cfg80211: Make pre-CAC results valid only for ETSI domain

DFS requirement for ETSI domain (section 4.7.1.4 in
ETSI EN 301 893 V1.8.1) is the only one which explicitly
states that once DFS channel is marked as available afer
the CAC, this channel will remain in available state even
moving to a different operating channel. But the same is
not explicitly stated in FCC DFS requirement. Also, Pre-CAC
requriements are not explicitly mentioned in FCC requirement.
Current implementation in keeping DFS channel in available
state is same as described in ETSI domain.

For non-ETSI DFS domain, this patch gives a grace period of 2 seconds
since the completion of successful CAC before moving the channel's
DFS state to 'usable' from 'available' state. The same grace period
is checked against the channel's dfs_state_entered timestamp while
deciding if a DFS channel is available for operation. There is a new
radar event, NL80211_RADAR_PRE_CAC_EXPIRED, reported when DFS channel
is moved from available to usable state after the grace period. Also
make sure the DFS channel state is reset to usable once the beaconing
operation on that channel is brought down (like stop_ap, leave_ibss
and leave_mesh) in non-ETSI domain.

Signed-off-by: Vasanthakumar Thiagarajan <vthiagar@qti.qualcomm.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 31 insertions, 9 deletions

diff --git a/net/wireless/mlme.c b/net/wireless/mlme.c
index 22b3d9990065..cd29366a5206 100644
--- a/net/wireless/mlme.c
+++ b/net/wireless/mlme.c
@@ -745,6 +745,12 @@ bool cfg80211_rx_mgmt(struct wireless_dev *wdev, int freq, int sig_mbm,
 }
 EXPORT_SYMBOL(cfg80211_rx_mgmt);
 
+void cfg80211_sched_dfs_chan_update(struct cfg80211_registered_device *rdev)
+{
+	cancel_delayed_work(&rdev->dfs_update_channels_wk);
+	queue_delayed_work(cfg80211_wq, &rdev->dfs_update_channels_wk, 0);
+}
+
 void cfg80211_dfs_channels_update_work(struct work_struct *work)
 {
 	struct delayed_work *delayed_work = to_delayed_work(work);
@@ -755,6 +761,8 @@ void cfg80211_dfs_channels_update_work(struct work_struct *work)
 	struct wiphy *wiphy;
 	bool check_again = false;
 	unsigned long timeout, next_time = 0;
+	unsigned long time_dfs_update;
+	enum nl80211_radar_event radar_event;
 	int bandid, i;
 
 	rdev = container_of(delayed_work, struct cfg80211_registered_device,
@@ -770,11 +778,27 @@ void cfg80211_dfs_channels_update_work(struct work_struct *work)
 		for (i = 0; i < sband->n_channels; i++) {
 			c = &sband->channels[i];
 
-			if (c->dfs_state != NL80211_DFS_UNAVAILABLE)
+			if (!(c->flags & IEEE80211_CHAN_RADAR))
+				continue;
+
+			if (c->dfs_state != NL80211_DFS_UNAVAILABLE &&
+			    c->dfs_state != NL80211_DFS_AVAILABLE)
 				continue;
 
-			timeout = c->dfs_state_entered + msecs_to_jiffies(
-					IEEE80211_DFS_MIN_NOP_TIME_MS);
+			if (c->dfs_state == NL80211_DFS_UNAVAILABLE) {
+				time_dfs_update = IEEE80211_DFS_MIN_NOP_TIME_MS;
+				radar_event = NL80211_RADAR_NOP_FINISHED;
+			} else {
+				if (regulatory_pre_cac_allowed(wiphy) ||
+				    cfg80211_any_wiphy_oper_chan(wiphy, c))
+					continue;
+
+				time_dfs_update = REG_PRE_CAC_EXPIRY_GRACE_MS;
+				radar_event = NL80211_RADAR_PRE_CAC_EXPIRED;
+			}
+
+			timeout = c->dfs_state_entered +
+				  msecs_to_jiffies(time_dfs_update);
 
 			if (time_after_eq(jiffies, timeout)) {
 				c->dfs_state = NL80211_DFS_USABLE;
@@ -784,8 +808,8 @@ void cfg80211_dfs_channels_update_work(struct work_struct *work)
 							NL80211_CHAN_NO_HT);
 
 				nl80211_radar_notify(rdev, &chandef,
-						     NL80211_RADAR_NOP_FINISHED,
-						     NULL, GFP_ATOMIC);
+						     radar_event, NULL,
+						     GFP_ATOMIC);
 				continue;
 			}
 
@@ -810,7 +834,6 @@ void cfg80211_radar_event(struct wiphy *wiphy,
 			  gfp_t gfp)
 {
 	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wiphy);
-	unsigned long timeout;
 
 	trace_cfg80211_radar_event(wiphy, chandef);
 
@@ -820,9 +843,7 @@ void cfg80211_radar_event(struct wiphy *wiphy,
 	 */
 	cfg80211_set_dfs_state(wiphy, chandef, NL80211_DFS_UNAVAILABLE);
 
-	timeout = msecs_to_jiffies(IEEE80211_DFS_MIN_NOP_TIME_MS);
-	queue_delayed_work(cfg80211_wq, &rdev->dfs_update_channels_wk,
-			   timeout);
+	cfg80211_sched_dfs_chan_update(rdev);
 
 	nl80211_radar_notify(rdev, chandef, NL80211_RADAR_DETECTED, NULL, gfp);
 }
@@ -851,6 +872,7 @@ void cfg80211_cac_event(struct net_device *netdev,
 			  msecs_to_jiffies(wdev->cac_time_ms);
 		WARN_ON(!time_after_eq(jiffies, timeout));
 		cfg80211_set_dfs_state(wiphy, chandef, NL80211_DFS_AVAILABLE);
+		cfg80211_sched_dfs_chan_update(rdev);
 		break;
 	case NL80211_RADAR_CAC_ABORTED:
 		break;