thr_setschedparam.c revision 174112 
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 174112 2007-11-30 17:20:29Z deischen $
33 */
34
35#include "namespace.h"
36#include <errno.h>
37#include <sys/param.h>
38#include <pthread.h>
39#include "un-namespace.h"
40#include "thr_private.h"
41
42LT10_COMPAT_PRIVATE(_pthread_setschedparam);
43LT10_COMPAT_DEFAULT(pthread_setschedparam);
44
45__weak_reference(_pthread_setschedparam, pthread_setschedparam);
46
47int
48_pthread_setschedparam(pthread_t pthread, int policy,
49	const struct sched_param *param)
50{
51	struct pthread *curthread = _get_curthread();
52	int	in_syncq;
53	int	in_readyq = 0;
54	int	old_prio;
55	int	ret = 0;
56
57	if ((param == NULL) || (policy < SCHED_FIFO) || (policy > SCHED_RR)) {
58		/* Return an invalid argument error: */
59		ret = EINVAL;
60	} else if ((param->sched_priority < THR_MIN_PRIORITY) ||
61	    (param->sched_priority > THR_MAX_PRIORITY)) {
62		/* Return an unsupported value error. */
63		ret = ENOTSUP;
64
65	/* Find the thread in the list of active threads: */
66	} else if ((ret = _thr_ref_add(curthread, pthread, /*include dead*/0))
67	    == 0) {
68		/*
69		 * Lock the threads scheduling queue while we change
70		 * its priority:
71		 */
72		THR_SCHED_LOCK(curthread, pthread);
73		if ((pthread->state == PS_DEAD) ||
74		    (pthread->state == PS_DEADLOCK) ||
75		    ((pthread->flags & THR_FLAGS_EXITING) != 0)) {
76			THR_SCHED_UNLOCK(curthread, pthread);
77			_thr_ref_delete(curthread, pthread);
78			return (ESRCH);
79		}
80		in_syncq = pthread->sflags & THR_FLAGS_IN_SYNCQ;
81
82		/* Set the scheduling policy: */
83		pthread->attr.sched_policy = policy;
84
85		if (param->sched_priority ==
86		    THR_BASE_PRIORITY(pthread->base_priority))
87			/*
88			 * There is nothing to do; unlock the threads
89			 * scheduling queue.
90			 */
91			THR_SCHED_UNLOCK(curthread, pthread);
92		else {
93			/*
94			 * Remove the thread from its current priority
95			 * queue before any adjustments are made to its
96			 * active priority:
97			 */
98			old_prio = pthread->active_priority;
99			if ((pthread->flags & THR_FLAGS_IN_RUNQ) != 0) {
100				in_readyq = 1;
101				THR_RUNQ_REMOVE(pthread);
102			}
103
104			/* Set the thread base priority: */
105			pthread->base_priority &=
106			    (THR_SIGNAL_PRIORITY | THR_RT_PRIORITY);
107			pthread->base_priority = param->sched_priority;
108
109			/* Recalculate the active priority: */
110			pthread->active_priority = MAX(pthread->base_priority,
111			    pthread->inherited_priority);
112
113			if (in_readyq) {
114				if ((pthread->priority_mutex_count > 0) &&
115				    (old_prio > pthread->active_priority)) {
116					/*
117					 * POSIX states that if the priority is
118					 * being lowered, the thread must be
119					 * inserted at the head of the queue for
120					 * its priority if it owns any priority
121					 * protection or inheritence mutexes.
122					 */
123					THR_RUNQ_INSERT_HEAD(pthread);
124				}
125				else
126					THR_RUNQ_INSERT_TAIL(pthread);
127			}
128
129			/* Unlock the threads scheduling queue: */
130			THR_SCHED_UNLOCK(curthread, pthread);
131
132			/*
133			 * Check for any mutex priority adjustments.  This
134			 * includes checking for a priority mutex on which
135			 * this thread is waiting.
136			 */
137			_mutex_notify_priochange(curthread, pthread, in_syncq);
138		}
139		_thr_ref_delete(curthread, pthread);
140	}
141	return (ret);
142}
143