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  */
  34 #include <errno.h>
  35 #include <sys/param.h>
  36 #include <pthread.h>
  37 #include "pthread_private.h"
  38
  39 __weak_reference(_pthread_setschedparam, pthread_setschedparam);
  40
  41 int
  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 }