[Xenomai-help] rt_mutex_acquire returns -3

[Xenomai-help] rt_mutex_acquire returns -3

[Hans Søndergaard (HSO)]

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I use objects of type:

typedef struct object {
  RT_MUTEX *rt_lock;
  ..
} Object;

int err = rt_mutex_create (ob->rt_lock, NULL);
printf ("[alloc.c]: rt_mutex_create err: %d; #%d \n", err, __LINE__);

err = rt_mutex_acquire (ob->rt_lock, TM_INFINITE);
printf ("[lock.c]: rt_mutex_acquire, err: %d; #%d \n", err, __LINE__);

On creation, rt_mutex_create returns 0 (as expected).
On acquiring, rt_mutex_acquire returns -3,
but this return value is not included among the possible return values in the documentation of Mutex services.

Could you please explain what this return value -3 means?

Best regards
Hans So



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Re: [Xenomai-help] rt_mutex_acquire returns -3

[Gilles Chanteperdrix]

Hans Søndergaard (HSO) wrote:
> I use objects of type:
> 
>  
> 
> typedef struct object {
> 
>   RT_MUTEX *rt_lock;
> 
>   ..
> 
> } Object;
> 
>  
> 
> int err = rt_mutex_create (ob->rt_lock, NULL);
> 
> printf ("[alloc.c]: rt_mutex_create err: %d; #%d \n", err, __LINE__);
> 
>  
> 
> err = rt_mutex_acquire (ob->rt_lock, TM_INFINITE);
> 
> printf ("[lock.c]: rt_mutex_acquire, err: %d; #%d \n", err, __LINE__);
> 

A question that may look stupid, is ob->rt_lock correctly initialised?
Also, why using a malloc for this, why not doing:

typedef struct object {
   RT_MUTEX rt_lock;
   /* ... */
} Object;

int err = rt_mutex_create (&ob->rt_lock, NULL);

err = rt_mutex_acquire (&ob->rt_lock, TM_INFINITE);

> On creation, rt_mutex_create returns 0 (as expected).
> 
> On acquiring, rt_mutex_acquire returns -3,
> 
> but this return value is not included among the possible return values
> in the documentation of Mutex services.
>  
> 
> Could you please explain what this return value -3 means?

3 is ESRCH, what version of Xenomai are you using?

-- 
                                          Gilles

Re: [Xenomai-help] rt_mutex_acquire returns -3

[Gilles Chanteperdrix]

Hans Søndergaard (HSO) wrote:
> I am using Xenomai-2.4.3 together with Linux-2.6.24.
> What does ESRCH mean?

I do not know, I would need to look into the sources, but before any
more search for an issue which may have already been resolved, could you
try xenomai 2.4.8 and see if you get the same problem?

Please do not forget to CC the mailing list.

-- 
                                          Gilles

Re: [Xenomai-help] rt_mutex_acquire returns -3

[Philippe Gerum]

On Fri, 2009-08-14 at 09:31 +0200, Hans Søndergaard (HSO) wrote:
> I use objects of type:
> 
>  
> 
> typedef struct object {
> 
>   RT_MUTEX *rt_lock;
> 
>   ..
> 
> } Object;
> 
>  
> 
> int err = rt_mutex_create (ob->rt_lock, NULL);
> 
> printf ("[alloc.c]: rt_mutex_create err: %d; #%d \n", err, __LINE__);
> 
>  
> 
> err = rt_mutex_acquire (ob->rt_lock, TM_INFINITE);
> 
> printf ("[lock.c]: rt_mutex_acquire, err: %d; #%d \n", err, __LINE__);
> 
>  
> 
> On creation, rt_mutex_create returns 0 (as expected).
> 
> On acquiring, rt_mutex_acquire returns -3,
> 

-ESRCH. This means that for some reason, the internal handle copied by
rt_mutex_create() to ob->rt_lock could not be found back in the system
registry when calling rt_mutex_acquire().

Any chance ob->rt_lock may have been overwritten, or this mutex deleted
by another thread in the meantime?

In userland, RT_MUTEX is a structure containing an opaque long integer
value. Maybe you could check that value (printf("%ld",
ob->rt_lock.opaque)) right after rt_mutex_create() returns, and just
before rt_mutex_acquire() is invoked.

> but this return value is not included among the possible return values
> in the documentation of Mutex services.
> 
>  
> 
> Could you please explain what this return value -3 means?
> 
>  
> 
> Best regards
> 
> Hans So  
> 
>  
> 
>  
> 
> 
> _______________________________________________
> Xenomai-help mailing list
> Xenomai-help@domain.hid
> https://mail.gna.org/listinfo/xenomai-help
-- 
Philippe.

