mac80211: add vif debugfs driver callbacks

Add debugfs driver callbacks so drivers can add
debugfs entries for interfaces. Note that they
_must_ remove the entries again as add/remove in
the driver doesn't correspond to add/remove in
debugfs; the former is up/down while the latter
is netdev create/destroy.

Signed-off-by: Alexander Bondar <alexander.bondar@intel.com>
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/mac80211.h

@@ -2167,6 +2167,18 @@ enum ieee80211_rate_control_changed {
  *	MAC address of the device going away.
  *	Hence, this callback must be implemented. It can sleep.
  *
+ * @add_interface_debugfs: Drivers can use this callback to add debugfs files
+ *	when a vif is added to mac80211. This callback and
+ *	@remove_interface_debugfs should be within a CONFIG_MAC80211_DEBUGFS
+ *	conditional. @remove_interface_debugfs must be provided for cleanup.
+ *	This callback can sleep.
+ *
+ * @remove_interface_debugfs: Remove the debugfs files which were added using
+ *	@add_interface_debugfs. This callback must remove all debugfs entries
+ *	that were added because mac80211 only removes interface debugfs when the
+ *	interface is destroyed, not when it is removed from the driver.
+ *	This callback can sleep.
+ *
  * @config: Handler for configuration requests. IEEE 802.11 code calls this
  *	function to change hardware configuration, e.g., channel.
  *	This function should never fail but returns a negative error code
@@ -2580,6 +2592,12 @@ struct ieee80211_ops {
 				   struct ieee80211_vif *vif,
 				   struct ieee80211_sta *sta,
 				   struct dentry *dir);
+	void (*add_interface_debugfs)(struct ieee80211_hw *hw,
+				      struct ieee80211_vif *vif,
+				      struct dentry *dir);
+	void (*remove_interface_debugfs)(struct ieee80211_hw *hw,
+					 struct ieee80211_vif *vif,
+					 struct dentry *dir);
 #endif
 	void (*sta_notify)(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 			enum sta_notify_cmd, struct ieee80211_sta *sta);

net/mac80211/driver-ops.h

@@ -528,6 +528,43 @@ static inline void drv_sta_remove_debugfs(struct ieee80211_local *local,
 		local->ops->sta_remove_debugfs(&local->hw, &sdata->vif,
 					       sta, dir);
 }
+
+static inline
+void drv_add_interface_debugfs(struct ieee80211_local *local,
+			       struct ieee80211_sub_if_data *sdata)
+{
+	might_sleep();
+
+	check_sdata_in_driver(sdata);
+
+	if (!local->ops->add_interface_debugfs)
+		return;
+
+	local->ops->add_interface_debugfs(&local->hw, &sdata->vif,
+					  sdata->debugfs.dir);
+}
+
+static inline
+void drv_remove_interface_debugfs(struct ieee80211_local *local,
+				  struct ieee80211_sub_if_data *sdata)
+{
+	might_sleep();
+
+	check_sdata_in_driver(sdata);
+
+	if (!local->ops->remove_interface_debugfs)
+		return;
+
+	local->ops->remove_interface_debugfs(&local->hw, &sdata->vif,
+					     sdata->debugfs.dir);
+}
+#else
+static inline
+void drv_add_interface_debugfs(struct ieee80211_local *local,
+			       struct ieee80211_sub_if_data *sdata) {}
+static inline
+void drv_remove_interface_debugfs(struct ieee80211_local *local,
+				  struct ieee80211_sub_if_data *sdata) {}
 #endif
 
 static inline __must_check

net/mac80211/iface.c

@@ -621,6 +621,8 @@ int ieee80211_do_open(struct wireless_dev *wdev, bool coming_up)
 				goto err_del_interface;
 		}
 
+		drv_add_interface_debugfs(local, sdata);
+
 		if (sdata->vif.type == NL80211_IFTYPE_AP) {
 			local->fif_pspoll++;
 			local->fif_probe_req++;
@@ -882,6 +884,8 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata,
 		 */
 		ieee80211_free_keys(sdata);
 
+		drv_remove_interface_debugfs(local, sdata);
+
 		if (going_down)
 			drv_remove_interface(local, sdata);
 	}