On 27 February 2014 15:41, Luca Coelho <luca@xxxxxxxxx> wrote:
> From: Luciano Coelho <luciano.coelho@xxxxxxxxx>
>
> In order to support channel switch with multiple vifs and multiple
> contexts, we implement a concept of channel context reservation. This
> allows us to reserve a channel context to be used later.
>
> The reservation functionality is not tied directly to channel switch
> and may be used in other situations (eg. reserving a channel context
> during IBSS join).
>
> When reserving the context, the following algorithm is used:
>
> 1) try to find an existing context that matches our future chandef and
> reserve it if it exists;
> 2) otherwise, check if we're the only vif in the current context, in
> which case we can just change our current context. To prevent
> other vifs from joining this context in the meantime, we mark it as
> exclusive. This is an optimization to avoid using extra contexts
> when not necessary and requires the driver to support changing a
> context on-the-fly;
This commit part is out of date (you've moved this into a separate patch).
> @@ -611,6 +614,142 @@ int ieee80211_vif_change_channel(struct ieee80211_sub_if_data *sdata,
> return ret;
> }
>
> +int ieee80211_vif_unreserve_chanctx(struct ieee80211_sub_if_data *sdata)
> +{
> +
> + lockdep_assert_held(&sdata->local->chanctx_mtx);
Empty line :-)
> + if (sdata->vif.bss_conf.chandef.width != ctx->conf.def.width)
> + local_changed |= BSS_CHANGED_BANDWIDTH;
> +
> + sdata->vif.bss_conf.chandef = ctx->conf.def;
I think you should be simply using sdata->csa_chandef here. What's the
point of setting the csa_chandef during reservation otherwise?
csa_chandef should probably be renamed to reserved_chandef for consistency.
> +
> + /* unref our reservation before assigning */
> + ctx->refcount--;
> + sdata->reserved_chanctx = NULL;
> + ret = ieee80211_assign_vif_chanctx(sdata, ctx);
> + if (ret) {
> + /* if assign fails refcount stays the same */
> + if (ctx->refcount == 0)
> + ieee80211_free_chanctx(local, ctx);
> + goto out;
> + }
> +
> + ieee80211_wake_queues_by_reason(&sdata->local->hw,
> + IEEE80211_MAX_QUEUE_MAP,
> + IEEE80211_QUEUE_STOP_REASON_CHANCTX);
If you fail to assign chanctx you don't wake queues back. Is this intended?
> diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
> index 8603dfb..998fbbb 100644
> --- a/net/mac80211/ieee80211_i.h
> +++ b/net/mac80211/ieee80211_i.h
> @@ -756,6 +756,8 @@ struct ieee80211_sub_if_data {
> bool csa_radar_required;
> struct cfg80211_chan_def csa_chandef;
>
> + struct ieee80211_chanctx *reserved_chanctx;
> +
It's a good idea to document this is protected by chanctx_mtx (and not
wdev.mtx).
Michał
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