Subversion Repositories HelenOS

Rev

Rev 4342 | Blame | Compare with Previous | Last modification | View Log | Download | RSS feed

  1. /*
  2.  * Copyright (c) 2001-2004 Jakub Jermar
  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 genericproc
  30.  * @{
  31.  */
  32.  
  33. /**
  34.  * @file
  35.  * @brief   Thread management functions.
  36.  */
  37.  
  38. #include <proc/scheduler.h>
  39. #include <proc/thread.h>
  40. #include <proc/task.h>
  41. #include <proc/uarg.h>
  42. #include <mm/frame.h>
  43. #include <mm/page.h>
  44. #include <arch/asm.h>
  45. #include <arch/cycle.h>
  46. #include <arch.h>
  47. #include <synch/synch.h>
  48. #include <synch/spinlock.h>
  49. #include <synch/waitq.h>
  50. #include <synch/rwlock.h>
  51. #include <cpu.h>
  52. #include <func.h>
  53. #include <context.h>
  54. #include <adt/avl.h>
  55. #include <adt/list.h>
  56. #include <time/clock.h>
  57. #include <time/timeout.h>
  58. #include <config.h>
  59. #include <arch/interrupt.h>
  60. #include <smp/ipi.h>
  61. #include <arch/faddr.h>
  62. #include <atomic.h>
  63. #include <memstr.h>
  64. #include <print.h>
  65. #include <mm/slab.h>
  66. #include <debug.h>
  67. #include <main/uinit.h>
  68. #include <syscall/copy.h>
  69. #include <errno.h>
  70.  
  71.  
  72. #ifndef LOADED_PROG_STACK_PAGES_NO
  73. #define LOADED_PROG_STACK_PAGES_NO 1
  74. #endif
  75.  
  76.  
  77. /** Thread states */
  78. char *thread_states[] = {
  79.     "Invalid",
  80.     "Running",
  81.     "Sleeping",
  82.     "Ready",
  83.     "Entering",
  84.     "Exiting",
  85.     "Lingering"
  86. };
  87.  
  88. /** Lock protecting the threads_tree AVL tree.
  89.  *
  90.  * For locking rules, see declaration thereof.
  91.  */
  92. SPINLOCK_INITIALIZE(threads_lock);
  93.  
  94. /** AVL tree of all threads.
  95.  *
  96.  * When a thread is found in the threads_tree AVL tree, it is guaranteed to
  97.  * exist as long as the threads_lock is held.
  98.  */
  99. avltree_t threads_tree;    
  100.  
  101. SPINLOCK_INITIALIZE(tidlock);
  102. thread_id_t last_tid = 0;
  103.  
  104. static slab_cache_t *thread_slab;
  105. #ifdef CONFIG_FPU
  106. slab_cache_t *fpu_context_slab;
  107. #endif
  108.  
  109. /** Thread wrapper.
  110.  *
  111.  * This wrapper is provided to ensure that every thread makes a call to
  112.  * thread_exit() when its implementing function returns.
  113.  *
  114.  * interrupts_disable() is assumed.
  115.  *
  116.  */
  117. static void cushion(void)
  118. {
  119.     void (*f)(void *) = THREAD->thread_code;
  120.     void *arg = THREAD->thread_arg;
  121.     THREAD->last_cycle = get_cycle();
  122.  
  123.     /* This is where each thread wakes up after its creation */
  124.     spinlock_unlock(&THREAD->lock);
  125.     interrupts_enable();
  126.  
  127.     f(arg);
  128.    
  129.     /* Accumulate accounting to the task */
  130.     ipl_t ipl = interrupts_disable();
  131.    
  132.     spinlock_lock(&THREAD->lock);
  133.     if (!THREAD->uncounted) {
  134.         thread_update_accounting();
  135.         uint64_t cycles = THREAD->cycles;
  136.         THREAD->cycles = 0;
  137.         spinlock_unlock(&THREAD->lock);
  138.        
  139.         spinlock_lock(&TASK->lock);
  140.         TASK->cycles += cycles;
  141.         spinlock_unlock(&TASK->lock);
  142.     } else
  143.         spinlock_unlock(&THREAD->lock);
  144.    
