Re: [RFC v2 1/7] mac80211: introduce channel contexts skeleton code

[Johannes Berg <johannes@sipsolutions.net>]

On Thu, 2012-06-21 at 14:03 +0200, Michal Kazior wrote:

> +++ b/include/net/mac80211.h
> @@ -143,6 +143,41 @@ struct ieee80211_low_level_stats {
>  	unsigned int dot11RTSSuccessCount;
>  };
>  
> +
> +/**
> + * enum ieee80211_chanctx_mode - channel context configuration mode
> + *
> + * @IEEE80211_CHANCTX_SHARED: channel context may be used by
> + *	multiple interfaces
> + * @IEEE80211_CHANCTX_EXCLUSIVE: channel context can be used
> + *	only by a single interface. This can be used for example for
> + *	non-fixed channel IBSS.
> + */
> +enum ieee80211_chanctx_mode {
> +	IEEE80211_CHANCTX_SHARED,
> +	IEEE80211_CHANCTX_EXCLUSIVE
> +};

Does the driver ever care about this? It seems mostly internal to
determine what's going on?


> + * @chanctx_conf: channel context vif is bound to, may be NULL

Maybe say "will be %NULL before the interface is assigned to a channel
context" or so?

> +	INIT_LIST_HEAD(&ctx->interfaces);

Is there really a need for this list? It seems only moderately less
efficient to iterate all interfaces and filter by channel context, and
that's probably easier to maintain?

> +static void
> +__ieee80211_vif_release_channel(struct ieee80211_sub_if_data *sdata)
> +{
> +	struct ieee80211_chanctx_conf *conf = sdata->vif.chanctx_conf;
> +	struct ieee80211_chanctx *ctx =
> +			container_of(conf, struct ieee80211_chanctx, conf);
> +
> +	if (!conf)
> +		return;
> +
> +	ieee80211_unassign_vif_chanctx(sdata, ctx);
> +	if (list_empty(&ctx->interfaces))
> +		ieee80211_free_chanctx(ctx);
> +}

Ah, ok. So I guess there's a good use for the list at least here.

johannes