Re: [Xenomai-core] [patch 2/4] RTDM support for select-like service.

[Jan Kiszka <jan.kiszka@domain.hid>]

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Gilles Chanteperdrix wrote:
> Jan Kiszka wrote:
>  > Gilles Chanteperdrix wrote:
>  > > stats:
>  > >  include/rtdm/rtdm.h        |    4 ++
>  > >  include/rtdm/rtdm_driver.h |   30 +++++++++++++++-
>  > >  ksrc/skins/rtdm/core.c     |   84 +++++++++++++++++++++++++++++++--------------
>  > >  ksrc/skins/rtdm/device.c   |   10 +++++
>  > >  ksrc/skins/rtdm/drvlib.c   |   76 ++++++++++++++++++++++++++++++++++++----
>  > >  5 files changed, 170 insertions(+), 34 deletions(-)
>  > > 
>  > 
>  > /me thinks that going for inline patches on this list is overdue...
>  > 
>  > > @@ -1148,8 +1208,8 @@ int rtdm_sem_timeddown(rtdm_sem_t *sem, 
>  > >  
>  > >  	if (testbits(sem->synch_base.status, RTDM_SYNCH_DELETED))
>  > >  		err = -EIDRM;
>  > > -	else if (sem->value > 0)
>  > > -		sem->value--;
>  > > +	else if (sem->value > 0 && !--sem->value)
>  > > +			xnselect_signal(&sem->select_block, 0);
>  > >  	else if (timeout < 0) /* non-blocking mode */
>  > >  		err = -EWOULDBLOCK;
>  > >  	else {
>  > 
>  > Uuuh, this doesn't look equivalent (for --sem->value < 0).
>  > 
>  > Otherwise it's OK with me.
> 
> After testing, it appears that the "owner" of a file descriptor changed from 
> current->mm 
> to
> container_of(xnshadow_ppd_get(__rtdm_muxid), struct rtdm_process, ppd)

Yes, indeed, forgot about it. We have a full-blown owner structure now
to track comm and pid.

> 
> So, I now need a ppd hash lookup in __rtdm_context_get.
> 

You could add mm to rtdm_process. This means another indirection and
makes things worse (more cache misses in the worst case...). Could you
live without the check until we have per-process fd tabled, or was it
essential for the select thing?

Jan


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