[Camera] Call RemoveSession method from Matter context (#41589)

* Call RemoveSession method from Matter context

* Update comments

Author: yufengwangca

examples/camera-app/linux/src/clusters/webrtc-provider/webrtc-provider-manager.cpp

@@ -887,42 +887,47 @@ void WebRTCProviderManager::OnConnectionStateChanged(bool connected, const uint1
     }
     else
     {
-        WebrtcTransport * transport = GetTransport(sessionId);
-        if (transport == nullptr)
-        {
-
-            ChipLogProgress(Camera,
-                            "Transport not found for session %u during disconnect; session may have already been cleaned up",
-                            sessionId);
-            return;
-        }
+        // Schedule cleanup on Matter thread to ensure proper locking when calling RemoveSession.
+        // Safe to capture 'this' by value: WebRTCProviderManager is a member of the global CameraDevice
+        // object which has static storage duration and lives for the entire program lifetime.
+        DeviceLayer::SystemLayer().ScheduleLambda([this, sessionId]() {
+            WebrtcTransport * transport = GetTransport(sessionId);
+            if (transport == nullptr)
+            {
+                ChipLogProgress(Camera,
+                                "Transport not found for session %u during disconnect; session may have already been cleaned up",
+                                sessionId);
+                return;
+            }
 
-        // Connection was closed/disconnected by the peer - clean up the session
-        ChipLogProgress(Camera, "Peer connection closed for session %u, cleaning up resources", sessionId);
+            // Connection was closed/disconnected by the peer - clean up the session
+            ChipLogProgress(Camera, "Peer connection closed for session %u, cleaning up resources", sessionId);
 
-        // Release the Video and Audio Streams from the CameraAVStreamManagement
-        // cluster and update the reference counts.
-        ReleaseAudioVideoStreams(sessionId);
+            // Release the Video and Audio Streams from the CameraAVStreamManagement
+            // cluster and update the reference counts.
+            ReleaseAudioVideoStreams(sessionId);
 
-        // Capture args before unregistering in case the transport is invalidated
-        WebrtcTransport::RequestArgs args = transport->GetRequestArgs();
+            // Capture args before unregistering in case the transport is invalidated
+            WebrtcTransport::RequestArgs args = transport->GetRequestArgs();
 
-        // Unregister the transport from the media controller
-        UnregisterWebrtcTransport(sessionId);
+            // Unregister the transport from the media controller
+            UnregisterWebrtcTransport(sessionId);
 
-        // Remove from session maps
-        mSessionIdMap.erase(ScopedNodeId(args.peerNodeId, args.fabricIndex));
+            // Remove from session maps
+            mSessionIdMap.erase(ScopedNodeId(args.peerNodeId, args.fabricIndex));
 
-        // Remove from current sessions list in the WebRTC Transport Provider
-        if (mWebRTCTransportProvider != nullptr)
-        {
-            mWebRTCTransportProvider->RemoveSession(sessionId);
-        }
+            // Remove from current sessions list in the WebRTC Transport Provider
+            // This MUST be called on the Matter thread with the stack lock held
+            if (mWebRTCTransportProvider != nullptr)
+            {
+                mWebRTCTransportProvider->RemoveSession(sessionId);
+            }
 
-        // Finally, remove and destroy the transport
-        mWebrtcTransportMap.erase(sessionId);
+            // Finally, remove and destroy the transport
+            mWebrtcTransportMap.erase(sessionId);
 
-        ChipLogProgress(Camera, "Session %u cleanup completed", sessionId);
+            ChipLogProgress(Camera, "Session %u cleanup completed", sessionId);
+        });
     }
 }
 

src/app/clusters/webrtc-transport-provider-server/webrtc-transport-provider-server.cpp

@@ -160,6 +160,8 @@ WebRTCSessionStruct * WebRTCTransportProviderServer::FindSession(uint16_t sessio
 
 WebRTCTransportProviderServer::UpsertResultEnum WebRTCTransportProviderServer::UpsertSession(const WebRTCSessionStruct & session)
 {
+    assertChipStackLockedByCurrentThread();
+
     UpsertResultEnum result;
     auto it = std::find_if(mCurrentSessions.begin(), mCurrentSessions.end(),
                            [id = session.id](const auto & existing) { return existing.id == id; });
@@ -183,6 +185,8 @@ WebRTCTransportProviderServer::UpsertResultEnum WebRTCTransportProviderServer::U
 
 void WebRTCTransportProviderServer::RemoveSession(uint16_t sessionId)
 {
+    assertChipStackLockedByCurrentThread();
+
     size_t originalSize = mCurrentSessions.size();
 
     // Erase-Remove idiom