From 728f46518ec9eba9ab7b1274944a59b3db2d6eb2 Mon Sep 17 00:00:00 2001
From: Stefano Avallone <stavallo@unina.it>
Date: Thu, 2 Nov 2023 10:17:57 +0100
Subject: [PATCH] wifi: PHY notifies MAC as the last action when RX ends

Because the MAC may request a PHY state change (channel switch, sleep)
when notified of an RX end, which may conflict with the actions
taken by the PHY when an RX ends.
---
 src/wifi/model/he/he-phy.cc  |  2 --
 src/wifi/model/phy-entity.cc | 23 +++++++++++++++++------
 2 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/src/wifi/model/he/he-phy.cc b/src/wifi/model/he/he-phy.cc
index bff4c7fe1..b42b31771 100644
--- a/src/wifi/model/he/he-phy.cc
+++ b/src/wifi/model/he/he-phy.cc
@@ -863,7 +863,6 @@ HePhy::RxPayloadSucceeded(Ptr<const WifiPsdu> psdu,
                           const std::vector<bool>& statusPerMpdu)
 {
     NS_LOG_FUNCTION(this << *psdu << txVector);
-    m_state->NotifyRxPsduSucceeded(psdu, rxSignalInfo, txVector, staId, statusPerMpdu);
     if (!IsUlMu(txVector.GetPreambleType()))
     {
         m_state->SwitchFromRxEndOk();
@@ -878,7 +877,6 @@ void
 HePhy::RxPayloadFailed(Ptr<const WifiPsdu> psdu, double snr, const WifiTxVector& txVector)
 {
     NS_LOG_FUNCTION(this << *psdu << txVector << snr);
-    m_state->NotifyRxPsduFailed(psdu, snr);
     if (!txVector.IsUlMu())
     {
         m_state->SwitchFromRxEndError();
diff --git a/src/wifi/model/phy-entity.cc b/src/wifi/model/phy-entity.cc
index e30af9345..f33adb409 100644
--- a/src/wifi/model/phy-entity.cc
+++ b/src/wifi/model/phy-entity.cc
@@ -709,31 +709,44 @@ PhyEntity::EndReceivePayload(Ptr<Event> event)
     NS_ASSERT(signalNoiseIt != m_signalNoiseMap.end());
     auto statusPerMpduIt = m_statusPerMpduMap.find({ppdu->GetUid(), staId});
     NS_ASSERT(statusPerMpduIt != m_statusPerMpduMap.end());
+    // store per-MPDU status, which is cleared by the call to DoEndReceivePayload below
+    auto statusPerMpdu = statusPerMpduIt->second;
 
-    if (std::count(statusPerMpduIt->second.begin(), statusPerMpduIt->second.end(), true))
+    RxSignalInfo rxSignalInfo;
+    bool success;
+
+    if (std::count(statusPerMpdu.cbegin(), statusPerMpdu.cend(), true))
     {
         // At least one MPDU has been successfully received
         m_wifiPhy->NotifyMonitorSniffRx(psdu,
                                         m_wifiPhy->GetFrequency(),
                                         txVector,
                                         signalNoiseIt->second,
-                                        statusPerMpduIt->second,
+                                        statusPerMpdu,
                                         staId);
-        RxSignalInfo rxSignalInfo;
         rxSignalInfo.snr = snr;
         rxSignalInfo.rssi = signalNoiseIt->second.signal; // same information for all MPDUs
-        RxPayloadSucceeded(psdu, rxSignalInfo, txVector, staId, statusPerMpduIt->second);
+        RxPayloadSucceeded(psdu, rxSignalInfo, txVector, staId, statusPerMpdu);
         m_wifiPhy->m_previouslyRxPpduUid =
             ppdu->GetUid(); // store UID only if reception is successful (because otherwise trigger
                             // won't be read by MAC layer)
+        success = true;
     }
     else
     {
         RxPayloadFailed(psdu, snr, txVector);
+        success = false;
     }
 
     DoEndReceivePayload(ppdu);
     m_wifiPhy->SwitchMaybeToCcaBusy(ppdu);
+
+    // notify the MAC through the PHY state helper as the last action. Indeed, the notification
+    // of the RX end may lead the MAC to request a PHY state change (e.g., channel switch, sleep).
+    // Hence, all actions the PHY has to perform when RX ends should be completed before
+    // notifying the MAC.
+    success ? m_state->NotifyRxPsduSucceeded(psdu, rxSignalInfo, txVector, staId, statusPerMpdu)
+            : m_state->NotifyRxPsduFailed(psdu, snr);
 }
 
 void
@@ -744,7 +757,6 @@ PhyEntity::RxPayloadSucceeded(Ptr<const WifiPsdu> psdu,
                               const std::vector<bool>& statusPerMpdu)
 {
     NS_LOG_FUNCTION(this << *psdu << txVector);
-    m_state->NotifyRxPsduSucceeded(psdu, rxSignalInfo, txVector, staId, statusPerMpdu);
     m_state->SwitchFromRxEndOk();
 }
 
@@ -752,7 +764,6 @@ void
 PhyEntity::RxPayloadFailed(Ptr<const WifiPsdu> psdu, double snr, const WifiTxVector& txVector)
 {
     NS_LOG_FUNCTION(this << *psdu << txVector << snr);
-    m_state->NotifyRxPsduFailed(psdu, snr);
     m_state->SwitchFromRxEndError();
 }