mac80211: Fix tx queue handling during scans

Scans currently work by stopping the netdev tx queues but leaving the
mac80211 queues active. This stops the flow of incoming packets while
still allowing mac80211 to transmit nullfunc and probe request frames to
facilitate scanning. However, the driver may try to wake the mac80211
queues while in this state, which will also wake the netdev queues.

To prevent this, add a new queue stop reason,
IEEE80211_QUEUE_STOP_REASON_OFFCHANNEL, to be used when stopping the tx
queues for off-channel operation. This prevents the netdev queues from
waking when a driver wakes the mac80211 queues.

This also stops all frames from being transmitted, even those meant to
be sent off-channel. Add a new tx control flag,
IEEE80211_TX_CTL_OFFCHAN_TX_OK, which allows frames to be transmitted
when the queues are stopped only for the off-channel stop reason. Update
all locations transmitting off-channel frames to use this flag.

Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 10 insertions, 20 deletions

diff --git a/net/mac80211/offchannel.c b/net/mac80211/offchannel.c
index 82baf5b..4c3ee3e 100644
--- a/net/mac80211/offchannel.c
+++ b/net/mac80211/offchannel.c
@@ -113,6 +113,10 @@ void ieee80211_offchannel_stop_vifs(struct ieee80211_local *local)
 	 * notify the AP about us leaving the channel and stop all
 	 * STA interfaces.
 	 */
+
+	ieee80211_stop_queues_by_reason(&local->hw,
+					IEEE80211_QUEUE_STOP_REASON_OFFCHANNEL);
+
 	mutex_lock(&local->iflist_mtx);
 	list_for_each_entry(sdata, &local->interfaces, list) {
 		if (!ieee80211_sdata_running(sdata))
@@ -133,12 +137,9 @@ void ieee80211_offchannel_stop_vifs(struct ieee80211_local *local)
 				sdata, BSS_CHANGED_BEACON_ENABLED);
 		}
 
-		if (sdata->vif.type != NL80211_IFTYPE_MONITOR) {
-			netif_tx_stop_all_queues(sdata->dev);
-			if (sdata->vif.type == NL80211_IFTYPE_STATION &&
-			    sdata->u.mgd.associated)
-				ieee80211_offchannel_ps_enable(sdata);
-		}
+		if (sdata->vif.type == NL80211_IFTYPE_STATION &&
+		    sdata->u.mgd.associated)
+			ieee80211_offchannel_ps_enable(sdata);
 	}
 	mutex_unlock(&local->iflist_mtx);
 }
@@ -166,20 +167,6 @@ void ieee80211_offchannel_return(struct ieee80211_local *local)
 		    sdata->u.mgd.associated)
 			ieee80211_offchannel_ps_disable(sdata);
 
-		if (sdata->vif.type != NL80211_IFTYPE_MONITOR) {
-			/*
-			 * This may wake up queues even though the driver
-			 * currently has them stopped. This is not very
-			 * likely, since the driver won't have gotten any
-			 * (or hardly any) new packets while we weren't
-			 * on the right channel, and even if it happens
-			 * it will at most lead to queueing up one more
-			 * packet per queue in mac80211 rather than on
-			 * the interface qdisc.
-			 */
-			netif_tx_wake_all_queues(sdata->dev);
-		}
-
 		if (test_and_clear_bit(SDATA_STATE_OFFCHANNEL_BEACON_STOPPED,
 				       &sdata->state)) {
 			sdata->vif.bss_conf.enable_beacon = true;
@@ -188,6 +175,9 @@ void ieee80211_offchannel_return(struct ieee80211_local *local)
 		}
 	}
 	mutex_unlock(&local->iflist_mtx);
+
+	ieee80211_wake_queues_by_reason(&local->hw,
+					IEEE80211_QUEUE_STOP_REASON_OFFCHANNEL);
 }
 
 void ieee80211_handle_roc_started(struct ieee80211_roc_work *roc)