  145.     interrupts_restore(ipl);
  146.    
  147.     thread_exit();
  148.     /* not reached */
  149. }
  150.  
  151. /** Initialization and allocation for thread_t structure */
  152. static int thr_constructor(void *obj, int kmflags)
  153. {
  154.     thread_t *t = (thread_t *) obj;
  155.  
  156.     spinlock_initialize(&t->lock, "thread_t_lock");
  157.     link_initialize(&t->rq_link);
  158.     link_initialize(&t->wq_link);
  159.     link_initialize(&t->th_link);
  160.  
  161.     /* call the architecture-specific part of the constructor */
  162.     thr_constructor_arch(t);
  163.    
  164. #ifdef CONFIG_FPU
  165. #ifdef CONFIG_FPU_LAZY
  166.     t->saved_fpu_context = NULL;
  167. #else
  168.     t->saved_fpu_context = slab_alloc(fpu_context_slab, kmflags);
  169.     if (!t->saved_fpu_context)
  170.         return -1;
  171. #endif
  172. #endif
  173.  
  174.     t->kstack = (uint8_t *) frame_alloc(STACK_FRAMES, FRAME_KA | kmflags);
  175.     if (!t->kstack) {
  176. #ifdef CONFIG_FPU
  177.         if (t->saved_fpu_context)
  178.             slab_free(fpu_context_slab, t->saved_fpu_context);
  179. #endif
  180.         return -1;
  181.     }
  182.  
  183. #ifdef CONFIG_UDEBUG
  184.     mutex_initialize(&t->udebug.lock, MUTEX_PASSIVE);
  185. #endif
  186.  
  187.     return 0;
  188. }
  189.  
  190. /** Destruction of thread_t object */
  191. static int thr_destructor(void *obj)
  192. {
  193.     thread_t *t = (thread_t *) obj;
  194.  
  195.     /* call the architecture-specific part of the destructor */
  196.     thr_destructor_arch(t);
  197.  
  198.     frame_free(KA2PA(t->kstack));
  199. #ifdef CONFIG_FPU
  200.     if (t->saved_fpu_context)
  201.         slab_free(fpu_context_slab, t->saved_fpu_context);
  202. #endif
  203.     return 1; /* One page freed */
  204. }
  205.  
  206. /** Initialize threads
  207.  *
  208.  * Initialize kernel threads support.
  209.  *
  210.  */
  211. void thread_init(void)
  212. {
  213.     THREAD = NULL;
  214.     atomic_set(&nrdy, 0);
  215.     thread_slab = slab_cache_create("thread_slab", sizeof(thread_t), 0,
  216.         thr_constructor, thr_destructor, 0);
  217.  
  218. #ifdef CONFIG_FPU
  219.     fpu_context_slab = slab_cache_create("fpu_slab", sizeof(fpu_context_t),
  220.         FPU_CONTEXT_ALIGN, NULL, NULL, 0);
  221. #endif
  222.  
  223.     avltree_create(&threads_tree);
  224. }
  225.  
  226. /** Make thread ready
  227.  *
  228.  * Switch thread t to the ready state.
  229.  *
  230.  * @param t Thread to make ready.
  231.  *
  232.  */
  233. void thread_ready(thread_t *t)
  234. {
  235.     cpu_t *cpu;
  236.     runq_t *r;
  237.     ipl_t ipl;
  238.     int i, avg;
  239.  
  240.     ipl = interrupts_disable();
  241.  
  242.     spinlock_lock(&t->lock);
  243.  
  244.     ASSERT(!(t->state == Ready));
  245.  
  246.     i = (t->priority < RQ_COUNT - 1) ? ++t->priority : t->priority;
  247.    
  248.     cpu = CPU;
  249.     if (t->flags & THREAD_FLAG_WIRED) {
  250.         ASSERT(t->cpu != NULL);
  251.         cpu = t->cpu;
  252.     }
  253.     t->state = Ready;
  254.     spinlock_unlock(&t->lock);
  255.    
