Jan Kiszka wrote:
> Gilles Chanteperdrix wrote:
> > Jan Kiszka wrote:
> > > Gilles Chanteperdrix wrote:
> > > > Would not it be simpler to put a pointer to the task_struct ? After
> > all,
> > > > it already has a pid, comm and mm, and a file descriptor will not
> > > > survive a task_struct thanks to automatic closing of file descriptors.
> > >
> > > Hmm, hmm, hmmmm... Sounds reasonable, should be safe.
> >
> > Actually no, we can not do that because a task_struct may well disappear
> > and the rtdm_process continue to exist as long as another thread uses the
> > same mm.
>
> Because we cleanup on mm exit, not task exit, right? OK, looks like I
> originally spent a few more thoughts than this time :-/.
>
> >
> > >
> > > >
> > > > Could you
> > > > > live without the check until we have per-process fd tabled, or was
> > it
> > > > > essential for the select thing?
> > > >
> > > > An application which I ported to Xenomai (and which uses the select
> > > > call) closes all file descriptors in a for loop. The purpose of this
> > > > loop is, I guess, to avoid leaving a file descriptor opened that was
> > > > passed through exec.
> > >
> > > OK.
> > >
> > > So, will you change rtdm_process too? Thanks.
> >
> > I commited the select support, without any change to rtdm_context_get or
> > rtdm_process. So, now, how do you prefer this to be fixed, by adding an
> > mm struct to the rtdm_process struct ? By the way, after thinking about
> > it I can live without this fix: I just have to stop the loop closing
> > file descriptors at 768, so that it will not try to close RTDM file
> > descriptors.
>
> If you can live with it, I would vote for fixing it by the intended
> redesign via per-process fds.
Ok.
>
> >
> > While commiting the support for select, I also had a dependency problem
> > in Kconfig: when support for posix select is enabled the posix module
> > uses a function defined in the RTDM module. So, there is one invalid
> > configuration: posix built-in with support for select and rtdm built as
> > a module. I could not find a way to express this condition in the
> > Kconfig language, so I just made a comment depend on this condition, but
> > would be happy if anyone found a better solution.
>
> I would say:
>
> config POSIX
> select RTDM if OPT_SELECT
But in this case, I can not have posix with select and without rtdm.
--
Gilles Chanteperdrix.
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