core: Switch to unique_ptr for usage of Common::Fiber.

- With using unique_ptr instead of shared_ptr, we have more explicit ownership of the context.
- Fixes a memory leak due to circular reference of the shared pointer.

5 files changed, 24 insertions, 23 deletions

diff --git a/src/core/hle/kernel/k_scheduler.cpp b/src/core/hle/kernel/k_scheduler.cpp
index bb5f43b53..465036f3d 100644
--- a/src/core/hle/kernel/k_scheduler.cpp
+++ b/src/core/hle/kernel/k_scheduler.cpp
@@ -608,7 +608,7 @@ void KScheduler::YieldToAnyThread(KernelCore& kernel) {
 }
 
 KScheduler::KScheduler(Core::System& system, s32 core_id) : system(system), core_id(core_id) {
-    switch_fiber = std::make_shared<Common::Fiber>(OnSwitch, this);
+    switch_fiber = std::make_unique<Common::Fiber>(OnSwitch, this);
     state.needs_scheduling.store(true);
     state.interrupt_task_thread_runnable = false;
     state.should_count_idle = false;
@@ -726,15 +726,15 @@ void KScheduler::ScheduleImpl() {
     // Save context for previous thread
     Unload(previous_thread);
 
-    std::shared_ptr<Common::Fiber>* old_context;
+    Common::Fiber* old_context;
     if (previous_thread != nullptr) {
-        old_context = &previous_thread->GetHostContext();
+        old_context = previous_thread->GetHostContext();
     } else {
-        old_context = &idle_thread->GetHostContext();
+        old_context = idle_thread->GetHostContext();
     }
     guard.unlock();
 
-    Common::Fiber::YieldTo(*old_context, switch_fiber);
+    Common::Fiber::YieldTo(old_context, switch_fiber.get());
     /// When a thread wakes up, the scheduler may have changed to other in another core.
     auto& next_scheduler = *system.Kernel().CurrentScheduler();
     next_scheduler.SwitchContextStep2();
@@ -769,13 +769,13 @@ void KScheduler::SwitchToCurrent() {
                     break;
                 }
             }
-            std::shared_ptr<Common::Fiber>* next_context;
+            Common::Fiber* next_context;
             if (next_thread != nullptr) {
-                next_context = &next_thread->GetHostContext();
+                next_context = next_thread->GetHostContext();
             } else {
-                next_context = &idle_thread->GetHostContext();
+                next_context = idle_thread->GetHostContext();
             }
-            Common::Fiber::YieldTo(switch_fiber, *next_context);
+            Common::Fiber::YieldTo(switch_fiber.get(), next_context);
         } while (!is_switch_pending());
     }
 }
diff --git a/src/core/hle/kernel/k_scheduler.h b/src/core/hle/kernel/k_scheduler.h
index f595b9a5c..a4285c595 100644
--- a/src/core/hle/kernel/k_scheduler.h
+++ b/src/core/hle/kernel/k_scheduler.h
@@ -68,12 +68,12 @@ public:
 
     void OnThreadStart();
 
-    [[nodiscard]] std::shared_ptr<Common::Fiber>& ControlContext() {
-        return switch_fiber;
+    [[nodiscard]] Common::Fiber* ControlContext() {
+        return switch_fiber.get();
     }
 
-    [[nodiscard]] const std::shared_ptr<Common::Fiber>& ControlContext() const {
-        return switch_fiber;
+    [[nodiscard]] const Common::Fiber* ControlContext() const {
+        return switch_fiber.get();
     }
 
     [[nodiscard]] u64 UpdateHighestPriorityThread(KThread* highest_thread);
@@ -178,7 +178,7 @@ private:
 
     KThread* idle_thread;
 
-    std::shared_ptr<Common::Fiber> switch_fiber{};
+    std::unique_ptr<Common::Fiber> switch_fiber{};
 
     struct SchedulingState {
         std::atomic<bool> needs_scheduling;
diff --git a/src/core/hle/kernel/k_thread.cpp b/src/core/hle/kernel/k_thread.cpp
index 1661afbd9..f49e31b72 100644
--- a/src/core/hle/kernel/k_thread.cpp
+++ b/src/core/hle/kernel/k_thread.cpp
@@ -991,10 +991,6 @@ void KThread::SetState(ThreadState state) {
     }
 }
 
-std::shared_ptr<Common::Fiber>& KThread::GetHostContext() {
-    return host_context;
-}
-
 ResultVal<std::shared_ptr<KThread>> KThread::Create(Core::System& system, ThreadType type_flags,
                                                     std::string name, VAddr entry_point,
                                                     u32 priority, u64 arg, s32 processor_id,
@@ -1028,7 +1024,7 @@ ResultVal<std::shared_ptr<KThread>> KThread::Create(Core::System& system, Thread
     scheduler.AddThread(thread);
 
     thread->host_context =
-        std::make_shared<Common::Fiber>(std::move(thread_start_func), thread_start_parameter);
+        std::make_unique<Common::Fiber>(std::move(thread_start_func), thread_start_parameter);
 
     return MakeResult<std::shared_ptr<KThread>>(std::move(thread));
 }
diff --git a/src/core/hle/kernel/k_thread.h b/src/core/hle/kernel/k_thread.h
index c8ac656a4..a2893d939 100644
--- a/src/core/hle/kernel/k_thread.h
+++ b/src/core/hle/kernel/k_thread.h
@@ -293,7 +293,13 @@ public:
         return thread_context_64;
     }
 
-    [[nodiscard]] std::shared_ptr<Common::Fiber>& GetHostContext();
+    [[nodiscard]] Common::Fiber* GetHostContext() {
+        return host_context.get();
+    }
+
+    [[nodiscard]] const Common::Fiber* GetHostContext() const {
+        return host_context.get();
+    }
 
     [[nodiscard]] ThreadState GetState() const {
         return thread_state & ThreadState::Mask;
@@ -719,7 +725,7 @@ private:
     Common::SpinLock context_guard{};
 
     // For emulation
-    std::shared_ptr<Common::Fiber> host_context{};
+    std::unique_ptr<Common::Fiber> host_context{};
 
     // For debugging
     std::vector<KSynchronizationObject*> wait_objects_for_debugging;
diff --git a/src/core/hle/kernel/svc.cpp b/src/core/hle/kernel/svc.cpp
index cc8fa6576..d04116115 100644
--- a/src/core/hle/kernel/svc.cpp
+++ b/src/core/hle/kernel/svc.cpp
@@ -2626,8 +2626,7 @@ void Call(Core::System& system, u32 immediate) {
     kernel.ExitSVCProfile();
 
     if (!thread->IsCallingSvc()) {
-        auto* host_context = thread->GetHostContext().get();
-        host_context->Rewind();
+        thread->GetHostContext()->Rewind();
     }
 
     system.EnterDynarmicProfile();