[PATCH 13/23] wifi: mt76: mt7925: do not deactivate shared NAN BSS on peer STA removal

[Sean Wang]

From: Jacobs Wu <jacobs.wu at mediatek.com>

mt7925_mac_sta_remove_links() sent BSS_INFO(active=0) for every vif type
except AP when a peer STA was removed. NAN (nan0) and NAN_DATA (ndi0)
BSSes host multiple peer STAs like an AP does: removing the NMI peer on
NDP teardown deactivated the shared NAN sync BSS in FW, after which FW
dropped every host-initiated NAN mgmt frame (TXM: An MMPDU for an
inactive BSS_INFO) until the next NAN_START. With partial availability
bitmaps this made every NDP re-establishment after a teardown fail
(unicast NAF TXCNT 15/15 no-ack); full bitmaps masked the bug. It also
tears down the shared data BSS while other NDPs on the same NDI live.

Exclude NAN and NAN_DATA vifs like AP.

Verified on 187/235: teardown no longer emits the BSS disable cmd, the
FW drop flood is gone, and half-bitmap re-establishment after
nan_ndp_terminate succeeds repeatedly (was 100% fail).

Co-developed-by: Sean Wang <sean.wang at mediatek.com>
Signed-off-by: Sean Wang <sean.wang at mediatek.com>
Signed-off-by: Jacobs Wu <jacobs.wu at mediatek.com>
---
 drivers/net/wireless/mediatek/mt76/mt7925/main.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7925/main.c b/drivers/net/wireless/mediatek/mt76/mt7925/main.c
index 64853fc7f60e..08a5bdcf1094 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7925/main.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7925/main.c
@@ -1489,7 +1489,16 @@ mt7925_mac_sta_remove_links(struct mt792x_dev *dev, struct ieee80211_vif *vif,
 		struct mt792x_bss_conf *mconf;
 		struct mt792x_link_sta *mlink;
 
-		if (vif->type == NL80211_IFTYPE_AP)
+		/* AP, NAN, and NAN_DATA BSSes host multiple peer STAs; removing
+		 * one peer must not deactivate the shared BSS. For NAN, doing
+		 * so would kill the sync BSS and the firmware would drop all
+		 * subsequent host-originated NAN management frames. For
+		 * NAN_DATA, it would tear down all other NDPs sharing the same
+		 * NDI.
+		 */
+		if (vif->type == NL80211_IFTYPE_AP ||
+		    vif->type == NL80211_IFTYPE_NAN ||
+		    vif->type == NL80211_IFTYPE_NAN_DATA)
 			break;
 
 		if (vif->type == NL80211_IFTYPE_STATION && sta->tdls)
-- 
2.43.0