  256.     /*
  257.      * Append t to respective ready queue on respective processor.
  258.      */
  259.     r = &cpu->rq[i];
  260.     spinlock_lock(&r->lock);
  261.     list_append(&t->rq_link, &r->rq_head);
  262.     r->n++;
  263.     spinlock_unlock(&r->lock);
  264.  
  265.     atomic_inc(&nrdy);
  266.     avg = atomic_get(&nrdy) / config.cpu_active;
  267.     atomic_inc(&cpu->nrdy);
  268.  
  269.     interrupts_restore(ipl);
  270. }
  271.  
  272. /** Create new thread
  273.  *
  274.  * Create a new thread.
  275.  *
  276.  * @param func      Thread's implementing function.
  277.  * @param arg       Thread's implementing function argument.
  278.  * @param task      Task to which the thread belongs. The caller must
  279.  *          guarantee that the task won't cease to exist during the
  280.  *          call. The task's lock may not be held.
  281.  * @param flags     Thread flags.
  282.  * @param name      Symbolic name (a copy is made).
  283.  * @param uncounted Thread's accounting doesn't affect accumulated task
  284.  *          accounting.
  285.  *
  286.  * @return      New thread's structure on success, NULL on failure.
  287.  *
  288.  */
  289. thread_t *thread_create(void (* func)(void *), void *arg, task_t *task,
  290.     int flags, char *name, bool uncounted)
  291. {
  292.     thread_t *t;
  293.     ipl_t ipl;
  294.    
  295.     t = (thread_t *) slab_alloc(thread_slab, 0);
  296.     if (!t)
  297.         return NULL;
  298.    
  299.     /* Not needed, but good for debugging */
  300.     memsetb(t->kstack, THREAD_STACK_SIZE * 1 << STACK_FRAMES, 0);
  301.    
  302.     ipl = interrupts_disable();
  303.     spinlock_lock(&tidlock);
  304.     t->tid = ++last_tid;
  305.     spinlock_unlock(&tidlock);
  306.     interrupts_restore(ipl);
  307.    
  308.     context_save(&t->saved_context);
  309.     context_set(&t->saved_context, FADDR(cushion), (uintptr_t) t->kstack,
  310.         THREAD_STACK_SIZE);
  311.    
  312.     the_initialize((the_t *) t->kstack);
  313.    
  314.     ipl = interrupts_disable();
  315.     t->saved_context.ipl = interrupts_read();
  316.     interrupts_restore(ipl);
  317.    
  318.     memcpy(t->name, name, THREAD_NAME_BUFLEN);
  319.     t->name[THREAD_NAME_BUFLEN - 1] = 0;
  320.    
  321.     t->thread_code = func;
  322.     t->thread_arg = arg;
  323.     t->ticks = -1;
  324.     t->cycles = 0;
  325.     t->uncounted = uncounted;
  326.     t->priority = -1;       /* start in rq[0] */
  327.     t->cpu = NULL;
  328.     t->flags = flags;
  329.     t->state = Entering;
  330.     t->call_me = NULL;
  331.     t->call_me_with = NULL;
  332.    
  333.     timeout_initialize(&t->sleep_timeout);
  334.     t->sleep_interruptible = false;
  335.     t->sleep_queue = NULL;
  336.     t->timeout_pending = 0;
  337.  
  338.     t->in_copy_from_uspace = false;
  339.     t->in_copy_to_uspace = false;
  340.  
  341.     t->interrupted = false;
  342.     t->detached = false;
  343.     waitq_initialize(&t->join_wq);
  344.    
  345.     t->rwlock_holder_type = RWLOCK_NONE;
  346.        
  347.     t->task = task;
  348.    
  349.     t->fpu_context_exists = 0;
  350.     t->fpu_context_engaged = 0;
  351.  
  352.     avltree_node_initialize(&t->threads_tree_node);
  353.     t->threads_tree_node.key = (uintptr_t) t;
  354.  
  355. #ifdef CONFIG_UDEBUG
  356.     /* Init debugging stuff */
  357.     udebug_thread_initialize(&t->udebug);
  358. #endif
  359.  
