cfg80211: track monitor interfaces count

Implements .set_monitor_enabled(wiphy, enabled).

Notifies driver upon change of interface layout.

If only monitor interfaces become present it is
called with 2nd argument being true. If
non-monitor interface appears then 2nd argument
is false. Driver is notified only upon change.

This makes it more obvious about the fact that
cfg80211 supports single monitor channel. Once we
implement multi-channel we don't want to allow
setting monitor channel while other interface
types are running. Otherwise it would be ambiguous
once we start considering num_different_channels.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/net/wireless/util.c b/net/wireless/util.c
index fc948d0a53f3..9b92ec57d07b 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -871,6 +871,11 @@ int cfg80211_change_iface(struct cfg80211_registered_device *rdev,
                 }
         }
 
+        if (!err && ntype != otype && netif_running(dev)) {
+                cfg80211_update_iface_num(rdev, ntype, 1);
+                cfg80211_update_iface_num(rdev, otype, -1);
+        }
+
         return err;
 }