[PATCH 18/23] wifi: mt76: mt7925: defer the NAN joined-cluster event out of NAN_START

[Sean Wang <sean.wang@kernel.org>]

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

The firmware can join an existing cluster from inside the passive scan it
runs at the start of NAN_START, so NAN_EVENT_ID_JOINED_CLUSTER lands while
the start path is still executing and ieee80211_vif_nan_started() is not
true yet. The handler dropped the event with a warning, leaving userspace
unaware of the cluster it had joined, and service discovery then never
completed: measured 4 failures in 12 NDP bring-ups on an MT7925 pair, each
one accompanied by exactly one dropped event on the joining side and none
on the side that created the cluster.

NAN_EVENT_ID_STARTED_CLUSTER already defers past NAN_START through
nan_deferred_work for the same reason; JOINED_CLUSTER is the other exit of
the same firmware warm-up branch and needs the same treatment. Queue it on
that work with its own cluster id, so a started and a joined event pending
at once cannot overwrite each other.

Fixes: a5487a682406 ("wifi: mt76: mt7925: add NAN MCU helpers")
Co-developed-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Jacobs Wu <jacobs.wu@mediatek.com>
---
 .../net/wireless/mediatek/mt76/mt7925/nan.c   | 20 ++++++++++++++++++-
 .../net/wireless/mediatek/mt76/mt7925/nan.h   |  1 +
 drivers/net/wireless/mediatek/mt76/mt792x.h   |  1 +
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7925/nan.c b/drivers/net/wireless/mediatek/mt76/mt7925/nan.c
index 715e080ce4ee..7aacfd6527e4 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7925/nan.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7925/nan.c
@@ -709,8 +709,20 @@ mt7925_nan_mcu_handle_de_event(struct mt792x_dev *dev, struct tlv *tlv)
 		return;
 	}
 
+	/* JOINED_CLUSTER has the same race as STARTED_CLUSTER above: the
+	 * firmware joins an existing cluster from inside its start-up passive
+	 * scan, so the event can land while NAN_START is still running and
+	 * nan.started is not set yet. Defer it the same way instead of
+	 * dropping it - a lost join leaves userspace unaware of the cluster it
+	 * is in and service discovery never completes.
+	 */
 	if (!dev->nan_vif || !ieee80211_vif_nan_started(dev->nan_vif)) {
-		dev_warn(dev->mt76.dev, "nan: joined-cluster event but NAN not started\n");
+		spin_lock_bh(&dev->nan_deferred_lock);
+		memcpy(dev->nan_joined_cluster_id, cluster_id, ETH_ALEN);
+		set_bit(MT7925_NAN_DEFERRED_JOINED_CLUSTER,
+			&dev->nan_deferred_pending);
+		spin_unlock_bh(&dev->nan_deferred_lock);
+		ieee80211_queue_work(dev->mt76.hw, &dev->nan_deferred_work);
 		return;
 	}
 
@@ -732,6 +744,7 @@ mt7925_nan_deferred_work(struct work_struct *work)
 {
 	struct mt792x_dev *dev = container_of(work, struct mt792x_dev,
 					      nan_deferred_work);
+	u8 joined_cluster_id[ETH_ALEN];
 	struct ieee80211_vif *vif;
 	unsigned long pending;
 	u8 cluster_id[ETH_ALEN];
@@ -740,6 +753,7 @@ mt7925_nan_deferred_work(struct work_struct *work)
 	pending = dev->nan_deferred_pending;
 	dev->nan_deferred_pending = 0;
 	memcpy(cluster_id, dev->nan_started_cluster_id, ETH_ALEN);
+	memcpy(joined_cluster_id, dev->nan_joined_cluster_id, ETH_ALEN);
 	spin_unlock_bh(&dev->nan_deferred_lock);
 
 	if (!pending)
@@ -753,6 +767,10 @@ mt7925_nan_deferred_work(struct work_struct *work)
 	if (test_bit(MT7925_NAN_DEFERRED_STARTED_CLUSTER, &pending))
 		ieee80211_nan_cluster_joined(vif, cluster_id, true, GFP_KERNEL);
 
+	if (test_bit(MT7925_NAN_DEFERRED_JOINED_CLUSTER, &pending))
+		ieee80211_nan_cluster_joined(vif, joined_cluster_id, false,
+					     GFP_KERNEL);
+
 	if (test_bit(MT7925_NAN_DEFERRED_SCHED_UPDATE_DONE, &pending))
 		ieee80211_nan_sched_update_done(vif);
 out:
diff --git a/drivers/net/wireless/mediatek/mt76/mt7925/nan.h b/drivers/net/wireless/mediatek/mt76/mt7925/nan.h
index 415fd6b6f0e6..32740e3769d6 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7925/nan.h
+++ b/drivers/net/wireless/mediatek/mt76/mt7925/nan.h
@@ -143,6 +143,7 @@ enum mt7925_nan_key_type {
  */
 enum mt7925_nan_deferred_event {
 	MT7925_NAN_DEFERRED_STARTED_CLUSTER,
+	MT7925_NAN_DEFERRED_JOINED_CLUSTER,
 	MT7925_NAN_DEFERRED_SCHED_UPDATE_DONE,
 };
 /* NAN 4.0 Table 79. Device Capability attribute format, Supported Bands */
diff --git a/drivers/net/wireless/mediatek/mt76/mt792x.h b/drivers/net/wireless/mediatek/mt76/mt792x.h
index ee462eab4028..8e1588970ac1 100644
--- a/drivers/net/wireless/mediatek/mt76/mt792x.h
+++ b/drivers/net/wireless/mediatek/mt76/mt792x.h
@@ -446,6 +446,7 @@ struct mt792x_dev {
 	spinlock_t nan_deferred_lock;
 	unsigned long nan_deferred_pending;
 	u8 nan_started_cluster_id[ETH_ALEN];
+	u8 nan_joined_cluster_id[ETH_ALEN];
 };
 
 static inline struct mt792x_bss_conf *
-- 
2.43.0