package/kernel/mac80211/patches/313-mac80211-fix-unnecessary-frame-drops-in-mesh-fwding.patch

   1 From: Michal Kazior <michal.kazior@tieto.com>
   2 Date: Mon, 25 Jan 2016 14:43:24 +0100
   3 Subject: [PATCH] mac80211: fix unnecessary frame drops in mesh fwding
   4
   5 The ieee80211_queue_stopped() expects hw queue
   6 number but it was given raw WMM AC number instead.
   7
   8 This could cause frame drops and problems with
   9 traffic in some cases - most notably if driver
  10 doesn't map AC numbers to queue numbers 1:1 and
  11 uses ieee80211_stop_queues() and
  12 ieee80211_wake_queue() only without ever calling
  13 ieee80211_wake_queues().
  14
  15 On ath10k it was possible to hit this problem in
  16 the following case:
  17
  18   1. wlan0 uses queue 0
  19      (ath10k maps queues per vif)
  20   2. offchannel uses queue 15
  21   3. queues 1-14 are unused
  22   4. ieee80211_stop_queues()
  23   5. ieee80211_wake_queue(q=0)
  24   6. ieee80211_wake_queue(q=15)
  25      (other queues are not woken up because both
  26       driver and mac80211 know other queues are
  27       unused)
  28   7. ieee80211_rx_h_mesh_fwding()
  29   8. ieee80211_select_queue_80211() returns 2
  30   9. ieee80211_queue_stopped(q=2) returns true
  31  10. frame is dropped (oops!)
  32
  33 Fixes: d3c1597b8d1b ("mac80211: fix forwarded mesh frame queue mapping")
  34 Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
  35 ---
  36
  37 --- a/net/mac80211/rx.c
  38 +++ b/net/mac80211/rx.c
  39 @@ -2235,7 +2235,7 @@ ieee80211_rx_h_mesh_fwding(struct ieee80
  40         struct ieee80211_local *local = rx->local;
  41         struct ieee80211_sub_if_data *sdata = rx->sdata;
  42         struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
  43 -       u16 q, hdrlen;
  44 +       u16 ac, q, hdrlen;
  45
  46         hdr = (struct ieee80211_hdr *) skb->data;
  47         hdrlen = ieee80211_hdrlen(hdr->frame_control);
  48 @@ -2304,7 +2304,8 @@ ieee80211_rx_h_mesh_fwding(struct ieee80
  49             ether_addr_equal(sdata->vif.addr, hdr->addr3))
  50                 return RX_CONTINUE;
  51
  52 -       q = ieee80211_select_queue_80211(sdata, skb, hdr);
  53 +       ac = ieee80211_select_queue_80211(sdata, skb, hdr);
  54 +       q = sdata->vif.hw_queue[ac];
  55         if (ieee80211_queue_stopped(&local->hw, q)) {
  56                 IEEE80211_IFSTA_MESH_CTR_INC(ifmsh, dropped_frames_congestion);
  57                 return RX_DROP_MONITOR;