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2 pj 1
/*
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 * Project: S.Ha.R.K.
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 *
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 * Coordinators:
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 *   Giorgio Buttazzo    <giorgio@sssup.it>
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 *   Paolo Gai           <pj@gandalf.sssup.it>
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 *
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 * Authors     :
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 *   Paolo Gai           <pj@gandalf.sssup.it>
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 *   Massimiliano Giorgi <massy@gandalf.sssup.it>
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 *   Luca Abeni          <luca@gandalf.sssup.it>
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 *   (see the web pages for full authors list)
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 *
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 * ReTiS Lab (Scuola Superiore S.Anna - Pisa - Italy)
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 *
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 * http://www.sssup.it
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 * http://retis.sssup.it
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 * http://shark.sssup.it
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 */
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/**
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 ------------
38 pj 23
 CVS :        $Id: nop.c,v 1.3 2003-01-07 17:07:50 pj Exp $
2 pj 24
 
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 File:        $File$
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 Revision:    $Revision: 1.3 $
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 Last update: $Date: 2003-01-07 17:07:50 $
2 pj 28
 ------------
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 Binary Semaphores. see nop.h for more details...
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**/
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/*
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 * Copyright (C) 2000 Paolo Gai
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 *
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 * This program is free software; you can redistribute it and/or modify
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 * it under the terms of the GNU General Public License as published by
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 * the Free Software Foundation; either version 2 of the License, or
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 * (at your option) any later version.
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 *
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 * This program is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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 * GNU General Public License for more details.
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 *
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 * You should have received a copy of the GNU General Public License
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 * along with this program; if not, write to the Free Software
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 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
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 *
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 */
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#include <modules/nop.h>
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#include <ll/ll.h>
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#include <ll/stdio.h>
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#include <ll/string.h>
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#include <kernel/const.h>
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#include <sys/types.h>
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#include <kernel/descr.h>
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#include <kernel/var.h>
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#include <kernel/func.h>
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/* The NOP resource level descriptor */
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typedef struct {
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  mutex_resource_des m;   /*+ the mutex interface +*/
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} NOP_mutex_resource_des;
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/* this is the structure normally pointed by the opt field in the
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   mutex_t structure */
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typedef struct {
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  PID owner;
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  IQUEUE blocked;
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} NOP_mutex_t;
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/* Wait status for this library */
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#define NOP_WAIT LIB_STATUS_BASE
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static int NOP_res_register(RLEVEL l, PID p, RES_MODEL *r)
2 pj 83
{
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  return -1;
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}
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static void NOP_res_detach(RLEVEL l, PID p)
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{
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}
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static int NOP_init(RLEVEL l, mutex_t *m, const mutexattr_t *a)
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{
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  NOP_mutex_t *p;
38 pj 94
 
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  if (a->mclass != NOP_MCLASS)
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    return -1;
2 pj 97
 
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  p = (NOP_mutex_t *) kern_alloc(sizeof(NOP_mutex_t));
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  /* control if there is enough memory; no control on init on a
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     non- destroyed mutex */
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  if (!p)
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    return (ENOMEM);
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  p->owner = NIL;
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  iq_init(&p->blocked, &freedesc, 0);
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  m->mutexlevel = l;
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  m->opt = (void *)p;
111
 
112
  return 0;
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}
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static int NOP_destroy(RLEVEL l, mutex_t *m)
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{
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//  NOP_mutex_resource_des *lev = (NOP_mutex_resource_des *)(resource_table[l]);
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120
  if ( ((NOP_mutex_t *)m->opt)->owner != NIL)
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    return (EBUSY);
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  kern_cli();
124
  if (m->opt) {
125
    kern_free(m->opt,sizeof(NOP_mutex_t));
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    m->opt = NULL;
127
  }
128
  kern_sti();
129
 
130
  return 0;
131
}
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static int NOP_lock(RLEVEL l, mutex_t *m)
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{
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  NOP_mutex_t *p;
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  kern_cli();
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139
  p = (NOP_mutex_t *)m->opt;
140
  if (!p) {
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    /* if the mutex is not initialized, initialize it! */
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    NOP_mutexattr_t a;
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    NOP_mutexattr_default(a);
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    NOP_init(l, m, &a);
145
  }
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147
  if (p->owner == exec_shadow) {
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    /* the task already owns the mutex */
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    kern_sti();
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    return (EDEADLK);
151
  }
152
 
