thr_setschedparam.c revision 53812 
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 53812 1999-11-28 05:38:13Z alfred $
33 */
34#include <errno.h>
35#include <sys/param.h>
36#ifdef _THREAD_SAFE
37#include <pthread.h>
38#include "pthread_private.h"
39
40int
41pthread_setschedparam(pthread_t pthread, int policy,
42	const struct sched_param *param)
43{
44	int old_prio, in_readyq = 0, ret = 0;
45
46	if ((param == NULL) || (param->sched_priority < PTHREAD_MIN_PRIORITY) ||
47	    (param->sched_priority > PTHREAD_MAX_PRIORITY) ||
48	    (policy < SCHED_FIFO) || (policy > SCHED_RR))
49		/* Return an invalid argument error: */
50		ret = EINVAL;
51
52	/* Find the thread in the list of active threads: */
53	else if ((ret = _find_thread(pthread)) == 0) {
54		/*
55		 * Defer signals to protect the scheduling queues from
56		 * access by the signal handler:
57		 */
58		_thread_kern_sig_defer();
59
60		if (param->sched_priority != pthread->base_priority) {
61			/*
62			 * Remove the thread from its current priority
63			 * queue before any adjustments are made to its
64			 * active priority:
65			 */
66			if ((pthread->flags & PTHREAD_FLAGS_IN_PRIOQ) != 0) {
67				in_readyq = 1;
68				old_prio = pthread->active_priority;
69				PTHREAD_PRIOQ_REMOVE(pthread);
70			}
71
72			/* Set the thread base priority: */
73			pthread->base_priority = param->sched_priority;
74
75			/* Recalculate the active priority: */
76			pthread->active_priority = MAX(pthread->base_priority,
77			    pthread->inherited_priority);
78
79			if (in_readyq) {
80				if ((pthread->priority_mutex_count > 0) &&
81				    (old_prio > pthread->active_priority)) {
82					/*
83					 * POSIX states that if the priority is
84					 * being lowered, the thread must be
85					 * inserted at the head of the queue for
86					 * its priority if it owns any priority
87					 * protection or inheritence mutexes.
88					 */
89					PTHREAD_PRIOQ_INSERT_HEAD(pthread);
90				}
91				else
92					PTHREAD_PRIOQ_INSERT_TAIL(pthread);
93			}
94
95			/*
96			 * Check for any mutex priority adjustments.  This
97			 * includes checking for a priority mutex on which
98			 * this thread is waiting.
99			 */
100			_mutex_notify_priochange(pthread);
101		}
102
103		/* Set the scheduling policy: */
104		pthread->attr.sched_policy = policy;
105
106		/*
107		 * Undefer and handle pending signals, yielding if
108		 * necessary:
109		 */
110		_thread_kern_sig_undefer();
111	}
112	return(ret);
113}
114#endif
115