Subversion Repositories HelenOS

Rev

Rev 3745 | Go to most recent revision | 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 ARCH_HAS_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 ARCH_HAS_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 ARCH_HAS_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 ARCH_HAS_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 ARCH_HAS_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.     if (cpu->arch.exec_unit)
  269.         atomic_inc(&(cpu->arch.exec_unit->nrdy));
  270.  
  271.     interrupts_restore(ipl);
  272. }
  273.  
  274. /** Create new thread
  275.  *
  276.  * Create a new thread.
  277.  *
  278.  * @param func      Thread's implementing function.
  279.  * @param arg       Thread's implementing function argument.
  280.  * @param task      Task to which the thread belongs. The caller must
  281.  *          guarantee that the task won't cease to exist during the
  282.  *          call. The task's lock may not be held.
  283.  * @param flags     Thread flags.
  284.  * @param name      Symbolic name (a copy is made).
  285.  * @param uncounted Thread's accounting doesn't affect accumulated task
  286.  *          accounting.
  287.  *
  288.  * @return      New thread's structure on success, NULL on failure.
  289.  *
  290.  */
  291. thread_t *thread_create(void (* func)(void *), void *arg, task_t *task,
  292.     int flags, char *name, bool uncounted)
  293. {
  294.     thread_t *t;
  295.     ipl_t ipl;
  296.    
  297.     t = (thread_t *) slab_alloc(thread_slab, 0);
  298.     if (!t)
  299.         return NULL;
  300.    
  301.     /* Not needed, but good for debugging */
  302.     memsetb(t->kstack, THREAD_STACK_SIZE * 1 << STACK_FRAMES, 0);
  303.    
  304.     ipl = interrupts_disable();
  305.     spinlock_lock(&tidlock);
  306.     t->tid = ++last_tid;
  307.     spinlock_unlock(&tidlock);
  308.     interrupts_restore(ipl);
  309.    
  310.     context_save(&t->saved_context);
  311.     context_set(&t->saved_context, FADDR(cushion), (uintptr_t) t->kstack,
  312.         THREAD_STACK_SIZE);
  313.    
  314.     the_initialize((the_t *) t->kstack);
  315.    
  316.     ipl = interrupts_disable();
  317.     t->saved_context.ipl = interrupts_read();
  318.     interrupts_restore(ipl);
  319.    
  320.     memcpy(t->name, name, THREAD_NAME_BUFLEN);
  321.     t->name[THREAD_NAME_BUFLEN - 1] = '\0';
  322.    
  323.     t->thread_code = func;
  324.     t->thread_arg = arg;
  325.     t->ticks = -1;
  326.     t->cycles = 0;
  327.     t->uncounted = uncounted;
  328.     t->priority = -1;       /* start in rq[0] */
  329.     t->cpu = NULL;
  330.     t->flags = flags;
  331.     t->state = Entering;
  332.     t->call_me = NULL;
  333.     t->call_me_with = NULL;
  334.    
  335.     timeout_initialize(&t->sleep_timeout);
  336.     t->sleep_interruptible = false;
  337.     t->sleep_queue = NULL;
  338.     t->timeout_pending = 0;
  339.  
  340.     t->in_copy_from_uspace = false;
  341.     t->in_copy_to_uspace = false;
  342.  
  343.     t->interrupted = false;
  344.     t->detached = false;
  345.     waitq_initialize(&t->join_wq);
  346.    
  347.     t->rwlock_holder_type = RWLOCK_NONE;
  348.        
  349.     t->task = task;
  350.    
  351.     t->fpu_context_exists = 0;
  352.     t->fpu_context_engaged = 0;
  353.  
  354.     avltree_node_initialize(&t->threads_tree_node);
  355.     t->threads_tree_node.key = (uintptr_t) t;
  356.  
  357. #ifdef CONFIG_UDEBUG
  358.     /* Init debugging stuff */
  359.     udebug_thread_initialize(&t->udebug);
  360. #endif
  361.  
  362.     /* might depend on previous initialization */
  363.     thread_create_arch(t); 
  364.  
