Hi,

----------------------------------------
> From: [email protected]
> To: [email protected]
> Date: Sun, 15 May 2011 17:32:59 +0200
> CC: [email protected]
> Subject: Re: [Xenomai-help] Problems with rt pipes after upgrade
>
> On Sun, 2011-05-15 at 17:26 +0200, Jan Kiszka wrote:
> > On 2011-05-15 17:21, Philippe Gerum wrote:
> > > On Sat, 2011-05-14 at 19:25 +0200, Gilles Chanteperdrix wrote:
> > >> On 05/14/2011 07:21 PM, Gilles Chanteperdrix wrote:
> > >>> On 05/14/2011 12:39 AM, Thomas Schaefer wrote:
> > >>>>
> > >>>> Hello,
> > >>>>
> > >>>> ----------------------------------------
> > >>>>> Subject: Re: [Xenomai-help] Problems with rt pipes after upgrade
> > >>>>> From: [email protected]
> > >>>>> To: [email protected]
> > >>>>> CC: [email protected]
> > >>>>> Date: Fri, 13 May 2011 12:26:26 +0200
> > >>>>>
> > >>>>> On Wed, 2011-05-11 at 07:46 -0700, Thomas Schaefer wrote:
> > >>>>>>
> > >>>>>> Hi,
> > >>>>>>
> > >>>>>> we are currently running an earlier version of Xenomai (2.5.3) on a 
> > >>>>>> Quad core Xeon with kernel 2.6.31.8(X86_64).
> > >>>>>> I was looking into upgrading to the latest Xenomai version from the 
> > >>>>>> git head and kernel 2.6.37.6.
> > >>>>>> Everything seems to work well except creating rt_pipes in the kernel 
> > >>>>>> driver.
> > >>>>>> First I thought this is a problem with our PCIe driver but I see the 
> > >>>>>> same problem when loading xeno_klat.
> > >>>>>>
> > >>>>>> # modprobe xeno_klat
> > >>>>>> [ 70.511784] ------------[ cut here ]------------
> > >>>>>> [ 70.516422] WARNING: at fs/proc/generic.c:860 
> > >>>>>> remove_proc_entry+0x25b/0x260()
> > >>>>>> [ 70.523556] Hardware name: D-Mitri
> > >>>>>> [ 70.526960] remove_proc_entry: removing non-empty directory 
> > >>>>>> 'native/pipes', leaking at least 'klat_pipe'
> > >>>>>> [ 70.536433] Modules linked in: xeno_klat bonding [last unloaded: 
> > >>>>>> scsi_wait_scan]
> > >>>>>> [ 70.545910] Pid: 296, comm: kworker/1:1 Not tainted 2.6.37.6 #4
> > >>>>>> [ 70.551834] Call Trace:
> > >>>>>> [ 70.554291] [] ? warn_slowpath_common+0x7b/0xc0
> > >>>>>> [ 70.560484] [] ? warn_slowpath_fmt+0x45/0x50
> > >>>>>> [ 70.566402] [] ? __xlate_proc_name+0x35/0xd0
> > >>>>>> [ 70.572330] [] ? remove_proc_entry+0x25b/0x260
> > >>>>>> [ 70.578434] [] ? registry_proc_callback+0x4b5/0x5c0
> > >>>>>> [ 70.584963] [] ? registry_proc_callback+0x0/0x5c0
> > >>>>>> [ 70.591330] [] ? process_one_work+0x107/0x3c0
> > >>>>>> [ 70.597351] [] ? worker_thread+0x14c/0x410
> > >>>>>> [ 70.603106] [] ? worker_thread+0x0/0x410
> > >>>>>> [ 70.608678] [] ? kthread+0x95/0xa0
> > >>>>>> [ 70.613758] [] ? kernel_thread_helper+0x4/0x10
> > >>>>>> [ 70.619857] [] ? kthread+0x0/0xa0
> > >>>>>> [ 70.624840] [] ? kernel_thread_helper+0x0/0x10
> > >>>>>> [ 70.630941] ---[ end trace 793ec26c5b485748 ]---
> > >>>>>>
> > >>>>>>
> > >>>>>> I would appreciate if someone could point me in the right direction 
> > >>>>>> of the possible cause.
> > >>>>>
> > >>>>> This very much looks like a race in the registry support. We have to
> > >>>>> resync registry object deletion done from primary mode with the linux
> > >>>>> kernel actually doing the work for us (via /procfs), and somehow, we
> > >>>>> don't do this right. This is not a critical issue and will likely not
> > >>>>> break your platform, but this is still quite ugly, and requires a fix.
> > >>>>>
> > >>>>> Could you give us some hints about how to reproduce this easily? TIA,
> > >>>>>
> > >>>>
> > >>>> I used VBox and installed a very basic Debian squeeze with the 
> > >>>> netinst.iso.
> > >>>> Installed our kernel into it from the debian package I created and 
> > >>>> copied xeno_klat.ko to it.
> > >>>> Running insmod xeno_klat.ko shows the same symptom.
> > >>>
> > >>> xeno_klat insmods here without any problem. You probably have some
> > >>> debugging option enabled. Could your post the .config of the kernel you 
> > >>> use?
> > >>>
> > >>
> > >> I enabled approximately all debugging options. Now I reproduce this bug.
> > >>
> > >>
> > >
> > > Ok, I introduced this one. Two bugs in one actually, here are the fixes:
> > >
> > > diff --git a/ksrc/nucleus/vfile.c b/ksrc/nucleus/vfile.c
> > > index d8ac398..6aa42b3 100644
> > > --- a/ksrc/nucleus/vfile.c
> > > +++ b/ksrc/nucleus/vfile.c
> > > @@ -752,8 +752,10 @@ int xnvfile_init_link(const char *from,
> > >
> > > ppde = parent->entry.pde;
> > > pde = proc_symlink(from, ppde, to);
> > > - if (vlink->entry.pde == NULL)
> > > + if (pde == NULL) {
> > > + remove_proc_entry(pde->name, ppde);
> >
> > Sure? :)
>
> This one should be better.
>
> diff --git a/ksrc/nucleus/vfile.c b/ksrc/nucleus/vfile.c
> index d8ac398..4898e86 100644
> --- a/ksrc/nucleus/vfile.c
> +++ b/ksrc/nucleus/vfile.c
> @@ -752,7 +752,7 @@ int xnvfile_init_link(const char *from,
>
> ppde = parent->entry.pde;
> pde = proc_symlink(from, ppde, to);
> - if (vlink->entry.pde == NULL)
> + if (pde == NULL)
> return -ENOMEM;
>
> vlink->entry.parent = parent;
>
> >
> > Jan
> >
> > > return -ENOMEM;
> > > + }
> > >
> > > vlink->entry.parent = parent;
> > > vlink->entry.pde = pde;
> > >
> >
>
> --
> Philippe.
>
 
 
Thank you very much.
This seems to have fixed the problem.
 
Thomas
 

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