On Sun, Aug 07, 2022 at 02:25:33PM +0300, Oded Gabbay wrote: > 2. Common code to handle drivers that want to allow a single user at a > time to run open the device char file. Note, that's an impossible request, and one that the kernel should never worry about, so don't even try it. Think about userspace doing an call to dup() on an open char file descriptor and then passing that off somewhere else. thanks, greg k-h