  365.     if (!(flags & THREAD_FLAG_NOATTACH))
  366.         thread_attach(t, task);
  367.  
  368.     return t;
  369. }
  370.  
  371. /** Destroy thread memory structure
  372.  *
  373.  * Detach thread from all queues, cpus etc. and destroy it.
  374.  *
  375.  * Assume thread->lock is held!!
  376.  */
  377. void thread_destroy(thread_t *t)
  378. {
  379.     ASSERT(t->state == Exiting || t->state == Lingering);
  380.     ASSERT(t->task);
  381.     ASSERT(t->cpu);
  382.  
  383.     spinlock_lock(&t->cpu->lock);
  384.     if (t->cpu->fpu_owner == t)
  385.         t->cpu->fpu_owner = NULL;
  386.     spinlock_unlock(&t->cpu->lock);
  387.  
  388.     spinlock_unlock(&t->lock);
  389.  
  390.     spinlock_lock(&threads_lock);
  391.     avltree_delete(&threads_tree, &t->threads_tree_node);
  392.     spinlock_unlock(&threads_lock);
  393.  
  394.     /*
  395.      * Detach from the containing task.
  396.      */
  397.     spinlock_lock(&t->task->lock);
  398.     list_remove(&t->th_link);
  399.     spinlock_unlock(&t->task->lock);   
  400.  
  401.     /*
  402.      * t is guaranteed to be the very last thread of its task.
  403.      * It is safe to destroy the task.
  404.      */
  405.     if (atomic_predec(&t->task->refcount) == 0)
  406.         task_destroy(t->task);
  407.    
  408.     slab_free(thread_slab, t);
  409. }
  410.  
  411. /** Make the thread visible to the system.
  412.  *
  413.  * Attach the thread structure to the current task and make it visible in the
  414.  * threads_tree.
  415.  *
  416.  * @param t Thread to be attached to the task.
  417.  * @param task  Task to which the thread is to be attached.
  418.  */
  419. void thread_attach(thread_t *t, task_t *task)
  420. {
  421.     ipl_t ipl;
  422.  
  423.     /*
  424.      * Attach to the specified task.
  425.      */
  426.     ipl = interrupts_disable();
  427.     spinlock_lock(&task->lock);
  428.  
  429.     atomic_inc(&task->refcount);
  430.  
  431.     /* Must not count kbox thread into lifecount */
  432.     if (t->flags & THREAD_FLAG_USPACE)
  433.         atomic_inc(&task->lifecount);
  434.  
  435.     list_append(&t->th_link, &task->th_head);
  436.     spinlock_unlock(&task->lock);
  437.  
  438.     /*
  439.      * Register this thread in the system-wide list.
  440.      */
  441.     spinlock_lock(&threads_lock);
  442.     avltree_insert(&threads_tree, &t->threads_tree_node);
  443.     spinlock_unlock(&threads_lock);
  444.    
  445.     interrupts_restore(ipl);
  446. }
  447.  
  448. /** Terminate thread.
  449.  *
  450.  * End current thread execution and switch it to the exiting state. All pending
  451.  * timeouts are executed.
  452.  */
  453. void thread_exit(void)
  454. {
  455.     ipl_t ipl;
  456.  
  457.     if (THREAD->flags & THREAD_FLAG_USPACE) {
  458. #ifdef CONFIG_UDEBUG
  459.         /* Generate udebug THREAD_E event */
  460.         udebug_thread_e_event();
  461. #endif
  462.         if (atomic_predec(&TASK->lifecount) == 0) {
  463.             /*
  464.              * We are the last userspace thread in the task that
  465.              * still has not exited. With the exception of the
  466.              * moment the task was created, new userspace threads
  467.              * can only be created by threads of the same task.
  468.              * We are safe to perform cleanup.
  469.              */
  470.             ipc_cleanup();
  471.             futex_cleanup();
  472.             LOG("Cleanup of task %" PRIu64" completed.", TASK->taskid);
  473.         }
  474.     }
  475.  
