On 05/26/2011 09:18 AM, Jan Kiszka wrote: > On 2011-05-25 20:48, Gilles Chanteperdrix wrote: >> On 05/25/2011 02:22 PM, Jan Kiszka wrote: >>> On 2011-05-25 14:19, Gilles Chanteperdrix wrote: >>>> On 05/25/2011 02:12 PM, Jan Kiszka wrote: >>>>> On 2011-05-25 13:58, Gilles Chanteperdrix wrote: >>>>>> On 05/25/2011 01:20 PM, Jan Kiszka wrote: >>>>>>> On 2011-05-24 16:03, Gilles Chanteperdrix wrote: >>>>>>>> On 05/24/2011 03:52 PM, Jan Kiszka wrote: >>>>>>>>> On 2011-05-24 14:30, Gilles Chanteperdrix wrote: >>>>>>>>>>>>>>> Do you already have an idea how to get that info to the delete >>>>>>>>>>>>>>> hook >>>>>>>>>>>>>>> function? >>>>>>>>>>>>>> >>>>>>>>>>>>>> Yes. We start by not applying the list reversal patch, then the >>>>>>>>>>>>>> sys_ppd >>>>>>>>>>>>>> is the first in the list. So, we can, in the function >>>>>>>>>>>>>> ppd_remove_mm, >>>>>>>>>>>>>> start by removing all the others ppd, then remove the sys ppd >>>>>>>>>>>>>> (that is >>>>>>>>>>>>>> the first), last. This changes a few signatures in the core >>>>>>>>>>>>>> code, a lot >>>>>>>>>>>>>> of things in the skin code, but that would be for the better... >>>>>>>>>>>>> >>>>>>>>>>>>> I still don't see how this affects the order we use in >>>>>>>>>>>>> do_taskexit_event, the one that prevents xnsys_get_ppd usage even >>>>>>>>>>>>> when >>>>>>>>>>>>> the mm is still present. >>>>>>>>>>>> >>>>>>>>>>>> The idea is to change the cleanup routines not to call >>>>>>>>>>>> xnsys_get_ppd. >>>>>>>>>>> >>>>>>>>>>> ...and use what instead? Sorry, I'm slow today. >>>>>>>>>> >>>>>>>>>> The sys_ppd passed as other argument to the cleanup function. >>>>>>>>> >>>>>>>>> That would affect all thread hooks, not only the one for deletion. And >>>>>>>>> it would pull in more shadow-specific bits into the pod. >>>>>>>>> >>>>>>>>> Moreover, I think we would still be in troubles as mm, thus ppd, >>>>>>>>> deletion takes place before last task deletion, thus taskexit hook >>>>>>>>> invocation. That's due to the cleanup ordering in the kernel's >>>>>>>>> do_exit. >>>>>>>>> >>>>>>>>> However, if you have a patch, I'd be happy to test and rework my >>>>>>>>> leakage >>>>>>>>> fix. >>>>>>>> >>>>>>>> I will work on this ASAP. >>>>>>> >>>>>>> Sorry for pushing, but I need to decide if we should role out my >>>>>>> imperfect fix or if there is chance to use some upstream version >>>>>>> directly. Were you able to look into this, or will this likely take a >>>>>>> bit more time? >>>>>> >>>>>> I intended to try and do this next week-end. If it is more urgent than >>>>>> that, I can try in one or two days. In any case, I do not think we >>>>>> should try and workaround the current code, it is way to fragile. >>>>> >>>>> Mmh, might be true. I'm getting the feeling we should locally revert all >>>>> the recent MPS changes to work around the issues. It looks like there >>>>> are more related problems sleeping (we are still facing spurious >>>>> fast-synch related crashes here - examining ATM). >>>> >>>> This is the development head, it may remain broken for short times while >>>> we are fixing. I would understand reverting on the 2.5 branch, not on >>>> -head. >>> >>> I was thinking loudly about our (Siemens) local branch, not -head. We >>> are forced to use head to have features like automatic non-RT shadow >>> migration. >> >> Now that I think about it, leaking a few bytes in the private heap is >> completely harmless, since it is destroyed anyway, > > Not at all harmless if you create and destroy tasks without restarting > the application. That's what our users are do, so this bug is killing them.
Still, it should not cause crashes. Only allocation returning NULL at some point. >> We do not care, we only use the mm pointer value as a key, and this one >> is still available when the exit callback is called. So, we have the mm >> pointer, we can have the process private ppd, normally, we have all that >> we need. It is just a question of finding an interface which is not too >> intrusive. > > The problem is that the heap we need to release the fastlock to will > already be history at this point - classic use after release... As I said, xnheap_free is robust against this, so, this user after release does not cause any trouble. But I have also already agreed that we should fix it. -- Gilles. _______________________________________________ Xenomai-core mailing list Xenomai-core@gna.org https://mail.gna.org/listinfo/xenomai-core