Patch "mac80211: use driver-indicated transmitter STA only for data frames" has been added to the 4.10-stable tree

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

mac80211: use driver-indicated transmitter STA only for data frames

to the 4.10-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-use-driver-indicated-transmitter-sta-only-for-data-frames.patch
and it can be found in the queue-4.10 subdirectory.

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

From: Johannes Berg <[email protected]>
Date: Mon, 27 Feb 2017 09:38:11 +0100
Subject: mac80211: use driver-indicated transmitter STA only for data frames
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From: Johannes Berg <[email protected]>

commit 19d19e960598161be92a7e4828eb7706c6410ce6 upstream.

When I originally introduced using the driver-indicated station as an optimisation to avoid the hashtable lookup/iteration, of course it wasn't intended to really functionally change anything.

I neglected, however, to take into account VLAN interfaces, which have the property that management and data frames are handled differently:
data frames go directly to the station and the VLAN while management frames continue to be processed over the underlying/associated AP-type interface. As a consequence, when a driver used this optimisation for management frames and the user enabled VLANs, my change broke things since any management frames, particularly disassoc/deauth, were missed by hostapd.

Fix this by restoring the original code path for non-data frames, they aren't critical for performance to begin with.

This fixes https://bugzilla.kernel.org/show_bug.cgi?id=194713.

Big thanks goes to Jarek who bisected the issue and provided a very detailed bug report, including the crucial information that he was using VLANs in his configuration.

---
 net/mac80211/rx.c |   16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

@@ -4089,15 +4089,17 @@ static void __ieee80211_rx_handle_packet
 		     ieee80211_is_beacon(hdr->frame_control)))
 		ieee80211_scan_rx(local, skb);
 
-	if (pubsta) {
-		rx.sta = container_of(pubsta, struct sta_info, sta);
-		rx.sdata = rx.sta->sdata;
-		if (ieee80211_prepare_and_rx_handle(&rx, skb, true))
-			return;
-		goto out;
-	} else if (ieee80211_is_data(fc)) {
+	if (ieee80211_is_data(fc)) {
 		struct sta_info *sta, *prev_sta;
 
+		if (pubsta) {
+			rx.sta = container_of(pubsta, struct sta_info, sta);
+			rx.sdata = rx.sta->sdata;
+			if (ieee80211_prepare_and_rx_handle(&rx, skb, true))
+				return;
+			goto out;
+		}
+
 		prev_sta = NULL;
 
 		for_each_sta_info(local, hdr->addr2, sta, tmp) {

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

queue-4.10/mac80211-don-t-reorder-frames-with-sn-smaller-than-ssn.patch queue-4.10/mac80211-use-driver-indicated-transmitter-sta-only-for-data-frames.patch queue-4.10/mac80211-flush-delayed-work-when-entering-suspend.patch queue-4.10/mac80211-don-t-handle-filtered-frames-within-a-ba-session.patch