Messages in this thread | | | Date | Thu, 20 Jul 2006 14:57:31 -0700 (PDT) | From | Trent Piepho <> | Subject | Re: [v4l-dvb-maintainer] Re: [PATCH] V4L: struct video_device corruption |
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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 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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