  476. restart:
  477.     ipl = interrupts_disable();
  478.     spinlock_lock(&THREAD->lock);
  479.     if (THREAD->timeout_pending) {
  480.         /* busy waiting for timeouts in progress */
  481.         spinlock_unlock(&THREAD->lock);
  482.         interrupts_restore(ipl);
  483.         goto restart;
  484.     }
  485.    
  486.     THREAD->state = Exiting;
  487.     spinlock_unlock(&THREAD->lock);
  488.     scheduler();
  489.  
  490.     /* Not reached */
  491.     while (1)
  492.         ;
  493. }
  494.  
  495.  
  496. /** Thread sleep
  497.  *
  498.  * Suspend execution of the current thread.
  499.  *
  500.  * @param sec Number of seconds to sleep.
  501.  *
  502.  */
  503. void thread_sleep(uint32_t sec)
  504. {
  505.     thread_usleep(sec * 1000000);
  506. }
  507.  
  508. /** Wait for another thread to exit.
  509.  *
  510.  * @param t Thread to join on exit.
  511.  * @param usec Timeout in microseconds.
  512.  * @param flags Mode of operation.
  513.  *
  514.  * @return An error code from errno.h or an error code from synch.h.
  515.  */
  516. int thread_join_timeout(thread_t *t, uint32_t usec, int flags)
  517. {
  518.     ipl_t ipl;
  519.     int rc;
  520.  
  521.     if (t == THREAD)
  522.         return EINVAL;
  523.  
  524.     /*
  525.      * Since thread join can only be called once on an undetached thread,
  526.      * the thread pointer is guaranteed to be still valid.
  527.      */
  528.    
  529.     ipl = interrupts_disable();
  530.     spinlock_lock(&t->lock);
  531.     ASSERT(!t->detached);
  532.     spinlock_unlock(&t->lock);
  533.     interrupts_restore(ipl);
  534.    
  535.     rc = waitq_sleep_timeout(&t->join_wq, usec, flags);
  536.    
  537.     return rc; 
  538. }
  539.  
  540. /** Detach thread.
  541.  *
  542.  * Mark the thread as detached, if the thread is already in the Lingering
  543.  * state, deallocate its resources.
  544.  *
  545.  * @param t Thread to be detached.
  546.  */
  547. void thread_detach(thread_t *t)
  548. {
  549.     ipl_t ipl;
  550.  
  551.     /*
  552.      * Since the thread is expected not to be already detached,
  553.      * pointer to it must be still valid.
  554.      */
  555.     ipl = interrupts_disable();
  556.     spinlock_lock(&t->lock);
  557.     ASSERT(!t->detached);
  558.     if (t->state == Lingering) {
  559.         thread_destroy(t);  /* unlocks &t->lock */
  560.         interrupts_restore(ipl);
  561.         return;
  562.     } else {
  563.         t->detached = true;
  564.     }
  565.     spinlock_unlock(&t->lock);
  566.     interrupts_restore(ipl);
  567. }
  568.  
  569. /** Thread usleep
  570.  *
  571.  * Suspend execution of the current thread.
  572.  *
  573.  * @param usec Number of microseconds to sleep.
  574.  *
  575.  */
  576. void thread_usleep(uint32_t usec)
  577. {
  578.     waitq_t wq;
  579.                  
  580.     waitq_initialize(&wq);
  581.  
  582.     (void) waitq_sleep_timeout(&wq, usec, SYNCH_FLAGS_NON_BLOCKING);
  583. }
  584.  
  585. /** Register thread out-of-context invocation
  586.  *
  587.  * Register a function and its argument to be executed
  588.  * on next context switch to the current thread.
  589.  *
  590.  * @param call_me      Out-of-context function.
  591.  * @param call_me_with Out-of-context function argument.
  592.  *
  593.  */
  594. void thread_register_call_me(void (* call_me)(void *), void *call_me_with)
  595. {
  596.     ipl_t ipl;
  597.    
