Merge pull request #495 from bunnei/fix-waitsynch

Fix WaitSynchronization

src/core/hle/kernel/address_arbiter.cpp

@@ -30,7 +30,8 @@ public:
 
 /// Arbitrate an address
 ResultCode ArbitrateAddress(Handle handle, ArbitrationType type, u32 address, s32 value, u64 nanoseconds) {
-    Object* object = Kernel::g_handle_table.GetGeneric(handle).get();
+    AddressArbiter* object = Kernel::g_handle_table.Get<AddressArbiter>(handle).get();
+
     if (object == nullptr)
         return InvalidHandle(ErrorModule::Kernel);
 
@@ -40,24 +41,24 @@ ResultCode ArbitrateAddress(Handle handle, ArbitrationType type, u32 address, s3
     case ArbitrationType::Signal:
         // Negative value means resume all threads
         if (value < 0) {
-            ArbitrateAllThreads(object, address);
+            ArbitrateAllThreads(address);
         } else {
             // Resume first N threads
             for(int i = 0; i < value; i++)
-                ArbitrateHighestPriorityThread(object, address);
+                ArbitrateHighestPriorityThread(address);
         }
         break;
 
     // Wait current thread (acquire the arbiter)...
     case ArbitrationType::WaitIfLessThan:
         if ((s32)Memory::Read32(address) <= value) {
-            Kernel::WaitCurrentThread(WAITTYPE_ARB, object, address);
+            Kernel::WaitCurrentThread_ArbitrateAddress(address);
             HLE::Reschedule(__func__);
         }
         break;
     case ArbitrationType::WaitIfLessThanWithTimeout:
         if ((s32)Memory::Read32(address) <= value) {
-            Kernel::WaitCurrentThread(WAITTYPE_ARB, object, address);
+            Kernel::WaitCurrentThread_ArbitrateAddress(address);
             Kernel::WakeThreadAfterDelay(GetCurrentThread(), nanoseconds);
             HLE::Reschedule(__func__);
         }
@@ -67,7 +68,7 @@ ResultCode ArbitrateAddress(Handle handle, ArbitrationType type, u32 address, s3
         s32 memory_value = Memory::Read32(address) - 1;
         Memory::Write32(address, memory_value);
         if (memory_value <= value) {
-            Kernel::WaitCurrentThread(WAITTYPE_ARB, object, address);
+            Kernel::WaitCurrentThread_ArbitrateAddress(address);
             HLE::Reschedule(__func__);
         }
         break;
@@ -77,7 +78,7 @@ ResultCode ArbitrateAddress(Handle handle, ArbitrationType type, u32 address, s3
         s32 memory_value = Memory::Read32(address) - 1;
         Memory::Write32(address, memory_value);
         if (memory_value <= value) {
-            Kernel::WaitCurrentThread(WAITTYPE_ARB, object, address);
+            Kernel::WaitCurrentThread_ArbitrateAddress(address);
             Kernel::WakeThreadAfterDelay(GetCurrentThread(), nanoseconds);
             HLE::Reschedule(__func__);
         }

src/core/hle/kernel/event.cpp

@@ -14,7 +14,7 @@
 
 namespace Kernel {
 
-class Event : public Object {
+class Event : public WaitObject {
 public:
     std::string GetTypeName() const override { return "Event"; }
     std::string GetName() const override { return name; }
@@ -25,99 +25,40 @@ public:
     ResetType intitial_reset_type;          ///< ResetType specified at Event initialization
     ResetType reset_type;                   ///< Current ResetType
 
-    bool locked;                            ///< Event signal wait
+    bool signaled;                          ///< Whether the event has already been signaled
-    bool permanent_locked;                  ///< Hack - to set event permanent state (for easy passthrough)
-    std::vector<Handle> waiting_threads;    ///< Threads that are waiting for the event
     std::string name;                       ///< Name of event (optional)
 
