mac80211: add sta_state callback

(based on Eliad's patch)

Add a callback to notify the low-level driver whenever
the state of a station changes. The driver is only
notified when the station is actually in the mac80211
hash table, not for pre-insert state transitions.

To allow the driver to replace sta_add/remove calls
with this, call extra transitions with the NOTEXIST
state.

This callback can fail, so we need to be careful in
handling it when a station is inserted, particularly
in the IBSS case where we still keep the station entry
around for mac80211 purposes.

Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 520eb4c..922313f 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -982,6 +982,25 @@
 };
 
 /**
+ * enum ieee80211_sta_state - station state
+ *
+ * @IEEE80211_STA_NOTEXIST: station doesn't exist at all,
+ *	this is a special state for add/remove transitions
+ * @IEEE80211_STA_NONE: station exists without special state
+ * @IEEE80211_STA_AUTH: station is authenticated
+ * @IEEE80211_STA_ASSOC: station is associated
+ * @IEEE80211_STA_AUTHORIZED: station is authorized (802.1X)
+ */
+enum ieee80211_sta_state {
+	/* NOTE: These need to be ordered correctly! */
+	IEEE80211_STA_NOTEXIST,
+	IEEE80211_STA_NONE,
+	IEEE80211_STA_AUTH,
+	IEEE80211_STA_ASSOC,
+	IEEE80211_STA_AUTHORIZED,
+};
+
+/**
  * struct ieee80211_sta - station table entry
  *
  * A station table entry represents a station we are possibly
@@ -1974,6 +1993,13 @@
  *	in AP mode, this callback will not be called when the flag
  *	%IEEE80211_HW_AP_LINK_PS is set. Must be atomic.
  *
+ * @sta_state: Notifies low level driver about state transition of a
+ *	station (which can be the AP, a client, IBSS/WDS/mesh peer etc.)
+ *	This callback is mutually exclusive with @sta_add/@sta_remove.
+ *	It must not fail for down transitions but may fail for transitions
+ *	up the list of states.
+ *	The callback can sleep.
+ *
  * @conf_tx: Configure TX queue parameters (EDCF (aifs, cw_min, cw_max),
  *	bursting) for a hardware TX queue.
  *	Returns a negative error code on failure.
@@ -2193,6 +2219,10 @@
 			  struct ieee80211_sta *sta);
 	void (*sta_notify)(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 			enum sta_notify_cmd, struct ieee80211_sta *sta);
+	int (*sta_state)(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
+			 struct ieee80211_sta *sta,
+			 enum ieee80211_sta_state old_state,
+			 enum ieee80211_sta_state new_state);
 	int (*conf_tx)(struct ieee80211_hw *hw,
 		       struct ieee80211_vif *vif, u16 queue,
 		       const struct ieee80211_tx_queue_params *params);