rom/exec/findtask.c

   1 /*
   2     Copyright © 1995-2017, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Search a task by name.
   6     Lang: english
   7 */
   8
   9 #define DEBUG 0
  10
  11 #include <exec/execbase.h>
  12 #include <aros/libcall.h>
  13 #include <proto/exec.h>
  14
  15 #include "exec_intern.h"
  16
  17 /*****************************************************************************
  18
  19     NAME */
  20
  21         AROS_LH1(struct Task *, FindTask,
  22
  23 /*  SYNOPSIS */
  24         AROS_LHA(CONST_STRPTR, name, A1),
  25
  26 /*  LOCATION */
  27         struct ExecBase *, SysBase, 49, Exec)
  28
  29 /*  FUNCTION
  30         Find a task with a given name or get the address of the current task.
  31         Finding the address of the current task is a very quick function
  32         call, but finding a special task is a very CPU intensive instruction.
  33         Note that generally a task may already be gone when this function
  34         returns.
  35
  36     INPUTS
  37         name - Pointer to name or NULL for current task.
  38
  39     RESULT
  40         Address of task structure found.
  41
  42     NOTES
  43
  44     EXAMPLE
  45
  46     BUGS
  47
  48     SEE ALSO
  49
  50     INTERNALS
  51
  52 ******************************************************************************/
  53 {
  54     AROS_LIBFUNC_INIT
  55
  56 #if defined(__AROSEXEC_SMP__)
  57     spinlock_t *listLock;
  58 #endif
  59     struct Task *ret, *thisTask = GET_THIS_TASK;
  60
  61     /* Quick return for a quick argument */
  62     if (name == NULL)
  63         return thisTask;
  64
  65     /* Always protect task lists */
  66 #if defined(__AROSEXEC_SMP__)
  67     listLock = EXECTASK_SPINLOCK_LOCKDISABLE(&PrivExecBase(SysBase)->TaskReadySpinLock, SPINLOCK_MODE_READ);
  68 #else
  69     Disable();
  70 #endif
  71
  72     /* First look into the ready list. */
  73     ret = (struct Task *)FindName(&SysBase->TaskReady, name);
  74     if (ret == NULL)
  75     {
  76 #if defined(__AROSEXEC_SMP__)
  77         EXECTASK_SPINLOCK_UNLOCK(listLock);
  78         Enable();
  79         listLock = EXECTASK_SPINLOCK_LOCKDISABLE(&PrivExecBase(SysBase)->TaskWaitSpinLock, SPINLOCK_MODE_READ);
  80 #endif
  81         /* Then into the waiting list. */
  82         ret = (struct Task *)FindName(&SysBase->TaskWait, name);
  83         if (ret == NULL)
  84         {
  85             /*
  86                 Finally test the running task(s). This is mainly of importance on smp systems.
  87             */
  88 #if defined(__AROSEXEC_SMP__)
  89             EXECTASK_SPINLOCK_UNLOCK(listLock);
  90             Enable();
  91             listLock = EXECTASK_SPINLOCK_LOCKDISABLE(&PrivExecBase(SysBase)->TaskRunningSpinLock, SPINLOCK_MODE_READ);
  92             ret = (struct Task *)FindName(&PrivExecBase(SysBase)->TaskRunning, name);
  93             if (ret == NULL)
  94             {
  95                 EXECTASK_SPINLOCK_UNLOCK(listLock);
  96                 Enable();
  97                 listLock = EXECTASK_SPINLOCK_LOCKDISABLE(&PrivExecBase(SysBase)->TaskSpinningLock, SPINLOCK_MODE_READ);
  98                 ret = (struct Task *)FindName(&PrivExecBase(SysBase)->TaskSpinning, name);
  99             }
 100 #else
 101
 102             char *s1;
 103             const char *s2 = name;
 104             s1 = thisTask->tc_Node.ln_Name;
 105             /* Check as long as the names are identical. */
 106             while (*s1++ == *s2)
 107                 /* Terminator found? */
 108                 if (!*s2++)
 109                 {
 110                     /* Got it. */
 111                     ret = thisTask;
 112                     break;
 113                 }
 114 #endif
 115         }
 116     }
 117
 118 #if defined(__AROSEXEC_SMP__)
 119     EXECTASK_SPINLOCK_UNLOCK(listLock);
 120 #endif
 121     Enable();
 122
 123     /* Return whatever was found. */
 124     return ret;
 125
 126     AROS_LIBFUNC_EXIT
 127 } /* FindTask */
 128