On Thu, 2014-02-27 at 16:16 +0100, Michal Kazior wrote:
> 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 This commit part is out of date (you've moved this into a separate patch).
Good point, I'll fix this part.
>
> > @@ -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 :-)
Oops!
> > + 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?
Yes, this is wrong.
> csa_chandef should probably be renamed to reserved_chandef for consistency.
I don't want to mess with CSA in this patch. I'll leave the csa_chandef
as it is. But you're right, I should use the "future" chandef, which
I'll add as reserved_chandef.
> > + /* 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?
This was not intended, it was a mistake. :) I'll fix it.
> > 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).
Good idea.
--
Luca.
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