Re: [Xenomai-help] rt_mutex_acquire returns -3

[Hans Søndergaard (HSO)]

Thank you to both Gilles and Philippe.
I followed the advises from you both:
typedef struct object {
  RT_MUTEX rt_lock; 
   .. 
 } Object;

and used:
  printf("%ld", ob->rt_lock.opaque);
to see output.
For a general orientation: I am rewriting a Java VM: JamVM, for a Predictable Java profile (nearly the same as the Safety Critical Java proposal from SUN). The profile will be presented at JTRES 2009.
I use Xenomai as real-time OS.
Vh/Regards
Hans Sø

-----Original Message-----
From: Philippe Gerum [mailto:rpm@xenomai.org] 
Sent: 14. august 2009 11:42
To: Hans Søndergaard (HSO)
Cc: xenomai-help@gna.org
Subject: Re: [Xenomai-help] rt_mutex_acquire returns -3

On Fri, 2009-08-14 at 09:31 +0200, Hans Søndergaard (HSO) wrote:
> I use objects of type:
> 
>  
> 
> typedef struct object {
> 
>   RT_MUTEX *rt_lock;
> 
>   ..
> 
> } Object;
> 
>  
> 
> int err = rt_mutex_create (ob->rt_lock, NULL);
> 
> printf ("[alloc.c]: rt_mutex_create err: %d; #%d \n", err, __LINE__);
> 
>  
> 
> err = rt_mutex_acquire (ob->rt_lock, TM_INFINITE);
> 
> printf ("[lock.c]: rt_mutex_acquire, err: %d; #%d \n", err, __LINE__);
> 
>  
> 
> On creation, rt_mutex_create returns 0 (as expected).
> 
> On acquiring, rt_mutex_acquire returns -3,
> 

-ESRCH. This means that for some reason, the internal handle copied by
rt_mutex_create() to ob->rt_lock could not be found back in the system
registry when calling rt_mutex_acquire().

Any chance ob->rt_lock may have been overwritten, or this mutex deleted
by another thread in the meantime?

In userland, RT_MUTEX is a structure containing an opaque long integer
value. Maybe you could check that value (printf("%ld",
ob->rt_lock.opaque)) right after rt_mutex_create() returns, and just
before rt_mutex_acquire() is invoked.

> but this return value is not included among the possible return values
> in the documentation of Mutex services.
> 
>  
> 
> Could you please explain what this return value -3 means?
> 
>  
> 
> Best regards
> 
> Hans So  
> 
>  
> 
>  
> 
> 
> _______________________________________________
> Xenomai-help mailing list
> Xenomai-help@gna.org
> https://mail.gna.org/listinfo/xenomai-help
-- 
Philippe.

Re: [Xenomai-help] rt_mutex_acquire returns -3

[Gilles Chanteperdrix]

Hans Søndergaard (HSO) wrote:
> Thank you to both Gilles and Philippe.
> I followed the advises from you both:
> typedef struct object {
>   RT_MUTEX rt_lock; 
>    .. 
>  } Object;
> 
> and used:
>   printf("%ld", ob->rt_lock.opaque);
> to see output.

So, what is the result? Did you find the bug?

-- 
					    Gilles.

Re: [Xenomai-help] rt_mutex_acquire returns -3

[Hans Søndergaard (HSO)]

> So, what is the result? Did you find the bug?
Yes, I think so. 
The problem was in my rewriting of JamVM. I have implemented Java PeriodicEventHandlers using periodic RT_TASKs, and re-implemented Java object allocation with synchronized methods, using RT_MUTEX to utilize the priority inheritance included in Xenomai. Each handler has a private native memoryArea (no Garbage Collector because of real-time constraints).
The allocation of a new object and calling its synchronized method now gives the output:

=> Native: enterNativeMemArea

[alloc.c]: rt_mutex_create err: 0; 
[alloc.c]: ob->rt_lock.opaque: 75; 

[lock.c]: ob->rt_lock.opaque: 75; 
[lock.c]: rt_mutex_acquire, result 0;

[lock.c]: ob->rt_lock.opaque: 75;
[lock.c]: rt_mutex_release, result 0; 

[alloc.c]: rt_mutex_delete, err: 0; 
[alloc.c]: ob->rt_lock.opaque: 75; 

=> Native: resetMemArea: after-before=used: 10232 - 10208 = 24 Bytes;

This should be OK.
I have (still) problems, if I use System.out.println in the synchronized method, but now I know it is because of my insufficient re-implementation of JamVM.
Vh/Regards
Hans Sø

-----Original Message-----
From: Gilles Chanteperdrix [mailto:gilles.chanteperdrix@xenomai.org] 
Sent: 22. august 2009 12:02
To: Hans Søndergaard (HSO)
Cc: xenomai-help@gna.org
Subject: Re: [Xenomai-help] rt_mutex_acquire returns -3

Hans Søndergaard (HSO) wrote:
> Thank you to both Gilles and Philippe.
> I followed the advises from you both:
> typedef struct object {
>   RT_MUTEX rt_lock; 
>    .. 
>  } Object;
> 
> and used:
>   printf("%ld", ob->rt_lock.opaque);
> to see output.

So, what is the result? Did you find the bug?

-- 
					    Gilles.