On Mon, Nov 30, 2009 at 15:20, Peter Soetens <pe...@thesourceworks.com> wrote: > On Thu, Nov 5, 2009 at 02:46, Gilles Chanteperdrix > <gilles.chanteperd...@xenomai.org> wrote: >> >> Peter Soetens wrote: >> > Hi, >> > >> > I'm creating my RT threads using the native API and I'm creating >> > mqueues, wrapped to the pthread_rt library. >> > I can read and write the mqueue (and it goes through Xenomai), but >> > when I select() on a receiving mqd_t, the select() calls returns that >> > there is data available on the mq (it fills in the FD_SET), but keeps >> > doing so even when it's empty (the select() is in a loop). Also, it's >> > modeswitching like nuts. >> > >> > I found out that the __wrap_select is correctly called, but returns >> > -EPERM. Kernel sources indicate that this is caused by >> > pse51_current_thread() alias thread2pthread() returning null. Since >> > EPERM is returned to userspace, the __real_select is called from user >> > space, causing the mode switches and bad behaviour. This is almost >> > certainly the thing that native + RTDM + select() is seeing too. >> > >> > My mqueues-only work probably because mq.c only uses >> > pse51_current_thread() in the mq_notify function. I'm guessing that >> > mq_notify would also not work in combination with native skin. >> > >> > I had two options in fixing this: add a xnselector to the native task >> > struct or to the nucleus xnthread_t. I choose the latter, such that >> > every skin kan use select() + RTDM and migrate gradualy to the RTDM >> > and/or Posix skin. >> > I needed to free the xnselector structure in xnpod_delete_thread() , I >> > chose a spot, but it causes a segfault in my native thread (which did >> > the select) during program cleanup. Any advice ? Also, maybe we should >> > separate select() from the posix skin and put it in a separate place >> > (in RTDM as rtdm_select() ?), such that we can start building around >> > it (posix just forwards to rtdm_select() then). >> > >> > A second patch was necessary to return the timeout case properly to >> > userspace (independent of first patch). >> > >> > Tested with native + posix loaded and mq. If you never quit your >> > application, this works :-) >> >> Hi, >> >> I have included a lightly modified version of this patch on head, I do >> not see any crash. However, I have some doubts about the current >> implementation: calling xnselector_destroy() opens opportunities for a >> rescheduling, which I am not sure is really what we want in the middle >> of xnpod_delete_thread(). Philippe, what do you think? > > I'll test this patch this week too. It seems you forgot to apply the > second patch, which can go straight into the 2.4 head, since it fixes > a bug in the select() wrapping code when timeouts are used. See > parent's 0002-posix-Fix-__wrap_select-when-timeout-happens.patch
I tested the 2.5 branch with this patch and it works here too. Peter _______________________________________________ Xenomai-core mailing list Xenomai-core@gna.org https://mail.gna.org/listinfo/xenomai-core