  360.     /* might depend on previous initialization */
  361.     thread_create_arch(t); 
  362.  
  363.     if (!(flags & THREAD_FLAG_NOATTACH))
  364.         thread_attach(t, task);
  365.  
  366.     return t;
  367. }
  368.  
  369. /** Destroy thread memory structure
  370.  *
  371.  * Detach thread from all queues, cpus etc. and destroy it.
  372.  *
  373.  * Assume thread->lock is held!!
  374.  */
  375. void thread_destroy(thread_t *t)
  376. {
  377.     ASSERT(t->state == Exiting || t->state == Lingering);
  378.     ASSERT(t->task);
  379.     ASSERT(t->cpu);
  380.  
  381.     spinlock_lock(&t->cpu->lock);
  382.     if (t->cpu->fpu_owner == t)
  383.         t->cpu->fpu_owner = NULL;
  384.     spinlock_unlock(&t->cpu->lock);
  385.  
  386.     spinlock_unlock(&t->lock);
  387.  
  388.     spinlock_lock(&threads_lock);
  389.     avltree_delete(&threads_tree, &t->threads_tree_node);
  390.     spinlock_unlock(&threads_lock);
  391.  
  392.     /*
  393.      * Detach from the containing task.
  394.      */
  395.     spinlock_lock(&t->task->lock);
  396.     list_remove(&t->th_link);
  397.     spinlock_unlock(&t->task->lock);   
  398.  
  399.     /*
  400.      * t is guaranteed to be the very last thread of its task.
  401.      * It is safe to destroy the task.
  402.      */
  403.     if (atomic_predec(&t->task->refcount) == 0)
  404.         task_destroy(t->task);
  405.    
  406.     slab_free(thread_slab, t);
  407. }
  408.  
  409. /** Make the thread visible to the system.
  410.  *
  411.  * Attach the thread structure to the current task and make it visible in the
  412.  * threads_tree.
  413.  *
  414.  * @param t Thread to be attached to the task.
  415.  * @param task  Task to which the thread is to be attached.
  416.  */
  417. void thread_attach(thread_t *t, task_t *task)
  418. {
  419.     ipl_t ipl;
  420.  
  421.     /*
  422.      * Attach to the specified task.
  423.      */
  424.     ipl = interrupts_disable();
  425.     spinlock_lock(&task->lock);
  426.  
  427.     atomic_inc(&task->refcount);
  428.  
  429.     /* Must not count kbox thread into lifecount */
  430.     if (t->flags & THREAD_FLAG_USPACE)
  431.         atomic_inc(&task->lifecount);
  432.  
  433.     list_append(&t->th_link, &task->th_head);
  434.     spinlock_unlock(&task->lock);
  435.  
  436.     /*
  437.      * Register this thread in the system-wide list.
  438.      */
  439.     spinlock_lock(&threads_lock);
  440.     avltree_insert(&threads_tree, &t->threads_tree_node);
  441.     spinlock_unlock(&threads_lock);
  442.    
  443.     interrupts_restore(ipl);
  444. }
  445.  
  446. /** Terminate thread.
  447.  *
  448.  * End current thread execution and switch it to the exiting state. All pending
  449.  * timeouts are executed.
  450.  */
  451. void thread_exit(void)
  452. {
  453.     ipl_t ipl;
  454.  
  455.     if (THREAD->flags & THREAD_FLAG_USPACE) {
  456. #ifdef CONFIG_UDEBUG
  457.         /* Generate udebug THREAD_E event */
  458.         udebug_thread_e_event();
  459. #endif
  460.         if (atomic_predec(&TASK->lifecount) == 0) {
  461.             /*
  462.              * We are the last userspace thread in the task that
  463.              * still has not exited. With the exception of the
  464.              * moment the task was created, new userspace threads
  465.              * can only be created by threads of the same task.
  466.              * We are safe to perform cleanup.
  467.              */
  468.             ipc_cleanup();
  469.             futex_cleanup();
  470.             LOG("Cleanup of task %" PRIu64" completed.", TASK->taskid);
  471.         }
  472.     }
  473.  
