How can I clean up devices such as `media*` or `tty*` under `/dev` properly from terminal?

Question

I am running Ubuntu 18.04.2 LTS on a DELL XPS13 9343 and seem to be suffering from a kernel bug (reference: https://www.spinics.net/lists/linux-media/msg135812.html), which leads to the problem that I now have media0 - media255 all occupied under dev, which in turn leads to the following problem (media: could not get a free minor):

dmesg | tail -13

[ 5068.870529] uvcvideo: Found UVC 1.00 device Integrated_Webcam_HD (0c45:670c)
[ 5068.911713] uvcvideo 2-5:1.0: Entity type for entity Extension 4 was not initialized!
[ 5068.911716] uvcvideo 2-5:1.0: Entity type for entity Extension 3 was not initialized!
[ 5068.911717] uvcvideo 2-5:1.0: Entity type for entity Processing 2 was not initialized!
[ 5068.911719] uvcvideo 2-5:1.0: Entity type for entity Camera 1 was not initialized!
[ 5068.911722] media: could not get a free minor
[ 5069.249598] usb 2-5: USB disconnect, device number 56
[ 5069.556176] usb 2-5: new high-speed USB device number 57 using xhci_hcd
[ 5069.767923] usb 2-5: New USB device found, idVendor=0c45, idProduct=670c
[ 5069.767929] usb 2-5: New USB device strings: Mfr=2, Product=1, SerialNumber=0
[ 5069.767934] usb 2-5: Product: Integrated_Webcam_HD
[ 5069.767938] usb 2-5: Manufacturer: CN09GTFM7248753ABDZMA00
[ 5069.779009] uvcvideo: Found UVC 1.00 device Integrated_Webcam_HD (0c45:670c)

Although this bug has been fixed, it looks like it's not yet back-ported to my LTS version (for reference: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1836654, entry media: uvcvideo: Fix driver reference counting).

My questions now are however:
1) how can I clean up these media controller devices (device controller nodes) manually (ideally from terminal) in a proper way?
2) in general, how can I figure out which items under /dev are inactive / obsolete and purge those?

---

Additional information:

Under /sys/devices/pci0000:00/0000:00:14.0/usb2 it keeps trying to add but afterwards removing a 2-5 directory.

Under /sys/dev/char I have lots of broken links of two sorts now:

lrwxrwxrwx 1 root root 0 Aug 15 09:52 13:256 -> ../../devices/pci0000:00/0000:00:14.0/usb2/2-5/2-5:1.0/input/input42/event256
lrwxrwxrwx 1 root root 0 Aug 15 09:52 13:257 -> ../../devices/pci0000:00/0000:00:14.0/usb2/2-5/2-5:1.0/input/input43/event257
............
lrwxrwxrwx 1 root root 0 Aug 15 09:52 13:495 -> ../../devices/pci0000:00/0000:00:14.0/usb2/2-5/2-5:1.0/input/input281/event495
lrwxrwxrwx 1 root root 0 Aug 15 09:52 13:496 -> ../../devices/pci0000:00/0000:00:14.0/usb2/2-5/2-5:1.0/input/input282/event496

---

lrwxrwxrwx 1 root root 0 Aug 15 09:52 241:0 -> ../../devices/pci0000:00/0000:00:14.0/usb2/2-5/2-5:1.0/media0
lrwxrwxrwx 1 root root 0 Aug 15 09:52 241:1 -> ../../devices/pci0000:00/0000:00:14.0/usb2/2-5/2-5:1.0/media1
lrwxrwxrwx 1 root root 0 Aug 15 09:52 241:10 -> ../../devices/pci0000:00/0000:00:14.0/usb2/2-5/2-5:1.0/media10
............
lrwxrwxrwx 1 root root 0 Aug 15 09:52 241:98 -> ../../devices/pci0000:00/0000:00:14.0/usb2/2-5/2-5:1.0/media98
lrwxrwxrwx 1 root root 0 Aug 15 09:52 241:99 -> ../../devices/pci0000:00/0000:00:14.0/usb2/2-5/2-5:1.0/media99

Then there is also /dev/char and /dev/input to consider (?)

Answer 1

1) how can I clean up these media controller devices (device controller nodes) manually (ideally from terminal) in a proper way?

You can remove all you want in /dev/ but on the next reboot it is all recreated. Basically that is how Linux can get away with a system that is as universal as possible: those /dev/ entries are created on the fly and as needed by the system so you take out the hard disk and put it into another machine ... next reboot /dev/ is created for THAT system. Works perfect except for 3rd party drivers where the other system does not have that 3rd party devive.

2) in general, how can I figure out which items under /dev are inactive / obsolete and purge those?

/dev/ is created based on what packages need as a device so all -should- be needed (though I will not be able to tell you what entry in /dev/ is needed for what purpose for all of them).

In theory a package should have a limited amount of /dev/ entries. When uvcvideo has a bug that creates lots of /dev/ entries we can not do a lot about it unless you consider removing uvcvideo an option. The problem is not with /dev/ ... that is the effect of the bug. Fixing uvcvideo is what should be done.

You could remove /dev/ entries manually but that is 1 time per reboot. And to do this with a script... I would hesitate to advice that. It will likely break things. Besides that: I would expect the system to start throwing errors during boot (so before your clean up).