mac80211: fix reordering of buffered broadcast packets

Signed-off-by: Felix Fietkau <nbd@nbd.name>

package/kernel/mac80211/patches/subsys/380-mac80211-fix-reordering-of-buffered-broadcast-packet.patch

@@ -0,0 +1,28 @@
+From: Felix Fietkau <nbd@nbd.name>
+Date: Wed, 28 Nov 2018 22:36:06 +0100
+Subject: [PATCH] mac80211: fix reordering of buffered broadcast packets
+
+If the buffered broadcast queue contains packets, letting new packets bypass
+that queue can lead to heavy reordering, since the driver is probably throttling
+transmission of buffered multicast packets after beacons.
+
+Keep buffering packets until the buffer has been cleared (and no client
+is in powersave mode).
+
+Cc: stable@vger.kernel.org
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+---
+
+--- a/net/mac80211/tx.c
++++ b/net/mac80211/tx.c
+@@ -435,8 +435,8 @@ ieee80211_tx_h_multicast_ps_buf(struct i
+ 	if (ieee80211_hw_check(&tx->local->hw, QUEUE_CONTROL))
+ 		info->hw_queue = tx->sdata->vif.cab_queue;
+ 
+-	/* no stations in PS mode */
+-	if (!atomic_read(&ps->num_sta_ps))
++	/* no stations in PS mode and no buffered packets */
++	if (!atomic_read(&ps->num_sta_ps) && skb_queue_empty(&ps->bc_buf))
+ 		return TX_CONTINUE;
+ 
+ 	info->flags |= IEEE80211_TX_CTL_SEND_AFTER_DTIM;