From: Trent Piepho <xyzzy@speakeasy.org>
To: Mauro Carvalho Chehab <mchehab@infradead.org>
Cc: Robert Fitzsimons <robfitz@273k.net>,
Andrew Morton <akpm@osdl.org>,
Linux and Kernel Video <video4linux-list@redhat.com>,
76306.1226@compuserve.com, fork0@t-online.de, greg@kroah.com,
linux-kernel@vger.kernel.org,
"Randy.Dunlap" <rdunlap@xenotime.net>,
v4l-dvb maintainer list <v4l-dvb-maintainer@linuxtv.org>,
shemminger@osdl.org
Subject: Re: [v4l-dvb-maintainer] Re: [PATCH] V4L: struct video_device corruption
Date: Thu, 20 Jul 2006 14:57:31 -0700 (PDT) [thread overview]
Message-ID: <Pine.LNX.4.58.0607201425060.18071@shell2.speakeasy.net> (raw)
In-Reply-To: <1153310092.27276.9.camel@praia>
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On Wed, 19 Jul 2006, Mauro Carvalho Chehab wrote:
> Em Seg, 2006-07-17 às 17:25 -0700, Trent Piepho escreveu:
> > On Sat, 15 Jul 2006, Mauro Carvalho Chehab wrote:
> > > Em Sb, 2006-07-15 s 23:08 +0000, Robert Fitzsimons escreveu:
> > > > The layout of struct video_device would change depending on whether
> > > > videodev.h (V4L1) was include or not before v4l2-dev.h, which caused
> > > > the structure to get corrupted.
> > I think that the real problem is that many drivers include the V4L1 API
> > file videodev.h when V4L1 is NOT on. Should drivers be providing V4L1 API
> > functions, or need anything from videodev.h, if V4L1 is not on?
> >
> > It seems like they either need to depend on VIDEO_V4L1 or only include the
> > V4L1 API header file when V4L1 is turned on. Which also means they would
> > need to #ifdef out any V4L1 code when V4L1 is turned off. The bttv driver
> > for example does not do this. It includes a bunch of V4L1 functions even
> > when V4L1 (and V4L1_COMPAT) are turned off.
I've looked into this more, and there is still a serious bug here. If you
turn off V4L1 and V4L1_COMPAT, many drivers will a big issue with struct
video_device.
In some files (saa7134-tvaudio.c, saa6752hs.c, v4l2-common.c, dozens
more), V4L1 will be off and HAVE_V4L1 will not be defined. This gives you
the struct video_dev _without_ vidiocgmbuf.
In other files (tveeprom.c, tvaudio.c, bttv-driver.c, and many more), V4L1
will still be off (of course) by HAVE_V4L1 _will_ be defined. This gives
you the struct viddeo_dev _with_ vidiocgmbuf.
The first thing to solve this that HAVE_V4L1 should die. Why have a define
that is supposed to mirror a Kconfig variable? If everyone used
CONFIG_VIDEO_V4L1_COMPAT then there wouldn't be this problem, which some
code things V4L1 is on, and some code thinks it's off.
The second thing, is that many drivers don't respect
CONFIG_VIDEO_V4L1_COMPAT. They include V4L1 code when V4L1 is turned off.
To fix this completely:
1. Find all unnecessary includes of videodev.h and remove them.
2. Any remaining includes of videodef.h in drivers which don't depend on
VIDEO_V4L1_COMPAT or VIDEO_V4L1 in Kconfig should be protected with
#ifdef CONFIG_VIDEO_V4L1_COMPAT. This will break many drivers.
3. Replace HAVE_V4L1 with CONFIG_VIDEO_V4L1_COMPAT everywhere.
This will break many drivers.
4. Any drivers broken by steps 2 and 3 should be fixed by either:
A. Protecting all V4L1 code with #ifdef CONFIG_VIDEO_V4L1_COMPAT
B. Making the drivers require V4L1 in Kconfig
next prev parent reply other threads:[~2006-07-20 21:57 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-07-13 4:43 oops in bttv Chuck Ebbert
2006-07-13 5:05 ` Greg KH
2006-07-13 5:24 ` Randy.Dunlap
2006-07-13 5:44 ` Andrew Morton
2006-07-15 23:08 ` [PATCH] V4L: struct video_device corruption Robert Fitzsimons
2006-07-16 1:31 ` Mauro Carvalho Chehab
2006-07-18 0:25 ` [v4l-dvb-maintainer] " Trent Piepho
2006-07-19 11:54 ` Mauro Carvalho Chehab
2006-07-19 15:36 ` Michael Krufky
2006-07-20 21:57 ` Trent Piepho [this message]
2006-07-21 12:26 ` Mauro Carvalho Chehab
2006-07-21 20:06 ` Trent Piepho
2006-07-21 20:30 ` Mauro Carvalho Chehab
2006-07-21 22:55 ` Trent Piepho
2006-07-23 9:35 ` Mauro Carvalho Chehab
2006-07-24 2:16 ` Trent Piepho
2006-07-24 12:34 ` Mauro Carvalho Chehab
2006-07-24 22:06 ` Trent Piepho
2006-07-25 17:59 ` Mauro Carvalho Chehab
2006-07-25 3:08 ` Andrew Morton
2006-07-25 7:57 ` [v4l-dvb-maintainer] " Manu Abraham
2006-07-25 8:42 ` Trent Piepho
2006-07-25 9:06 ` Andrew Morton
2006-07-25 12:28 ` Mauro Carvalho Chehab
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