[Xenomai-help] Problem with tcb.handle and taskDesc.td_tid

[Xenomai-help] Problem with tcb.handle and taskDesc.td_tid

[Matthieu]

Hi

I would like to understand the coherence between the task identifier of the
task control block and the task id given by taskDesk (function
taskInfoGet()). In fact, I init a task with taskInit, I get the tid using
tid=tcb.handle. The use of taskInfoGet(tid, taskDesc) gives me a
taskDesk.td_tid different from the tid.

I want to test if the task is suspended using taskIsSuspended(tid) or
taskIsSuspended(taskDesc.td_tid), but both get me  a 3d0001 errno (code
error of WIND_OBJ_ERR_BASE S_objLib_OBJ_ID_ERROR). The PID given by
/proc/xenomai/stat also has no connection. Idem with a ps -AfL

Thank you in advance for your explanations

Matthieu

Re: [Xenomai-help] Problem with tcb.handle and taskDesc.td_tid

[Gilles Chanteperdrix]

Matthieu wrote:
> Hi
> 
> I would like to understand the coherence between the task identifier of the
> task control block and the task id given by taskDesk (function
> taskInfoGet()). In fact, I init a task with taskInit, I get the tid using
> tid=tcb.handle. The use of taskInfoGet(tid, taskDesc) gives me a
> taskDesk.td_tid different from the tid.
> 
> I want to test if the task is suspended using taskIsSuspended(tid) or
> taskIsSuspended(taskDesc.td_tid), but both get me  a 3d0001 errno (code
> error of WIND_OBJ_ERR_BASE S_objLib_OBJ_ID_ERROR). The PID given by
> /proc/xenomai/stat also has no connection. Idem with a ps -AfL
> 
> Thank you in advance for your explanations

You are not supposed to use the internal fields of the structures. A
valid id is one returned by the taskIdSelf(), taskNameToId(),
taskIdDefault(). I can not find a service which returns the task Id for
a given TCB. Is it what you are looking for ?

-- 
                                                 Gilles.

Re: [Xenomai-help] Problem with tcb.handle and taskDesc.td_tid

[Gilles Chanteperdrix]

Gilles Chanteperdrix wrote:
> Matthieu wrote:
>> Hi
>>
>> I would like to understand the coherence between the task identifier of the
>> task control block and the task id given by taskDesk (function
>> taskInfoGet()). In fact, I init a task with taskInit, I get the tid using
>> tid=tcb.handle. The use of taskInfoGet(tid, taskDesc) gives me a
>> taskDesk.td_tid different from the tid.
>>
>> I want to test if the task is suspended using taskIsSuspended(tid) or
>> taskIsSuspended(taskDesc.td_tid), but both get me  a 3d0001 errno (code
>> error of WIND_OBJ_ERR_BASE S_objLib_OBJ_ID_ERROR). The PID given by
>> /proc/xenomai/stat also has no connection. Idem with a ps -AfL
>>
>> Thank you in advance for your explanations
> 
> You are not supposed to use the internal fields of the structures. A
> valid id is one returned by the taskIdSelf(), taskNameToId(),
> taskIdDefault(). I can not find a service which returns the task Id for
> a given TCB. Is it what you are looking for ?

By the way, if you could call taskInfoGet, you already have a valid task
id...

-- 
                                                 Gilles.

[Xenomai-help] Re: Problem with tcb.handle and taskDesc.td_tid

[Matthieu]

