rom/exec/remtask.c

   1 /*
   2     Copyright © 1995-2001, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Remove a task
   6     Lang: english
   7 */
   8 #include <exec/execbase.h>
   9 #include <exec/tasks.h>
  10 #include <aros/libcall.h>
  11 #include <proto/exec.h>
  12
  13 #include "exec_util.h"
  14 #include "exec_debug.h"
  15 #ifndef DEBUG_RemTask
  16 #   define DEBUG_RemTask 0
  17 #endif
  18 #undef DEBUG
  19 #if DEBUG_RemTask
  20 #   define DEBUG 1
  21 #endif
  22 #include <aros/debug.h>
  23
  24 /*****************************************************************************
  25
  26     NAME */
  27
  28         AROS_LH1(void, RemTask,
  29
  30 /*  SYNOPSIS */
  31         AROS_LHA(struct Task *,     task, A1),
  32
  33 /*  LOCATION */
  34         struct ExecBase *, SysBase, 48, Exec)
  35
  36 /*  FUNCTION
  37         Remove a task from the task lists. All memory in the tc_MemEntry list
  38         is freed and a rescedule is done. It's safe to call RemTask() out
  39         of Forbid() or Disable().
  40         This function is one way to get rid of the current task. The other way
  41         is to fall through the end of the entry point.
  42
  43     INPUTS
  44         task - Task to be removed. NULL means current task.
  45
  46     RESULT
  47
  48     NOTES
  49
  50     EXAMPLE
  51
  52     BUGS
  53
  54     SEE ALSO
  55         AddTask()
  56
  57     INTERNALS
  58
  59 ******************************************************************************/
  60 {
  61     AROS_LIBFUNC_INIT
  62     struct MemList *mb;
  63     struct ETask *et;
  64
  65     /* A value of NULL means current task */
  66     if (task==NULL)
  67         task=SysBase->ThisTask;
  68
  69     D(bug("Call RemTask (%08lx (\"%s\"))\n", task, task->tc_Node.ln_Name));
  70
  71     /*
  72         Since it's possible that the following will free a task
  73         structure that is used for some time afterwards it's
  74         necessary to protect the free memory list so that nobody
  75         can allocate that memory.
  76     */
  77     Forbid();
  78
  79     /* Remove() here, before freeing the MemEntry list. Because
  80        the MemEntry list might contain the task struct itself! */
  81
  82     if(task != SysBase->ThisTask)
  83     {
  84         /* disable interrupts when changing the task lists */
  85         Disable();
  86         Remove(&task->tc_Node);
  87         Enable();
  88
  89         /* force the task into the removed state, otherwise a received signal
  90          * can bring it back to life */
  91         task->tc_State = TS_REMOVED;
  92     }
  93
  94     /* Free all memory in the tc_MemEntry list. */
  95     while((mb=(struct MemList *)RemHead(&task->tc_MemEntry))!=NULL)
  96         /* Free one MemList node */
  97         FreeEntry(mb);
  98
  99     /* Uninitialize ETask structure */
 100     et = GetETask(task);
 101     if(et != NULL)
 102     {
 103         CleanupETask(task, et);
 104     }
 105
 106     /* Changing the task lists always needs a Disable(). */
 107     Disable();
 108
 109     /* Freeing myself? */
 110     if(task==SysBase->ThisTask)
 111     {
 112         /* Can't do that - let the dispatcher do it. */
 113         task->tc_State=TS_REMOVED;
 114
 115         /*
 116             Since I don't know how many levels of Forbid()
 117             are already pending I set a default value.
 118         */
 119         SysBase->TDNestCnt=-1;
 120
 121         /* And force a task switch */
 122         Switch();
 123         /* Does not return. */
 124     }
 125
 126     /* All done. */
 127     Enable();
 128     Permit();
 129
 130     ReturnVoid ("RemTask");
 131     AROS_LIBFUNC_EXIT
 132 } /* RemTask() */
 133