lib/libc_r/uthread/uthread_setschedparam.c

   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/libc_r/uthread/uthread_setschedparam.c,v 1.5.2.3 2002/10/22 14:44:03 fjoe Exp $
  33  * $DragonFly: src/lib/libc_r/uthread/uthread_setschedparam.c,v 1.3 2005/05/30 22:50:53 joerg Exp $
  34  */
  35 #include <errno.h>
  36 #include <sys/param.h>
  37 #include <pthread.h>
  38 #include "pthread_private.h"
  39
  40 int
  41 _pthread_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) || (policy < SCHED_FIFO) || (policy > SCHED_RR)) {
  47                 /* Return an invalid argument error: */
  48                 ret = EINVAL;
  49         } else if ((param->sched_priority < PTHREAD_MIN_PRIORITY) ||
  50             (param->sched_priority > PTHREAD_MAX_PRIORITY)) {
  51                 /* Return an unsupported value error. */
  52                 ret = ENOTSUP;
  53
  54         /* Find the thread in the list of active threads: */
  55         } else if ((ret = _find_thread(pthread)) == 0) {
  56                 /*
  57                  * Defer signals to protect the scheduling queues from
  58                  * access by the signal handler:
  59                  */
  60                 _thread_kern_sig_defer();
  61
  62                 if (param->sched_priority !=
  63                     PTHREAD_BASE_PRIORITY(pthread->base_priority)) {
  64                         /*
  65                          * Remove the thread from its current priority
  66                          * queue before any adjustments are made to its
  67                          * active priority:
  68                          */
  69                         old_prio = pthread->active_priority;
  70                         if ((pthread->flags & PTHREAD_FLAGS_IN_PRIOQ) != 0) {
  71                                 in_readyq = 1;
  72                                 PTHREAD_PRIOQ_REMOVE(pthread);
  73                         }
  74
  75                         /* Set the thread base priority: */
  76                         pthread->base_priority &=
  77                             (PTHREAD_SIGNAL_PRIORITY | PTHREAD_RT_PRIORITY);
  78                         pthread->base_priority = param->sched_priority;
  79
  80                         /* Recalculate the active priority: */
  81                         pthread->active_priority = MAX(pthread->base_priority,
  82                             pthread->inherited_priority);
  83
  84                         if (in_readyq) {
  85                                 if ((pthread->priority_mutex_count > 0) &&
  86                                     (old_prio > pthread->active_priority)) {
  87                                         /*
  88                                          * POSIX states that if the priority is
  89                                          * being lowered, the thread must be
  90                                          * inserted at the head of the queue for
  91                                          * its priority if it owns any priority
  92                                          * protection or inheritence mutexes.
  93                                          */
  94                                         PTHREAD_PRIOQ_INSERT_HEAD(pthread);
  95                                 }
  96                                 else
  97                                         PTHREAD_PRIOQ_INSERT_TAIL(pthread);
  98                         }
  99
 100                         /*
 101                          * Check for any mutex priority adjustments.  This
 102                          * includes checking for a priority mutex on which
 103                          * this thread is waiting.
 104                          */
 105                         _mutex_notify_priochange(pthread);
 106                 }
 107
 108                 /* Set the scheduling policy: */
 109                 pthread->attr.sched_policy = policy;
 110
 111                 /*
 112                  * Undefer and handle pending signals, yielding if
 113                  * necessary:
 114                  */
 115                 _thread_kern_sig_undefer();
 116         }
 117         return(ret);
 118 }
 119
 120 __strong_reference(_pthread_setschedparam, pthread_setschedparam);