-    ResultVal<bool> WaitSynchronization() override {
+    bool ShouldWait() override {
-        bool wait = locked;
+        return !signaled;
-        if (locked) {
+    }
-            Handle thread = GetCurrentThread()->GetHandle();
+
-            if (std::find(waiting_threads.begin(), waiting_threads.end(), thread) == waiting_threads.end()) {
+    void Acquire() override {
-                waiting_threads.push_back(thread);
+        _assert_msg_(Kernel, !ShouldWait(), "object unavailable!");
-            }
+
-            Kernel::WaitCurrentThread(WAITTYPE_EVENT, this);
+        // Release the event if it's not sticky...
-        }
+        if (reset_type != RESETTYPE_STICKY)
-        if (reset_type != RESETTYPE_STICKY && !permanent_locked) {
+            signaled = false;
-            locked = true;
-        }
-        return MakeResult<bool>(wait);
     }
 };
 
-/**
- * Hackish function to set an events permanent lock state, used to pass through synch blocks
- * @param handle Handle to event to change
- * @param permanent_locked Boolean permanent locked value to set event
- * @return Result of operation, 0 on success, otherwise error code
- */
-ResultCode SetPermanentLock(Handle handle, const bool permanent_locked) {
-    Event* evt = g_handle_table.Get<Event>(handle).get();
-    if (evt == nullptr) return InvalidHandle(ErrorModule::Kernel);
-
-    evt->permanent_locked = permanent_locked;
-    return RESULT_SUCCESS;
-}
-
-/**
- * Changes whether an event is locked or not
- * @param handle Handle to event to change
- * @param locked Boolean locked value to set event
- * @return Result of operation, 0 on success, otherwise error code
- */
-ResultCode SetEventLocked(const Handle handle, const bool locked) {
-    Event* evt = g_handle_table.Get<Event>(handle).get();
-    if (evt == nullptr) return InvalidHandle(ErrorModule::Kernel);
-
-    if (!evt->permanent_locked) {
-        evt->locked = locked;
-    }
-    return RESULT_SUCCESS;
-}
-
-/**
- * Signals an event
- * @param handle Handle to event to signal
- * @return Result of operation, 0 on success, otherwise error code
- */
 ResultCode SignalEvent(const Handle handle) {
     Event* evt = g_handle_table.Get<Event>(handle).get();
-    if (evt == nullptr) return InvalidHandle(ErrorModule::Kernel);
+    if (evt == nullptr)
+        return InvalidHandle(ErrorModule::Kernel);
 
-    // Resume threads waiting for event to signal
+    evt->signaled = true;
-    bool event_caught = false;
+    evt->WakeupAllWaitingThreads();
-    for (size_t i = 0; i < evt->waiting_threads.size(); ++i) {
-        Thread* thread = Kernel::g_handle_table.Get<Thread>(evt->waiting_threads[i]).get();
-        if (thread != nullptr)
-            thread->ResumeFromWait();
 
-        // If any thread is signalled awake by this event, assume the event was "caught" and reset
-        // the event. This will result in the next thread waiting on the event to block. Otherwise,
-        // the event will not be reset, and the next thread to call WaitSynchronization on it will
-        // not block. Not sure if this is correct behavior, but it seems to work.
-        event_caught = true;
-    }
-    evt->waiting_threads.clear();
-
-    if (!evt->permanent_locked) {
-        evt->locked = event_caught;
-    }
     return RESULT_SUCCESS;
 }
 
-/**
- * Clears an event
- * @param handle Handle to event to clear
- * @return Result of operation, 0 on success, otherwise error code
- */
 ResultCode ClearEvent(Handle handle) {
     Event* evt = g_handle_table.Get<Event>(handle).get();
-    if (evt == nullptr) return InvalidHandle(ErrorModule::Kernel);
+    if (evt == nullptr)
+        return InvalidHandle(ErrorModule::Kernel);
+
+    evt->signaled = false;
 
-    if (!evt->permanent_locked) {
-        evt->locked = true;
-    }
     return RESULT_SUCCESS;
 }
 