On Tue, 26 Aug 2008 14:55:19 +0200, Gilles Chanteperdrix
<gilles.chanteperdrix@xenomai.org> wrote:
> Gilles Chanteperdrix wrote:
>> Matthieu wrote:
>>> Hi
>>>
>>> I would like to understand the coherence between the task identifier of
> the
>>> task control block and the task id given by taskDesk (function
>>> taskInfoGet()). In fact, I init a task with taskInit, I get the tid
> using
>>> tid=tcb.handle. The use of taskInfoGet(tid, taskDesc) gives me a
>>> taskDesk.td_tid different from the tid.
>>>
>>> I want to test if the task is suspended using taskIsSuspended(tid) or
>>> taskIsSuspended(taskDesc.td_tid), but both get me  a 3d0001 errno (code
>>> error of WIND_OBJ_ERR_BASE S_objLib_OBJ_ID_ERROR). The PID given by
>>> /proc/xenomai/stat also has no connection. Idem with a ps -AfL
>>>
>>> Thank you in advance for your explanations
>>
>> You are not supposed to use the internal fields of the structures. A
>> valid id is one returned by the taskIdSelf(), taskNameToId(),
>> taskIdDefault(). I can not find a service which returns the task Id for
>> a given TCB. Is it what you are looking for ?
> 
> By the way, if you could call taskInfoGet, you already have a valid task
> id...
> 

But using taskNameToId, taskSuspend(tid) makes the same error and so is
taskInfoGet(). In the sources, I saw that taskInfoGet seems to be a
reentrant routine (see ksrc/skins/vxworks/syscall.c where a taskInfoGet is
call in the taskInfoGet routine) 

Matthieu

> --
>                                                  Gilles.

Re: [Xenomai-help] Problem with tcb.handle and taskDesc.td_tid

[Gilles Chanteperdrix]

Matthieu wrote:
> 
> On Tue, 26 Aug 2008 14:55:19 +0200, Gilles Chanteperdrix
> <gilles.chanteperdrix@xenomai.org> wrote:
>> Gilles Chanteperdrix wrote:
>>> Matthieu wrote:
>>>> Hi
>>>>
>>>> I would like to understand the coherence between the task identifier of
>> the
>>>> task control block and the task id given by taskDesk (function
>>>> taskInfoGet()). In fact, I init a task with taskInit, I get the tid
>> using
>>>> tid=tcb.handle. The use of taskInfoGet(tid, taskDesc) gives me a
>>>> taskDesk.td_tid different from the tid.
>>>>
>>>> I want to test if the task is suspended using taskIsSuspended(tid) or
>>>> taskIsSuspended(taskDesc.td_tid), but both get me  a 3d0001 errno (code
>>>> error of WIND_OBJ_ERR_BASE S_objLib_OBJ_ID_ERROR). The PID given by
>>>> /proc/xenomai/stat also has no connection. Idem with a ps -AfL
>>>>
>>>> Thank you in advance for your explanations
>>> You are not supposed to use the internal fields of the structures. A
>>> valid id is one returned by the taskIdSelf(), taskNameToId(),
>>> taskIdDefault(). I can not find a service which returns the task Id for
>>> a given TCB. Is it what you are looking for ?
>> By the way, if you could call taskInfoGet, you already have a valid task
>> id...
>>
> 
> But using taskNameToId, taskSuspend(tid) makes the same error and so is
> taskInfoGet().

Ok. So, we have a bug and these functions do not work as expected.

In the sources, I saw that taskInfoGet seems to be a
> reentrant routine (see ksrc/skins/vxworks/syscall.c where a taskInfoGet is
> call in the taskInfoGet routine) 

If by reentrant you mean recursive, no, not at all, taskInfoGet is not
recursive. You see, the interface between user-space and kernel-space is
not a simple function call, it is a system call, that is the way the
whole Linux kernel works. The difference between Linux and Xenomai is
that Xenomai APIs are symetric between kernel-space and user-space. So,
the function implementing a kernel-space service is used to implement
the system call used by the user-space service of the same name.

What you see in ksrc/skins/vxworks/syscall.c is that the function
__wind_task_info_get, which is the handler of the vxworks skin
__vxworks_taskinfo_get system call, calls the kernel-space taskInfoGet
function, so there is no recursion.
in src/skins/vxworks/taskInfo.c, you will see that the taskInfoGet
function emits the _vxworks_taskinfo_get system call.

-- 
                                                 Gilles.

