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  1. /*
  2.  * Copyright (C) 2006 Ondrej Palkovsky
  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.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. #include <libadt/list.h>
  30. #include <psthread.h>
  31. #include <malloc.h>
  32. #include <unistd.h>
  33. #include <thread.h>
  34. #include <stdio.h>
  35. #include <kernel/arch/faddr.h>
  36.  
  37. static LIST_INITIALIZE(ready_list);
  38.  
  39. static void psthread_exit(void) __attribute__ ((noinline));
  40. static void psthread_main(void);
  41.  
  42. /** Function to preempt to other pseudo thread without adding
  43.  * currently running pseudo thread to ready_list.
  44.  */
  45. void psthread_exit(void)
  46. {
  47.     psthread_data_t *pt;
  48.  
  49.     if (list_empty(&ready_list)) {
  50.         /* Wait on IPC queue etc... */
  51.         printf("Cannot exit!!!\n");
  52.         _exit(0);
  53.     }
  54.     pt = list_get_instance(ready_list.next, psthread_data_t, link);
  55.     list_remove(&pt->link);
  56.     context_restore(&pt->ctx);
  57. }
  58.  
  59. /** Function that is called on entry to new uspace thread */
  60. void psthread_main(void)
  61. {
  62.     psthread_data_t *pt = __tls_get();
  63.     pt->retval = pt->func(pt->arg);
  64.  
  65.     pt->finished = 1;
  66.     if (pt->waiter)
  67.         list_append(&pt->waiter->link, &ready_list);
  68.  
  69.     psthread_exit();
  70. }
  71.  
  72. /** Schedule next userspace pseudo thread.
  73.  *
  74.  * @return 0 if there is no ready pseudo thread, 1 otherwise.
  75.  */
  76. int psthread_schedule_next(void)
  77. {
  78.     psthread_data_t *pt;
  79.  
  80.     if (list_empty(&ready_list))
  81.         return 0;
  82.  
  83.     pt = __tls_get();
  84.     if (!context_save(&pt->ctx))
  85.         return 1;
  86.    
  87.     list_append(&pt->link, &ready_list);
  88.     pt = list_get_instance(ready_list.next, psthread_data_t, link);
  89.     list_remove(&pt->link);
  90.  
  91.     context_restore(&pt->ctx);
  92. }
  93.  
  94. /** Wait for uspace pseudo thread to finish.
  95.  *
  96.  * @param psthrid Pseudo thread to wait for.
  97.  *
  98.  * @return Value returned by the finished thread.
  99.  */
  100. int psthread_join(pstid_t psthrid)
  101. {
  102.     volatile psthread_data_t *pt, *mypt;
  103.     volatile int retval;
  104.  
  105.     /* Handle psthrid = Kernel address -> it is wait for call */
  106.  
  107.     pt = (psthread_data_t *) psthrid;
  108.  
  109.     if (!pt->finished) {
  110.         mypt = __tls_get();
  111.         if (context_save(&((psthread_data_t *) mypt)->ctx)) {
  112.             pt->waiter = (psthread_data_t *) mypt;
  113.             psthread_exit();
  114.         }
  115.     }
  116.     retval = pt->retval;
  117.  
  118.     free(pt->stack);
  119.     __free_tls((psthread_data_t *) pt);
  120.  
  121.     return retval;
  122. }
  123.  
  124. /**
  125.  * Create a userspace thread and append it to ready list.
  126.  *
  127.  * @param func Pseudo thread function.
  128.  * @param arg Argument to pass to func.
  129.  *
  130.  * @return 0 on failure, TLS of the new pseudo thread.
  131.  */
  132. pstid_t psthread_create(int (*func)(void *), void *arg)
  133. {
  134.     psthread_data_t *pt;
  135.  
  136.     pt = __make_tls();
  137.     pt->stack = (char *) malloc(getpagesize());
  138.  
  139.     if (!pt->stack) {
  140.         return 0;
  141.     }
  142.  
  143.     pt->arg= arg;
  144.     pt->func = func;
  145.     pt->finished = 0;
  146.     pt->waiter = NULL;
  147.  
  148.     context_save(&pt->ctx);
  149.     context_set(&pt->ctx, FADDR(psthread_main), pt->stack, getpagesize(), pt);
  150.  
  151.     list_append(&pt->link, &ready_list);
  152.  
  153.     return (pstid_t )pt;
  154. }
  155.