  474. restart:
  475.     ipl = interrupts_disable();
  476.     spinlock_lock(&THREAD->lock);
  477.     if (THREAD->timeout_pending) {
  478.         /* busy waiting for timeouts in progress */
  479.         spinlock_unlock(&THREAD->lock);
  480.         interrupts_restore(ipl);
  481.         goto restart;
  482.     }
  483.    
  484.     THREAD->state = Exiting;
  485.     spinlock_unlock(&THREAD->lock);
  486.     scheduler();
  487.  
  488.     /* Not reached */
  489.     while (1)
  490.         ;
  491. }
  492.  
  493.  
  494. /** Thread sleep
  495.  *
  496.  * Suspend execution of the current thread.
  497.  *
  498.  * @param sec Number of seconds to sleep.
  499.  *
  500.  */
  501. void thread_sleep(uint32_t sec)
  502. {
  503.     thread_usleep(sec * 1000000);
  504. }
  505.  
  506. /** Wait for another thread to exit.
  507.  *
  508.  * @param t Thread to join on exit.
  509.  * @param usec Timeout in microseconds.
  510.  * @param flags Mode of operation.
  511.  *
  512.  * @return An error code from errno.h or an error code from synch.h.
  513.  */
  514. int thread_join_timeout(thread_t *t, uint32_t usec, int flags)
  515. {
  516.     ipl_t ipl;
  517.     int rc;
  518.  
  519.     if (t == THREAD)
  520.         return EINVAL;
  521.  
  522.     /*
  523.      * Since thread join can only be called once on an undetached thread,
  524.      * the thread pointer is guaranteed to be still valid.
  525.      */
  526.    
  527.     ipl = interrupts_disable();
  528.     spinlock_lock(&t->lock);
  529.     ASSERT(!t->detached);
  530.     spinlock_unlock(&t->lock);
  531.     interrupts_restore(ipl);
  532.    
  533.     rc = waitq_sleep_timeout(&t->join_wq, usec, flags);
  534.    
  535.     return rc; 
  536. }
  537.  
  538. /** Detach thread.
  539.  *
  540.  * Mark the thread as detached, if the thread is already in the Lingering
  541.  * state, deallocate its resources.
  542.  *
  543.  * @param t Thread to be detached.
  544.  */
  545. void thread_detach(thread_t *t)
  546. {
  547.     ipl_t ipl;
  548.  
  549.     /*
  550.      * Since the thread is expected not to be already detached,
  551.      * pointer to it must be still valid.
  552.      */
  553.     ipl = interrupts_disable();
  554.     spinlock_lock(&t->lock);
  555.     ASSERT(!t->detached);
  556.     if (t->state == Lingering) {
  557.         thread_destroy(t);  /* unlocks &t->lock */
  558.         interrupts_restore(ipl);
  559.         return;
  560.     } else {
  561.         t->detached = true;
  562.     }
  563.     spinlock_unlock(&t->lock);
  564.     interrupts_restore(ipl);
  565. }
  566.  
  567. /** Thread usleep
  568.  *
  569.  * Suspend execution of the current thread.
  570.  *
  571.  * @param usec Number of microseconds to sleep.
  572.  *
  573.  */
  574. void thread_usleep(uint32_t usec)
  575. {
  576.     waitq_t wq;
  577.                  
  578.     waitq_initialize(&wq);
  579.  
  580.     (void) waitq_sleep_timeout(&wq, usec, SYNCH_FLAGS_NON_BLOCKING);
  581. }
  582.  
  583. /** Register thread out-of-context invocation
  584.  *
  585.  * Register a function and its argument to be executed
  586.  * on next context switch to the current thread.
  587.  *
  588.  * @param call_me      Out-of-context function.
  589.  * @param call_me_with Out-of-context function argument.
  590.  *
  591.  */
  592. void thread_register_call_me(void (* call_me)(void *), void *call_me_with)
  593. {
  594.     ipl_t ipl;
  595.    