[Xenomai-help] Re: Re: Problem with tcb.handle and taskDesc.td_tid

[Matthieu]

On Tue, 26 Aug 2008 16:37:27 +0200, Gilles Chanteperdrix
<gilles.chanteperdrix@xenomai.org> wrote:
> Matthieu wrote:
>>
>> On Tue, 26 Aug 2008 14:55:19 +0200, Gilles Chanteperdrix
>> <gilles.chanteperdrix@xenomai.org> wrote:
>>> Gilles Chanteperdrix wrote:
>>>> Matthieu wrote:
>>>>> Hi
>>>>>
>>>>> I would like to understand the coherence between the task identifier
> of
>>> the
>>>>> task control block and the task id given by taskDesk (function
>>>>> taskInfoGet()). In fact, I init a task with taskInit, I get the tid
>>> using
>>>>> tid=tcb.handle. The use of taskInfoGet(tid, taskDesc) gives me a
>>>>> taskDesk.td_tid different from the tid.
>>>>>
>>>>> I want to test if the task is suspended using taskIsSuspended(tid) or
>>>>> taskIsSuspended(taskDesc.td_tid), but both get me  a 3d0001 errno
> (code
>>>>> error of WIND_OBJ_ERR_BASE S_objLib_OBJ_ID_ERROR). The PID given by
>>>>> /proc/xenomai/stat also has no connection. Idem with a ps -AfL
>>>>>
>>>>> Thank you in advance for your explanations
>>>> You are not supposed to use the internal fields of the structures. A
>>>> valid id is one returned by the taskIdSelf(), taskNameToId(),
>>>> taskIdDefault(). I can not find a service which returns the task Id
> for
>>>> a given TCB. Is it what you are looking for ?
>>> By the way, if you could call taskInfoGet, you already have a valid
> task
>>> id...
>>>
>>
>> But using taskNameToId, taskSuspend(tid) makes the same error and so is
>> taskInfoGet().
> 
> Ok. So, we have a bug and these functions do not work as expected.
> 
> In the sources, I saw that taskInfoGet seems to be a
>> reentrant routine (see ksrc/skins/vxworks/syscall.c where a taskInfoGet
> is
>> call in the taskInfoGet routine)
> 
> If by reentrant you mean recursive, no, not at all, taskInfoGet is not
> recursive. You see, the interface between user-space and kernel-space is
> not a simple function call, it is a system call, that is the way the
> whole Linux kernel works. The difference between Linux and Xenomai is
> that Xenomai APIs are symetric between kernel-space and user-space. So,
> the function implementing a kernel-space service is used to implement
> the system call used by the user-space service of the same name.
> 
> What you see in ksrc/skins/vxworks/syscall.c is that the function
> __wind_task_info_get, which is the handler of the vxworks skin
> __vxworks_taskinfo_get system call, calls the kernel-space taskInfoGet
> function, so there is no recursion.
> in src/skins/vxworks/taskInfo.c, you will see that the taskInfoGet
> function emits the _vxworks_taskinfo_get system call.
> 
> --
>                                                  Gilles.

Reading that I'm not supposed to use the internal fields of the structures,
and using taskInfoGet, I have some doubts about what I'm doing : I get a
taskDesc structure and I modify its field td_entry to set the function
pointer of the routine (FUNCPTR). I'm not really sure this going to works.
On WINDRIVER, I were able to directly modify the field WIND_TCB->entry.
What do you thing about this ?

 Matthieu 

Re: [Xenomai-help] Problem with tcb.handle and taskDesc.td_tid

[Gilles Chanteperdrix]

