hle: kernel: Refactor to allocate a ServiceThread per service handler.

- Previously, we would allocate a thread per session, which adds new threads on CloneCurrentObject.
- This results in race conditions with N sessions queuing requests to the same service interface.
- Fixes Pokken Tournament DX crashes/softlocks, which were regressed by #6347.

src/core/hle/kernel/hle_ipc.cpp

@@ -30,9 +30,16 @@
 
 namespace Kernel {
 
-SessionRequestHandler::SessionRequestHandler() = default;
+SessionRequestHandler::SessionRequestHandler(KernelCore& kernel_, const char* service_name_)
+    : kernel{kernel_}, service_thread{kernel.CreateServiceThread(service_name_)} {}
 
-SessionRequestHandler::~SessionRequestHandler() = default;
+SessionRequestHandler::~SessionRequestHandler() {
+    kernel.ReleaseServiceThread(service_thread);
+}
+
+SessionRequestManager::SessionRequestManager(KernelCore& kernel_) : kernel{kernel_} {}
+
+SessionRequestManager::~SessionRequestManager() {}
 
 void SessionRequestHandler::ClientConnected(KServerSession* session) {
     session->SetSessionHandler(shared_from_this());

src/core/hle/kernel/hle_ipc.h

@@ -46,6 +46,7 @@ class KThread;
 class KReadableEvent;
 class KSession;
 class KWritableEvent;
+class ServiceThread;
 
 enum class ThreadWakeupReason;
 
@@ -56,7 +57,7 @@ enum class ThreadWakeupReason;
  */
 class SessionRequestHandler : public std::enable_shared_from_this<SessionRequestHandler> {
 public:
-    SessionRequestHandler();
+    SessionRequestHandler(KernelCore& kernel, const char* service_name_);
     virtual ~SessionRequestHandler();
 
     /**
@@ -83,6 +84,14 @@ public:
      * @param server_session ServerSession associated with the connection.
      */
     void ClientDisconnected(KServerSession* session);
+
+    std::weak_ptr<ServiceThread> GetServiceThread() const {
+        return service_thread;
+    }
+
+protected:
+    KernelCore& kernel;
+    std::weak_ptr<ServiceThread> service_thread;
 };
 
 using SessionRequestHandlerPtr = std::shared_ptr<SessionRequestHandler>;
@@ -94,7 +103,8 @@ using SessionRequestHandlerPtr = std::shared_ptr<SessionRequestHandler>;
  */
 class SessionRequestManager final {
 public:
-    SessionRequestManager() = default;
+    explicit SessionRequestManager(KernelCore& kernel);
+    ~SessionRequestManager();
 
     bool IsDomain() const {
         return is_domain;
@@ -142,10 +152,18 @@ public:
         session_handler = std::move(handler);
     }
 
+    std::weak_ptr<ServiceThread> GetServiceThread() const {
+        return session_handler->GetServiceThread();
+    }
+
 private:
     bool is_domain{};
     SessionRequestHandlerPtr session_handler;
     std::vector<SessionRequestHandlerPtr> domain_handlers;
+
+private:
+    KernelCore& kernel;
+    std::weak_ptr<ServiceThread> service_thread;
 };
 
 /**

src/core/hle/kernel/k_client_port.cpp

@@ -56,7 +56,8 @@ bool KClientPort::IsSignaled() const {
     return num_sessions < max_sessions;
 }
 
-ResultCode KClientPort::CreateSession(KClientSession** out) {
+ResultCode KClientPort::CreateSession(KClientSession** out,
+                                      std::shared_ptr<SessionRequestManager> session_manager) {
     // Reserve a new session from the resource limit.
     KScopedResourceReservation session_reservation(kernel.CurrentProcess()->GetResourceLimit(),
                                                    LimitableResource::Sessions);
@@ -101,7 +102,7 @@ ResultCode KClientPort::CreateSession(KClientSession** out) {
     }
 
     // Initialize the session.
-    session->Initialize(this, parent->GetName());
+    session->Initialize(this, parent->GetName(), session_manager);
 
     // Commit the session reservation.
     session_reservation.Commit();

src/core/hle/kernel/k_client_port.h

@@ -16,6 +16,7 @@ namespace Kernel {
 class KClientSession;
 class KernelCore;
 class KPort;
+class SessionRequestManager;
 
 class KClientPort final : public KSynchronizationObject {
     KERNEL_AUTOOBJECT_TRAITS(KClientPort, KSynchronizationObject);
@@ -52,7 +53,8 @@ public:
     void Destroy() override;
     bool IsSignaled() const override;
 
