Date: Thu, 3 Feb 2011 11:51:23 +0100 From: Monthadar Al Jaberi <monthadar@gmail.com> To: "Bjoern A. Zeeb" <bzeeb-lists@lists.zabbadoz.net> Cc: FreeBSD virtualization mailing list <freebsd-virtualization@freebsd.org> Subject: Re: simulating wireless device (if_alloc panic, VirtualBox, VIMAGE) Message-ID: <AANLkTinY0AVSsEE5PZaJOqyuinsAN6wkUL9URAqYs0X4@mail.gmail.com> In-Reply-To: <20110203095019.N80258@maildrop.int.zabbadoz.net> References: <AANLkTik8D_bLwcUKZdBT-kpkJdDXtPTLvAqfUe0cLoSz@mail.gmail.com> <4D484213.6050100@freebsd.org> <AANLkTikJKZLQVA5X2PQs0oT4iFsZYBw7K07kjQTc9iGD@mail.gmail.com> <4D486108.5060805@freebsd.org> <AANLkTi=mk2vfyXJBaK5mV2sBWEj0-RDZneLs%2BXq_c7sb@mail.gmail.com> <20110202164827.I80258@maildrop.int.zabbadoz.net> <4D4994CE.2090209@freebsd.org> <AANLkTimDZRefv57_nanxGUbHjP1wqeQ41iWHvpXogmvU@mail.gmail.com> <4D49AB29.7070909@freebsd.org> <AANLkTinONnLE9D=c57nQmGBFbWJgqJmeKiRViW3gga2a@mail.gmail.com> <20110203095019.N80258@maildrop.int.zabbadoz.net>
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On Thu, Feb 3, 2011 at 10:55 AM, Bjoern A. Zeeb
<bzeeb-lists@lists.zabbadoz.net> wrote:
> On Thu, 3 Feb 2011, Monthadar Al Jaberi wrote:
>
>> On Wed, Feb 2, 2011 at 8:06 PM, Julian Elischer <julian@freebsd.org>
>> wrote:
>>>
>>> On 2/2/11 10:05 AM, Monthadar Al Jaberi wrote:
>>>>
>>>> I just tried something that seems to work, but please dont hit me ^^;;=
;
>>>>
>>>> in wtap_ioctl I assigned curthread->td_vnet myself to point to a VNET
>>>> (saved it when the module first loaded) (I have not created any jails
>>>> yet)... and it works... I didnt put any CURVNET macros...
>>>
>>> td->td_vnet is exactly what the CURVNET_SET macro sets.
>>> You should use the Macros because we may change the place where we stor=
e
>>> it.
>>>
>>> The vnet for the current thread is picked up from several places
>>> depending
>>> on the context,
>>> and it is cleared again when it is not needed. =A0the V_xxx usages in t=
he
>>> code
>>> end up being
>>> in effect expanded to curthread->td_vnet.xxx, where each 'xxx' is sort =
of
>>> like an element in a structure
>>> but not quite.
>>>
>>> Now, theoretically we could just leave it set all the time but then it
>>> would
>>> be nearly impossible
>>> to find places where we should have changed it, but forgot and just got
>>> the
>>> existing one.
>>>
>>> if you want to find the correct place to go, then look at the vnet of t=
he
>>> calling process
>>> which should be in the process cred. or just use vnet0.
>>
>> Can I check it from user space?
>>
>>>
>>> I don't understand why you saw a CRED_TO_VNET of 0
>>> I was under the impression that every process/thread in the system woul=
d
>>> be
>>> on vnet0
>>> in a vimage kernel.
>>
>> This is how my printf looks like:
>> struct thread *td =3D curthread;
>> struct vnet *v =3D TD_TO_VNET(td);
>> struct ucred *cred =3D CRED_TO_VNET(td->ucred);
>> struct vnet *td_vnet =3D td->td_vnet;
>
> here's your problem:
>
> strcut vnet *vnet =3D cred->cr_prison->pr_vnet;
When I add CURVNET_SET(CRED_TO_VNET(curthread->td_ucred)); I get a panic to=
o...
But your suggestion works if I do like this:
curthread->td_vnet =3D curthread->td_ucred->cr_prison->pr_vnet;
CRED_TO_VNET(curthread->td_ucred) returns NULL
>
>
>> printf("td=3D%p, td->td_vnet=3D%p, td->td_ucred=3D%p, TD_TO_VNET=3D%p,
>> CRED_TO_VNET=3D%p\n", td, td_vnet, td->td_ucred, v, cred);
>>
>> I made a fast search in /usr/src for "td_vnet" and found it was
>> assigned only in
>> int fork1(td, flags, pages, procp):
>> #ifdef VIMAGE
>> =A0 =A0 =A0 =A0td2->td_vnet =3D NULL;
>> =A0 =A0 =A0 =A0td2->td_vnet_lpush =3D NULL;
>> #endif
>
> Nice try. =A0Want another search? =A0Hint: there is this in vnet.h:
>
> #define curvnet curthread->td_vnet
>
> And then you'll, again, find the CURVNET_SET_* macros.