Matthieu Connaulte wrote:
> On Tue, 26 Aug 2008 16:37:27 +0200, Gilles Chanteperdrix
> <gilles.chanteperdrix@xenomai.org> wrote:
>> Matthieu wrote:
>>> On Tue, 26 Aug 2008 14:55:19 +0200, Gilles Chanteperdrix
>>> <gilles.chanteperdrix@xenomai.org> wrote:
>>>> Gilles Chanteperdrix wrote:
>>>>> Matthieu wrote:
>>>>>> Hi
>>>>>>
>>>>>> I would like to understand the coherence between the task identifier
>> of
>>>> the
>>>>>> task control block and the task id given by taskDesk (function
>>>>>> taskInfoGet()). In fact, I init a task with taskInit, I get the tid
>>>> using
>>>>>> tid=tcb.handle. The use of taskInfoGet(tid, taskDesc) gives me a
>>>>>> taskDesk.td_tid different from the tid.
>>>>>>
>>>>>> I want to test if the task is suspended using taskIsSuspended(tid) or
>>>>>> taskIsSuspended(taskDesc.td_tid), but both get me  a 3d0001 errno
>> (code
>>>>>> error of WIND_OBJ_ERR_BASE S_objLib_OBJ_ID_ERROR). The PID given by
>>>>>> /proc/xenomai/stat also has no connection. Idem with a ps -AfL
>>>>>>
>>>>>> Thank you in advance for your explanations
>>>>> You are not supposed to use the internal fields of the structures. A
>>>>> valid id is one returned by the taskIdSelf(), taskNameToId(),
>>>>> taskIdDefault(). I can not find a service which returns the task Id
>> for
>>>>> a given TCB. Is it what you are looking for ?
>>>> By the way, if you could call taskInfoGet, you already have a valid
>> task
>>>> id...
>>>>
>>> But using taskNameToId, taskSuspend(tid) makes the same error and so is
>>> taskInfoGet().
>> Ok. So, we have a bug and these functions do not work as expected.
>>
>> In the sources, I saw that taskInfoGet seems to be a
>>> reentrant routine (see ksrc/skins/vxworks/syscall.c where a taskInfoGet
>> is
>>> call in the taskInfoGet routine)
>> If by reentrant you mean recursive, no, not at all, taskInfoGet is not
>> recursive. You see, the interface between user-space and kernel-space is
>> not a simple function call, it is a system call, that is the way the
>> whole Linux kernel works. The difference between Linux and Xenomai is
>> that Xenomai APIs are symetric between kernel-space and user-space. So,
>> the function implementing a kernel-space service is used to implement
>> the system call used by the user-space service of the same name.
>>
>> What you see in ksrc/skins/vxworks/syscall.c is that the function
>> __wind_task_info_get, which is the handler of the vxworks skin
>> __vxworks_taskinfo_get system call, calls the kernel-space taskInfoGet
>> function, so there is no recursion.
>> in src/skins/vxworks/taskInfo.c, you will see that the taskInfoGet
>> function emits the _vxworks_taskinfo_get system call.
>>
>> --
> 
> Reading that I'm not supposed to use the internal fields of the structures,
> and using taskInfoGet, I have some doubts about what I'm doing : I get a
> taskDesc structure and I modify its field td_entry to set the function
> pointer of the routine (FUNCPTR). I'm not really sure this going to works.
> On WINDRIVER, I were able to directly modify the field WIND_TCB->entry.
> What do you thing about this ?

What do YOU think ?

-- 
					    Gilles.

Re: [Xenomai-help] Problem with tcb.handle and taskDesc.td_tid

[Philippe Gerum]

Gilles Chanteperdrix wrote:
> Matthieu wrote:
>> On Tue, 26 Aug 2008 14:55:19 +0200, Gilles Chanteperdrix
>> <gilles.chanteperdrix@xenomai.org> wrote:
>>> Gilles Chanteperdrix wrote:
>>>> Matthieu wrote:
>>>>> Hi
>>>>>
>>>>> I would like to understand the coherence between the task identifier of
>>> the
>>>>> task control block and the task id given by taskDesk (function
>>>>> taskInfoGet()). In fact, I init a task with taskInit, I get the tid
>>> using
>>>>> tid=tcb.handle. The use of taskInfoGet(tid, taskDesc) gives me a
>>>>> taskDesk.td_tid different from the tid.
>>>>>
>>>>> I want to test if the task is suspended using taskIsSuspended(tid) or
>>>>> taskIsSuspended(taskDesc.td_tid), but both get me  a 3d0001 errno (code
>>>>> error of WIND_OBJ_ERR_BASE S_objLib_OBJ_ID_ERROR). The PID given by
>>>>> /proc/xenomai/stat also has no connection. Idem with a ps -AfL
>>>>>
>>>>> Thank you in advance for your explanations
>>>> You are not supposed to use the internal fields of the structures. A
>>>> valid id is one returned by the taskIdSelf(), taskNameToId(),
>>>> taskIdDefault(). I can not find a service which returns the task Id for
>>>> a given TCB. Is it what you are looking for ?
>>> By the way, if you could call taskInfoGet, you already have a valid task
>>> id...
>>>
>> But using taskNameToId, taskSuspend(tid) makes the same error and so is
>> taskInfoGet().
> 
> Ok. So, we have a bug and these functions do not work as expected.
>

