wifi: mac80211: add support to accumulate removed link statistics

Currently, if a link gets removed in between for a station then
directly accumulated data will fall down to sum of other active links.
This will bring inconsistency in station dump statistics.

For instance, let's take Tx packets
- at t=0-> link-0:2 link-1:3 Tx packets => accumulated = 5
- at t=1-> link-0:4 link-1:6 Tx packets => accumulated = 10
let say at t=2, link-0 went down => link-0:0 link-1:7 => accumulated = 7
Here, suddenly accumulated Tx packets will come down to 7 from 10.
This is showing inconsistency.

Therefore, store link-0 data when it went down and add to accumulated
Tx packet = 11.

Hence, store the removed link statistics data in sta structure and
add it in accumulated statistics for consistency.

Signed-off-by: Sarika Sharma <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Johannes Berg <[e-mail]>

net/mac80211/cfg.c

···
 		ret = 0;
 		memcpy(mac, sta->sta.addr, ETH_ALEN);
 		sta_set_sinfo(sta, sinfo, true);
+
+		/* Add accumulated removed link data to sinfo data for
+		 * consistency for MLO
+		 */
+		if (sinfo->valid_links)
+			sta_set_accumulated_removed_links_sinfo(sta, sinfo);
+
 	}
 
 	return ret;
···
 	if (sta) {
 		ret = 0;
 		sta_set_sinfo(sta, sinfo, true);
+
+		/* Add accumulated removed link data to sinfo data for
+		 * consistency for MLO
+		 */
+		if (sinfo->valid_links)
+			sta_set_accumulated_removed_links_sinfo(sta, sinfo);
 	}
 
 	return ret;

net/mac80211/sta_info.c

···
 	free_percpu(link_sta->pcpu_rx_stats);
 }
 
+static void sta_accumulate_removed_link_stats(struct sta_info *sta, int link_id)
+{
+	struct link_sta_info *link_sta = wiphy_dereference(sta->local->hw.wiphy,
+							   sta->link[link_id]);
+	struct ieee80211_link_data *link;
+	int ac, tid;
+	u32 thr;
+
+	for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {
+		sta->rem_link_stats.tx_packets +=
+			link_sta->tx_stats.packets[ac];
+		sta->rem_link_stats.tx_bytes += link_sta->tx_stats.bytes[ac];
+	}
+
+	sta->rem_link_stats.rx_packets += link_sta->rx_stats.packets;
+	sta->rem_link_stats.rx_bytes += link_sta->rx_stats.bytes;
+	sta->rem_link_stats.tx_retries += link_sta->status_stats.retry_count;
+	sta->rem_link_stats.tx_failed += link_sta->status_stats.retry_failed;
+	sta->rem_link_stats.rx_dropped_misc += link_sta->rx_stats.dropped;
+
+	thr = sta_get_expected_throughput(sta);
+	if (thr != 0)
+		sta->rem_link_stats.expected_throughput += thr;
+
+	for (tid = 0; tid < IEEE80211_NUM_TIDS; tid++) {
+		sta->rem_link_stats.pertid_stats.rx_msdu +=
+			link_sta->rx_stats.msdu[tid];
+		sta->rem_link_stats.pertid_stats.tx_msdu +=
+			link_sta->tx_stats.msdu[tid];
+		sta->rem_link_stats.pertid_stats.tx_msdu_retries +=
+			link_sta->status_stats.msdu_retries[tid];
+		sta->rem_link_stats.pertid_stats.tx_msdu_failed +=
+			link_sta->status_stats.msdu_failed[tid];
+	}
+
+	if (sta->sdata->vif.type == NL80211_IFTYPE_STATION) {
+		link = wiphy_dereference(sta->sdata->local->hw.wiphy,
+					 sta->sdata->link[link_id]);
+		if (link)
+			sta->rem_link_stats.beacon_loss_count +=
+				link->u.mgd.beacon_loss_count;
+	}
+}
+
 static void sta_remove_link(struct sta_info *sta, unsigned int link_id,
 			    bool unhash)
 {
···
 		alloc = container_of(link_sta, typeof(*alloc), info);
 