  596.     ipl = interrupts_disable();
  597.     spinlock_lock(&THREAD->lock);
  598.     THREAD->call_me = call_me;
  599.     THREAD->call_me_with = call_me_with;
  600.     spinlock_unlock(&THREAD->lock);
  601.     interrupts_restore(ipl);
  602. }
  603.  
  604. static bool thread_walker(avltree_node_t *node, void *arg)
  605. {
  606.     thread_t *t = avltree_get_instance(node, thread_t, threads_tree_node);
  607.    
  608.     uint64_t cycles;
  609.     char suffix;
  610.     order(t->cycles, &cycles, &suffix);
  611.  
  612. #ifdef __32_BITS__
  613.     printf("%-6" PRIu64" %-10s %10p %-8s %10p %-3" PRIu32 " %10p %10p %9" PRIu64 "%c ",
  614.         t->tid, t->name, t, thread_states[t->state], t->task,
  615.         t->task->context, t->thread_code, t->kstack, cycles, suffix);
  616. #endif
  617.  
  618. #ifdef __64_BITS__
  619.     printf("%-6" PRIu64" %-10s %18p %-8s %18p %-3" PRIu32 " %18p %18p %9" PRIu64 "%c ",
  620.         t->tid, t->name, t, thread_states[t->state], t->task,
  621.         t->task->context, t->thread_code, t->kstack, cycles, suffix);
  622. #endif
  623.            
  624.     if (t->cpu)
  625.         printf("%-4u", t->cpu->id);
  626.     else
  627.         printf("none");
  628.            
  629.     if (t->state == Sleeping) {
  630. #ifdef __32_BITS__
  631.         printf(" %10p", t->sleep_queue);
  632. #endif
  633.  
  634. #ifdef __64_BITS__
  635.         printf(" %18p", t->sleep_queue);
  636. #endif
  637.     }
  638.            
  639.     printf("\n");
  640.  
  641.     return true;
  642. }
  643.  
  644. /** Print list of threads debug info */
  645. void thread_print_list(void)
  646. {
  647.     ipl_t ipl;
  648.    
  649.     /* Messing with thread structures, avoid deadlock */
  650.     ipl = interrupts_disable();
  651.     spinlock_lock(&threads_lock);
  652.  
  653. #ifdef __32_BITS__ 
  654.     printf("tid    name       address    state    task       "
  655.         "ctx code       stack      cycles     cpu  "
  656.         "waitqueue\n");
  657.     printf("------ ---------- ---------- -------- ---------- "
  658.         "--- ---------- ---------- ---------- ---- "
  659.         "----------\n");
  660. #endif
  661.  
  662. #ifdef __64_BITS__
  663.     printf("tid    name       address            state    task               "
  664.         "ctx code               stack              cycles     cpu  "
  665.         "waitqueue\n");
  666.     printf("------ ---------- ------------------ -------- ------------------ "
  667.         "--- ------------------ ------------------ ---------- ---- "
  668.         "------------------\n");
  669. #endif
  670.  
  671.     avltree_walk(&threads_tree, thread_walker, NULL);
  672.  
  673.     spinlock_unlock(&threads_lock);
  674.     interrupts_restore(ipl);
  675. }
  676.  
  677. /** Check whether thread exists.
  678.  *
  679.  * Note that threads_lock must be already held and
  680.  * interrupts must be already disabled.
  681.  *
  682.  * @param t Pointer to thread.
  683.  *
  684.  * @return True if thread t is known to the system, false otherwise.
  685.  */
  686. bool thread_exists(thread_t *t)
  687. {
  688.     avltree_node_t *node;
  689.  
  690.     node = avltree_search(&threads_tree, (avltree_key_t) ((uintptr_t) t));
  691.    
  692.     return node != NULL;
  693. }
  694.  
  695. /** Update accounting of current thread.
  696.  *
  697.  * Note that thread_lock on THREAD must be already held and
  698.  * interrupts must be already disabled.
  699.  *
  700.  */
  701. void thread_update_accounting(void)
  702. {
  703.     uint64_t time = get_cycle();
  704.     THREAD->cycles += time - THREAD->last_cycle;
  705.     THREAD->last_cycle = time;
  706. }
  707.  
