mac80211: introduce channel context skeleton code

Channel context are the foundation for multi-channel
operation. They are are immutable and are re-created
(or re-used if other interfaces are bound to a certain
channel and a compatible channel type) on channel
switching.

This is an initial implementation and more features
will come in separate patches.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
[some changes including RCU protection]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 35 insertions, 0 deletions

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 8c804550465b..9a058e58d53e 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -658,6 +658,30 @@ enum ieee80211_sdata_state_bits {
         SDATA_STATE_OFFCHANNEL,
 };
 
+/**
+ * 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
+};
+
+struct ieee80211_chanctx {
+        struct list_head list;
+        struct rcu_head rcu_head;
+
+        enum ieee80211_chanctx_mode mode;
+        int refcount;
+
+        struct ieee80211_chanctx_conf conf;
+};
+
 struct ieee80211_sub_if_data {
         struct list_head list;
 
@@ -987,6 +1011,10 @@ struct ieee80211_local {
         struct ieee80211_channel *tmp_channel;
         enum nl80211_channel_type tmp_channel_type;
 
+        /* channel contexts */
+        struct list_head chanctx_list;
+        struct mutex chanctx_mtx;
+
         /* SNMP counters */
         /* dot11CountersTable */
         u32 dot11TransmittedFragmentCount;
@@ -1510,6 +1538,13 @@ bool ieee80211_set_channel_type(struct ieee80211_local *local,
 enum nl80211_channel_type
 ieee80211_ht_oper_to_channel_type(struct ieee80211_ht_operation *ht_oper);
 
+int __must_check
+ieee80211_vif_use_channel(struct ieee80211_sub_if_data *sdata,
+                          struct ieee80211_channel *channel,
+                          enum nl80211_channel_type channel_type,
+                          enum ieee80211_chanctx_mode mode);
+void ieee80211_vif_release_channel(struct ieee80211_sub_if_data *sdata);
+
 #ifdef CONFIG_MAC80211_NOINLINE
 #define debug_noinline noinline
 #else