 	sta->sta.valid_links &= ~BIT(link_id);
+
+	/* store removed link info for accumulated stats consistency */
+	sta_accumulate_removed_link_stats(sta, link_id);
+
 	RCU_INIT_POINTER(sta->link[link_id], NULL);
 	RCU_INIT_POINTER(sta->sta.link[link_id], NULL);
 	if (alloc) {
···
 	sinfo->airtime_link_metric = airtime_link_metric_get(local, sta);
 }
 #endif
+
+void sta_set_accumulated_removed_links_sinfo(struct sta_info *sta,
+					     struct station_info *sinfo)
+{
+	/* Accumulating the removed link statistics. */
+	sinfo->tx_packets = sta->rem_link_stats.tx_packets;
+	sinfo->rx_packets = sta->rem_link_stats.rx_packets;
+	sinfo->tx_bytes = sta->rem_link_stats.tx_bytes;
+	sinfo->rx_bytes = sta->rem_link_stats.rx_bytes;
+	sinfo->tx_retries = sta->rem_link_stats.tx_retries;
+	sinfo->tx_failed = sta->rem_link_stats.tx_failed;
+	sinfo->rx_dropped_misc = sta->rem_link_stats.rx_dropped_misc;
+	sinfo->beacon_loss_count = sta->rem_link_stats.beacon_loss_count;
+	sinfo->expected_throughput = sta->rem_link_stats.expected_throughput;
+
+	if (sinfo->pertid) {
+		sinfo->pertid->rx_msdu =
+			sta->rem_link_stats.pertid_stats.rx_msdu;
+		sinfo->pertid->tx_msdu =
+			sta->rem_link_stats.pertid_stats.tx_msdu;
+		sinfo->pertid->tx_msdu_retries =
+			sta->rem_link_stats.pertid_stats.tx_msdu_retries;
+		sinfo->pertid->tx_msdu_failed =
+			sta->rem_link_stats.pertid_stats.tx_msdu_failed;
+	}
+}
 
 void sta_set_sinfo(struct sta_info *sta, struct station_info *sinfo,
 		   bool tidstats)

net/mac80211/sta_info.h

···
 };
 
 /**
+ * struct ieee80211_sta_removed_link_stats - Removed link sta data
+ *
+ * keep required accumulated removed link data for stats
+ *
+ * @rx_packets: accumulated packets (MSDUs & MMPDUs) received from
+ *	this station for removed links
+ * @tx_packets: accumulated packets (MSDUs & MMPDUs) transmitted to
+ *	this station for removed links
+ * @rx_bytes: accumulated bytes (size of MPDUs) received from this
+ *	station for removed links
+ * @tx_bytes: accumulated bytes (size of MPDUs) transmitted to this
+ *	station for removed links
+ * @tx_retries: cumulative retry counts (MPDUs) for removed links
+ * @tx_failed: accumulated number of failed transmissions (MPDUs)
+ *	(retries exceeded, no ACK) for removed links
+ * @rx_dropped_misc: accumulated dropped packets for un-specified reason
+ *	from this station for removed links
+ * @beacon_loss_count: Number of times beacon loss event has triggered
+ *	from this station for removed links.
+ * @expected_throughput: expected throughput in kbps (including 802.11
+ *	headers) towards this station for removed links
+ * @pertid_stats: accumulated per-TID statistics for removed link of
+ *	station
+ * @pertid_stats.rx_msdu : accumulated number of received MSDUs towards
+ *	this station for removed links.
+ * @pertid_stats.tx_msdu: accumulated number of (attempted) transmitted
+ *	MSDUs towards this station for removed links
+ * @pertid_stats.tx_msdu_retries: accumulated number of retries (not
+ *	counting the first) for transmitted MSDUs towards this station
+ *	for removed links
+ * @pertid_stats.tx_msdu_failed: accumulated number of failed transmitted
+ *	MSDUs towards this station for removed links
+ */
+struct ieee80211_sta_removed_link_stats {
+	u32 rx_packets;
+	u32 tx_packets;
+	u64 rx_bytes;
+	u64 tx_bytes;
+	u32 tx_retries;
+	u32 tx_failed;
+	u32 rx_dropped_misc;
+	u32 beacon_loss_count;
+	u32 expected_throughput;
+	struct {
+		u64 rx_msdu;
+		u64 tx_msdu;
+		u64 tx_msdu_retries;
+		u64 tx_msdu_failed;
+	} pertid_stats;
+};
+
+/**
  * struct sta_info - STA information
  *
  * This structure collects information about a station that
···
  *	@deflink address and remaining would be allocated and the address
  *	would be assigned to link[link_id] where link_id is the id assigned
  *	by the AP.
+ * @rem_link_stats: accumulated removed link stats
  */
 struct sta_info {
 	/* General information, mostly static */
···
 	struct ieee80211_sta_aggregates cur;
 	struct link_sta_info deflink;
 	struct link_sta_info __rcu *link[IEEE80211_MLD_MAX_NUM_LINKS];
+	struct ieee80211_sta_removed_link_stats rem_link_stats;
 
 	/* keep last! */
 	struct ieee80211_sta sta;
···
 			  struct rate_info *rinfo);
 void sta_set_sinfo(struct sta_info *sta, struct station_info *sinfo,
 		   bool tidstats);
+
+void sta_set_accumulated_removed_links_sinfo(struct sta_info *sta,
+					     struct station_info *sinfo);
 
 u32 sta_get_expected_throughput(struct sta_info *sta);