mac80211: let flush() drop packets when possible

When roaming / suspending, it makes no sense to wait until
the transmit queues of the device are empty. In extreme
condition they can be starved (VO saturating the air), but
even in regular cases, it is pointless to delay the roaming
because the low level driver is trying to send packets to
an AP which is far away. We'd rather drop these packets and
let TCP retransmit if needed. This will allow to speed up
the roaming.

For suspend, the explanation is even more trivial.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/cfg.c

@@ -3665,7 +3665,7 @@ static int ieee80211_del_tx_ts(struct wiphy *wiphy, struct net_device *dev,
 		 * queues.
 		 */
 		synchronize_net();
-		ieee80211_flush_queues(local, sdata);
+		ieee80211_flush_queues(local, sdata, false);
 
 		/* restore the normal QoS parameters
 		 * (unconditionally to avoid races)

net/mac80211/ieee80211_i.h

@@ -1882,10 +1882,10 @@ void ieee80211_add_pending_skb(struct ieee80211_local *local,
 void ieee80211_add_pending_skbs(struct ieee80211_local *local,
 				struct sk_buff_head *skbs);
 void ieee80211_flush_queues(struct ieee80211_local *local,
-			    struct ieee80211_sub_if_data *sdata);
+			    struct ieee80211_sub_if_data *sdata, bool drop);
 void __ieee80211_flush_queues(struct ieee80211_local *local,
 			      struct ieee80211_sub_if_data *sdata,
-			      unsigned int queues);
+			      unsigned int queues, bool drop);
 
 void ieee80211_send_auth(struct ieee80211_sub_if_data *sdata,
 			 u16 transaction, u16 auth_alg, u16 status,

net/mac80211/iface.c

@@ -93,7 +93,7 @@ static u32 __ieee80211_idle_on(struct ieee80211_local *local)
 	if (local->hw.conf.flags & IEEE80211_CONF_IDLE)
 		return 0;
 
-	ieee80211_flush_queues(local, NULL);
+	ieee80211_flush_queues(local, NULL, false);
 
 	local->hw.conf.flags |= IEEE80211_CONF_IDLE;
 	return IEEE80211_CONF_CHANGE_IDLE;

net/mac80211/mlme.c

@@ -1604,7 +1604,7 @@ void ieee80211_dynamic_ps_enable_work(struct work_struct *work)
 		} else {
 			ieee80211_send_nullfunc(local, sdata, 1);
 			/* Flush to get the tx status of nullfunc frame */
-			ieee80211_flush_queues(local, sdata);
+			ieee80211_flush_queues(local, sdata, false);
 		}
 	}
 
@@ -2011,18 +2011,23 @@ static void ieee80211_set_disassoc(struct ieee80211_sub_if_data *sdata,
 	/* disable per-vif ps */
 	ieee80211_recalc_ps_vif(sdata);
 
-	/* flush out any pending frame (e.g. DELBA) before deauth/disassoc */
+	/*
+	 * drop any frame before deauth/disassoc, this can be data or
+	 * management frame. Since we are disconnecting, we should not
+	 * insist sending these frames which can take time and delay
+	 * the disconnection and possible the roaming.
+	 */
 	if (tx)
-		ieee80211_flush_queues(local, sdata);
+		ieee80211_flush_queues(local, sdata, true);
 
 	/* deauthenticate/disassociate now */
 	if (tx || frame_buf)
 		ieee80211_send_deauth_disassoc(sdata, ifmgd->bssid, stype,
 					       reason, tx, frame_buf);
 
-	/* flush out frame */
+	/* flush out frame - make sure the deauth was actually sent */
 	if (tx)
-		ieee80211_flush_queues(local, sdata);
+		ieee80211_flush_queues(local, sdata, false);
 
 	/* clear bssid only after building the needed mgmt frames */
 	memset(ifmgd->bssid, 0, ETH_ALEN);

net/mac80211/offchannel.c

@@ -121,7 +121,7 @@ void ieee80211_offchannel_stop_vifs(struct ieee80211_local *local)
 	ieee80211_stop_queues_by_reason(&local->hw, IEEE80211_MAX_QUEUE_MAP,
 					IEEE80211_QUEUE_STOP_REASON_OFFCHANNEL,
 					false);
-	ieee80211_flush_queues(local, NULL);
+	ieee80211_flush_queues(local, NULL, false);
 
 	mutex_lock(&local->iflist_mtx);
 	list_for_each_entry(sdata, &local->interfaces, list) {
@@ -398,7 +398,7 @@ void ieee80211_sw_roc_work(struct work_struct *work)
 		ieee80211_roc_notify_destroy(roc, !roc->abort);
 
 		if (started && !on_channel) {
-			ieee80211_flush_queues(local, NULL);
+			ieee80211_flush_queues(local, NULL, false);
 
 			local->tmp_channel = NULL;
 			ieee80211_hw_config(local, 0);

net/mac80211/pm.c

@@ -41,7 +41,7 @@ int __ieee80211_suspend(struct ieee80211_hw *hw, struct cfg80211_wowlan *wowlan)
 	/* flush out all packets */
 	synchronize_net();
 
