wifi: mt76: mt7996: hold dev->mutex in remove_interface teardown

mt7996_remove_interface() destroys the remaining vif links, clearing
omac_mask, vif_mask and mld_idx_mask, with only the wiphy mutex held.
Those masks are modified under dev->mutex everywhere else, so the
unlocked clears can race the scan-link teardown and the reset work
and lose updates.

Take dev->mutex around the link destroy loop, matching
mt7996_add_interface() and mt7915_remove_interface(). The mutex is
released before mt76_vif_cleanup(), which aborts a pending scan and
takes the mutex itself.

Signed-off-by: Chad Monroe <[email protected]>
Signed-off-by: Felix Fietkau <[email protected]>

mt7996/main.c

@@ -606,6 +606,8 @@ static void mt7996_remove_interface(struct ieee80211_hw *hw,
 	unsigned int link_id;
 	int i;
 
+	mutex_lock(&dev->mt76.mutex);
+
 	/* Remove all active links */
 	for_each_set_bit(link_id, &rem_links, IEEE80211_MLD_MAX_NUM_LINKS) {
 		struct mt7996_vif_link *link;
@@ -622,6 +624,8 @@ static void mt7996_remove_interface(struct ieee80211_hw *hw,
 		mt7996_vif_link_destroy(phy, link, vif, NULL);
 	}
 
+	mutex_unlock(&dev->mt76.mutex);
+
 	ieee80211_iterate_active_interfaces_mtx(hw, 0, mt7996_remove_iter,
 						&rdata);
 	mt76_vif_cleanup(&dev->mt76, vif);