Re: [Xenomai-core] [PATCH] provide rtdm_mmap_to_user / rtdm_munmap

[Rodrigo Rosenfeld Rosas <lbocseg@domain.hid>]

Hi Jan, it just happened once and I couldn't reproduce (I didn't want to=20
reproduce it too since I would need to restart my computer because the driv=
er=20
wouldn't unload)...

When it happened I forgot to start the timer running the latency program an=
d=20
my driver failed to load and due to some mistake I've made (I have not=20
indentified it yet), it crashed on rmmoding. I need to check this, but I=20
still think it is a good idea to make the sanity checks...

I have not written the user-space program yet, so you'll have to wait until=
=20
monday, when I'll be able to test it, hopefully. But it seems to be=20
working... I changed my driver design. I do the mmap's on driver=20
initialization and just pass the returned addresses on the IOCTL, so I can =
do=20
them in a RT-context. The problem is that even if the user call an IOCTL to=
=20
munmap, it will still be possible to him to continue using the provided=20
address and this would result in a problem. But, as in all situations, ther=
e=20
are trade-offs and I prefer to rely on the user, while providing a=20
RT-MMAP-IOCTL. Of course it isn't really a mmap, but if the user don't mess=
=20
with the pointers, it will work like if it was...

Hope you understood me, I wrote it a little confusing... :)

Until monday! ;)

Rodrigo.

____________________________________________________________
Em Sexta 10 Fevereiro 2006 18:58, Rodrigo Rosenfeld Rosas escreveu:

>Hi Jan, I started the tests and had problems on unloading the module.
>
>I am probably doing something wrong but I think the driver shouldn't crash.
>Probably it is missing some sanity checks on rtdm_munmap like
>
>if (! (user_info && user_info->mm))
>	return -EXXX;
>
>I'll investigate the problems... I had some unexpected things to investiga=
te
>today and haven't had enought time to test the patch but hopefully I'll do
> it on monday...
>
>That was the result:
>
>Unable to handle kernel NULL pointer dereference at virtual address 000000=
30
> printing eip:
>e0a1f2fc
>*pde =3D 00000000
>Oops: 0002 [#1]
>PREEMPT
>Modules linked in: rt_dt3153 parport_pc lp parport af_packet nls_iso8859_1
>nls_cp437 v4l2_common videodev video_buf xeno_rtdm xeno_native xeno_nucleus
>snd_seq_dummy snd_seq_oss snd_seq_midi snd_rawmidi snd_seq_midi_event
> snd_seq snd_seq_device snd_intel8x0 snd_ac97_codec snd_ac97_bus snd_pcm_o=
ss
> snd_mixer_oss snd_pcm e100 mii snd_timer evdev snd soundcore snd_page_all=
oc
> hw_random i2c_i801 i2c_core ehci_hcd intel_agp agpgart ide_cd uhci_hcd
> usbcore cdrom
>CPU:    0
>EIP:    0060:[<e0a1f2fc>]    Not tainted VLI
>EFLAGS: 00010286   (2.6.15.4-adeos)
>EIP is at rtdm_munmap+0x11/0x44 [xeno_rtdm]
>eax: 00000030   ebx: d2e45a70   ecx: 00000000   edx: ffff0001
>esi: bfd72660   edi: 00000880   ebp: c2b20000   esp: c2b21f4c
>ds: 007b   es: 007b   ss: 0068
>Process rmmod (pid: 4254, threadinfo=3Dc2b20000 task=3Dd70bf550)
>Stack: e0bfafa0 bfd72660 e0bf7cbc d2e45a70 b7d92000 00096000 e0bfad80
> c0132e0d 645f7472 35313374 c0320033 00000246 c03fa4cc c013c881 00000021
> c0324200 00000246 c2b21fbc 00000021 00000001 c0324200 bfd72660 00d72660
> 00000000 Call Trace:
> [<e0bf7cbc>] cleanup_module+0x24/0x50 [rt_dt3153]
> [<c0132e0d>] sys_delete_module+0x12e/0x15f
> [<c013c881>] __ipipe_dispatch_event+0x56/0xd5
> [<c0102fc8>] syscall_call+0x7/0xb
>Code: 5f 89 e8 81 fd 18 fc ff ff 77 08 8b 5c 24 2c 89 2b 31 c0 59 5b 5b 5e
> 5f 5d c3 56 53 8b 5c 24 0c 8b 4b 78 8d 41 30 ba 01 00 ff ff <0f> c1 10 85
> d2 75 4c ff 74 24 14 ff 74 24 14 ff 73 78 e8 2f 02
>
>Regards,
>
>Rodrigo.
>
>____________________________________________________________
>
>Em Quinta 09 Fevereiro 2006 22:37, Jan Kiszka escreveu:
>>Jan Kiszka wrote:
>>> Hi all,
>>>
>>> this is a first attempt to add the requested mmap functionality to the
>>> RTDM driver API.
>>
>>... and this version is even more useful than the previous one (now with
>>EXPORT_SYMBOL!). Be warned: I just compiled it, I count on third-party
>>testers.
>>
>>Jan
>
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