[bug report] mt76: mt76_connac: create mcu library

[Dan Carpenter <dan.carpenter@oracle.com>]

Hello Lorenzo Bianconi,

The patch d0e274af2f2e: "mt76: mt76_connac: create mcu library" from
Jan 26, 2021, leads to the following static checker warning:

	drivers/net/wireless/mediatek/mt76/mt76_connac_mcu.c:837 mt76_connac_mcu_add_sta_cmd()
	error: 'wtbl_hdr' dereferencing possible ERR_PTR()

drivers/net/wireless/mediatek/mt76/mt76_connac_mcu.c
   810  int mt76_connac_mcu_add_sta_cmd(struct mt76_phy *phy,
   811                                  struct ieee80211_vif *vif,
   812                                  struct ieee80211_sta *sta,
   813                                  struct mt76_wcid *wcid,
   814                                  bool enable, int cmd)
   815  {
   816          struct mt76_vif *mvif = (struct mt76_vif *)vif->drv_priv;
   817          struct mt76_dev *dev = phy->dev;
   818          struct wtbl_req_hdr *wtbl_hdr;
   819          struct tlv *sta_wtbl;
   820          struct sk_buff *skb;
   821  
   822          skb = mt76_connac_mcu_alloc_sta_req(dev, mvif, wcid);
   823          if (IS_ERR(skb))
   824                  return PTR_ERR(skb);
   825  
   826          mt76_connac_mcu_sta_basic_tlv(skb, vif, sta, enable);
   827          if (enable && sta)
   828                  mt76_connac_mcu_sta_tlv(phy, skb, sta, vif);
   829  
   830          sta_wtbl = mt76_connac_mcu_add_tlv(skb, STA_REC_WTBL,
   831                                             sizeof(struct tlv));
   832  
   833          wtbl_hdr = mt76_connac_mcu_alloc_wtbl_req(dev, wcid,
   834                                                    WTBL_RESET_AND_SET,
   835                                                    sta_wtbl, &skb);

if (IS_ERR(wtbl_hdr)) {
	do some cleanup?
	return PTR_ERR(wtbl_hdr);
}

   836          if (enable) {
   837                  mt76_connac_mcu_wtbl_generic_tlv(dev, skb, vif, sta, sta_wtbl,
   838                                                   wtbl_hdr);
   839                  if (sta)
   840                          mt76_connac_mcu_wtbl_ht_tlv(dev, skb, sta, sta_wtbl,
   841                                                      wtbl_hdr);
   842          }
   843  
   844          return mt76_mcu_skb_send_msg(dev, skb, cmd, true);
   845  }

regards,
dan carpenter