  598.     ipl = interrupts_disable();
  599.     spinlock_lock(&THREAD->lock);
  600.     THREAD->call_me = call_me;
  601.     THREAD->call_me_with = call_me_with;
  602.     spinlock_unlock(&THREAD->lock);
  603.     interrupts_restore(ipl);
  604. }
  605.  
  606. static bool thread_walker(avltree_node_t *node, void *arg)
  607. {
  608.     thread_t *t = avltree_get_instance(node, thread_t, threads_tree_node);
  609.    
  610.     uint64_t cycles;
  611.     char suffix;
  612.     order(t->cycles, &cycles, &suffix);
  613.  
  614. #ifdef __32_BITS__
  615.     printf("%-6" PRIu64" %-10s %10p %-8s %10p %-3" PRIu32 " %10p %10p %9" PRIu64 "%c ",
  616.         t->tid, t->name, t, thread_states[t->state], t->task,
  617.         t->task->context, t->thread_code, t->kstack, cycles, suffix);
  618. #endif
  619.  
  620. #ifdef __64_BITS__
  621.     printf("%-6" PRIu64" %-10s %18p %-8s %18p %-3" PRIu32 " %18p %18p %9" PRIu64 "%c ",
  622.         t->tid, t->name, t, thread_states[t->state], t->task,
  623.         t->task->context, t->thread_code, t->kstack, cycles, suffix);
  624. #endif
  625.            
  626.     if (t->cpu)
  627.         printf("%-4u", t->cpu->id);
  628.     else
  629.         printf("none");
  630.            
  631.     if (t->state == Sleeping) {
  632. #ifdef __32_BITS__
  633.         printf(" %10p", t->sleep_queue);
  634. #endif
  635.  
  636. #ifdef __64_BITS__
  637.         printf(" %18p", t->sleep_queue);
  638. #endif
  639.     }
  640.            
  641.     printf("\n");
  642.  
  643.     return true;
  644. }
  645.  
  646. /** Print list of threads debug info */
  647. void thread_print_list(void)
  648. {
  649.     ipl_t ipl;
  650.    
  651.     /* Messing with thread structures, avoid deadlock */
  652.     ipl = interrupts_disable();
  653.     spinlock_lock(&threads_lock);
  654.  
  655. #ifdef __32_BITS__ 
  656.     printf("tid    name       address    state    task       "
  657.         "ctx code       stack      cycles     cpu  "
  658.         "waitqueue\n");
  659.     printf("------ ---------- ---------- -------- ---------- "
  660.         "--- ---------- ---------- ---------- ---- "
  661.         "----------\n");
  662. #endif
  663.  
  664. #ifdef __64_BITS__
  665.     printf("tid    name       address            state    task               "
  666.         "ctx code               stack              cycles     cpu  "
  667.         "waitqueue\n");
  668.     printf("------ ---------- ------------------ -------- ------------------ "
  669.         "--- ------------------ ------------------ ---------- ---- "
  670.         "------------------\n");
  671. #endif
  672.  
  673.     avltree_walk(&threads_tree, thread_walker, NULL);
  674.  
  675.     spinlock_unlock(&threads_lock);
  676.     interrupts_restore(ipl);
  677. }
  678.  
  679. /** Check whether thread exists.
  680.  *
  681.  * Note that threads_lock must be already held and
  682.  * interrupts must be already disabled.
  683.  *
  684.  * @param t Pointer to thread.
  685.  *
  686.  * @return True if thread t is known to the system, false otherwise.
  687.  */
  688. bool thread_exists(thread_t *t)
  689. {
  690.     avltree_node_t *node;
  691.  
  692.     node = avltree_search(&threads_tree, (avltree_key_t) ((uintptr_t) t));
  693.    
  694.     return node != NULL;
  695. }
  696.  
  697. /** Update accounting of current thread.
  698.  *
  699.  * Note that thread_lock on THREAD must be already held and
  700.  * interrupts must be already disabled.
  701.  *
  702.  */
  703. void thread_update_accounting(void)
  704. {
  705.     uint64_t time = get_cycle();
  706.     THREAD->cycles += time - THREAD->last_cycle;
  707.     THREAD->last_cycle = time;
  708. }
  709.  
