mac80211: track scheduled scan virtual interface

Instead of tracking whether or not we're in a
scheduled scan, track the virtual interface
(sdata) in an RCU-protected pointer to make it
usable from RX to check the MAC address.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/ieee80211_i.h

@@ -965,9 +965,9 @@ struct ieee80211_local {
 	int scan_channel_idx;
 	int scan_ies_len;
 
-	bool sched_scanning;
 	struct ieee80211_sched_scan_ies sched_scan_ies;
 	struct work_struct sched_scan_stopped_work;
+	struct ieee80211_sub_if_data __rcu *sched_scan_sdata;
 
 	unsigned long leave_oper_channel_time;
 	enum mac80211_scan_state next_scan_state;

net/mac80211/main.c

@@ -322,7 +322,8 @@ static void ieee80211_restart_work(struct work_struct *work)
 
 	mutex_lock(&local->mtx);
 	WARN(test_bit(SCAN_HW_SCANNING, &local->scanning) ||
-	     local->sched_scanning,
+	     rcu_dereference_protected(local->sched_scan_sdata,
+				       lockdep_is_held(&local->mtx)),
 		"%s called with hardware scan in progress\n", __func__);
 	mutex_unlock(&local->mtx);
 

net/mac80211/rx.c

@@ -421,13 +421,13 @@ ieee80211_rx_h_passive_scan(struct ieee80211_rx_data *rx)
 	struct sk_buff *skb = rx->skb;
 
 	if (likely(!(status->rx_flags & IEEE80211_RX_IN_SCAN) &&
-		   !local->sched_scanning))
+		   !rcu_access_pointer(local->sched_scan_sdata)))
 		return RX_CONTINUE;
 
 	if (test_bit(SCAN_HW_SCANNING, &local->scanning) ||
 	    test_bit(SCAN_SW_SCANNING, &local->scanning) ||
 	    test_bit(SCAN_ONCHANNEL_SCANNING, &local->scanning) ||
-	    local->sched_scanning)
+	    rcu_access_pointer(local->sched_scan_sdata))
 		return ieee80211_scan_rx(rx->sdata, skb);
 
 	/* scanning finished during invoking of handlers */

net/mac80211/scan.c

@@ -930,9 +930,9 @@ int ieee80211_request_sched_scan_start(struct ieee80211_sub_if_data *sdata,
 	struct ieee80211_local *local = sdata->local;
 	int ret, i;
 
-	mutex_lock(&sdata->local->mtx);
+	mutex_lock(&local->mtx);
 
-	if (local->sched_scanning) {
+	if (rcu_access_pointer(local->sched_scan_sdata)) {
 		ret = -EBUSY;
 		goto out;
 	}
@@ -966,7 +966,7 @@ int ieee80211_request_sched_scan_start(struct ieee80211_sub_if_data *sdata,
 	ret = drv_sched_scan_start(local, sdata, req,
 				   &local->sched_scan_ies);
 	if (ret == 0) {
-		local->sched_scanning = true;
+		rcu_assign_pointer(local->sched_scan_sdata, sdata);
 		goto out;
 	}
 
@@ -974,7 +974,7 @@ int ieee80211_request_sched_scan_start(struct ieee80211_sub_if_data *sdata,
 	while (i > 0)
 		kfree(local->sched_scan_ies.ie[--i]);
 out:
-	mutex_unlock(&sdata->local->mtx);
+	mutex_unlock(&local->mtx);
 	return ret;
 }
 
@@ -983,22 +983,22 @@ int ieee80211_request_sched_scan_stop(struct ieee80211_sub_if_data *sdata)
 	struct ieee80211_local *local = sdata->local;
 	int ret = 0, i;
 
-	mutex_lock(&sdata->local->mtx);
+	mutex_lock(&local->mtx);
 
 	if (!local->ops->sched_scan_stop) {
 		ret = -ENOTSUPP;
 		goto out;
 	}
 
-	if (local->sched_scanning) {
+	if (rcu_access_pointer(local->sched_scan_sdata)) {
 		for (i = 0; i < IEEE80211_NUM_BANDS; i++)
 			kfree(local->sched_scan_ies.ie[i]);
 
 		drv_sched_scan_stop(local, sdata);
-		local->sched_scanning = false;
+		rcu_assign_pointer(local->sched_scan_sdata, NULL);
 	}
 out:
-	mutex_unlock(&sdata->local->mtx);
+	mutex_unlock(&local->mtx);
 
 	return ret;
 }
@@ -1022,7 +1022,7 @@ void ieee80211_sched_scan_stopped_work(struct work_struct *work)
 
 	mutex_lock(&local->mtx);
 
-	if (!local->sched_scanning) {
+	if (!rcu_access_pointer(local->sched_scan_sdata)) {
 		mutex_unlock(&local->mtx);
 		return;
 	}
@@ -1030,7 +1030,7 @@ void ieee80211_sched_scan_stopped_work(struct work_struct *work)
 	for (i = 0; i < IEEE80211_NUM_BANDS; i++)
 		kfree(local->sched_scan_ies.ie[i]);
 
-	local->sched_scanning = false;
+	rcu_assign_pointer(local->sched_scan_sdata, NULL);
 
 	mutex_unlock(&local->mtx);