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: src/lib/libpthread/thread/thr_setschedparam.c,v 1.13 2003/04/21 04:02:56 deischen Exp $
33  * $DragonFly: src/lib/libthread_xu/thread/thr_setschedparam.c,v 1.2 2005/03/29 19:26:20 joerg Exp $
34  */
35 
36 #include <machine/tls.h>
37 
38 #include <errno.h>
39 #include <sys/param.h>
40 #include <pthread.h>
41 #include "thr_private.h"
42 
43 __weak_reference(_pthread_setschedparam, pthread_setschedparam);
44 
45 int
46 _pthread_setschedparam(pthread_t pthread, int policy,
47 	const struct sched_param *param)
48 {
49 	struct pthread *curthread = tls_get_curthread();
50 	int	in_syncq;
51 	int	in_readyq = 0;
52 	int	old_prio;
53 	int	ret = 0;
54 
55 	if ((param == NULL) || (policy < SCHED_FIFO) || (policy > SCHED_RR)) {
56 		/* Return an invalid argument error: */
57 		ret = EINVAL;
58 	} else if ((param->sched_priority < THR_MIN_PRIORITY) ||
59 	    (param->sched_priority > THR_MAX_PRIORITY)) {
60 		/* Return an unsupported value error. */
61 		ret = ENOTSUP;
62 
63 	/* Find the thread in the list of active threads: */
64 	} else if ((ret = _thr_ref_add(curthread, pthread, /*include dead*/0))
65 	    == 0) {
66 		/*
67 		 * Lock the threads scheduling queue while we change
68 		 * its priority:
69 		 */
70 		THR_THREAD_LOCK(curthread, pthread);
71 		if (pthread->state == PS_DEAD) {
72 			THR_THREAD_UNLOCK(curthread, pthread);
73 			_thr_ref_delete(curthread, pthread);
74 			return (ESRCH);
75 		}
76 		in_syncq = pthread->sflags & THR_FLAGS_IN_SYNCQ;
77 
78 		/* Set the scheduling policy: */
79 		pthread->attr.sched_policy = policy;
80 
81 		if (param->sched_priority ==
82 		    THR_BASE_PRIORITY(pthread->base_priority))
83 			/*
84 			 * There is nothing to do; unlock the threads
85 			 * scheduling queue.
86 			 */
87 			THR_THREAD_UNLOCK(curthread, pthread);
88 		else {
89 			/*
90 			 * Remove the thread from its current priority
91 			 * queue before any adjustments are made to its
92 			 * active priority:
93 			 */
94 			old_prio = pthread->active_priority;
95 			/* if ((pthread->flags & THR_FLAGS_IN_RUNQ) != 0) */ {
96 				in_readyq = 1;
97 				/* THR_RUNQ_REMOVE(pthread); */
98 			}
99 
100 			/* Set the thread base priority: */
101 			pthread->base_priority &=
102 			    (THR_SIGNAL_PRIORITY | THR_RT_PRIORITY);
103 			pthread->base_priority = param->sched_priority;
104 
105 			/* Recalculate the active priority: */
106 			pthread->active_priority = MAX(pthread->base_priority,
107 			    pthread->inherited_priority);
108 
109 			if (in_readyq) {
110 				if ((pthread->priority_mutex_count > 0) &&
111 				    (old_prio > pthread->active_priority)) {
112 					/*
113 					 * POSIX states that if the priority is
114 					 * being lowered, the thread must be
115 					 * inserted at the head of the queue for
116 					 * its priority if it owns any priority
117 					 * protection or inheritence mutexes.
118 					 */
119 					/* THR_RUNQ_INSERT_HEAD(pthread); */
120 				}
121 				else
122 					/* THR_RUNQ_INSERT_TAIL(pthread)*/ ;
123 			}
124 
125 			/* Unlock the threads scheduling queue: */
126 			THR_THREAD_UNLOCK(curthread, pthread);
127 
128 			/*
129 			 * Check for any mutex priority adjustments.  This
130 			 * includes checking for a priority mutex on which
131 			 * this thread is waiting.
132 			 */
133 			_mutex_notify_priochange(curthread, pthread, in_syncq);
134 		}
135 		_thr_ref_delete(curthread, pthread);
136 	}
137 	return (ret);
138 }
139