Kernel to userland id. translation was missing for the taskNameToId() wrapper.

Index: include/vxworks/vxworks.h
===================================================================
--- include/vxworks/vxworks.h	(revision 4121)
+++ include/vxworks/vxworks.h	(working copy)
@@ -232,6 +232,8 @@

 typedef void (*wind_tick_handler_t)(long);

+xnhandle_t taskNameToHandle(const char *name);
+
 #ifdef errno
 #undef errno
 #endif
Index: ksrc/skins/vxworks/syscall.c
===================================================================
--- ksrc/skins/vxworks/syscall.c	(revision 4121)
+++ ksrc/skins/vxworks/syscall.c	(working copy)
@@ -411,7 +411,7 @@
 {
 	char name[XNOBJECT_NAME_LEN];
 	WIND_TCB_PLACEHOLDER ph;
-	TASK_ID task_id;
+	xnhandle_t handle;

 	if (!__xn_access_ok
 	    (curr, VERIFY_WRITE, __xn_reg_arg2(regs), sizeof(ph)))
@@ -429,12 +429,11 @@
 			       sizeof(name) - 1);
 	name[sizeof(name) - 1] = '\0';

-	task_id = taskNameToId(name);
-
-	if (task_id == ERROR)
+	handle = taskNameToHandle(name);
+	if (handle == XN_NO_HANDLE)
 		return wind_errnoget();

-	ph.handle = task_id;	/* Copy back the task handle. */
+	ph.handle = handle; /* Copy back the task handle. */

 	__xn_copy_to_user(curr, (void __user *)__xn_reg_arg2(regs), &ph,
 			  sizeof(ph));
Index: ksrc/skins/vxworks/taskLib.c
===================================================================
--- ksrc/skins/vxworks/taskLib.c	(revision 4121)
+++ ksrc/skins/vxworks/taskLib.c	(working copy)
@@ -551,9 +551,9 @@
    wind_tasks_q */
 TASK_ID taskNameToId(const char *name)
 {
+	TASK_ID result = (TASK_ID)ERROR;
 	xnholder_t *holder;
 	wind_task_t *task;
-	int result = ERROR;
 	spl_t s;

 	if (!name)
@@ -578,6 +578,28 @@
 	return result;
 }

+xnhandle_t taskNameToHandle(const char *name)
+{
+	xnhandle_t handle;
+	wind_task_t *task;
+	TASK_ID task_id;
+	spl_t s;
+
+	xnlock_get_irqsave(&nklock, s);
+
+	task_id = taskNameToId(name);
+	if (task_id == ERROR) {
+		handle = XN_NO_HANDLE;
+		goto out;
+	}
+	task = (wind_task_t *)task_id;
+	handle = xnthread_handle(&task->threadbase);
+out:
+	xnlock_put_irqrestore(&nklock, s);
+
+	return handle;
+}
+
 /* nklock must be locked on entry, interrupts off */
 static int testSafe(wind_task_t *task)
 {

-- 
Philippe.

[Xenomai-help] Re: Problem with tcb.handle and taskDesc.td_tid

[Matthieu]

I tested the patch. TaskInfoGet works. It gives me a taskDesc.td_tid
different from tid given by taskNameToId, but I don't known if there is any
relation.
I try to know if my task is suspended, but I always have the result 0 from
taskIsSuspended(tid) while my task has been initiated but not activated. So
I would like to know if a taskInit turn the task in suspended state ? If
so, what can be my error ?

Matthieu