wifi: mac80211: make bss_param_ch_cnt available for the low level driver

Drivers may need to track this. Make it available for them, and maintain
the value when beacons are received.
When link X receives a beacon, iterate the RNR elements and update all
the links with their respective data.
Track the link id that updated the data so that each link can know
whether the update came from its own beacon or from another link.
In case, the update came from the link's own beacon, always update the
updater link id.
The purpose is to let the low level driver know if a link is losing its
beacons. If link X is losing its beacons, it can still track the
bss_param_ch_cnt and know where the update came from.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://patch.msgid.link/20241007144851.e2d8d1a722ad.I04b883daba2cd48e5730659eb62ca1614c899cbb@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

2 files changed, 91 insertions, 4 deletions

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index afb867dc6b24..d884d05826d3 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1015,8 +1015,6 @@ struct ieee80211_link_data_managed {
 
 	int wmm_last_param_set;
 	int mu_edca_last_param_set;
-
-	u8 bss_param_ch_cnt;
 };
 
 struct ieee80211_link_data_ap {
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 0303972c23e4..93a11a59339c 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -2643,6 +2643,89 @@ ieee80211_sta_process_chanswitch(struct ieee80211_link_data *link,
 			 &ifmgd->csa_connection_drop_work);
 }
 
+struct sta_bss_param_ch_cnt_data {
+	struct ieee80211_sub_if_data *sdata;
+	u8 reporting_link_id;
+	u8 mld_id;
+};
+
+static enum cfg80211_rnr_iter_ret
+ieee80211_sta_bss_param_ch_cnt_iter(void *_data, u8 type,
+				    const struct ieee80211_neighbor_ap_info *info,
+				    const u8 *tbtt_info, u8 tbtt_info_len)
+{
+	struct sta_bss_param_ch_cnt_data *data = _data;
+	struct ieee80211_sub_if_data *sdata = data->sdata;
+	const struct ieee80211_tbtt_info_ge_11 *ti;
+	u8 bss_param_ch_cnt;
+	int link_id;
+
+	if (type != IEEE80211_TBTT_INFO_TYPE_TBTT)
+		return RNR_ITER_CONTINUE;
+
+	if (tbtt_info_len < sizeof(*ti))
+		return RNR_ITER_CONTINUE;
+
+	ti = (const void *)tbtt_info;
+
+	if (ti->mld_params.mld_id != data->mld_id)
+		return RNR_ITER_CONTINUE;
+
+	link_id = le16_get_bits(ti->mld_params.params,
+				IEEE80211_RNR_MLD_PARAMS_LINK_ID);
+	bss_param_ch_cnt =
+		le16_get_bits(ti->mld_params.params,
+			      IEEE80211_RNR_MLD_PARAMS_BSS_CHANGE_COUNT);
+
+	if (bss_param_ch_cnt != 255 &&
+	    link_id < ARRAY_SIZE(sdata->link)) {
+		struct ieee80211_link_data *link =
+			sdata_dereference(sdata->link[link_id], sdata);
+
+		if (link && link->conf->bss_param_ch_cnt != bss_param_ch_cnt) {
+			link->conf->bss_param_ch_cnt = bss_param_ch_cnt;
+			link->conf->bss_param_ch_cnt_link_id =
+				data->reporting_link_id;
+		}
+	}
+
+	return RNR_ITER_CONTINUE;
+}
+
+static void
+ieee80211_mgd_update_bss_param_ch_cnt(struct ieee80211_sub_if_data *sdata,
+				      struct ieee80211_bss_conf *bss_conf,
+				      struct ieee802_11_elems *elems)
+{
+	struct sta_bss_param_ch_cnt_data data = {
+		.reporting_link_id = bss_conf->link_id,
+		.sdata = sdata,
+	};
+	int bss_param_ch_cnt;
+
+	if (!elems->ml_basic)
+		return;
+
+	data.mld_id = ieee80211_mle_get_mld_id((const void *)elems->ml_basic);
+
+	cfg80211_iter_rnr(elems->ie_start, elems->total_len,
+			  ieee80211_sta_bss_param_ch_cnt_iter, &data);
+
+	bss_param_ch_cnt =
+		ieee80211_mle_get_bss_param_ch_cnt((const void *)elems->ml_basic);
+
+	/*
+	 * Update bss_param_ch_cnt_link_id even if bss_param_ch_cnt
+	 * didn't change to indicate that we got a beacon on our own
+	 * link.
+	 */
+	if (bss_param_ch_cnt >= 0 && bss_param_ch_cnt != 255) {
+		bss_conf->bss_param_ch_cnt = bss_param_ch_cnt;
+		bss_conf->bss_param_ch_cnt_link_id =
+			bss_conf->link_id;
+	}
+}
+
 static bool
 ieee80211_find_80211h_pwr_constr(struct ieee80211_sub_if_data *sdata,
 				 struct ieee80211_channel *channel,
@@ -4667,7 +4750,8 @@ static bool ieee80211_assoc_config_link(struct ieee80211_link_data *link,
 				ret = false;
 				goto out;
 			}
-			link->u.mgd.bss_param_ch_cnt = bss_param_ch_cnt;
+			bss_conf->bss_param_ch_cnt = bss_param_ch_cnt;
+			bss_conf->bss_param_ch_cnt_link_id = link_id;
 		}
 	} else if (elems->parse_error & IEEE80211_PARSE_ERR_DUP_NEST_ML_BASIC ||
 		   !elems->prof ||
@@ -4677,6 +4761,7 @@ static bool ieee80211_assoc_config_link(struct ieee80211_link_data *link,
 	} else {
 		const u8 *ptr = elems->prof->variable +
 				elems->prof->sta_info_len - 1;
+		int bss_param_ch_cnt;
 
 		/*
 		 * During parsing, we validated that these fields exist,
@@ -4684,8 +4769,10 @@ static bool ieee80211_assoc_config_link(struct ieee80211_link_data *link,
 		 */
 		capab_info = get_unaligned_le16(ptr);
 		assoc_data->link[link_id].status = get_unaligned_le16(ptr + 2);
-		link->u.mgd.bss_param_ch_cnt =
+		bss_param_ch_cnt =
 			ieee80211_mle_basic_sta_prof_bss_param_ch_cnt(elems->prof);
+		bss_conf->bss_param_ch_cnt = bss_param_ch_cnt;
+		bss_conf->bss_param_ch_cnt_link_id = link_id;
 
 		if (assoc_data->link[link_id].status != WLAN_STATUS_SUCCESS) {
 			link_info(link, "association response status code=%u\n",
@@ -6913,6 +7000,8 @@ static void ieee80211_rx_mgmt_beacon(struct ieee80211_link_data *link,
 	/* note that after this elems->ml_basic can no longer be used fully */
 	ieee80211_mgd_check_cross_link_csa(sdata, rx_status->link_id, elems);
 
+	ieee80211_mgd_update_bss_param_ch_cnt(sdata, bss_conf, elems);
+
 	if (!link->u.mgd.disable_wmm_tracking &&
 	    ieee80211_sta_wmm_params(local, link, elems->wmm_param,
 				     elems->wmm_param_len,