@@ -134,20 +75,13 @@ Event* CreateEvent(Handle& handle, const ResetType reset_type, const std::string
     // TOOD(yuriks): Fix error reporting
     handle = Kernel::g_handle_table.Create(evt).ValueOr(INVALID_HANDLE);
 
-    evt->locked = true;
+    evt->signaled = false;
-    evt->permanent_locked = false;
     evt->reset_type = evt->intitial_reset_type = reset_type;
     evt->name = name;
 
     return evt;
 }
 
-/**
- * Creates an event
- * @param reset_type ResetType describing how to create event
- * @param name Optional name of event
- * @return Handle to newly created Event object
- */
 Handle CreateEvent(const ResetType reset_type, const std::string& name) {
     Handle handle;
     Event* evt = CreateEvent(handle, reset_type, name);

src/core/hle/kernel/event.h

@@ -11,29 +11,17 @@
 
 namespace Kernel {
 
-/**
- * Changes whether an event is locked or not
- * @param handle Handle to event to change
- * @param locked Boolean locked value to set event
- */
-ResultCode SetEventLocked(const Handle handle, const bool locked);
-
-/**
- * Hackish function to set an events permanent lock state, used to pass through synch blocks
- * @param handle Handle to event to change
- * @param permanent_locked Boolean permanent locked value to set event
- */
-ResultCode SetPermanentLock(Handle handle, const bool permanent_locked);
-
 /**
  * Signals an event
  * @param handle Handle to event to signal
+ * @return Result of operation, 0 on success, otherwise error code
  */
 ResultCode SignalEvent(const Handle handle);
 
 /**
  * Clears an event
  * @param handle Handle to event to clear
+ * @return Result of operation, 0 on success, otherwise error code
  */
 ResultCode ClearEvent(Handle handle);
 

src/core/hle/kernel/kernel.cpp

@@ -18,6 +18,41 @@ SharedPtr<Thread> g_main_thread = nullptr;
 HandleTable g_handle_table;
 u64 g_program_id = 0;
 
+void WaitObject::AddWaitingThread(Thread* thread) {
+    auto itr = std::find(waiting_threads.begin(), waiting_threads.end(), thread);
+    if (itr == waiting_threads.end())
+        waiting_threads.push_back(thread);
+}
+
+void WaitObject::RemoveWaitingThread(Thread* thread) {
+    auto itr = std::find(waiting_threads.begin(), waiting_threads.end(), thread);
+    if (itr != waiting_threads.end())
+        waiting_threads.erase(itr);
+}
+
+Thread* WaitObject::WakeupNextThread() {
+    if (waiting_threads.empty())
+        return nullptr;
+
+    auto next_thread = waiting_threads.front();
+    waiting_threads.erase(waiting_threads.begin());
+
+    next_thread->ReleaseWaitObject(this);
+
+    return next_thread;
+}
+
+void WaitObject::WakeupAllWaitingThreads() {
+    auto waiting_threads_copy = waiting_threads;
+
+    // We use a copy because ReleaseWaitObject will remove the thread from this object's
+    // waiting_threads list
+    for (auto thread : waiting_threads_copy)
+        thread->ReleaseWaitObject(this);
+
+    _assert_msg_(Kernel, waiting_threads.empty(), "failed to awaken all waiting threads!");
+}
+
 HandleTable::HandleTable() {
     next_generation = 1;
     Clear();

src/core/hle/kernel/kernel.h

@@ -8,6 +8,8 @@
 
 #include <array>
 #include <string>
+#include <vector>
+
 #include "common/common.h"
 #include "core/hle/result.h"
 
@@ -58,17 +60,35 @@ class Object : NonCopyable {
 public:
     virtual ~Object() {}
     Handle GetHandle() const { return handle; }
+
     virtual std::string GetTypeName() const { return "[BAD KERNEL OBJECT TYPE]"; }
     virtual std::string GetName() const { return "[UNKNOWN KERNEL OBJECT]"; }
     virtual Kernel::HandleType GetHandleType() const = 0;
 
