Re: [PATCH v4 5/6] nl80211/cfg80211: add ap channel switch command

[Michal Kazior <michal.kazior@tieto.com>]

On 14/10/12 16:48, Victor Goldenshtein wrote:
> +static int nl80211_ap_channel_switch(struct sk_buff *skb,
> +				     struct genl_info *info)
> +{

This function should probably enforce interface combinations with 
`cfg80211_can_use_chan()`. Otherwise we might end up in a state which 
doesn't correspond to any interface combination - and won't be able to 
bring up new interfaces.

This however introduces a new problem. Let's suppose we have 2 APs on 
channel 1. The device doesn't support multi-channel. We won't be able to 
switch channel on these APs at all.

We might want to change the channel switch to resolve around the channel 
itself (not the interface) - so we'd be saying "move all interfaces with 
channel X to channel Y" instead of "move interface X to channel Y".

Or we could let the driver decide what it'll do - e.g. silently switch 
more than one interface to a different channel (which makes sense with 
AP/DFS I guess) and just notify cfg/userspace about it. That would 
require us to provide a way to switch interfaces (atomically possibly) 
between channels while keeping in sync with interface combinations though.

We might try addressing station CSA issue at the same time maybe?


-- Pozdrawiam / Best regards, Michal Kazior.