On 05/24/2011 11:36 AM, Jan Kiszka wrote:
> On 2011-05-24 11:32, Gilles Chanteperdrix wrote:
>> On 05/24/2011 11:13 AM, Jan Kiszka wrote:
>>> On 2011-05-24 06:31, Gilles Chanteperdrix wrote:
>>>> On 05/23/2011 03:53 PM, Jan Kiszka wrote:
>>>>> The following changes since commit 
>>>>> aec30a2543afa18fa7832deee85e187b0faeb1f0:
>>>>>
>>>>>   xeno-test: fix reference to @XENO_TEST_DIR@ (2011-05-15 21:20:41 +0200)
>>>>>
>>>>> are available in the git repository at:
>>>>>   git://git.xenomai.org/xenomai-jki.git for-upstream
>>>>>
>>>>> Jan Kiszka (1):
>>>>>       native: Fix msendq fastlock leakage
>>>>>
>>>>>  include/native/task.h    |    5 +++++
>>>>>  ksrc/skins/native/task.c |   13 ++++++-------
>>>>>  2 files changed, 11 insertions(+), 7 deletions(-)
>>>>>
>>>>> ------8<------
>>>>>
>>>>> When a native task terminates without going through rt_task_delete, we
>>>>> leaked the fastlock so far. Fix it by moving the release into the delete
>>>>> hook. As the ppd is already invalid at that point, we have to save the
>>>>> heap address in the task data structure.
>>>>
>>>> I Jan, I once worked on a patch to reverse the ppd cleanup order, in order
>>>> to fix bugs of this kind. Here it comes. I do not remember why I did not
>>>> commit it, but I guess it was not working well. Could we restart working
>>>> from this patch?
>>>>
>>>> From 038ecf08cd66b3112e0fe277d71d294b8eb83bcc Mon Sep 17 00:00:00 2001
>>>> From: Gilles Chanteperdrix <gilles.chanteperd...@xenomai.org>
>>>> Date: Sun, 29 Aug 2010 14:52:08 +0200
>>>> Subject: [PATCH] nucleus: reverse ppd cleanup order
>>>>
>>>> ---
>>>>  ksrc/nucleus/shadow.c |   11 ++++++-----
>>>>  1 files changed, 6 insertions(+), 5 deletions(-)
>>>>
>>>> diff --git a/ksrc/nucleus/shadow.c b/ksrc/nucleus/shadow.c
>>>> index b2d4326..725ae43 100644
>>>> --- a/ksrc/nucleus/shadow.c
>>>> +++ b/ksrc/nucleus/shadow.c
>>>> @@ -556,7 +556,7 @@ static unsigned ppd_lookup_inner(xnqueue_t **pq,
>>>>    }
>>>>    while (holder &&
>>>>           (ppd->key.mm < pkey->mm ||
>>>> -          (ppd->key.mm == pkey->mm && ppd->key.muxid < pkey->muxid)));
>>>> +          (ppd->key.mm == pkey->mm && ppd->key.muxid > pkey->muxid)));
>>>>  
>>>>    if (ppd->key.mm == pkey->mm && ppd->key.muxid == pkey->muxid) {
>>>>            /* found it, return it. */
>>>> @@ -566,7 +566,7 @@ static unsigned ppd_lookup_inner(xnqueue_t **pq,
>>>>  
>>>>    /* not found, return successor for insertion. */
>>>>    if (ppd->key.mm < pkey->mm ||
>>>> -      (ppd->key.mm == pkey->mm && ppd->key.muxid < pkey->muxid))
>>>> +      (ppd->key.mm == pkey->mm && ppd->key.muxid > pkey->muxid))
>>>>            *pholder = holder ? link2ppd(holder) : NULL;
>>>>    else
>>>>            *pholder = ppd;
>>>> @@ -589,10 +589,11 @@ static int ppd_insert(xnshadow_ppd_t * holder)
>>>>    }
>>>>  
>>>>    inith(&holder->link);
>>>> -  if (next)
>>>> +  if (next) {
>>>>            insertq(q, &next->link, &holder->link);
>>>> -  else
>>>> +  } else {
>>>>            appendq(q, &holder->link);
>>>> +  }
>>>>    xnlock_put_irqrestore(&nklock, s);
>>>>  
>>>>    return 0;
>>>> @@ -640,7 +641,7 @@ static inline void ppd_remove_mm(struct mm_struct *mm,
>>>>    xnqueue_t *q;
>>>>    spl_t s;
>>>>  
>>>> -  key.muxid = 0;
>>>> +  key.muxid = ~0UL;
>>>>    key.mm = mm;
>>>>    xnlock_get_irqsave(&nklock, s);
>>>>    ppd_lookup_inner(&q, &ppd, &key);
>>>
>>> Unfortunately, that won't help. I think we are forced to clear
>>> xnshadow_thrptd before calling into xnpod_delete_thread, but we would
>>> need that for xnshadow_ppd_get (=>xnpod_userspace_p()).
>>
>> I remember that now. Even if it worked, when the cleanup handler is
>> called, current->mm is NULL. We need to do this differently, the sys ppd
>> should be treated differently and passed to the other ppds cleanup routines.
> 
> 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...

-- 
                                                                Gilles.

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