rom/exec/service.c

   1 /*
   2     Copyright © 1995-2017, 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 <exec/execbase.h>
  11 #include <exec/tasks.h>
  12 #include <aros/libcall.h>
  13 #include <proto/exec.h>
  14
  15 #include "exec_intern.h"
  16 #include "exec_util.h"
  17 #include "exec_debug.h"
  18
  19 void ServiceTask(struct ExecBase *SysBase)
  20 {
  21     struct Task *task;
  22     struct MemList *mb, *mbnext;
  23
  24     DINIT("ServiceTask: Started up");
  25
  26     do
  27     { /* forever */
  28
  29
  30         while ((task = (struct Task *)GetMsg(PrivExecBase(SysBase)->ServicePort)))
  31         {
  32             DREMTASK("ServiceTask: Request for task 0x%p, state %08X\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_INVALID:
  43             case TS_REMOVED:
  44                 DREMTASK("ServiceTask: Removal request for task 0x%p <%s>", task, task->tc_Node.ln_Name);
  45
  46                 // TODO: Make sure the task has terminated..
  47                 task->tc_State = TS_INVALID;
  48
  49                 /*
  50                  * Note tc_MemEntry list is part of the task structure which
  51                  * usually is also placed in tc_MemEntry. MungWall_Check()
  52                  * will fill freed memory and destroy our list while we are
  53                  * iterating or the freed memory including our list could be
  54                  * reused by some other task. We take special care of this by
  55                  * resetting ln_Succ of the last node to NULL. This way we
  56                  * avoid getting back to our List structure.
  57                  */
  58                 task->tc_MemEntry.lh_TailPred->ln_Succ = NULL;
  59
  60                 for (mb = (struct MemList *)task->tc_MemEntry.lh_Head; mb; mb = mbnext)
  61                 {
  62                     /* Free one MemList node */
  63                     mbnext = (struct MemList *)mb->ml_Node.ln_Succ;
  64
  65                     DREMTASK("ServiceTask: Freeing MemList 0x%p", mb);
  66                     FreeEntry(mb);
  67                 }
  68                 break;
  69
  70             default:
  71                 /* FIXME: Add fault handling here. Perhaps kernel-level GURU. */
  72                 DREMTASK("ServiceTask: task 0x%p <%s> not in tombstoned state!\n", task, task->tc_Node.ln_Name);
  73                 DREMTASK("ServiceTask: state = %08X\n", task->tc_State);
  74                 /* The task is ready to run again. Move it back to TaskReady list. */
  75 #if !defined(EXEC_REMTASK_NEEDSSWITCH)
  76                 task->tc_State = TS_READY;
  77                 Enqueue(&SysBase->TaskReady, &task->tc_Node);
  78 #else
  79                 krnSysCallReschedTask(task, TS_READY);
  80 #endif
  81                 break;
  82             }
  83         }
  84
  85         WaitPort(PrivExecBase(SysBase)->ServicePort);
  86     } while(1);
  87 }