cfg80211: track monitor channel

Make it even more obvious we support single
monitor channel. This will allow us to remove
.get_channel.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/wireless/chan.c b/net/wireless/chan.c
index 019401b..434c56b 100644
--- a/net/wireless/chan.c
+++ b/net/wireless/chan.c
@@ -82,6 +82,7 @@
 				 int freq, enum nl80211_channel_type chantype)
 {
 	struct ieee80211_channel *chan;
+	int err;
 
 	if (!rdev->ops->set_monitor_channel)
 		return -EOPNOTSUPP;
@@ -92,7 +93,13 @@
 	if (!chan)
 		return -EINVAL;
 
-	return rdev->ops->set_monitor_channel(&rdev->wiphy, chan, chantype);
+	err = rdev->ops->set_monitor_channel(&rdev->wiphy, chan, chantype);
+	if (!err) {
+		rdev->monitor_channel = chan;
+		rdev->monitor_channel_type = chantype;
+	}
+
+	return err;
 }
 
 void
diff --git a/net/wireless/core.c b/net/wireless/core.c
index 8412da7d..1b5daa7 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -730,9 +730,15 @@
 		rdev->num_running_monitor_ifaces += num;
 
 	has_monitors_only_new = cfg80211_has_monitors_only(rdev);
-	if (has_monitors_only_new != has_monitors_only_old)
+	if (has_monitors_only_new != has_monitors_only_old) {
 		rdev->ops->set_monitor_enabled(&rdev->wiphy,
 					       has_monitors_only_new);
+
+		if (!has_monitors_only_new) {
+			rdev->monitor_channel = NULL;
+			rdev->monitor_channel_type = NL80211_CHAN_NO_HT;
+		}
+	}
 }
 
 static int cfg80211_netdev_notifier_call(struct notifier_block *nb,
diff --git a/net/wireless/core.h b/net/wireless/core.h
index 99acd51..d5efe1b 100644
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@ -59,6 +59,9 @@
 	int num_running_ifaces;
 	int num_running_monitor_ifaces;
 
+	struct ieee80211_channel *monitor_channel;
+	enum nl80211_channel_type monitor_channel_type;
+
 	/* BSSes/scanning */
 	spinlock_t bss_lock;
 	struct list_head bss_list;