wifi: mac80211: track capability/opmode NSS separately

We're currently tracking rx_nss for each station, and that
is meant to be initialized to the capability NSS and later
reduced by the operating mode notification NSS.

However, we're mixing up capabilities and operating mode
NSS in the same variable. This forces us to recalculate
the NSS capability on operating mode notification RX,
which is a bit strange; due to the previous fix I had to
never keep rx_nss as zero, it also means that the capa is
never taken into account properly.

Fix all this by storing the capability value, that can be
recalculated unconditionally whenever needed, and storing
the operating mode notification NSS separately, taking it
into account when assigning the final rx_nss value.

Cc: stable@vger.kernel.org
Fixes: dd6c064cfc3f ("wifi: mac80211: set station RX-NSS on reconfig")
Reviewed-by: Miriam Rachel Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://msgid.link/20240228120157.0e1c41924d1d.I0acaa234e0267227b7e3ef81a59117c8792116bc@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 22 insertions, 24 deletions

diff --git a/net/mac80211/vht.c b/net/mac80211/vht.c
index 2c475c439ba9..642891cafbaf 100644
--- a/net/mac80211/vht.c
+++ b/net/mac80211/vht.c
@@ -4,7 +4,7 @@
  *
  * Portions of this file
  * Copyright(c) 2015 - 2016 Intel Deutschland GmbH
- * Copyright (C) 2018 - 2023 Intel Corporation
+ * Copyright (C) 2018 - 2024 Intel Corporation
  */
 
 #include <linux/ieee80211.h>
@@ -541,15 +541,11 @@ ieee80211_sta_cur_vht_bw(struct link_sta_info *link_sta)
 	return bw;
 }
 
-void ieee80211_sta_set_rx_nss(struct link_sta_info *link_sta)
+void ieee80211_sta_init_nss(struct link_sta_info *link_sta)
 {
 	u8 ht_rx_nss = 0, vht_rx_nss = 0, he_rx_nss = 0, eht_rx_nss = 0, rx_nss;
 	bool support_160;
 
-	/* if we received a notification already don't overwrite it */
-	if (link_sta->pub->rx_nss)
-		return;
-
 	if (link_sta->pub->eht_cap.has_eht) {
 		int i;
 		const u8 *rx_nss_mcs = (void *)&link_sta->pub->eht_cap.eht_mcs_nss_supp;
@@ -627,7 +623,15 @@ void ieee80211_sta_set_rx_nss(struct link_sta_info *link_sta)
 	rx_nss = max(vht_rx_nss, ht_rx_nss);
 	rx_nss = max(he_rx_nss, rx_nss);
 	rx_nss = max(eht_rx_nss, rx_nss);
-	link_sta->pub->rx_nss = max_t(u8, 1, rx_nss);
+	rx_nss = max_t(u8, 1, rx_nss);
+	link_sta->capa_nss = rx_nss;
+
+	/* that shouldn't be set yet, but we can handle it anyway */
+	if (link_sta->op_mode_nss)
+		link_sta->pub->rx_nss =
+			min_t(u8, rx_nss, link_sta->op_mode_nss);
+	else
+		link_sta->pub->rx_nss = rx_nss;
 }
 
 u32 __ieee80211_vht_handle_opmode(struct ieee80211_sub_if_data *sdata,
@@ -637,7 +641,7 @@ u32 __ieee80211_vht_handle_opmode(struct ieee80211_sub_if_data *sdata,
 	enum ieee80211_sta_rx_bandwidth new_bw;
 	struct sta_opmode_info sta_opmode = {};
 	u32 changed = 0;
-	u8 nss, cur_nss;
+	u8 nss;
 
 	/* ignore - no support for BF yet */
 	if (opmode & IEEE80211_OPMODE_NOTIF_RX_NSS_TYPE_BF)
@@ -647,23 +651,17 @@ u32 __ieee80211_vht_handle_opmode(struct ieee80211_sub_if_data *sdata,
 	nss >>= IEEE80211_OPMODE_NOTIF_RX_NSS_SHIFT;
 	nss += 1;
 
-	if (link_sta->pub->rx_nss != nss) {
-		cur_nss = link_sta->pub->rx_nss;
-		/* Reset rx_nss and call ieee80211_sta_set_rx_nss() which
-		 * will set the same to max nss value calculated based on capability.
-		 */
-		link_sta->pub->rx_nss = 0;
-		ieee80211_sta_set_rx_nss(link_sta);
-		/* Do not allow an nss change to rx_nss greater than max_nss
-		 * negotiated and capped to APs capability during association.
-		 */
-		if (nss <= link_sta->pub->rx_nss) {
-			link_sta->pub->rx_nss = nss;
-			sta_opmode.rx_nss = nss;
-			changed |= IEEE80211_RC_NSS_CHANGED;
-			sta_opmode.changed |= STA_OPMODE_N_SS_CHANGED;
+	if (link_sta->op_mode_nss != nss) {
+		if (nss <= link_sta->capa_nss) {
+			link_sta->op_mode_nss = nss;
+
+			if (nss != link_sta->pub->rx_nss) {
+				link_sta->pub->rx_nss = nss;
+				changed |= IEEE80211_RC_NSS_CHANGED;
+				sta_opmode.rx_nss = link_sta->pub->rx_nss;
+				sta_opmode.changed |= STA_OPMODE_N_SS_CHANGED;
+			}
 		} else {
-			link_sta->pub->rx_nss = cur_nss;
 			pr_warn_ratelimited("Ignoring NSS change in VHT Operating Mode Notification from %pM with invalid nss %d",
 					    link_sta->pub->addr, nss);
 		}