wifi: mt76: mt7996: rely on mt76_connac2_mac_tx_rate_val

In order to fix a possible NULL pointer dereference in
mt7996_mac_write_txwi() of vif pointer, export
mt76_connac2_mac_tx_rate_val utility routine and reuse it
in mt7996 driver.

Fixes: 98686cd2 ("wifi: mt76: mt7996: add driver for MediaTek Wi-Fi 7 (802.11be) devices")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt76_connac.h

@@ -370,6 +370,9 @@ void mt76_connac2_mac_write_txwi(struct mt76_dev *dev, __le32 *txwi,
 				 struct sk_buff *skb, struct mt76_wcid *wcid,
 				 struct ieee80211_key_conf *key, int pid,
 				 enum mt76_txq_id qid, u32 changed);
+u16 mt76_connac2_mac_tx_rate_val(struct mt76_phy *mphy,
+				 struct ieee80211_vif *vif,
+				 bool beacon, bool mcast);
 bool mt76_connac2_mac_fill_txs(struct mt76_dev *dev, struct mt76_wcid *wcid,
 			       __le32 *txs_data);
 bool mt76_connac2_mac_add_txs_skb(struct mt76_dev *dev, struct mt76_wcid *wcid,

drivers/net/wireless/mediatek/mt76/mt76_connac_mac.c

@@ -267,9 +267,9 @@ int mt76_connac_init_tx_queues(struct mt76_phy *phy, int idx, int n_desc,
 }
 EXPORT_SYMBOL_GPL(mt76_connac_init_tx_queues);
 
-static u16
-mt76_connac2_mac_tx_rate_val(struct mt76_phy *mphy, struct ieee80211_vif *vif,
-			     bool beacon, bool mcast)
+u16 mt76_connac2_mac_tx_rate_val(struct mt76_phy *mphy,
+				 struct ieee80211_vif *vif,
+				 bool beacon, bool mcast)
 {
 	u8 mode = 0, band = mphy->chandef.chan->band;
 	int rateidx = 0, mcast_rate;
@@ -319,6 +319,7 @@ mt76_connac2_mac_tx_rate_val(struct mt76_phy *mphy, struct ieee80211_vif *vif,
 	return FIELD_PREP(MT_TX_RATE_IDX, rateidx) |
 	       FIELD_PREP(MT_TX_RATE_MODE, mode);
 }
+EXPORT_SYMBOL_GPL(mt76_connac2_mac_tx_rate_val);
 
 static void
 mt76_connac2_mac_write_txwi_8023(__le32 *txwi, struct sk_buff *skb,

drivers/net/wireless/mediatek/mt76/mt7996/mac.c

@@ -959,51 +959,6 @@ mt7996_mac_write_txwi_80211(struct mt7996_dev *dev, __le32 *txwi,
 	}
 }
 
-static u16
-mt7996_mac_tx_rate_val(struct mt76_phy *mphy, struct ieee80211_vif *vif,
-		       bool beacon, bool mcast)
-{
-	u8 mode = 0, band = mphy->chandef.chan->band;
-	int rateidx = 0, mcast_rate;
-
-	if (beacon) {
-		struct cfg80211_bitrate_mask *mask;
-
-		mask = &vif->bss_conf.beacon_tx_rate;
-		if (hweight16(mask->control[band].he_mcs[0]) == 1) {
-			rateidx = ffs(mask->control[band].he_mcs[0]) - 1;
-			mode = MT_PHY_TYPE_HE_SU;
-			goto out;
-		} else if (hweight16(mask->control[band].vht_mcs[0]) == 1) {
-			rateidx = ffs(mask->control[band].vht_mcs[0]) - 1;
-			mode = MT_PHY_TYPE_VHT;
-			goto out;
-		} else if (hweight8(mask->control[band].ht_mcs[0]) == 1) {
-			rateidx = ffs(mask->control[band].ht_mcs[0]) - 1;
-			mode = MT_PHY_TYPE_HT;
-			goto out;
-		} else if (hweight32(mask->control[band].legacy) == 1) {
-			rateidx = ffs(mask->control[band].legacy) - 1;
-			goto legacy;
-		}
-	}
-
-	mcast_rate = vif->bss_conf.mcast_rate[band];
-	if (mcast && mcast_rate > 0)
-		rateidx = mcast_rate - 1;
-	else
-		rateidx = ffs(vif->bss_conf.basic_rates) - 1;
-
-legacy:
-	rateidx = mt76_calculate_default_rate(mphy, rateidx);
-	mode = rateidx >> 8;
-	rateidx &= GENMASK(7, 0);
-
-out:
-	return FIELD_PREP(MT_TX_RATE_IDX, rateidx) |
-	       FIELD_PREP(MT_TX_RATE_MODE, mode);
-}
-
 void mt7996_mac_write_txwi(struct mt7996_dev *dev, __le32 *txwi,
 			   struct sk_buff *skb, struct mt76_wcid *wcid, int pid,
 			   struct ieee80211_key_conf *key, u32 changed)
@@ -1091,7 +1046,8 @@ void mt7996_mac_write_txwi(struct mt7996_dev *dev, __le32 *txwi,
 		/* Fixed rata is available just for 802.11 txd */
 		struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
 		bool multicast = is_multicast_ether_addr(hdr->addr1);
-		u16 rate = mt7996_mac_tx_rate_val(mphy, vif, beacon, multicast);
+		u16 rate = mt76_connac2_mac_tx_rate_val(mphy, vif, beacon,
+							multicast);
 
 		/* fix to bw 20 */
 		val = MT_TXD6_FIXED_BW |