mac80211: implement STA CSA for drivers using channel contexts

Limit the current implementation to a single channel context used by
a single vif, thereby avoiding multi-vif/channel complexities.

Reuse the main function from AP CSA code, but move a portion out in
order to fit the STA scenario.

Add a new mac80211 HW flag so we don't break devices that don't support
channel switch with channel-contexts. The new behavior will be opt-in.
Signed-off-by: Arik Nemtsov <arik@wizery.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/mac80211.h

@@ -1502,6 +1502,11 @@ struct ieee80211_tx_control {
  *
  * @IEEE80211_HW_TIMING_BEACON_ONLY: Use sync timing from beacon frames
  *	only, to allow getting TBTT of a DTIM beacon.
+ *
+ * @IEEE80211_HW_CHANCTX_STA_CSA: Support 802.11h based channel-switch (CSA)
+ *	for a single active channel while using channel contexts. When support
+ *	is not enabled the default action is to disconnect when getting the
+ *	CSA frame.
  */
 enum ieee80211_hw_flags {
 	IEEE80211_HW_HAS_RATE_CONTROL			= 1<<0,
@@ -1532,6 +1537,7 @@ enum ieee80211_hw_flags {
 	IEEE80211_HW_P2P_DEV_ADDR_FOR_INTF		= 1<<25,
 	IEEE80211_HW_TIMING_BEACON_ONLY			= 1<<26,
 	IEEE80211_HW_SUPPORTS_HT_CCK_RATES		= 1<<27,
+	IEEE80211_HW_CHANCTX_STA_CSA			= 1<<28,
 };
 
 /**

net/mac80211/cfg.c

@@ -2871,6 +2871,11 @@ void ieee80211_csa_finalize_work(struct work_struct *work)
 	if (WARN_ON(err < 0))
 		return;
 
+	if (!local->use_chanctx) {
+		local->_oper_chandef = local->csa_chandef;
+		ieee80211_hw_config(local, 0);
+	}
+
 	ieee80211_bss_info_change_notify(sdata, changed);
 
 	switch (sdata->vif.type) {

net/mac80211/chan.c

@@ -453,11 +453,6 @@ int ieee80211_vif_change_channel(struct ieee80211_sub_if_data *sdata,
 	chanctx_changed |= IEEE80211_CHANCTX_CHANGE_CHANNEL;
 	drv_change_chanctx(local, ctx, chanctx_changed);
 
-	if (!local->use_chanctx) {
-		local->_oper_chandef = *chandef;
-		ieee80211_hw_config(local, 0);
-	}
-
 	ieee80211_recalc_chanctx_chantype(local, ctx);
 	ieee80211_recalc_smps_chanctx(local, ctx);
 	ieee80211_recalc_radar_chanctx(local, ctx);

net/mac80211/mlme.c

@@ -876,6 +876,8 @@ static void ieee80211_chswitch_work(struct work_struct *work)
 		container_of(work, struct ieee80211_sub_if_data, u.mgd.chswitch_work);
 	struct ieee80211_local *local = sdata->local;
 	struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
+	u32 changed = 0;
+	int ret;
 
 	if (!ieee80211_sdata_running(sdata))
 		return;
@@ -884,24 +886,39 @@ static void ieee80211_chswitch_work(struct work_struct *work)
 	if (!ifmgd->associated)
 		goto out;
 
-	local->_oper_chandef = local->csa_chandef;
+	ret = ieee80211_vif_change_channel(sdata, &local->csa_chandef,
+					   &changed);
+	if (ret) {
+		sdata_info(sdata,
+			   "vif channel switch failed, disconnecting\n");
+		ieee80211_queue_work(&sdata->local->hw,
+				     &ifmgd->csa_connection_drop_work);
+		goto out;
+	}
 
-	if (!local->ops->channel_switch) {
-		/* call "hw_config" only if doing sw channel switch */
-		ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
-	} else {
-		/* update the device channel directly */
+	if (!local->use_chanctx) {
+		local->_oper_chandef = local->csa_chandef;
+		/* Call "hw_config" only if doing sw channel switch.
+		 * Otherwise update the channel directly
+		 */
+		if (!local->ops->channel_switch)
+			ieee80211_hw_config(local, 0);
+		else
 			local->hw.conf.chandef = local->_oper_chandef;
 	}
 
 	/* XXX: shouldn't really modify cfg80211-owned data! */
-	ifmgd->associated->channel = local->_oper_chandef.chan;
+	ifmgd->associated->channel = local->csa_chandef.chan;
 
 	/* XXX: wait for a beacon first? */
 	ieee80211_wake_queues_by_reason(&local->hw,
 					IEEE80211_MAX_QUEUE_MAP,
 					IEEE80211_QUEUE_STOP_REASON_CSA);
+
+	ieee80211_bss_info_change_notify(sdata, changed);
+
  out:
+	sdata->vif.csa_active = false;
 	ifmgd->flags &= ~IEEE80211_STA_CSA_RECEIVED;
 	sdata_unlock(sdata);
 }
@@ -983,17 +1000,28 @@ ieee80211_sta_process_chanswitch(struct ieee80211_sub_if_data *sdata,
 	}
 
 	ifmgd->flags |= IEEE80211_STA_CSA_RECEIVED;
+	sdata->vif.csa_active = true;
 
+	mutex_lock(&local->chanctx_mtx);
 	if (local->use_chanctx) {
+		u32 num_chanctx = 0;
+		list_for_each_entry(chanctx, &local->chanctx_list, list)
+		       num_chanctx++;
+
+		if (num_chanctx > 1 ||
+		    !(local->hw.flags & IEEE80211_HW_CHANCTX_STA_CSA)) {
 			sdata_info(sdata,
-			   "not handling channel switch with channel contexts\n");
+				   "not handling chan-switch with channel contexts\n");
 			ieee80211_queue_work(&local->hw,
 					     &ifmgd->csa_connection_drop_work);
+			mutex_unlock(&local->chanctx_mtx);
 			return;
 		}
+	}
 
-	mutex_lock(&local->chanctx_mtx);
 	if (WARN_ON(!rcu_access_pointer(sdata->vif.chanctx_conf))) {
+		ieee80211_queue_work(&local->hw,
+				     &ifmgd->csa_connection_drop_work);
 		mutex_unlock(&local->chanctx_mtx);
 		return;
 	}
@@ -1955,6 +1983,7 @@ static void __ieee80211_disconnect(struct ieee80211_sub_if_data *sdata)
 			       WLAN_REASON_DISASSOC_DUE_TO_INACTIVITY,
 			       true, frame_buf);
 	ifmgd->flags &= ~IEEE80211_STA_CSA_RECEIVED;
+	sdata->vif.csa_active = false;
 	ieee80211_wake_queues_by_reason(&sdata->local->hw,
 					IEEE80211_MAX_QUEUE_MAP,
 					IEEE80211_QUEUE_STOP_REASON_CSA);