wireless: Only join DFS channels in mesh mode if userspace flags support

When joining a mesh network it is not guaranteed that userspace has a
daemon listening for radar events. This is however required for channels
requiring DFS. To flag that userspace will handle radar events, it needs
to set NL80211_ATTR_HANDLE_DFS.

This matches the current mechanism used for IBSS mode.

Signed-off-by: Benjamin Berg <benjamin@sipsolutions.net>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index b083e6c..fa25fbb 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -1441,6 +1441,9 @@ struct mesh_config {
  * @mcast_rate: multicat rate for Mesh Node [6Mbps is the default for 802.11a]
  * @basic_rates: basic rates to use when creating the mesh
  * @beacon_rate: bitrate to be used for beacons
+ * @userspace_handles_dfs: whether user space controls DFS operation, i.e.
+ *	changes the channel when a radar is detected. This is required
+ *	to operate on DFS channels.
  *
  * These parameters are fixed when the mesh is created.
  */
@@ -1462,6 +1465,7 @@ struct mesh_setup {
 	int mcast_rate[NUM_NL80211_BANDS];
 	u32 basic_rates;
 	struct cfg80211_bitrate_mask beacon_rate;
+	bool userspace_handles_dfs;
 };
 
 /**