-	ieee80211_flush_queues(local, NULL);
+	ieee80211_flush_queues(local, NULL, true);
 
 	local->quiescing = true;
 	/* make quiescing visible to timers everywhere */

net/mac80211/scan.c

@@ -416,7 +416,7 @@ static int ieee80211_start_sw_scan(struct ieee80211_local *local,
 	ieee80211_offchannel_stop_vifs(local);
 
 	/* ensure nullfunc is transmitted before leaving operating channel */
-	ieee80211_flush_queues(local, NULL);
+	ieee80211_flush_queues(local, NULL, false);
 
 	ieee80211_configure_filter(local);
 
@@ -805,7 +805,7 @@ static void ieee80211_scan_state_resume(struct ieee80211_local *local,
 	ieee80211_offchannel_stop_vifs(local);
 
 	if (local->ops->flush) {
-		ieee80211_flush_queues(local, NULL);
+		ieee80211_flush_queues(local, NULL, false);
 		*next_delay = 0;
 	} else
 		*next_delay = HZ / 10;

net/mac80211/tdls.c

@@ -912,7 +912,7 @@ ieee80211_tdls_mgmt_setup(struct wiphy *wiphy, struct net_device *dev,
 		rcu_read_unlock();
 	}
 
-	ieee80211_flush_queues(local, sdata);
+	ieee80211_flush_queues(local, sdata, false);
 
 	ret = ieee80211_tdls_prep_mgmt_packet(wiphy, dev, peer, action_code,
 					      dialog_token, status_code,
@@ -952,7 +952,7 @@ ieee80211_tdls_mgmt_teardown(struct wiphy *wiphy, struct net_device *dev,
 	 */
 	ieee80211_stop_vif_queues(local, sdata,
 				  IEEE80211_QUEUE_STOP_REASON_TDLS_TEARDOWN);
-	ieee80211_flush_queues(local, sdata);
+	ieee80211_flush_queues(local, sdata, false);
 
 	ret = ieee80211_tdls_prep_mgmt_packet(wiphy, dev, peer, action_code,
 					      dialog_token, status_code,
@@ -1098,7 +1098,7 @@ int ieee80211_tdls_oper(struct wiphy *wiphy, struct net_device *dev,
 		 */
 		tasklet_kill(&local->tx_pending_tasklet);
 		/* flush a potentially queued teardown packet */
-		ieee80211_flush_queues(local, sdata);
+		ieee80211_flush_queues(local, sdata, false);
 
 		ret = sta_info_destroy_addr(sdata, peer);
 		break;

net/mac80211/tx.c

@@ -3155,7 +3155,7 @@ int ieee80211_reserve_tid(struct ieee80211_sta *pubsta, u8 tid)
 	}
 
 	queues = BIT(sdata->vif.hw_queue[ieee802_1d_to_ac[tid]]);
-	__ieee80211_flush_queues(local, sdata, queues);
+	__ieee80211_flush_queues(local, sdata, queues, false);
 
 	sta->reserved_tid = tid;
 

net/mac80211/util.c

@@ -578,7 +578,7 @@ ieee80211_get_vif_queues(struct ieee80211_local *local,
 
 void __ieee80211_flush_queues(struct ieee80211_local *local,
 			      struct ieee80211_sub_if_data *sdata,
-			      unsigned int queues)
+			      unsigned int queues, bool drop)
 {
 	if (!local->ops->flush)
 		return;
@@ -594,7 +594,7 @@ void __ieee80211_flush_queues(struct ieee80211_local *local,
 					IEEE80211_QUEUE_STOP_REASON_FLUSH,
 					false);
 
-	drv_flush(local, sdata, queues, false);
+	drv_flush(local, sdata, queues, drop);
 
 	ieee80211_wake_queues_by_reason(&local->hw, queues,
 					IEEE80211_QUEUE_STOP_REASON_FLUSH,
@@ -602,9 +602,9 @@ void __ieee80211_flush_queues(struct ieee80211_local *local,
 }
 
 void ieee80211_flush_queues(struct ieee80211_local *local,
-			    struct ieee80211_sub_if_data *sdata)
+			    struct ieee80211_sub_if_data *sdata, bool drop)
 {
-	__ieee80211_flush_queues(local, sdata, 0);
+	__ieee80211_flush_queues(local, sdata, 0, drop);
 }
 
 void ieee80211_stop_vif_queues(struct ieee80211_local *local,