rom/exec/service.c

   1 /*
   2     Copyright © 1995-2011, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: exec.library's internal service task. Performs memory management according
   6           to task scheduler's requests.
   7     Lang: english
   8 */
   9
  10 #include <aros/debug.h>
  11 #include <exec/execbase.h>
  12 #include <exec/tasks.h>
  13 #include <aros/libcall.h>
  14 #include <proto/exec.h>
  15 #include <proto/kernel.h>
  16
  17 #include "exec_intern.h"
  18 #include "exec_util.h"
  19 #include "exec_debug.h"
  20
  21 void ServiceTask(struct ExecBase *SysBase)
  22 {
  23     DINIT("Service task started up");
  24
  25     do
  26     { /* forever */
  27         struct Task *task;
  28         struct MemList *mb, *mbnext;
  29
  30         while ((task = (struct Task *)GetMsg(PrivExecBase(SysBase)->ServicePort)))
  31         {
  32             D(bug("[exec] Service request for task 0x%p, state %d\n", task, task->tc_State));
  33
  34             /*
  35              * If we ever need to use TSS here, we'll need to explicitly check its size here.
  36              * However we don't need this, because we never call so high-level libraries.
  37              * So, currently we ignore this.
  38              */
  39
  40             switch (task->tc_State)
  41             {
  42             case TS_REMOVED:
  43                 DREMTASK("Removal request for task 0x%p <%s>", task, task->tc_Node.ln_Name);
  44
  45                 /*
  46                  * Note tc_MemEntry list is part of the task structure which
  47                  * usually is also placed in tc_MemEntry. MungWall_Check()
  48                  * will fill freed memory and destroy our list while we are
  49                  * iterating or the freed memory including our list could be
  50                  * reused by some other task. We take special care of this by
  51                  * resetting ln_Succ of the last node to NULL. This way we
  52                  * avoid getting back to our List structure.
  53                  */
  54                 task->tc_MemEntry.lh_TailPred->ln_Succ = NULL;
  55
  56                 for (mb = (struct MemList *)task->tc_MemEntry.lh_Head; mb; mb = mbnext)
  57                 {
  58                     /* Free one MemList node */
  59                     mbnext = (struct MemList *)mb->ml_Node.ln_Succ;
  60
  61                     DREMTASK("Freeing MemList 0x%p", mb);
  62                     FreeEntry(mb);
  63                 }
  64                 break;
  65
  66             default:
  67                 /* FIXME: Add fault handling here. Perhaps kernel-level GURU. */
  68
  69                 /* The task is ready to run again. Move it back to TaskReady list. */
  70                 task->tc_State = TS_READY;
  71                 Enqueue(&SysBase->TaskReady,&task->tc_Node);
  72
  73                 break;
  74             }
  75         }
  76
  77         WaitPort(PrivExecBase(SysBase)->ServicePort);
  78     } while(1);
  79 }