mac80211: implement chanctx reservation

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).

We first check if an existing compatible context exists and if it
does, we reserve it.  If there is no compatible context we create a
new one and reserve it.

Additionally, split ieee80211_vif_copy_chanctx_to_vlans() so we can
call it while already holding the chanctx mutex.

Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index c422f81d93ae..3dd21116332f 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -756,6 +756,10 @@ struct ieee80211_sub_if_data {
         bool csa_radar_required;
         struct cfg80211_chan_def csa_chandef;
 
+        /* context reservation -- protected with chanctx_mtx */
+        struct ieee80211_chanctx *reserved_chanctx;
+        struct cfg80211_chan_def reserved_chandef;
+
         /* used to reconfigure hardware SM PS */
         struct work_struct recalc_smps;
 
@@ -1771,6 +1775,15 @@ ieee80211_vif_use_channel(struct ieee80211_sub_if_data *sdata,
                           const struct cfg80211_chan_def *chandef,
                           enum ieee80211_chanctx_mode mode);
 int __must_check
+ieee80211_vif_reserve_chanctx(struct ieee80211_sub_if_data *sdata,
+                              const struct cfg80211_chan_def *chandef,
+                              enum ieee80211_chanctx_mode mode);
+int __must_check
+ieee80211_vif_use_reserved_context(struct ieee80211_sub_if_data *sdata,
+                                   u32 *changed);
+int ieee80211_vif_unreserve_chanctx(struct ieee80211_sub_if_data *sdata);
+
+int __must_check
 ieee80211_vif_change_bandwidth(struct ieee80211_sub_if_data *sdata,
                                const struct cfg80211_chan_def *chandef,
                                u32 *changed);