     /**
-     * Wait for kernel object to synchronize.
+     * Check if a thread can wait on the object
-     * @return True if the current thread should wait as a result of the wait
+     * @return True if a thread can wait on the object, otherwise false
      */
-    virtual ResultVal<bool> WaitSynchronization() {
+    bool IsWaitable() const {
-        LOG_ERROR(Kernel, "(UNIMPLEMENTED)");
+        switch (GetHandleType()) {
-        return UnimplementedFunction(ErrorModule::Kernel);
+        case HandleType::Session:
+        case HandleType::Event:
+        case HandleType::Mutex:
+        case HandleType::Thread:
+        case HandleType::Semaphore:
+        case HandleType::Timer:
+            return true;
+
+        case HandleType::Unknown:
+        case HandleType::Port:
+        case HandleType::SharedMemory:
+        case HandleType::Redirection:
+        case HandleType::Process:
+        case HandleType::AddressArbiter:
+            return false;
+        }
+
+        return false;
     }
 
 private:
@@ -92,6 +112,44 @@ inline void intrusive_ptr_release(Object* object) {
 template <typename T>
 using SharedPtr = boost::intrusive_ptr<T>;
 
+/// Class that represents a Kernel object that a thread can be waiting on
+class WaitObject : public Object {
+public:
+
+    /**
+     * Check if the current thread should wait until the object is available
+     * @return True if the current thread should wait due to this object being unavailable
+     */
+    virtual bool ShouldWait() = 0;
+
+    /// Acquire/lock the object if it is available
+    virtual void Acquire() = 0;
+
+    /**
+     * Add a thread to wait on this object
+     * @param thread Pointer to thread to add
+     */
+    void AddWaitingThread(Thread* thread);
+
+    /**
+     * Removes a thread from waiting on this object (e.g. if it was resumed already)
+     * @param thread Pointer to thread to remove
+     */
+    void RemoveWaitingThread(Thread* thead);
+
+    /**
+     * Wake up the next thread waiting on this object
+     * @return Pointer to the thread that was resumed, nullptr if no threads are waiting
+     */
+    Thread* WakeupNextThread();
+
+    /// Wake up all threads waiting on this object
+    void WakeupAllWaitingThreads();
+
+private:
+    std::vector<Thread*> waiting_threads; ///< Threads waiting for this object to become available
+};
+
 /**
  * This class allows the creation of Handles, which are references to objects that can be tested
  * for validity and looked up. Here they are used to pass references to kernel objects to/from the
@@ -146,14 +204,14 @@ public:
 
     /**
      * Looks up a handle.
-     * @returns Pointer to the looked-up object, or `nullptr` if the handle is not valid.
+     * @return Pointer to the looked-up object, or `nullptr` if the handle is not valid.
      */
     SharedPtr<Object> GetGeneric(Handle handle) const;
 
     /**
      * Looks up a handle while verifying its type.
-     * @returns Pointer to the looked-up object, or `nullptr` if the handle is not valid or its
+     * @return Pointer to the looked-up object, or `nullptr` if the handle is not valid or its
-     *          type differs from the handle type `T::HANDLE_TYPE`.
+     *         type differs from the handle type `T::HANDLE_TYPE`.
      */
     template <class T>
     SharedPtr<T> Get(Handle handle) const {
@@ -164,6 +222,19 @@ public:
         return nullptr;
     }
 
+    /**
+     * Looks up a handle while verifying that it is an object that a thread can wait on
+     * @return Pointer to the looked-up object, or `nullptr` if the handle is not valid or it is
+     *         not a waitable object.
+     */
+    SharedPtr<WaitObject> GetWaitObject(Handle handle) const {
+        SharedPtr<Object> object = GetGeneric(handle);
+        if (object != nullptr && object->IsWaitable()) {
+            return boost::static_pointer_cast<WaitObject>(std::move(object));
+        }
+        return nullptr;
+    }
+
     /// Closes all handles held in this table.
     void Clear();
 

