mac80211: fix reordering of buffered broadcast packets

BugLink: https://bugs.launchpad.net/bugs/1837161
commit 9ec1190d065998650fd9260dea8cf3e1f56c0e8c upstream.

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>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 784918678a006979fb3973734ad103b0811bb4c0..640086b230bd7163e89bbae9cae68d2d842022d4 100644 (file)
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -435,8 +435,8 @@ ieee80211_tx_h_multicast_ps_buf(struct ieee80211_tx_data *tx)
        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;