-    ResultCode CreateSession(KClientSession** out);
+    ResultCode CreateSession(KClientSession** out,
+                             std::shared_ptr<SessionRequestManager> session_manager = nullptr);
 
 private:
     std::atomic<s32> num_sessions{};

src/core/hle/kernel/k_server_session.cpp

@@ -13,8 +13,10 @@
 #include "core/hle/kernel/hle_ipc.h"
 #include "core/hle/kernel/k_client_port.h"
 #include "core/hle/kernel/k_handle_table.h"
+#include "core/hle/kernel/k_port.h"
 #include "core/hle/kernel/k_process.h"
 #include "core/hle/kernel/k_scheduler.h"
+#include "core/hle/kernel/k_server_port.h"
 #include "core/hle/kernel/k_server_session.h"
 #include "core/hle/kernel/k_session.h"
 #include "core/hle/kernel/k_thread.h"
@@ -23,18 +25,21 @@
 
 namespace Kernel {
 
-KServerSession::KServerSession(KernelCore& kernel_)
-    : KSynchronizationObject{kernel_}, manager{std::make_shared<SessionRequestManager>()} {}
+KServerSession::KServerSession(KernelCore& kernel_) : KSynchronizationObject{kernel_} {}
 
-KServerSession::~KServerSession() {
-    kernel.ReleaseServiceThread(service_thread);
-}
+KServerSession::~KServerSession() {}
 
-void KServerSession::Initialize(KSession* parent_, std::string&& name_) {
+void KServerSession::Initialize(KSession* parent_, std::string&& name_,
+                                std::shared_ptr<SessionRequestManager> manager_) {
     // Set member variables.
     parent = parent_;
     name = std::move(name_);
-    service_thread = kernel.CreateServiceThread(name);
+
+    if (manager_) {
+        manager = manager_;
+    } else {
+        manager = std::make_shared<SessionRequestManager>(kernel);
+    }
 }
 
 void KServerSession::Destroy() {
@@ -114,7 +119,7 @@ ResultCode KServerSession::QueueSyncRequest(KThread* thread, Core::Memory::Memor
 
     context->PopulateFromIncomingCommandBuffer(kernel.CurrentProcess()->GetHandleTable(), cmd_buf);
 
-    if (auto strong_ptr = service_thread.lock()) {
+    if (auto strong_ptr = manager->GetServiceThread().lock()) {
         strong_ptr->QueueSyncRequest(*parent, std::move(context));
         return ResultSuccess;
     }

src/core/hle/kernel/k_server_session.h

@@ -32,6 +32,7 @@ class HLERequestContext;
 class KernelCore;
 class KSession;
 class SessionRequestHandler;
+class SessionRequestManager;
 class KThread;
 
 class KServerSession final : public KSynchronizationObject,
@@ -46,7 +47,8 @@ public:
 
     void Destroy() override;
 
-    void Initialize(KSession* parent_, std::string&& name_);
+    void Initialize(KSession* parent_, std::string&& name_,
+                    std::shared_ptr<SessionRequestManager> manager_);
 
     KSession* GetParent() {
         return parent;
@@ -104,16 +106,6 @@ public:
         return manager;
     }
 
-    /// Gets the session request manager, which forwards requests to the underlying service
-    const std::shared_ptr<SessionRequestManager>& GetSessionRequestManager() const {
-        return manager;
-    }
-
-    /// Sets the session request manager, which forwards requests to the underlying service
-    void SetSessionRequestManager(std::shared_ptr<SessionRequestManager> manager_) {
-        manager = std::move(manager_);
-    }
-
 private:
     /// Queues a sync request from the emulated application.
     ResultCode QueueSyncRequest(KThread* thread, Core::Memory::Memory& memory);
@@ -131,9 +123,6 @@ private:
     /// When set to True, converts the session to a domain at the end of the command
     bool convert_to_domain{};
 
-    /// Thread to dispatch service requests
-    std::weak_ptr<ServiceThread> service_thread;
-
     /// KSession that owns this KServerSession
     KSession* parent{};
 };

src/core/hle/kernel/k_session.cpp

@@ -15,7 +15,8 @@ KSession::KSession(KernelCore& kernel_)
     : KAutoObjectWithSlabHeapAndContainer{kernel_}, server{kernel_}, client{kernel_} {}
 KSession::~KSession() = default;
 
-void KSession::Initialize(KClientPort* port_, const std::string& name_) {
+void KSession::Initialize(KClientPort* port_, const std::string& name_,
+                          std::shared_ptr<SessionRequestManager> manager_) {
     // Increment reference count.
     // Because reference count is one on creation, this will result
     // in a reference count of two. Thus, when both server and client are closed
@@ -27,7 +28,7 @@ void KSession::Initialize(KClientPort* port_, const std::string& name_) {
     KAutoObject::Create(std::addressof(client));
 
     // Initialize our sub sessions.
-    server.Initialize(this, name_ + ":Server");
+    server.Initialize(this, name_ + ":Server", manager_);
     client.Initialize(this, name_ + ":Client");
 
     // Set state and name.

src/core/hle/kernel/k_session.h

@@ -13,6 +13,8 @@
 
 namespace Kernel {
 
+class SessionRequestManager;
+
 class KSession final : public KAutoObjectWithSlabHeapAndContainer<KSession, KAutoObjectWithList> {
     KERNEL_AUTOOBJECT_TRAITS(KSession, KAutoObject);
 
@@ -20,7 +22,8 @@ public:
     explicit KSession(KernelCore& kernel_);
     ~KSession() override;
 
-    void Initialize(KClientPort* port_, const std::string& name_);
+    void Initialize(KClientPort* port_, const std::string& name_,
+                    std::shared_ptr<SessionRequestManager> manager_ = nullptr);
 
     void Finalize() override;