rom/exec/settaskpri.c

   1 /*
   2     Copyright © 1995-2015, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Change the priority of a task.
   6     Lang: english
   7 */
   8 #define DEBUG 0
   9
  10 #include <aros/debug.h>
  11 #include <exec/execbase.h>
  12 #include <aros/libcall.h>
  13 #include <proto/exec.h>
  14
  15 #include "exec_intern.h"
  16 #if defined(__AROSEXEC_SMP__)
  17 #include <proto/kernel.h>
  18 #include "etask.h"
  19 #endif
  20
  21 /*****************************************************************************
  22
  23     NAME */
  24
  25         AROS_LH2(BYTE, SetTaskPri,
  26
  27 /*  SYNOPSIS */
  28         AROS_LHA(struct Task *, task,      A1),
  29         AROS_LHA(LONG,          priority,  D0),
  30
  31 /*  LOCATION */
  32         struct ExecBase *, SysBase, 50, Exec)
  33
  34 /*  FUNCTION
  35         Change the priority of a given task. As a general rule the higher
  36         the priority the more CPU time a task gets. Useful values are within
  37         -127 to 5.
  38
  39     INPUTS
  40         task     - Pointer to task structure.
  41         priority - New priority of the task.
  42
  43     RESULT
  44         Old task priority.
  45
  46     NOTES
  47
  48     EXAMPLE
  49
  50     BUGS
  51
  52     SEE ALSO
  53
  54     INTERNALS
  55
  56     HISTORY
  57
  58 ******************************************************************************/
  59 {
  60     AROS_LIBFUNC_INIT
  61
  62 #if defined(__AROSEXEC_SMP__)
  63     spinlock_t *task_listlock = NULL;
  64     int cpunum = KrnGetCPUNumber();
  65 #endif
  66     BYTE old;
  67
  68     D(bug("[Exec] SetTaskPri(0x%p, %d)\n", task, priority);)
  69
  70     /* Always Disable() when doing something with task lists. */
  71 #if defined(__AROSEXEC_SMP__)
  72     switch (task->tc_State)
  73     {
  74         case TS_RUN:
  75             task_listlock =&PrivExecBase(SysBase)->TaskRunningSpinLock;
  76             break;
  77         case TS_WAIT:
  78             task_listlock = &PrivExecBase(SysBase)->TaskWaitSpinLock;
  79             break;
  80         default:
  81             task_listlock = &PrivExecBase(SysBase)->TaskReadySpinLock;
  82             break;
  83     }
  84     EXEC_SPINLOCK_LOCK(task_listlock, (task->tc_State == TS_READY) ? SPINLOCK_MODE_WRITE : SPINLOCK_MODE_READ);
  85 #endif
  86     Disable();
  87
  88     /* Get returncode */
  89     old = task->tc_Node.ln_Pri;
  90
  91     /* Set new value. */
  92     task->tc_Node.ln_Pri = priority;
  93
  94     /* Check if the task is willing to run. */
  95     if (task->tc_State != TS_WAIT)
  96     {
  97         /* If it is in the ready list remove and reinsert it. */
  98         if (task->tc_State == TS_READY)
  99         {
 100             Remove(&task->tc_Node);
 101             Enqueue(&SysBase->TaskReady, &task->tc_Node);
 102         }
 103
 104         if (
 105 #if defined(__AROSEXEC_SMP__)
 106              (IntETask(task->tc_UnionETask.tc_ETask)->iet_CpuNumber == cpunum) &&
 107 #endif
 108             ((task->tc_State == TS_RUN) || ( task->tc_Node.ln_Pri > GET_THIS_TASK->tc_Node.ln_Pri))
 109         )
 110         {
 111 #if defined(__AROSEXEC_SMP__)
 112             EXEC_SPINLOCK_UNLOCK(task_listlock);
 113             task_listlock = NULL;
 114 #endif
 115             Reschedule();
 116         }
 117 #if defined(__AROSEXEC_SMP__)
 118         else
 119         {
 120             bug("[Exec] SetTaskPri:\n");
 121         }
 122 #endif
 123     }
 124
 125     /* All done. */
 126 #if defined(__AROSEXEC_SMP__)
 127     if (task_listlock)
 128     {
 129         EXEC_SPINLOCK_UNLOCK(task_listlock);
 130     }
 131 #endif
 132     Enable();
 133
 134     return old;
 135
 136     AROS_LIBFUNC_EXIT
 137 } /* SetTaskPri */