On 2011-05-24 11:58, Gilles Chanteperdrix wrote:
> 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...
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.
Jan
--
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
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