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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. /** @addtogroup libc
  30.  * @{
  31.  */
  32. /** @file
  33.  */
  34.  
  35. #include <libadt/list.h>
  36. #include <psthread.h>
  37. #include <malloc.h>
  38. #include <unistd.h>
  39. #include <thread.h>
  40. #include <stdio.h>
  41. #include <libarch/faddr.h>
  42. #include <futex.h>
  43. #include <assert.h>
  44. #include <async.h>
  45.  
  46. #ifndef PSTHREAD_INITIAL_STACK_PAGES_NO
  47. #define PSTHREAD_INITIAL_STACK_PAGES_NO 1
  48. #endif
  49.  
  50. static LIST_INITIALIZE(ready_list);
  51. static LIST_INITIALIZE(serialized_list);
  52. static LIST_INITIALIZE(manager_list);
  53.  
  54. static void psthread_main(void);
  55.  
  56. static atomic_t psthread_futex = FUTEX_INITIALIZER;
  57. /** Count of real threads that are in async_serialized mode */
  58. static int serialized_threads; /* Protected by async_futex */
  59. /** Thread-local count of serialization. If >0, we must not preempt */
  60. static __thread int serialization_count;
  61. /** Counter of threads residing in async_manager */
  62. static int threads_in_manager;
  63.  
  64. /** Setup psthread information into TCB structure */
  65. psthread_data_t * psthread_setup()
  66. {
  67.     psthread_data_t *pt;
  68.     tcb_t *tcb;
  69.  
  70.     tcb = __make_tls();
  71.     if (!tcb)
  72.         return NULL;
  73.  
  74.     pt = malloc(sizeof(*pt));
  75.     if (!pt) {
  76.         __free_tls(tcb);
  77.         return NULL;
  78.     }
  79.  
  80.     tcb->pst_data = pt;
  81.     pt->tcb = tcb;
  82.  
  83.     return pt;
  84. }
  85.  
  86. void psthread_teardown(psthread_data_t *pt)
  87. {
  88.     __free_tls(pt->tcb);
  89.     free(pt);
  90. }
  91.  
  92. /** Function that is called on entry to new pseudo thread */
  93. void psthread_main(void)
  94. {
  95.     psthread_data_t *pt = __tcb_get()->pst_data;
  96.  
  97.     pt->retval = pt->func(pt->arg);
  98.  
  99.     pt->finished = 1;
  100.     if (pt->waiter)
  101.         list_append(&pt->waiter->link, &ready_list);
  102.  
  103.     psthread_schedule_next_adv(PS_FROM_DEAD);
  104. }
  105.  
  106. /** Schedule next userspace pseudo thread.
  107.  *
  108.  * If calling with PS_TO_MANAGER parameter, the async_futex should be
  109.  * held.
  110.  *
  111.  * @param ctype Type of switch.
  112.  * @return 0 if there is no ready pseudo thread, 1 otherwise.
  113.  */
  114. int psthread_schedule_next_adv(pschange_type ctype)
  115. {
  116.     psthread_data_t *srcpt, *dstpt;
  117.     int retval = 0;
  118.    
  119.     futex_down(&psthread_futex);
  120.  
  121.     if (ctype == PS_PREEMPT && list_empty(&ready_list))
  122.         goto ret_0;
  123.  
  124.     if (ctype == PS_FROM_MANAGER) {
  125.         if (list_empty(&ready_list) && list_empty(&serialized_list))
  126.             goto ret_0;
  127.         /* Do not preempt if there is not sufficient count of thread managers */
  128.         if (list_empty(&serialized_list) && threads_in_manager <= serialized_threads) {
  129.             goto ret_0;
  130.         }
  131.     }
  132.     /* If we are going to manager and none exists, create it */
  133.     if (ctype == PS_TO_MANAGER || ctype == PS_FROM_DEAD) {
  134.         while (list_empty(&manager_list)) {
  135.             futex_up(&psthread_futex);
  136.             async_create_manager();
  137.             futex_down(&psthread_futex);
  138.         }
  139.     }
  140.    
  141.     if (ctype != PS_FROM_DEAD) {
  142.         /* Save current state */
  143.         srcpt = __tcb_get()->pst_data;
  144.         if (!context_save(&srcpt->ctx)) {
  145.             if (serialization_count)
  146.                 srcpt->flags &= ~PSTHREAD_SERIALIZED;
  147.             return 1; // futex_up already done here
  148.         }
  149.  
  150.         /* Save myself to correct run list */
  151.         if (ctype == PS_PREEMPT)
  152.             list_append(&srcpt->link, &ready_list);
  153.         else if (ctype == PS_FROM_MANAGER) {
  154.             list_append(&srcpt->link, &manager_list);
  155.             threads_in_manager--;
  156.         } /* If ctype == PS_TO_MANAGER, don't save ourselves to any list, we should
  157.            * already be somewhere, or we will be lost */
  158.     } else
  159.         srcpt = NULL; /* Avoid GCC warning, if ctype == PS_FROM_DEAD, srcpt is not used */
  160.  
