rom/exec/findtask.c

   1 /*
   2     Copyright © 1995-2015, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Search a task by name.
   6     Lang: english
   7 */
   8 #include <exec/execbase.h>
   9 #include <aros/libcall.h>
  10 #include <proto/exec.h>
  11
  12 #include "exec_intern.h"
  13
  14 /*****************************************************************************
  15
  16     NAME */
  17
  18         AROS_LH1(struct Task *, FindTask,
  19
  20 /*  SYNOPSIS */
  21         AROS_LHA(CONST_STRPTR, name, A1),
  22
  23 /*  LOCATION */
  24         struct ExecBase *, SysBase, 49, Exec)
  25
  26 /*  FUNCTION
  27         Find a task with a given name or get the address of the current task.
  28         Finding the address of the current task is a very quick function
  29         call, but finding a special task is a very CPU intensive instruction.
  30         Note that generally a task may already be gone when this function
  31         returns.
  32
  33     INPUTS
  34         name - Pointer to name or NULL for current task.
  35
  36     RESULT
  37         Address of task structure found.
  38
  39     NOTES
  40
  41     EXAMPLE
  42
  43     BUGS
  44
  45     SEE ALSO
  46
  47     INTERNALS
  48
  49 ******************************************************************************/
  50 {
  51     AROS_LIBFUNC_INIT
  52
  53 #if defined(__AROSEXEC_SMP__)
  54     spinlock_t *listLock;
  55 #endif
  56     struct Task *ret;
  57
  58     /* Quick return for a quick argument */
  59     if (name == NULL)
  60         return GET_THIS_TASK;
  61
  62     /* Always protect task lists */
  63 #if defined(__AROSEXEC_SMP__)
  64     listLock = EXEC_SPINLOCK_LOCK(&PrivExecBase(SysBase)->TaskReadySpinLock, SPINLOCK_MODE_READ);
  65     Forbid();
  66 #else
  67     Disable();
  68 #endif
  69
  70     /* First look into the ready list. */
  71     ret = (struct Task *)FindName(&SysBase->TaskReady, name);
  72     if (ret == NULL)
  73     {
  74 #if defined(__AROSEXEC_SMP__)
  75         EXEC_SPINLOCK_UNLOCK(listLock);
  76         Permit();
  77         listLock = EXEC_SPINLOCK_LOCK(&PrivExecBase(SysBase)->TaskWaitSpinLock, SPINLOCK_MODE_READ);
  78         Forbid();
  79 #endif
  80         /* Then into the waiting list. */
  81         ret = (struct Task *)FindName(&SysBase->TaskWait, name);
  82         if (ret == NULL)
  83         {
  84             /*
  85                 Finally test the running task(s). This is mainly of importance on smp systems.
  86             */
  87 #if defined(__AROSEXEC_SMP__)
  88             listLock = EXEC_SPINLOCK_LOCK(&PrivExecBase(SysBase)->TaskRunningSpinLock, SPINLOCK_MODE_READ);
  89             Forbid();
  90             ret = (struct Task *)FindName(&PrivExecBase(SysBase)->TaskRunning, name);
  91             if (ret == NULL)
  92             {
  93                 EXEC_SPINLOCK_UNLOCK(listLock);
  94                 Permit();
  95                 listLock = EXEC_SPINLOCK_LOCK(&PrivExecBase(SysBase)->TaskSpinningLock, SPINLOCK_MODE_READ);
  96                 Forbid();
  97                 ret = (struct Task *)FindName(&PrivExecBase(SysBase)->TaskSpinning, name);
  98             }
  99 #else
 100
 101             char *s1;
 102             const char *s2 = name;
 103             s1 = GET_THIS_TASK->tc_Node.ln_Name;
 104             /* Check as long as the names are identical. */
 105             while (*s1++ == *s2)
 106                 /* Terminator found? */
 107                 if (!*s2++)
 108                 {
 109                     /* Got it. */
 110                     ret = GET_THIS_TASK;
 111                     break;
 112                 }
 113 #endif
 114         }
 115     }
 116
 117 #if defined(__AROSEXEC_SMP__)
 118     EXEC_SPINLOCK_UNLOCK(listLock);
 119     Permit();
 120 #else
 121     Enable();
 122 #endif
 123
 124     /* Return whatever was found. */
 125     return ret;
 126
 127     AROS_LIBFUNC_EXIT
 128 } /* FindTask */
 129