[PATCH 4.9 48/51] mac80211: fix reordering of buffered broadcast packets

Greg Kroah-Hartman
2018-12-11T15:50:39Z

From: Felix Fietkau <nbd@nbd.name>

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>

---
net/mac80211/tx.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -434,8 +434,8 @@ 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;