I made a quick implementation which is available here: http://www.linuxtv.org/hg/~hverkuil/v4l-dvb-serialize It's pretty easy to use and it also gives you a very simple way to block access to the video device nodes until all have been allocated by simply taking the serialization lock and holding it until we are done with the initialization. I converted radio-mr800.c and ivtv. That said, almost all drivers that register multiple device nodes probably suffer from a race condition when one of the device node registrations returns an error and all devices have to be unregistered and the driver needs to release all resources. Currently most if not all drivers just release resources and free the memory. But if an application managed to open one device before the driver removes it again, then we have almost certainly a crash. It is possible to do this correctly in the driver, but it really needs core support where a release callback can be installed in v4l2_device that is called when the last video_device is closed by the application. We already can cleanup correctly after the last close of a video_device, but there is no top-level release yet. Anyway, I tried to use the serialization flag in bttv as well, but I ran into problems with videobuf. Basically when you need to wait for some event you should release the serialization lock and grab it after the event arrives. Unfortunately videobuf has no access to v4l2_device at the moment. If we would have that, then videobuf can just release the serialization lock while waiting for something to happen. Regards, Hans -- Hans Verkuil - video4linux developer - sponsored by TANDBERG -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