src/core/hle/kernel/mutex.cpp

@@ -13,7 +13,7 @@
 
 namespace Kernel {
 
-class Mutex : public Object {
+class Mutex : public WaitObject {
 public:
     std::string GetTypeName() const override { return "Mutex"; }
     std::string GetName() const override { return name; }
@@ -23,39 +23,26 @@ public:
 
     bool initial_locked;                        ///< Initial lock state when mutex was created
     bool locked;                                ///< Current locked state
-    Handle lock_thread;                         ///< Handle to thread that currently has mutex
-    std::vector<Handle> waiting_threads;        ///< Threads that are waiting for the mutex
     std::string name;                           ///< Name of mutex (optional)
+    SharedPtr<Thread> holding_thread;           ///< Thread that has acquired the mutex
 
-    ResultVal<bool> WaitSynchronization() override;
+    bool ShouldWait() override;
+    void Acquire() override;
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-typedef std::multimap<Handle, Handle> MutexMap;
+typedef std::multimap<SharedPtr<Thread>, SharedPtr<Mutex>> MutexMap;
 static MutexMap g_mutex_held_locks;
 
 /**
  * Acquires the specified mutex for the specified thread
  * @param mutex Mutex that is to be acquired
- * @param thread Thread that will acquired
+ * @param thread Thread that will acquire the mutex
  */
-void MutexAcquireLock(Mutex* mutex, Handle thread = GetCurrentThread()->GetHandle()) {
+void MutexAcquireLock(Mutex* mutex, Thread* thread) {
-    g_mutex_held_locks.insert(std::make_pair(thread, mutex->GetHandle()));
+    g_mutex_held_locks.insert(std::make_pair(thread, mutex));
-    mutex->lock_thread = thread;
+    mutex->holding_thread = thread;
-}
-
-bool ReleaseMutexForThread(Mutex* mutex, Handle thread_handle) {
-    MutexAcquireLock(mutex, thread_handle);
-
-    Thread* thread = Kernel::g_handle_table.Get<Thread>(thread_handle).get();
-    if (thread == nullptr) {
-        LOG_ERROR(Kernel, "Called with invalid handle: %08X", thread_handle);
-        return false;
-    }
-
-    thread->ResumeFromWait();
-    return true;
 }
 
 /**
@@ -64,56 +51,41 @@ bool ReleaseMutexForThread(Mutex* mutex, Handle thread_handle) {
  */
 void ResumeWaitingThread(Mutex* mutex) {
     // Find the next waiting thread for the mutex...
-    if (mutex->waiting_threads.empty()) {
+    auto next_thread = mutex->WakeupNextThread();
+    if (next_thread != nullptr) {
+        MutexAcquireLock(mutex, next_thread);
+    } else {
         // Reset mutex lock thread handle, nothing is waiting
         mutex->locked = false;
-        mutex->lock_thread = -1;
+        mutex->holding_thread = nullptr;
-    }
-    else {
-        // Resume the next waiting thread and re-lock the mutex
-        std::vector<Handle>::iterator iter = mutex->waiting_threads.begin();
-        ReleaseMutexForThread(mutex, *iter);
-        mutex->waiting_threads.erase(iter);
     }
 }
 
-void MutexEraseLock(Mutex* mutex) {
+void ReleaseThreadMutexes(Thread* thread) {
-    Handle handle = mutex->GetHandle();
-    auto locked = g_mutex_held_locks.equal_range(mutex->lock_thread);
-    for (MutexMap::iterator iter = locked.first; iter != locked.second; ++iter) {
-        if (iter->second == handle) {
-            g_mutex_held_locks.erase(iter);
-            break;
-        }
-    }
-    mutex->lock_thread = -1;
-}
-
-void ReleaseThreadMutexes(Handle thread) {
     auto locked = g_mutex_held_locks.equal_range(thread);
     
     // Release every mutex that the thread holds, and resume execution on the waiting threads
-    for (MutexMap::iterator iter = locked.first; iter != locked.second; ++iter) {
+    for (auto iter = locked.first; iter != locked.second; ++iter) {
-        Mutex* mutex = g_handle_table.Get<Mutex>(iter->second).get();
+        ResumeWaitingThread(iter->second.get());
-        ResumeWaitingThread(mutex);
     }
 
