wifi: mac80211: determine missing link_id in ieee80211_rx_for_interface() based on frequency

For broadcast frames, every interface might have to process it and
therefore the link_id cannot be determined in the driver.

In mac80211, when the frame is about to be forwarded to each interface,
we can use the member "freq" in struct ieee80211_rx_status to determine
the "link_id" for each interface.

Signed-off-by: Michael-CY Lee <[e-mail]>
Reviewed-by: Money Wang <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
[simplify, remove unnecessary link->conf check]
Signed-off-by: Johannes Berg <[e-mail]>

net/mac80211/rx.c

···
 		struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
 
 		sta = sta_info_get_bss(rx->sdata, hdr->addr2);
-		if (status->link_valid)
+		if (status->link_valid) {
 			link_id = status->link_id;
+		} else if (ieee80211_vif_is_mld(&rx->sdata->vif) &&
+			   status->freq) {
+			struct ieee80211_link_data *link;
+			struct ieee80211_chanctx_conf *conf;
+
+			for_each_link_data_rcu(rx->sdata, link) {
+				conf = rcu_dereference(link->conf->chanctx_conf);
+				if (!conf || !conf->def.chan)
+					continue;
+
+				if (status->freq == conf->def.chan->center_freq) {
+					link_id = link->link_id;
+					break;
+				}
+			}
+		}
 	}
 
 	if (!ieee80211_rx_data_set_sta(rx, sta, link_id))