  708. /** Process syscall to create new thread.
  709.  *
  710.  */
  711. unative_t sys_thread_create(uspace_arg_t *uspace_uarg, char *uspace_name,
  712.     size_t name_len, thread_id_t *uspace_thread_id)
  713. {
  714.     thread_t *t;
  715.     char namebuf[THREAD_NAME_BUFLEN];
  716.     uspace_arg_t *kernel_uarg;
  717.     int rc;
  718.  
  719.     if (name_len > THREAD_NAME_BUFLEN - 1)
  720.         name_len = THREAD_NAME_BUFLEN - 1;
  721.  
  722.     rc = copy_from_uspace(namebuf, uspace_name, name_len);
  723.     if (rc != 0)
  724.         return (unative_t) rc;
  725.  
  726.     namebuf[name_len] = 0;
  727.  
  728.     /*
  729.      * In case of failure, kernel_uarg will be deallocated in this function.
  730.      * In case of success, kernel_uarg will be freed in uinit().
  731.      */
  732.     kernel_uarg = (uspace_arg_t *) malloc(sizeof(uspace_arg_t), 0);
  733.    
  734.     rc = copy_from_uspace(kernel_uarg, uspace_uarg, sizeof(uspace_arg_t));
  735.     if (rc != 0) {
  736.         free(kernel_uarg);
  737.         return (unative_t) rc;
  738.     }
  739.  
  740.     t = thread_create(uinit, kernel_uarg, TASK,
  741.         THREAD_FLAG_USPACE | THREAD_FLAG_NOATTACH, namebuf, false);
  742.     if (t) {
  743.         if (uspace_thread_id != NULL) {
  744.             int rc;
  745.  
  746.             rc = copy_to_uspace(uspace_thread_id, &t->tid,
  747.                 sizeof(t->tid));
  748.             if (rc != 0) {
  749.                 /*
  750.                  * We have encountered a failure, but the thread
  751.                  * has already been created. We need to undo its
  752.                  * creation now.
  753.                  */
  754.  
  755.                 /*
  756.                  * The new thread structure is initialized, but
  757.                  * is still not visible to the system.
  758.                  * We can safely deallocate it.
  759.                  */
  760.                 slab_free(thread_slab, t);
  761.                 free(kernel_uarg);
  762.  
  763.                 return (unative_t) rc;
  764.              }
  765.         }
  766. #ifdef CONFIG_UDEBUG
  767.         /*
  768.          * Generate udebug THREAD_B event and attach the thread.
  769.          * This must be done atomically (with the debug locks held),
  770.          * otherwise we would either miss some thread or receive
  771.          * THREAD_B events for threads that already existed
  772.          * and could be detected with THREAD_READ before.
  773.          */
  774.         udebug_thread_b_event_attach(t, TASK);
  775. #else
  776.         thread_attach(t, TASK);
  777. #endif
  778.         thread_ready(t);
  779.  
  780.         return 0;
  781.     } else
  782.         free(kernel_uarg);
  783.  
  784.     return (unative_t) ENOMEM;
  785. }
  786.  
  787. /** Process syscall to terminate thread.
  788.  *
  789.  */
  790. unative_t sys_thread_exit(int uspace_status)
  791. {
  792.     thread_exit();
  793.     /* Unreachable */
  794.     return 0;
  795. }
  796.  
  797. /** Syscall for getting TID.
  798.  *
  799.  * @param uspace_thread_id Userspace address of 8-byte buffer where to store
  800.  * current thread ID.
  801.  *
  802.  * @return 0 on success or an error code from @ref errno.h.
  803.  */
  804. unative_t sys_thread_get_id(thread_id_t *uspace_thread_id)
  805. {
  806.     /*
  807.      * No need to acquire lock on THREAD because tid
  808.      * remains constant for the lifespan of the thread.
  809.      */
  810.     return (unative_t) copy_to_uspace(uspace_thread_id, &THREAD->tid,
  811.         sizeof(THREAD->tid));
  812. }
  813.  
  814. /** @}
  815.  */
  816.