[bug report] ath11k: report rssi of each chain to mac80211 for QCA6390/WCN6855

[Dan Carpenter]

Hello Wen Gong,

The patch b488c766442f: "ath11k: report rssi of each chain to
mac80211 for QCA6390/WCN6855" from Dec 17, 2021, leads to the
following Smatch static checker warning:

	drivers/net/wireless/ath/ath11k/wmi.c:5800 ath11k_wmi_tlv_rssi_chain_parse()
	warn: missing error code here? 'ieee80211_find_sta_by_ifaddr()' failed. 'ret' = '0'

drivers/net/wireless/ath/ath11k/wmi.c
    5755 static int ath11k_wmi_tlv_rssi_chain_parse(struct ath11k_base *ab,
    5756                                            u16 tag, u16 len,
    5757                                            const void *ptr, void *data)
    5758 {
    5759         struct wmi_tlv_fw_stats_parse *parse = data;
    5760         const struct wmi_stats_event *ev = parse->ev;
    5761         struct ath11k_fw_stats *stats = parse->stats;
    5762         struct ath11k *ar;
    5763         struct ath11k_vif *arvif;
    5764         struct ieee80211_sta *sta;
    5765         struct ath11k_sta *arsta;
    5766         const struct wmi_rssi_stats *stats_rssi = (const struct wmi_rssi_stats *)ptr;
    5767         int j, ret = 0;
    5768 
    5769         if (tag != WMI_TAG_RSSI_STATS)
    5770                 return -EPROTO;
    5771 
    5772         rcu_read_lock();
    5773 
    5774         ar = ath11k_mac_get_ar_by_pdev_id(ab, ev->pdev_id);
    5775         stats->stats_id = WMI_REQUEST_RSSI_PER_CHAIN_STAT;
    5776 
    5777         ath11k_dbg(ab, ATH11K_DBG_WMI,
    5778                    "wmi stats vdev id %d mac %pM\n",
    5779                    stats_rssi->vdev_id, stats_rssi->peer_macaddr.addr);
    5780 
    5781         arvif = ath11k_mac_get_arvif(ar, stats_rssi->vdev_id);
    5782         if (!arvif) {
    5783                 ath11k_warn(ab, "not found vif for vdev id %d\n",
    5784                             stats_rssi->vdev_id);
    5785                 ret = -EPROTO;
    5786                 goto exit;
    5787         }
    5788 
    5789         ath11k_dbg(ab, ATH11K_DBG_WMI,
    5790                    "wmi stats bssid %pM vif %pK\n",
    5791                    arvif->bssid, arvif->vif);
    5792 
    5793         sta = ieee80211_find_sta_by_ifaddr(ar->hw,
    5794                                            arvif->bssid,
    5795                                            NULL);
    5796         if (!sta) {
    5797                 ath11k_dbg(ab, ATH11K_DBG_WMI,
    5798                            "not found station of bssid %pM for rssi chain\n",
    5799                            arvif->bssid);
--> 5800                 goto exit;

Should this return an error code or zero?  It's hard for me to tell.
If returning a zero is correct then doing the "ret = 0;" assignment
within 4 (or 5?) lines of the "goto exit;" will silence the warning.

    5801         }
    5802 
    5803         arsta = (struct ath11k_sta *)sta->drv_priv;
    5804 
    5805         BUILD_BUG_ON(ARRAY_SIZE(arsta->chain_signal) >
    5806                      ARRAY_SIZE(stats_rssi->rssi_avg_beacon));
    5807 
    5808         for (j = 0; j < ARRAY_SIZE(arsta->chain_signal); j++) {
    5809                 arsta->chain_signal[j] = stats_rssi->rssi_avg_beacon[j];
    5810                 ath11k_dbg(ab, ATH11K_DBG_WMI,
    5811                            "wmi stats beacon rssi[%d] %d data rssi[%d] %d\n",
    5812                            j,
    5813                            stats_rssi->rssi_avg_beacon[j],
    5814                            j,
    5815                            stats_rssi->rssi_avg_data[j]);
    5816         }
    5817 
    5818 exit:
    5819         rcu_read_unlock();
    5820         return ret;
    5821 }

regards,
dan carpenter