Patch "mac80211: fix unnecessary frame drops in mesh fwding" has been added to the 3.14-stable tree

This is a note to let you know that I've just added the patch titled

mac80211: fix unnecessary frame drops in mesh fwding

to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
mac80211-fix-unnecessary-frame-drops-in-mesh-fwding.patch
and it can be found in the queue-3.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Michal Kazior <[email protected]>
Date: Mon, 25 Jan 2016 14:43:24 +0100
Subject: mac80211: fix unnecessary frame drops in mesh fwding

From: Michal Kazior <[email protected]>

commit cf44012810ccdd8fd947518e965cb04b7b8498be upstream.

The ieee80211_queue_stopped() expects hw queue number but it was given raw WMM AC number instead.

This could cause frame drops and problems with
traffic in some cases - most notably if driver
doesn't map AC numbers to queue numbers 1:1 and
uses ieee80211_stop_queues() and
ieee80211_wake_queue() only without ever calling
ieee80211_wake_queues().

On ath10k it was possible to hit this problem in
the following case:

1. wlan0 uses queue 0
(ath10k maps queues per vif)
2. offchannel uses queue 15
3. queues 1-14 are unused
4. ieee80211_stop_queues()
5. ieee80211_wake_queue(q=0)
6. ieee80211_wake_queue(q=15)
(other queues are not woken up because both
driver and mac80211 know other queues are
unused)
7. ieee80211_rx_h_mesh_fwding()
8. ieee80211_select_queue_80211() returns 2
9. ieee80211_queue_stopped(q=2) returns true
10. frame is dropped (oops!)

---
 net/mac80211/rx.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

@@ -2087,7 +2087,7 @@ ieee80211_rx_h_mesh_fwding(struct ieee80
 	struct ieee80211_sub_if_data *sdata = rx->sdata;
 	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
 	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
-	u16 q, hdrlen;
+	u16 ac, q, hdrlen;
 
 	hdr = (struct ieee80211_hdr *) skb->data;
 	hdrlen = ieee80211_hdrlen(hdr->frame_control);

@@ -2157,7 +2157,8 @@ ieee80211_rx_h_mesh_fwding(struct ieee80
 	    ether_addr_equal(sdata->vif.addr, hdr->addr3))
 		return RX_CONTINUE;
 
-	q = ieee80211_select_queue_80211(sdata, skb, hdr);
+	ac = ieee80211_select_queue_80211(sdata, skb, hdr);
+	q = sdata->vif.hw_queue[ac];
 	if (ieee80211_queue_stopped(&local->hw, q)) {
 		IEEE80211_IFSTA_MESH_CTR_INC(ifmsh, dropped_frames_congestion);
 		return RX_DROP_MONITOR;

Patches currently in stable-queue which might be from [email protected] are

queue-3.14/mac80211-fix-unnecessary-frame-drops-in-mesh-fwding.patch