153
  if (p->owner != NIL)  {           /* We must block exec task   */
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       LEVEL l;            /* for readableness only */
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       proc_table[exec_shadow].context = kern_context_save();
38 pj 157
       kern_epilogue_macro();
2 pj 158
 
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       l = proc_table[exec_shadow].task_level;
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       level_table[l]->public_block(l,exec_shadow);
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       /* we insert the task in the semaphore queue */
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       proc_table[exec_shadow].status = NOP_WAIT;
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       iq_insertlast(exec_shadow,&p->blocked);
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       /* and finally we reschedule */
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       exec = exec_shadow = -1;
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       scheduler();
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       kern_context_load(proc_table[exec_shadow].context);
170
  }
171
  else {
172
    /* the mutex is free, We can lock it! */
173
    p->owner = exec_shadow;
174
    kern_sti();
175
  }
176
 
177
  return 0;
178
}
179
 
180
static int NOP_trylock(RLEVEL l, mutex_t *m)
181
{
182
  NOP_mutex_t *p;
183
 
184
  kern_cli();
185
 
186
  p = (NOP_mutex_t *)m->opt;
187
  if (!p) {
188
    /* if the mutex is not initialized, initialize it! */
189
    NOP_mutexattr_t a;
190
    NOP_mutexattr_default(a);
191
    NOP_init(l, m, &a);
192
  }
193
 
194
  if (p->owner != NIL)  {
195
    /* a task already owns the mutex */
196
    kern_sti();
197
    return (EBUSY);
198
  }
199
  else {
200
    /* the mutex is free, We can lock it! */
201
    p->owner = exec_shadow;
202
    kern_sti();
203
  }
204
 
205
  return 0;
206
}
207
 
208
static int NOP_unlock(RLEVEL l, mutex_t *m)
209
{
210
  NOP_mutex_t *p;
211
 
212
  p = (NOP_mutex_t *)m->opt;
213
  if (!p)
214
    return (EINVAL);
215
 
216
  if (p->owner != exec_shadow) {
217
    /* the mutex is owned by another task!!! */
218
    kern_sti();
219
    return (EPERM);
220
  }
221
 
222
  proc_table[exec_shadow].context = kern_context_save();
223
 
224
  /* the mutex is mine, pop the firsttask to extract */
29 pj 225
  p->owner = iq_getfirst(&p->blocked);
2 pj 226
  if (p->owner != NIL) {
227
    l = proc_table[p->owner].task_level;
38 pj 228
    level_table[l]->public_unblock(l,p->owner);
2 pj 229
  }
230
 
231
  scheduler();
232
  kern_context_load(proc_table[exec_shadow].context);
233
 
234
  return 0;
235
}
236
 
38 pj 237
RLEVEL NOP_register_module(void)
2 pj 238
{
239
  RLEVEL l;                  /* the level that we register */
240
  NOP_mutex_resource_des *m;  /* for readableness only */
241
 
242
  printk("NOP_register_module\n");
243
 
244
  /* request an entry in the level_table */
245
  l = resource_alloc_descriptor();
246
 
247
  /* alloc the space needed for the EDF_level_des */
248
  m = (NOP_mutex_resource_des *)kern_alloc(sizeof(NOP_mutex_resource_des));
249
 
250
  /* update the level_table with the new entry */
251
  resource_table[l] = (resource_des *)m;
252
 
253
  /* fill the resource_des descriptor */
254
  m->m.r.rtype                       = MUTEX_RTYPE;
255
  m->m.r.res_register                = NOP_res_register;
256
  m->m.r.res_detach                  = NOP_res_detach;
257
 
258
  /* fill the mutex_resource_des descriptor */
259
  m->m.init                          = NOP_init;
260
  m->m.destroy                       = NOP_destroy;
261
  m->m.lock                          = NOP_lock;
262
  m->m.trylock                       = NOP_trylock;
263
  m->m.unlock                        = NOP_unlock;
264
 
38 pj 265
  return l;
2 pj 266
}
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