sys/kern/kern_usched.c

   1 /*
   2  * Copyright (c) 2005 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Sergey Glushchenko <deen@smz.com.ua>
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  * 3. Neither the name of The DragonFly Project nor the names of its
  18  *    contributors may be used to endorse or promote products derived
  19  *    from this software without specific, prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  * $DragonFly: src/sys/kern/kern_usched.c,v 1.1 2005/11/16 02:24:30 dillon Exp $
  35  */
  36
  37 #include <sys/errno.h>
  38 #include <sys/globaldata.h>             /* curthread */
  39 #include <sys/proc.h>
  40 #include <sys/sysproto.h>               /* struct usched_set_args */
  41 #include <sys/systm.h>                  /* strcmp() */
  42 #include <sys/usched.h>
  43
  44 static TAILQ_HEAD(, usched) usched_list = TAILQ_HEAD_INITIALIZER(usched_list);
  45
  46 /*
  47  * Called from very low level boot code, i386/i386/machdep.c/init386().
  48  * We cannot do anything fancy.  no malloc's, no nothing other then
  49  * static initialization.
  50  */
  51 struct usched *
  52 usched_init(void)
  53 {
  54         /*
  55          * Add the bsd4 userland scheduler to the system.
  56          */
  57         usched_ctl(&usched_bsd4, USCH_ADD);
  58         return(&usched_bsd4);
  59 }
  60
  61 /*
  62  * USCHED_CTL
  63  *
  64  * SYNOPSIS:
  65  *      Add/remove usched to/from list.
  66  *
  67  * ARGUMENTS:
  68  *      usched - pointer to target scheduler
  69  *      action - addition or removal ?
  70  *
  71  * RETURN VALUES:
  72  *      0 - success
  73  *      EINVAL - error
  74  */
  75 int
  76 usched_ctl(struct usched *usched, int action)
  77 {
  78         struct usched *item;    /* temporaly for TAILQ processing */
  79         int error = 0;
  80
  81         switch(action) {
  82         case USCH_ADD:
  83                 /*
  84                  * Make sure it isn't already on the list
  85                  */
  86 #ifdef INVARIANTS
  87                 TAILQ_FOREACH(item, &usched_list, entry) {
  88                         KKASSERT(item != usched);
  89                 }
  90 #endif
  91                 /*
  92                  * Optional callback to the scheduler before we officially
  93                  * add it to the list.
  94                  */
  95                 if (usched->usched_register)
  96                         usched->usched_register();
  97                 TAILQ_INSERT_TAIL(&usched_list, usched, entry);
  98                 break;
  99         case USCH_REM:
 100                 /*
 101                  * Do not allow the default scheduler to be removed
 102                  */
 103                 if (strcmp(usched->name, "bsd4") == 0) {
 104                         error = EINVAL;
 105                         break;
 106                 }
 107                 TAILQ_FOREACH(item, &usched_list, entry) {
 108                         if (item == usched)
 109                                 break;
 110                 }
 111                 if (item) {
 112                         if (item->usched_unregister)
 113                                 item->usched_unregister();
 114                         TAILQ_REMOVE(&usched_list, item, entry);
 115                 } else {
 116                         error = EINVAL;
 117                 }
 118                 break;
 119         default:
 120                 error = EINVAL;
 121                 break;
 122         }
 123         return (error);
 124 }
 125
 126 /*
 127  * USCHED_SET(syscall)
 128  *
 129  * SYNOPSIS:
 130  *      Setting up a proc's usched.
 131  *
 132  * ARGUMENTS:
 133  *      name - usched's name
 134  *
 135  * RETURN VALUES:
 136  *      0 - success
 137  *      EINVAL - error
 138  */
 139 int
 140 usched_set(struct usched_set_args *uap)
 141 {
 142         struct proc *p = curthread->td_proc;
 143         struct usched *item;    /* temporaly for TAILQ processing */
 144         int error;
 145
 146         if ((error = suser(curthread)) != 0)
 147                 return (error);
 148
 149         TAILQ_FOREACH(item, &usched_list, entry) {
 150                 if (strcmp(item->name, uap->name) == 0)
 151                         break;
 152         }
 153
 154         /*
 155          * If the scheduler for a process is being changed, disassociate
 156          * the old scheduler before switching to the new one.
 157          *
 158          * XXX we might have to add an additional ABI call to do a 'full
 159          * disassociation' and another ABI call to do a 'full reassociation'
 160          */
 161         if (item && item != p->p_usched) {
 162                 p->p_usched->release_curproc(&p->p_lwp);
 163                 p->p_usched = item;
 164         } else if (item == NULL) {
 165                 error = EINVAL;
 166         }
 167         return (error);
 168 }
 169