority,
83			    pthread->inherited_priority);
84
85			if (in_readyq) {
86				if ((pthread->priority_mutex_count > 0) &&
87				    (old_prio > pthread->active_priority)) {
88					/*
89					 * POSIX states that if the priority is
90					 * being lowered, the thread must be
91					 * inserted at the head of the queue for
92					 * its priority if it owns any priority
93					 * protection or inheritence mutexes.
94					 */
95					PTHREAD_PRIOQ_INSERT_HEAD(pthread);
96				}
97				else
98					PTHREAD_PRIOQ_INSERT_TAIL(pthread);
99			}
100
101			/*
102			 * Check for any mutex priority adjustments.  This
103			 * includes checking for a priority mutex on which
104			 * this thread is waiting.
105			 */
106			_mutex_notify_priochange(pthread);
107		}
108
109		/* Set the scheduling policy: */
110		pthread->attr.sched_policy = policy;
111
112		/*
113		 * Undefer and handle pending signals, yielding if
114		 * necessary:
115		 */
116		_thread_kern_sig_undefer();
117	}
118	return(ret);
119}
120