Thank you
>
>
>
>> Maybe something wrong with how I declare my wtap_ioctl:
>>
>> static struct cdevsw wtap_cdevsw =3D {
>> =A0 =A0 =A0 =A0.d_version =3D =A0 =A0D_VERSION,
>> =A0 =A0 =A0 =A0.d_flags =3D =A0 =A0 =A00,
>> =A0 =A0 =A0 =A0.d_ioctl =3D =A0 =A0 =A0wtap_ioctl,
>> =A0 =A0 =A0 =A0.d_name =3D =A0 =A0 =A0 "wtapctl",
>> };
>> ...
>> make_dev(&wtap_cdevsw,0,UID_ROOT,GID_WHEEL,0600,(const char *)"wtapctl")=
;
>>
>>>
>>> your stored vnet idea is ok as well, but may go strange if you load the
>>> driver from a vnet jail
>>> and then remove the jail.
>>
>> Ok, will document it in the code for now
>>
>>>
>>>
>>>
>>>
>>>> my assumption is that if ath drivers dont use VNET I shouldnt :P
>>>>
>>>> What is wrong with this hack?
>>>>
>>>> br,
>>>>
>>>> P.S. I have printed "porting to vnet" text to have it always at hand,
>>>> but its a bit hard for me... doing my best.
>>>>
>>>> On Wed, Feb 2, 2011 at 6:30 PM, Julian Elischer<julian@freebsd.org>
>>>> =A0wrote:
>>>>>
>>>>> On 2/2/11 9:12 AM, Bjoern A. Zeeb wrote:
>>>>>>
>>>>>> On Wed, 2 Feb 2011, Monthadar Al Jaberi wrote:
>>>>>>
>>>>>> Hi,
>>>>>>
>>>>>>> Thanx makes more sense, but I have noticed something weired if you
>>>>>>> can
>>>>>>> shade some light on.
>>>>>>>
>>>>>>> I added printfs one when the module is first loaded (static int
>>>>>>> event_handler(module_t module, int event, void *arg)):
>>>>>>> curthread=3D0xc3f95870
>>>>>>> curthread->td_vnet=3D0xc3170e00
>>>>>>> curthread->td_ucred=3D0xc3185d00
>>>>>>> TD_TO_VNET=3D0
>>>>>>> CRED_TO_VNET=3D0
>>>>>>
>>>>>> Try to load it from laoder on boot; I think that should work as we a=
re
>>>>>> setting the curvent for the kernel startup.
>>>>>>
>>>>>> The problem you are seeing is a bug in the current implementation th=
at
>>>>>> you cannot add any physical network interface after the kernel
>>>>>> started.
>>>>>> This applies to cardbus/usb/... as well as any kind of ethernet
>>>>>> interface, so a kldload igb should yield it as well.
>>>>>>
>>>>>> The fix for that is easy and hard at the same time:
>>>>>> A) either touch all drivers
>>>>>> B) or touch all cloned interfaces and change 3 common lines.
>>>>>> =A0 or try to make cloners aware of vimages.
>>>>>>
>>>>>> Solution B) is sitting in perforce with the entire stuff that it
>>>>>> depends
>>>>>> on and was started with CH=3D179022,179255 but not limited to that i=
f
>>>>>> you
>>>>>> want to have a peek.
>>>>>>
>>>>>> What you certainly can do locally to your driver for now is to make =
a
>>>>>> change like this:
>>>>>>
>>>>>> +#ifdef VIMAGE
>>>>>> + =A0 =A0 =A0 CURVNET_SET(vnet0);
>>>>>> +#endif
>>>>>> =A0 =A0 =A0 =A0ifp =3D if_alloc(IFT_ETHER);
>>>>>> +#ifdef VIMAGE
>>>>>> + =A0 =A0 =A0 CURVNET_RESTORE();
>>>>>> +#endif
>>>>>>
>>>>> you don't really need =A0the #ifdef except for readability as CURVNET=
_XXX
>>>>> ar
>>>>> enot defined for !vnet
>>>>>
>>>>>> It's the type A) kind of change from above that will break eventuall=
y
>>>>>> in the future.
>>>>>>
>>>>>> /bz
>>>>>>
>>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>>
>>
>
> --
> Bjoern A. Zeeb =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 You have to have visions!
> =A0 =A0 =A0 =A0<ks> Going to jail sucks -- <bz> All my daemons like it!
> =A0http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/jails.html
--=20
//Monthadar Al Jaberi
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