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Message-ID: <82e4877d0808030052g4c345811u642667b2a8d87a1d@mail.gmail.com>
Date: Sun, 3 Aug 2008 03:52:24 -0400
From: "Parag Warudkar" <parag.warudkar@gmail.com>
To: "Rabin Vincent" <rabin@rab.in>
Subject: Re: gspca_zc3xx oops - 2.6.27-rc1
Cc: "Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
       Serge.A.S@tochka.ru, mxhaard@users.sourceforge.net, moinejf@free.fr,
       "Mauro Carvalho Chehab" <mchehab@infradead.org>,
       video4linux-list@redhat.com
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On Sun, Aug 3, 2008 at 3:37 AM, Rabin Vincent <rabin@rab.in> wrote:

>  2b:   0f b6 37                movzbl (%edi),%esi <---- offender
>  2e:   0f af f0                imul   %eax,%esi
>  31:   8d b6 00 00 00 00       lea    0x0(%esi),%esi
>  37:   0f b6 83 00 dc 15 f9    movzbl -0x6ea2400(%ebx),%eax
>
> %edi is Tgamma, and it is NULL because sd->gamma was 0, and the zeroth element
> of gamma_tb was loaded.

Yep - I arrived at the same conclusion and sent a patch few minutes
before I saw your mail.
I am clueless about V4L and gspca workings but I chose a different
approach to fix this -
http://marc.info/?l=linux-kernel&m=121774817612391&w=2 .

>
> Now sd->gamma shouldn't be zero because in sd_ctrls, the minimum value for it
> is set to 1.  This range should be checked by vidioc_s_ctrl in gspca.c, and we
> have this there:
>
>               if (ctrl->value < ctrls->qctrl.minimum
>                   && ctrl->value > ctrls->qctrl.maximum)
>                        return -ERANGE;
>

Sounds more appropriate but I am not sure how vidioc_s_ctrl leads to
the call trace in the OOPS - at least it doesn't show up there.


Thanks

Parag
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