On Thu, Oct 24, 2019 at 10:23:57PM +0200, Marcel Holtmann wrote: > Hi Greg, > > >> udev has a feature of creating /dev/<node> device-nodes if it finds > >> a devnode:<node> modalias. This allows for auto-loading of modules that > >> provide the node. This requires to use a statically allocated minor > >> number for misc character devices. > >> > >> However, rfkill uses dynamic minor numbers and prevents auto-loading > >> of the module. So allocate the next static misc minor number and use > >> it for rfkill. > > > > As rfkill has been around for a long time, what new use case is needing > > to auto-load this based on a major number? > > we have bug reports from iwd users where it fails opening /dev/rfkill. Since iwd can be actually started before the WiFi hardware is fully probed and all its drivers are loaded, we have a race-condition here if rfkill is not capable of auto-loading. > > The difference is really that iwd is a fully self-contained WiFi daemon compared to wpa_supplicant which is just some sort of helper. iwd is fully hot plug capable as well compared to wpa_supplicant. It looks like this is exposing the race condition for our users. Frankly, we should have fixed rfkill a long time ago when we fixed uinput, uhid etc, but seems we forgot it. I assume mainly because it magically got loaded in time by some module dependencies. You need a better email client, one with \n characters... Anyway, this sounds reasonable, I'll go queue this up for 5.5. thanks, greg k-h
