[PATCH wireless-next v3 13/21] wifi: mac80211: apply SMD BSS Transition STA sub-states

[Pooventhiran G]

During SMD BSS Transition, the non-AP STA MLD roaming from the current
AP MLD to the target AP MLD switches its new SMD sub-states. Capture
these state transitions to track the station roaming.

These are transient sub-states of WLAN_STA_AUTHORIZED with the SMD-ME.
The station remains authenticated, associated, and RSNA-established
throughout. At most one of the three may be set at a time; mutual
exclusion is enforced in sta_apply_smd_state_flags().

Signed-off-by: Pooventhiran G <pooventhiran.g@xxxxxxxxxxxxxxxx>
---
 net/mac80211/cfg.c         | 60 ++++++++++++++++++++++++++++++++++++++++++++++
 net/mac80211/debugfs_sta.c |  3 +++
 net/mac80211/sta_info.h    |  8 +++++++
 3 files changed, 71 insertions(+)

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 37329d8748ae..1e0ef74a7420 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -2704,6 +2704,55 @@ static int sta_link_apply_parameters(struct ieee80211_local *local,
 	return 0;
 }
 
+static int sta_apply_smd_state_flags(struct sta_info *sta,
+				     u32 mask, u32 set)
+{
+	bool smd_prep_target, smd_exec_current, smd_dl_drain;
+	u32 expected_mask = BIT(NL80211_STA_FLAG_SMD_PREP_TARGET) |
+			    BIT(NL80211_STA_FLAG_SMD_EXEC_CURRENT) |
+			    BIT(NL80211_STA_FLAG_SMD_DL_DRAIN);
+	u32 smd_flags;
+
+	if (!(mask & expected_mask))
+		return 0;
+
+	smd_flags = mask & expected_mask & set;
+	if (WARN_ON(hweight32(smd_flags) > 1))
+		return -EINVAL;
+
+	smd_prep_target =
+		!!(smd_flags & BIT(NL80211_STA_FLAG_SMD_PREP_TARGET));
+	smd_exec_current =
+		!!(smd_flags & BIT(NL80211_STA_FLAG_SMD_EXEC_CURRENT));
+	smd_dl_drain =
+		!!(smd_flags & BIT(NL80211_STA_FLAG_SMD_DL_DRAIN));
+
+	if (!test_sta_flag(sta, WLAN_STA_AUTHORIZED) &&
+	    (smd_exec_current || smd_dl_drain))
+		return -EINVAL;
+
+	if (smd_prep_target) {
+		clear_sta_flag(sta, WLAN_STA_SMD_EXEC_CURRENT);
+		clear_sta_flag(sta, WLAN_STA_SMD_DL_DRAIN);
+		set_sta_flag(sta, WLAN_STA_SMD_PREP_TARGET);
+	} else if (smd_exec_current) {
+		clear_sta_flag(sta, WLAN_STA_SMD_PREP_TARGET);
+		clear_sta_flag(sta, WLAN_STA_SMD_DL_DRAIN);
+		set_sta_flag(sta, WLAN_STA_SMD_EXEC_CURRENT);
+	} else if (smd_dl_drain) {
+		clear_sta_flag(sta, WLAN_STA_SMD_PREP_TARGET);
+		clear_sta_flag(sta, WLAN_STA_SMD_EXEC_CURRENT);
+		set_sta_flag(sta, WLAN_STA_SMD_DL_DRAIN);
+	} else {
+		/* all flags revert back to none being set */
+		clear_sta_flag(sta, WLAN_STA_SMD_PREP_TARGET);
+		clear_sta_flag(sta, WLAN_STA_SMD_EXEC_CURRENT);
+		clear_sta_flag(sta, WLAN_STA_SMD_DL_DRAIN);
+	}
+
+	return 0;
+}
+
 static int sta_apply_parameters(struct ieee80211_local *local,
 				struct sta_info *sta,
 				struct station_parameters *params)
@@ -2790,6 +2839,17 @@ static int sta_apply_parameters(struct ieee80211_local *local,
 	if (params->smd_params.smd_sta)
 		sta->sta.smd_params = params->smd_params;
 
+	/*
+	 * SMD BSS Transition sub-states (IEEE P802.11bn/D2.0, Aug 2026,
+	 * subclause 11.3.1).
+	 * Only meaningful for SMD-capable stations (WLAN_STA_SMD set).
+	 */
+	if (test_sta_flag(sta, WLAN_STA_SMD)) {
+		ret = sta_apply_smd_state_flags(sta, mask, set);
+		if (ret)
+			return ret;
+	}
+
 	/* mark TDLS channel switch support, if the AP allows it */
 	if (test_sta_flag(sta, WLAN_STA_TDLS_PEER) &&
 	    !sdata->deflink.u.mgd.tdls_chan_switch_prohibited &&
diff --git a/net/mac80211/debugfs_sta.c b/net/mac80211/debugfs_sta.c
index c2268f79601b..8071ca4c5f06 100644
--- a/net/mac80211/debugfs_sta.c
+++ b/net/mac80211/debugfs_sta.c
@@ -79,6 +79,9 @@ static const char * const sta_flag_names[] = {
 	FLAG(USES_ENCRYPTION),
 	FLAG(DECAP_OFFLOAD),
 	FLAG(SMD),
+	FLAG(SMD_PREP_TARGET),
+	FLAG(SMD_EXEC_CURRENT),
+	FLAG(SMD_DL_DRAIN),
 #undef FLAG
 };
 
diff --git a/net/mac80211/sta_info.h b/net/mac80211/sta_info.h
index 54c4c613a2da..2e9bb2ab567f 100644
--- a/net/mac80211/sta_info.h
+++ b/net/mac80211/sta_info.h
@@ -73,6 +73,11 @@
  *	so drop all packets without a key later.
  * @WLAN_STA_DECAP_OFFLOAD: This station uses rx decap offload
  * @WLAN_STA_SMD: this station is associated to an SMD-ME.
+ * @WLAN_STA_SMD_PREP_TARGET: this SMD station is prepared at the target AP MLD.
+ * @WLAN_STA_SMD_EXEC_CURRENT: this SMD station has started execution at
+ *	the current AP MLD.
+ * @WLAN_STA_SMD_DL_DRAIN: this SMD station has started draining at
+ *	the current AP MLD.
  *
  * @NUM_WLAN_STA_FLAGS: number of defined flags
  */
@@ -106,6 +111,9 @@ enum ieee80211_sta_info_flags {
 	WLAN_STA_USES_ENCRYPTION,
 	WLAN_STA_DECAP_OFFLOAD,
 	WLAN_STA_SMD,
+	WLAN_STA_SMD_PREP_TARGET,
+	WLAN_STA_SMD_EXEC_CURRENT,
+	WLAN_STA_SMD_DL_DRAIN,
 
 	NUM_WLAN_STA_FLAGS,
 };

-- 
2.34.1