mt76: mt7921: fix key set/delete issue

Similar to the mt7915 driver, deleting a key with the previous key index
deletes the current key. Rework the code to better keep track of
multiple keys and check for the key index before deleting the current
key
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt7921/main.c

@@ -412,7 +412,8 @@ static int mt7921_set_key(struct ieee80211_hw *hw, enum set_key_cmd cmd,
 	struct mt7921_sta *msta = sta ? (struct mt7921_sta *)sta->drv_priv :
 				  &mvif->sta;
 	struct mt76_wcid *wcid = &msta->wcid;
-	int idx = key->keyidx;
+	u8 *wcid_keyidx = &wcid->hw_key_idx;
+	int idx = key->keyidx, err = 0;
 
 	/* The hardware does not support per-STA RX GTK, fallback
 	 * to software mode for these.
@@ -428,6 +429,7 @@ static int mt7921_set_key(struct ieee80211_hw *hw, enum set_key_cmd cmd,
 	switch (key->cipher) {
 	case WLAN_CIPHER_SUITE_AES_CMAC:
 		key->flags |= IEEE80211_KEY_FLAG_GENERATE_MMIE;
+		wcid_keyidx = &wcid->hw_key_idx2;
 		break;
 	case WLAN_CIPHER_SUITE_TKIP:
 	case WLAN_CIPHER_SUITE_CCMP:
@@ -442,16 +444,23 @@ static int mt7921_set_key(struct ieee80211_hw *hw, enum set_key_cmd cmd,
 		return -EOPNOTSUPP;
 	}
 
-	if (cmd == SET_KEY) {
-		key->hw_key_idx = wcid->idx;
-		wcid->hw_key_idx = idx;
-	} else if (idx == wcid->hw_key_idx) {
-		wcid->hw_key_idx = -1;
-	}
+	mt7921_mutex_acquire(dev);
+
+	if (cmd == SET_KEY)
+		*wcid_keyidx = idx;
+	else if (idx == *wcid_keyidx)
+		*wcid_keyidx = -1;
+	else
+		goto out;
+
 	mt76_wcid_key_setup(&dev->mt76, wcid,
 			    cmd == SET_KEY ? key : NULL);
 
-	return mt7921_mcu_add_key(dev, vif, msta, key, cmd);
+	err = mt7921_mcu_add_key(dev, vif, msta, key, cmd);
+out:
+	mt7921_mutex_release(dev);
+
+	return err;
 }
 
 static int mt7921_config(struct ieee80211_hw *hw, u32 changed)