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