  161.     /* Choose new thread to run */
  162.     if (ctype == PS_TO_MANAGER || ctype == PS_FROM_DEAD) {
  163.         dstpt = list_get_instance(manager_list.next,psthread_data_t, link);
  164.         if (serialization_count && ctype == PS_TO_MANAGER) {
  165.             serialized_threads++;
  166.             srcpt->flags |= PSTHREAD_SERIALIZED;
  167.         }
  168.         threads_in_manager++;
  169.     } else {
  170.         if (!list_empty(&serialized_list)) {
  171.             dstpt = list_get_instance(serialized_list.next, psthread_data_t, link);
  172.             serialized_threads--;
  173.         } else
  174.             dstpt = list_get_instance(ready_list.next, psthread_data_t, link);
  175.     }
  176.     list_remove(&dstpt->link);
  177.  
  178.     futex_up(&psthread_futex);
  179.     context_restore(&dstpt->ctx);
  180.  
  181. ret_0:
  182.     futex_up(&psthread_futex);
  183.     return retval;
  184. }
  185.  
  186. /** Wait for uspace pseudo thread to finish.
  187.  *
  188.  * @param psthrid Pseudo thread to wait for.
  189.  *
  190.  * @return Value returned by the finished thread.
  191.  */
  192. int psthread_join(pstid_t psthrid)
  193. {
  194.     volatile psthread_data_t *pt;
  195.     volatile int retval;
  196.  
  197.     /* Handle psthrid = Kernel address -> it is wait for call */
  198.     pt = (psthread_data_t *) psthrid;
  199.  
  200.     /* TODO */
  201.     printf("join unsupported\n");
  202.     _exit(1);
  203.  
  204.     retval = pt->retval;
  205.  
  206.     free(pt->stack);
  207.     psthread_teardown((void *)pt);
  208.  
  209.     return retval;
  210. }
  211.  
  212. /** Create a userspace pseudo thread.
  213.  *
  214.  * @param func Pseudo thread function.
  215.  * @param arg Argument to pass to func.
  216.  *
  217.  * @return 0 on failure, TLS of the new pseudo thread.
  218.  */
  219. pstid_t psthread_create(int (*func)(void *), void *arg)
  220. {
  221.     psthread_data_t *pt;
  222.  
  223.     pt = psthread_setup();
  224.     if (!pt)
  225.         return 0;
  226.     pt->stack = (char *) malloc(PSTHREAD_INITIAL_STACK_PAGES_NO*getpagesize());
  227.  
  228.     if (!pt->stack) {
  229.         psthread_teardown(pt);
  230.         return 0;
  231.     }
  232.  
  233.     pt->arg= arg;
  234.     pt->func = func;
  235.     pt->finished = 0;
  236.     pt->waiter = NULL;
  237.     pt->flags = 0;
  238.  
  239.     context_save(&pt->ctx);
  240.     context_set(&pt->ctx, FADDR(psthread_main), pt->stack, PSTHREAD_INITIAL_STACK_PAGES_NO*getpagesize(), pt->tcb);
  241.  
  242.     return (pstid_t )pt;
  243. }
  244.  
  245. /** Add a thread to ready list */
  246. void psthread_add_ready(pstid_t psthrid)
  247. {
  248.     psthread_data_t *pt;
  249.  
  250.     pt = (psthread_data_t *) psthrid;
  251.     futex_down(&psthread_futex);
  252.     if ((pt->flags & PSTHREAD_SERIALIZED))
  253.         list_append(&pt->link, &serialized_list);
  254.     else
  255.         list_append(&pt->link, &ready_list);
  256.     futex_up(&psthread_futex);
  257. }
  258.  
  259. /** Add a thread to manager list */
  260. void psthread_add_manager(pstid_t psthrid)
  261. {
  262.     psthread_data_t *pt;
  263.  
  264.     pt = (psthread_data_t *) psthrid;
  265.  
  266.     futex_down(&psthread_futex);
  267.     list_append(&pt->link, &manager_list);
  268.     futex_up(&psthread_futex);
  269. }
  270.  
  271. /** Remove one manager from manager list */
  272. void psthread_remove_manager()
  273. {
  274.     futex_down(&psthread_futex);
  275.     if (list_empty(&manager_list)) {
  276.         futex_up(&psthread_futex);
  277.         return;
  278.     }
  279.     list_remove(manager_list.next);
  280.     futex_up(&psthread_futex);
  281. }
  282.  
  283. /** Return thread id of current running thread */
  284. pstid_t psthread_get_id(void)
  285. {
  286.     return (pstid_t)__tcb_get()->pst_data;
  287. }
  288.  
  289. /** Disable preemption
  290.  *
  291.  * If the thread wants to send several message in row and does not want
  292.  * to be preempted, it should start async_serialize_start() in the beginning
  293.  * of communication and async_serialize_end() in the end. If it is a
  294.  * true multithreaded application, it should protect the communication channel
  295.  * by a futex as well. Interrupt messages will can still be preempted.
  296.  */
  297. void psthread_inc_sercount(void)
  298. {
  299.     serialization_count++;
  300. }
  301.  
  302. void psthread_dec_sercount(void)
  303. {
  304.     serialization_count--;
  305. }
  306.  
  307. /** @}
  308.  */
  309.