mac80211: mask nested A-MSDU support for mesh

mac80211 incorrectly processes A-MSDUs contained in A-MPDU frames. This
results in dropped packets and severely impacted throughput.

As a workaround, don't indicate support for A-MSDUs contained in
A-MPDUs. This improves throughput over mesh links by factor 10.

Ref: https://github.com/openwrt/mt76/issues/450

Signed-off-by: David Bauer <mail@david-bauer.net>

diff --git a/package/kernel/mac80211/patches/subsys/800-mac80211-mask-nested-A-MSDU-support-for-mesh.patch b/package/kernel/mac80211/patches/subsys/800-mac80211-mask-nested-A-MSDU-support-for-mesh.patch
new file mode 100644 (file)
index 0000000..415c6df
--- /dev/null
+++ b/package/kernel/mac80211/patches/subsys/800-mac80211-mask-nested-A-MSDU-support-for-mesh.patch
@@ -0,0 +1,31 @@
+From 313d8c18385f10957402b475f9b0c209ceab6c5a Mon Sep 17 00:00:00 2001
+From: David Bauer <mail@david-bauer.net>
+Date: Fri, 8 Oct 2021 00:25:19 +0200
+Subject: [PATCH] mac80211: mask nested A-MSDU support for mesh
+
+mac80211 incorrectly processes A-MSDUs contained in A-MPDU frames. This
+results in dropped packets and severely impacted throughput.
+
+As a workaround, don't indicate support for A-MSDUs contained in
+A-MPDUs. This improves throughput over mesh links by factor 10.
+
+Ref: https://github.com/openwrt/mt76/issues/450
+
+Signed-off-by: David Bauer <mail@david-bauer.net>
+---
+ net/mac80211/agg-rx.c | 4 +++-
+ 1 file changed, 3 insertions(+), 1 deletion(-)
+
+--- a/net/mac80211/agg-rx.c
++++ b/net/mac80211/agg-rx.c
+@@ -251,7 +251,9 @@ static void ieee80211_send_addba_resp(st
+       mgmt->u.action.u.addba_resp.action_code = WLAN_ACTION_ADDBA_RESP;
+       mgmt->u.action.u.addba_resp.dialog_token = dialog_token;
+ 
+-      capab = u16_encode_bits(amsdu, IEEE80211_ADDBA_PARAM_AMSDU_MASK);
++      capab = 0;
++      if (!sta->mesh)
++              capab = u16_encode_bits(amsdu, IEEE80211_ADDBA_PARAM_AMSDU_MASK);
+       capab |= u16_encode_bits(policy, IEEE80211_ADDBA_PARAM_POLICY_MASK);
+       capab |= u16_encode_bits(tid, IEEE80211_ADDBA_PARAM_TID_MASK);
+       capab |= u16_encode_bits(buf_size, IEEE80211_ADDBA_PARAM_BUF_SIZE_MASK);