  710. /** Process syscall to create new thread.
  711.  *
  712.  */
  713. unative_t sys_thread_create(uspace_arg_t *uspace_uarg, char *uspace_name,
  714.     size_t name_len, thread_id_t *uspace_thread_id)
  715. {
  716.     thread_t *t;
  717.     char namebuf[THREAD_NAME_BUFLEN];
  718.     uspace_arg_t *kernel_uarg;
  719.     int rc;
  720.  
  721.     if (name_len > THREAD_NAME_BUFLEN - 1)
  722.         name_len = THREAD_NAME_BUFLEN - 1;
  723.  
  724.     rc = copy_from_uspace(namebuf, uspace_name, name_len);
  725.     if (rc != 0)
  726.         return (unative_t) rc;
  727.  
  728.     namebuf[name_len] = '\0';
  729.  
  730.     /*
  731.      * In case of failure, kernel_uarg will be deallocated in this function.
  732.      * In case of success, kernel_uarg will be freed in uinit().
  733.      */
  734.     kernel_uarg = (uspace_arg_t *) malloc(sizeof(uspace_arg_t), 0);
  735.    
  736.     rc = copy_from_uspace(kernel_uarg, uspace_uarg, sizeof(uspace_arg_t));
  737.     if (rc != 0) {
  738.         free(kernel_uarg);
  739.         return (unative_t) rc;
  740.     }
  741.  
  742.     t = thread_create(uinit, kernel_uarg, TASK,
  743.         THREAD_FLAG_USPACE | THREAD_FLAG_NOATTACH, namebuf, false);
  744.     if (t) {
  745.         if (uspace_thread_id != NULL) {
  746.             int rc;
  747.  
  748.             rc = copy_to_uspace(uspace_thread_id, &t->tid,
  749.                 sizeof(t->tid));
  750.             if (rc != 0) {
  751.                 /*
  752.                  * We have encountered a failure, but the thread
  753.                  * has already been created. We need to undo its
  754.                  * creation now.
  755.                  */
  756.  
  757.                 /*
  758.                  * The new thread structure is initialized, but
  759.                  * is still not visible to the system.
  760.                  * We can safely deallocate it.
  761.                  */
  762.                 slab_free(thread_slab, t);
  763.                 free(kernel_uarg);
  764.  
  765.                 return (unative_t) rc;
  766.              }
  767.         }
  768. #ifdef CONFIG_UDEBUG
  769.         /*
  770.          * Generate udebug THREAD_B event and attach the thread.
  771.          * This must be done atomically (with the debug locks held),
  772.          * otherwise we would either miss some thread or receive
  773.          * THREAD_B events for threads that already existed
  774.          * and could be detected with THREAD_READ before.
  775.          */
  776.         udebug_thread_b_event_attach(t, TASK);
  777. #else
  778.         thread_attach(t, TASK);
  779. #endif
  780.         thread_ready(t);
  781.  
  782.         return 0;
  783.     } else
  784.         free(kernel_uarg);
  785.  
  786.     return (unative_t) ENOMEM;
  787. }
  788.  
  789. /** Process syscall to terminate thread.
  790.  *
  791.  */
  792. unative_t sys_thread_exit(int uspace_status)
  793. {
  794.     thread_exit();
  795.     /* Unreachable */
  796.     return 0;
  797. }
  798.  
  799. /** Syscall for getting TID.
  800.  *
  801.  * @param uspace_thread_id Userspace address of 8-byte buffer where to store
  802.  * current thread ID.
  803.  *
  804.  * @return 0 on success or an error code from @ref errno.h.
  805.  */
  806. unative_t sys_thread_get_id(thread_id_t *uspace_thread_id)
  807. {
  808.     /*
  809.      * No need to acquire lock on THREAD because tid
  810.      * remains constant for the lifespan of the thread.
  811.      */
  812.     return (unative_t) copy_to_uspace(uspace_thread_id, &THREAD->tid,
  813.         sizeof(THREAD->tid));
  814. }
  815.  
  816. /** @}
  817.  */
  818.