mac80211: TDLS: correctly configure SMPS state

The IEEE802.11-2012 specification is vague regarding SMPS operation during
TDLS. It does not define a clear way to transition between SMPS states.

To avoid interop issues, set SMPS to off when TDLS peers are connected.
Accomplish this by extending the definition of the AUTOMATIC state. If the
driver forces a state other than OFF, disconnect all TDLS peers.

While at it, avoid changing the SMPS state of the peer STA. We have no
way to control it, so try and behave correctly towards it.

Move the TDLS peer-teardown function to where the rest of the TDLS code
resides.

Signed-off-by: Arik Nemtsov <[e-mail]>
Signed-off-by: Johannes Berg <[e-mail]>

net/mac80211/cfg.c

···
 	const u8 *ap;
 	enum ieee80211_smps_mode old_req;
 	int err;
+	struct sta_info *sta;
+	bool tdls_peer_found = false;
 
 	lockdep_assert_held(&sdata->wdev.mtx);
 
···
 
 	ap = sdata->u.mgd.associated->bssid;
 
+	rcu_read_lock();
+	list_for_each_entry_rcu(sta, &sdata->local->sta_list, list) {
+		if (!sta->sta.tdls || sta->sdata != sdata || !sta->uploaded ||
+		    !test_sta_flag(sta, WLAN_STA_AUTHORIZED))
+			continue;
+
+		tdls_peer_found = true;
+		break;
+	}
+	rcu_read_unlock();
+
 	if (smps_mode == IEEE80211_SMPS_AUTOMATIC) {
-		if (sdata->u.mgd.powersave)
-			smps_mode = IEEE80211_SMPS_DYNAMIC;
-		else
+		if (tdls_peer_found || !sdata->u.mgd.powersave)
 			smps_mode = IEEE80211_SMPS_OFF;
+		else
+			smps_mode = IEEE80211_SMPS_DYNAMIC;
 	}
 
 	/* send SM PS frame to AP */
···
 					 ap, ap);
 	if (err)
 		sdata->u.mgd.req_smps = old_req;
+	else if (smps_mode != IEEE80211_SMPS_OFF && tdls_peer_found)
+		ieee80211_teardown_tdls_peers(sdata);
 
 	return err;
 }

net/mac80211/ieee80211_i.h

···
 					  const u8 *addr);
 void ieee80211_process_tdls_channel_switch(struct ieee80211_sub_if_data *sdata,
 					   struct sk_buff *skb);
+void ieee80211_teardown_tdls_peers(struct ieee80211_sub_if_data *sdata);
 
 extern const struct ethtool_ops ieee80211_ethtool_ops;
 

net/mac80211/mlme.c

···
 	ieee80211_queue_work(&sdata->local->hw, &sdata->u.mgd.chswitch_work);
 }
 
-static void ieee80211_teardown_tdls_peers(struct ieee80211_sub_if_data *sdata)
-{
-	struct sta_info *sta;
-	u16 reason = WLAN_REASON_TDLS_TEARDOWN_UNSPECIFIED;
-
-	rcu_read_lock();
-	list_for_each_entry_rcu(sta, &sdata->local->sta_list, list) {
-		if (!sta->sta.tdls || sta->sdata != sdata || !sta->uploaded ||
-		    !test_sta_flag(sta, WLAN_STA_AUTHORIZED))
-			continue;
-
-		ieee80211_tdls_oper_request(&sdata->vif, sta->sta.addr,
-					    NL80211_TDLS_TEARDOWN, reason,
-					    GFP_ATOMIC);
-	}
-	rcu_read_unlock();
-}
-
 static void
 ieee80211_sta_process_chanswitch(struct ieee80211_sub_if_data *sdata,
 				 u64 timestamp, u32 device_timestamp,

net/mac80211/tdls.c

···
  * Copyright 2006-2010	Johannes Berg <[e-mail]>
  * Copyright 2014, Intel Corporation
  * Copyright 2014  Intel Mobile Communications GmbH
+ * Copyright 2015  Intel Deutschland GmbH
  *
  * This file is GPLv2 as found in COPYING.
  */
···
 		ieee80211_ie_build_ht_cap(pos, &ht_cap, ht_cap.cap);
 	} else if (action_code == WLAN_TDLS_SETUP_RESPONSE &&
 		   ht_cap.ht_supported && sta->sta.ht_cap.ht_supported) {
-		/* disable SMPS in TDLS responder */
-		sta->sta.ht_cap.cap |= WLAN_HT_CAP_SM_PS_DISABLED
-					<< IEEE80211_HT_CAP_SM_PS_SHIFT;
-
 		/* the peer caps are already intersected with our own */
 		memcpy(&ht_cap, &sta->sta.ht_cap, sizeof(ht_cap));
 
···
 {
 	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
 	struct ieee80211_local *local = sdata->local;
+	enum ieee80211_smps_mode smps_mode = sdata->u.mgd.driver_smps_mode;
 	int ret;
+
+	/* don't support setup with forced SMPS mode that's not off */
+	if (smps_mode != IEEE80211_SMPS_AUTOMATIC &&
+	    smps_mode != IEEE80211_SMPS_OFF) {
+		tdls_dbg(sdata, "Aborting TDLS setup due to SMPS mode %d\n",
+			 smps_mode);
+		return -ENOTSUPP;
+	}
 
 	mutex_lock(&local->mtx);
 
···
 		cancel_delayed_work(&sdata->u.mgd.tdls_peer_del_work);
 		eth_zero_addr(sdata->u.mgd.tdls_peer);
 	}
+
+	if (ret == 0)
+		ieee80211_queue_work(&sdata->local->hw,
+				     &sdata->u.mgd.request_smps_work);
 
 	mutex_unlock(&local->mtx);
 	return ret;
···
 		WARN_ON_ONCE(1);
 		return;
 	}
+}
+
+void ieee80211_teardown_tdls_peers(struct ieee80211_sub_if_data *sdata)
+{
+	struct sta_info *sta;
+	u16 reason = WLAN_REASON_TDLS_TEARDOWN_UNSPECIFIED;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(sta, &sdata->local->sta_list, list) {
+		if (!sta->sta.tdls || sta->sdata != sdata || !sta->uploaded ||
+		    !test_sta_flag(sta, WLAN_STA_AUTHORIZED))
+			continue;
+
+		ieee80211_tdls_oper_request(&sdata->vif, sta->sta.addr,
+					    NL80211_TDLS_TEARDOWN, reason,
+					    GFP_ATOMIC);
+	}
+	rcu_read_unlock();
 }