mac80211: support runtime interface type changes

Add support to mac80211 for changing the interface
type even when the interface is UP, if the driver
supports it.

To achieve this
 * add a new driver callback for switching,
 * split some of the interface up/down code out
   into new functions (do_open/do_stop), and
 * maintain an own __SDATA_RUNNING bit that will
   not be set during interface type, so that any
   other code doesn't use the interface.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/driver-trace.h b/net/mac80211/driver-trace.h
index b5a9558..f6f3d89 100644
--- a/net/mac80211/driver-trace.h
+++ b/net/mac80211/driver-trace.h
@@ -136,6 +136,31 @@
 	)
 );
 
+TRACE_EVENT(drv_change_interface,
+	TP_PROTO(struct ieee80211_local *local,
+		 struct ieee80211_sub_if_data *sdata,
+		 enum nl80211_iftype type),
+
+	TP_ARGS(local, sdata, type),
+
+	TP_STRUCT__entry(
+		LOCAL_ENTRY
+		VIF_ENTRY
+		__field(u32, new_type)
+	),
+
+	TP_fast_assign(
+		LOCAL_ASSIGN;
+		VIF_ASSIGN;
+		__entry->new_type = type;
+	),
+
+	TP_printk(
+		LOCAL_PR_FMT  VIF_PR_FMT " new type:%d",
+		LOCAL_PR_ARG, VIF_PR_ARG, __entry->new_type
+	)
+);
+
 TRACE_EVENT(drv_remove_interface,
 	TP_PROTO(struct ieee80211_local *local, struct ieee80211_sub_if_data *sdata),