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  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. #include <time/clock.h>
  30. #include <time/timeout.h>
  31. #include <arch/types.h>
  32. #include <config.h>
  33. #include <synch/spinlock.h>
  34. #include <synch/waitq.h>
  35. #include <func.h>
  36. #include <proc/scheduler.h>
  37. #include <cpu.h>
  38. #include <print.h>
  39. #include <arch.h>
  40. #include <list.h>
  41.  
  42. #ifdef __SMP__
  43. #include <arch/smp/atomic.h>
  44. #endif
  45.  
  46. /** Clock routine
  47.  *
  48.  * Clock routine executed from clock interrupt handler
  49.  * (assuming cpu_priority_high()). Runs expired timeouts
  50.  * and preemptive scheduling.
  51.  *
  52.  */
  53. void clock(void)
  54. {
  55.     link_t *l;
  56.     timeout_t *h;
  57.     timeout_handler f;
  58.     void *arg;
  59.  
  60.     /*
  61.      * To avoid lock ordering problems,
  62.      * run all expired timeouts as you visit them.
  63.      */
  64.     spinlock_lock(&CPU->timeoutlock);
  65.     while ((l = CPU->timeout_active_head.next) != &CPU->timeout_active_head) {
  66.         h = list_get_instance(l, timeout_t, link);
  67.         spinlock_lock(&h->lock);
  68.         if (h->ticks-- != 0) {
  69.             spinlock_unlock(&h->lock);
  70.             break;
  71.         }
  72.         list_remove(l);
  73.         f = h->handler;
  74.         arg = h->arg;
  75.         timeout_reinitialize(h);
  76.         spinlock_unlock(&h->lock); 
  77.         spinlock_unlock(&CPU->timeoutlock);
  78.  
  79.         f(arg);
  80.  
  81.         spinlock_lock(&CPU->timeoutlock);
  82.     }
  83.     spinlock_unlock(&CPU->timeoutlock);
  84.  
  85.     /*
  86.      * Do CPU usage accounting and find out whether to preempt THREAD.
  87.      */
  88.  
  89.     if (THREAD) {
  90.         spinlock_lock(&CPU->lock);
  91.         CPU->needs_relink++;
  92.         spinlock_unlock(&CPU->lock);   
  93.    
  94.         spinlock_lock(&THREAD->lock);
  95.             if (!THREAD->ticks--) {
  96.             spinlock_unlock(&THREAD->lock);
  97.             scheduler();
  98.         }
  99.         else {
  100.             spinlock_unlock(&THREAD->lock);
  101.         }
  102.     }
  103.  
  104. }
  105.