     // Erase all the locks that this thread holds
     g_mutex_held_locks.erase(thread);
 }
 
-bool LockMutex(Mutex* mutex) {
-    // Mutex alread locked?
-    if (mutex->locked) {
-        return false;
-    }
-    MutexAcquireLock(mutex);
-    return true;
-}
-
 bool ReleaseMutex(Mutex* mutex) {
-    MutexEraseLock(mutex);
+    if (mutex->locked) {
-    ResumeWaitingThread(mutex);
+        auto locked = g_mutex_held_locks.equal_range(mutex->holding_thread);
+
+        for (MutexMap::iterator iter = locked.first; iter != locked.second; ++iter) {
+            if (iter->second == mutex) {
+                g_mutex_held_locks.erase(iter);
+                break;
+            }
+        }
+
+        ResumeWaitingThread(mutex);
+    }
     return true;
 }
 
@@ -148,15 +120,12 @@ Mutex* CreateMutex(Handle& handle, bool initial_locked, const std::string& name)
 
     mutex->locked = mutex->initial_locked = initial_locked;
     mutex->name = name;
+    mutex->holding_thread = nullptr;
 
     // Acquire mutex with current thread if initialized as locked...
-    if (mutex->locked) {
+    if (mutex->locked)
-        MutexAcquireLock(mutex);
+        MutexAcquireLock(mutex, GetCurrentThread());
 
-    // Otherwise, reset lock thread handle
-    } else {
-        mutex->lock_thread = -1;
-    }
     return mutex;
 }
 
@@ -172,17 +141,14 @@ Handle CreateMutex(bool initial_locked, const std::string& name) {
     return handle;
 }
 
-ResultVal<bool> Mutex::WaitSynchronization() {
+bool Mutex::ShouldWait() {
-    bool wait = locked;
+    return locked && holding_thread != GetCurrentThread();
-    if (locked) {
-        waiting_threads.push_back(GetCurrentThread()->GetHandle());
-        Kernel::WaitCurrentThread(WAITTYPE_MUTEX, this);
-    } else {
-        // Lock the mutex when the first thread accesses it
-        locked = true;
-        MutexAcquireLock(this);
-    }
-
-    return MakeResult<bool>(wait);
 }
+
+void Mutex::Acquire() {
+    _assert_msg_(Kernel, !ShouldWait(), "object unavailable!");
+    locked = true;
+    MutexAcquireLock(this, GetCurrentThread());
+}
+
 } // namespace

src/core/hle/kernel/mutex.h

@@ -28,6 +28,6 @@ Handle CreateMutex(bool initial_locked, const std::string& name="Unknown");
  * Releases all the mutexes held by the specified thread
  * @param thread Thread that is holding the mutexes
  */
-void ReleaseThreadMutexes(Handle thread);
+void ReleaseThreadMutexes(Thread* thread);
 
 } // namespace

src/core/hle/kernel/semaphore.cpp

@@ -12,7 +12,7 @@
 
 namespace Kernel {
 
-class Semaphore : public Object {
+class Semaphore : public WaitObject {
 public:
     std::string GetTypeName() const override { return "Semaphore"; }
     std::string GetName() const override { return name; }
@@ -22,28 +22,15 @@ public:
 
     s32 max_count;                              ///< Maximum number of simultaneous holders the semaphore can have
     s32 available_count;                        ///< Number of free slots left in the semaphore
-    std::queue<Handle> waiting_threads;         ///< Threads that are waiting for the semaphore
     std::string name;                           ///< Name of semaphore (optional)
 
-    /**
+    bool ShouldWait() override {
-     * Tests whether a semaphore still has free slots
+        return available_count <= 0;
-     * @return Whether the semaphore is available
-     */
-    bool IsAvailable() const {
-        return available_count > 0;
     }
 
