[openwrt/openwrt] mac80211: fix AQL issue with multicast traffic

[LEDE Commits]

nbd pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/9f1d6223289b5571ddc77c0e5327ab51137199d9

commit 9f1d6223289b5571ddc77c0e5327ab51137199d9
Author: Felix Fietkau <nbd at nbd.name>
AuthorDate: Wed Jul 13 07:52:04 2022 +0200

    mac80211: fix AQL issue with multicast traffic
    
    Exclude multicast from pending AQL budget
    
    Signed-off-by: Felix Fietkau <nbd at nbd.name>
---
 ...clude-multicast-packets-from-AQL-pending-.patch | 30 ++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/package/kernel/mac80211/patches/subsys/339-mac80211-exclude-multicast-packets-from-AQL-pending-.patch b/package/kernel/mac80211/patches/subsys/339-mac80211-exclude-multicast-packets-from-AQL-pending-.patch
new file mode 100644
index 0000000000..43c3e75d65
--- /dev/null
+++ b/package/kernel/mac80211/patches/subsys/339-mac80211-exclude-multicast-packets-from-AQL-pending-.patch
@@ -0,0 +1,30 @@
+From: Felix Fietkau <nbd at nbd.name>
+Date: Wed, 13 Jul 2022 07:32:26 +0200
+Subject: [PATCH] mac80211: exclude multicast packets from AQL pending airtime
+
+In AP mode, multicast traffic is handled very differently from normal traffic,
+especially if at least one client is in powersave mode.
+This means that multicast packets can be buffered a lot longer than normal
+unicast packets, and can eat up the AQL budget very quickly because of the low
+data rate.
+Along with the recent change to maintain a global PHY AQL limit, this can lead
+to significant latency spikes for unicast traffic.
+
+Since queueing multicast to hardware is currently not constrained by AQL limits
+anyway, let's just exclude it from the AQL pending airtime calculation entirely.
+
+Fixes: 8e4bac067105 ("wifi: mac80211: add a per-PHY AQL limit to improve fairness")
+Signed-off-by: Felix Fietkau <nbd at nbd.name>
+---
+
+--- a/net/mac80211/tx.c
++++ b/net/mac80211/tx.c
+@@ -3792,7 +3792,7 @@ begin:
+ encap_out:
+ 	IEEE80211_SKB_CB(skb)->control.vif = vif;
+ 
+-	if (vif &&
++	if (tx.sta &&
+ 	    wiphy_ext_feature_isset(local->hw.wiphy, NL80211_EXT_FEATURE_AQL)) {
+ 		bool ampdu = txq->ac != IEEE80211_AC_VO;
+ 		u32 airtime;