kernel: Fix reference management for client/server session.

- Fixes shutdown crash and crash in Pokemon SwSh.

src/core/hle/kernel/client_session.cpp

@@ -16,20 +16,18 @@ ClientSession::ClientSession(KernelCore& kernel) : Object{kernel} {}
 ClientSession::~ClientSession() {
     // This destructor will be called automatically when the last ClientSession handle is closed by
     // the emulated application.
-    if (parent->server) {
-        parent->server->ClientDisconnected();
+    if (auto server = parent->server.lock()) {
+        server->ClientDisconnected();
     }
-
-    parent->client = nullptr;
 }
 
 ResultCode ClientSession::SendSyncRequest(Thread* thread) {
-    // Keep ServerSession alive until we're done working with it.
-    if (parent->server == nullptr)
-        return ERR_SESSION_CLOSED_BY_REMOTE;
-
     // Signal the server session that new data is available
-    return parent->server->HandleSyncRequest(SharedFrom(thread));
+    if (auto server = parent->server.lock()) {
+        return server->HandleSyncRequest(SharedFrom(thread));
+    }
+
+    return ERR_SESSION_CLOSED_BY_REMOTE;
 }
 
 } // namespace Kernel

src/core/hle/kernel/server_session.cpp

@@ -31,8 +31,6 @@ ServerSession::~ServerSession() {
     if (parent->port) {
         parent->port->ConnectionClosed();
     }
-
-    parent->server = nullptr;
 }
 
 ResultVal<std::shared_ptr<ServerSession>> ServerSession::Create(KernelCore& kernel,
@@ -46,13 +44,15 @@ ResultVal<std::shared_ptr<ServerSession>> ServerSession::Create(KernelCore& kern
 }
 
 bool ServerSession::ShouldWait(const Thread* thread) const {
-    // Closed sessions should never wait, an error will be returned from svcReplyAndReceive.
-    if (parent->client == nullptr)
-        return false;
     // Wait if we have no pending requests, or if we're currently handling a request.
+    if (auto client = parent->client.lock()) {
         return pending_requesting_threads.empty() || currently_handling != nullptr;
     }
 
+    // Closed sessions should never wait, an error will be returned from svcReplyAndReceive.
+    return {};
+}
+
 void ServerSession::Acquire(Thread* thread) {
     ASSERT_MSG(!ShouldWait(thread), "object unavailable!");
     // We are now handling a request, pop it from the stack.
@@ -192,9 +192,9 @@ ServerSession::SessionPair ServerSession::CreateSessionPair(KernelCore& kernel,
     std::shared_ptr<ClientSession> client_session = std::make_shared<ClientSession>(kernel);
     client_session->name = name + "_Client";
 
-    std::shared_ptr<Session> parent(new Session);
-    parent->client = client_session.get();
-    parent->server = server_session.get();
+    std::shared_ptr<Session> parent = std::make_shared<Session>();
+    parent->client = client_session;
+    parent->server = server_session;
     parent->port = std::move(port);
 
     client_session->parent = parent;

src/core/hle/kernel/session.h

@@ -20,8 +20,8 @@ class ServerSession;
  */
 class Session final {
 public:
-    ClientSession* client = nullptr;  ///< The client endpoint of the session.
-    ServerSession* server = nullptr;  ///< The server endpoint of the session.
+    std::weak_ptr<ClientSession> client; ///< The client endpoint of the session.
+    std::weak_ptr<ServerSession> server; ///< The server endpoint of the session.
     std::shared_ptr<ClientPort> port; ///< The port that this session is associated with (optional).
 };
 } // namespace Kernel