-    ResultVal<bool> WaitSynchronization() override {
+    void Acquire() override {
-        bool wait = !IsAvailable();
+        _assert_msg_(Kernel, !ShouldWait(), "object unavailable!");
-
+        --available_count;
-        if (wait) {
-            Kernel::WaitCurrentThread(WAITTYPE_SEMA, this);
-            waiting_threads.push(GetCurrentThread()->GetHandle());
-        } else {
-            --available_count;
-        }
-
-        return MakeResult<bool>(wait);
     }
 };
 
@@ -83,12 +70,8 @@ ResultCode ReleaseSemaphore(s32* count, Handle handle, s32 release_count) {
 
     // Notify some of the threads that the semaphore has been released
     // stop once the semaphore is full again or there are no more waiting threads
-    while (!semaphore->waiting_threads.empty() && semaphore->IsAvailable()) {
+    while (!semaphore->ShouldWait() && semaphore->WakeupNextThread() != nullptr) {
-        Thread* thread = Kernel::g_handle_table.Get<Thread>(semaphore->waiting_threads.front()).get();
+        semaphore->Acquire();
-        if (thread != nullptr)
-            thread->ResumeFromWait();
-        semaphore->waiting_threads.pop();
-        --semaphore->available_count;
     }
 
     return RESULT_SUCCESS;

src/core/hle/kernel/session.h

@@ -41,7 +41,7 @@ inline static u32* GetCommandBuffer(const int offset=0) {
  * CTR-OS so that IPC calls can be optionally handled by the real implementations of processes, as
  * opposed to HLE simulations.
  */
-class Session : public Object {
+class Session : public WaitObject {
 public:
     std::string GetTypeName() const override { return "Session"; }
 
@@ -53,6 +53,17 @@ public:
      * aren't supported yet.
      */
     virtual ResultVal<bool> SyncRequest() = 0;
+
+    // TODO(bunnei): These functions exist to satisfy a hardware test with a Session object
+    // passed into WaitSynchronization. Figure out the meaning of them.
+
+    bool ShouldWait() override {
+        return true;
+    }
+
+    void Acquire() override {
+        _assert_msg_(Kernel, !ShouldWait(), "object unavailable!");
+    }
 };
 
 }

src/core/hle/kernel/thread.cpp

@@ -22,17 +22,12 @@
 
 namespace Kernel {
 
-ResultVal<bool> Thread::WaitSynchronization() {
+bool Thread::ShouldWait() {
-    const bool wait = status != THREADSTATUS_DORMANT;
+    return status != THREADSTATUS_DORMANT;
-    if (wait) {
+}
-        Thread* thread = GetCurrentThread();
-        if (std::find(waiting_threads.begin(), waiting_threads.end(), thread) == waiting_threads.end()) {
-            waiting_threads.push_back(thread);
-        }
-        WaitCurrentThread(WAITTYPE_THREADEND, this);
-    }
 
-    return MakeResult<bool>(wait);
+void Thread::Acquire() {
+    _assert_msg_(Kernel, !ShouldWait(), "object unavailable!");
 }
 
 // Lists all thread ids that aren't deleted/etc.
@@ -67,8 +62,8 @@ static void ResetThread(Thread* t, u32 arg, s32 lowest_priority) {
     if (t->current_priority < lowest_priority) {
         t->current_priority = t->initial_priority;
     }
-    t->wait_type = WAITTYPE_NONE;
+
-    t->wait_object = nullptr;
+    t->wait_objects.clear();
     t->wait_address = 0;
 }
 
@@ -88,37 +83,32 @@ static void ChangeReadyState(Thread* t, bool ready) {
     }
 }
 
-/// Check if a thread is blocking on a specified wait type
+/// Check if a thread is waiting on a the specified wait object
-static bool CheckWaitType(const Thread* thread, WaitType type) {
+static bool CheckWait_WaitObject(const Thread* thread, WaitObject* wait_object) {
-    return (type == thread->wait_type) && (thread->IsWaiting());
+    auto itr = std::find(thread->wait_objects.begin(), thread->wait_objects.end(), wait_object);
+
+    if (itr != thread->wait_objects.end())
+        return thread->IsWaiting();
+
+    return false;
 }
 
