Re: [PATCH] nl80211: Support mgmt frame unregistrations

[Johannes Berg <johannes@sipsolutions.net>]

On Wed, 2019-09-04 at 11:22 -0500, Denis Kenzior wrote:
> To state another way, it is
> currently not possible to write a userspace application that utilizes a
> single nl80211 genl socket, instead it must open multiple genl sockets
> for multiple wdevs on multiple phys.

I don't see how this is too onerous for the application, every
application is basically going to have an event loop anyway.

Thus, I don't really see any reason for us to add a bunch of code just
to make an application track fewer file descriptors - we need to have
the cleanup on close already anyway, so why not actually exercise those
code paths?

I do note that with the "unregister on iftype change" patch you could
switch to an unsupported type and reach this, but I don't think you'd
want to rely on that :-)

Possibly I could imagine a reason for this if you needed a single socket
for functional reason, but you're not really giving any such reason. I
could imagine that there might be races, but I'm having a hard time
coming up with a scenario where they actually matter ... if you really
really get a race between e.g. RX-AUTH and INTERFACE-DEL you'll try to
do some operations that will just fail, but so what?

johannes