-/// Check if a thread is blocking on a specified wait type with a specified handle
+/// Check if the specified thread is waiting on the specified address to be arbitrated
-static bool CheckWaitType(const Thread* thread, WaitType type, Object* wait_object) {
+static bool CheckWait_AddressArbiter(const Thread* thread, VAddr wait_address) {
-    return CheckWaitType(thread, type) && wait_object == thread->wait_object;
+    return thread->IsWaiting() && thread->wait_objects.empty() && wait_address == thread->wait_address;
-}
-
-/// Check if a thread is blocking on a specified wait type with a specified handle and address
-static bool CheckWaitType(const Thread* thread, WaitType type, Object* wait_object, VAddr wait_address) {
-    return CheckWaitType(thread, type, wait_object) && (wait_address == thread->wait_address);
 }
 
 /// Stops the current thread
 void Thread::Stop(const char* reason) {
     // Release all the mutexes that this thread holds
-    ReleaseThreadMutexes(GetHandle());
+    ReleaseThreadMutexes(this);
 
     ChangeReadyState(this, false);
     status = THREADSTATUS_DORMANT;
-    for (auto& waiting_thread : waiting_threads) {
+    WakeupAllWaitingThreads();
-        if (CheckWaitType(waiting_thread.get(), WAITTYPE_THREADEND, this))
-            waiting_thread->ResumeFromWait();
-    }
-    waiting_threads.clear();
 
     // Stopped threads are never waiting.
-    wait_type = WAITTYPE_NONE;
+    wait_objects.clear();
-    wait_object = nullptr;
     wait_address = 0;
 }
 
@@ -129,26 +119,20 @@ static void ChangeThreadState(Thread* t, ThreadStatus new_status) {
     }
     ChangeReadyState(t, (new_status & THREADSTATUS_READY) != 0);
     t->status = new_status;
-
-    if (new_status == THREADSTATUS_WAIT) {
-        if (t->wait_type == WAITTYPE_NONE) {
-            LOG_ERROR(Kernel, "Waittype none not allowed");
-        }
-    }
 }
 
 /// Arbitrate the highest priority thread that is waiting
-Thread* ArbitrateHighestPriorityThread(Object* arbiter, u32 address) {
+Thread* ArbitrateHighestPriorityThread(u32 address) {
     Thread* highest_priority_thread = nullptr;
     s32 priority = THREADPRIO_LOWEST;
 
     // Iterate through threads, find highest priority thread that is waiting to be arbitrated...
     for (auto& thread : thread_list) {
-        if (!CheckWaitType(thread.get(), WAITTYPE_ARB, arbiter, address))
+        if (!CheckWait_AddressArbiter(thread.get(), address))
             continue;
 
         if (thread == nullptr)
-            continue; // TODO(yuriks): Thread handle will hang around forever. Should clean up.
+            continue;
 
         if(thread->current_priority <= priority) {
             highest_priority_thread = thread.get();
@@ -165,11 +149,11 @@ Thread* ArbitrateHighestPriorityThread(Object* arbiter, u32 address) {
 }
 
 /// Arbitrate all threads currently waiting
-void ArbitrateAllThreads(Object* arbiter, u32 address) {
+void ArbitrateAllThreads(u32 address) {
 
     // Iterate through threads, find highest priority thread that is waiting to be arbitrated...
     for (auto& thread : thread_list) {
-        if (CheckWaitType(thread.get(), WAITTYPE_ARB, arbiter, address))
+        if (CheckWait_AddressArbiter(thread.get(), address))
             thread->ResumeFromWait();
     }
 }
@@ -177,9 +161,6 @@ void ArbitrateAllThreads(Object* arbiter, u32 address) {
 /// Calls a thread by marking it as "ready" (note: will not actually execute until current thread yields)
 static void CallThread(Thread* t) {
     // Stop waiting
-    if (t->wait_type != WAITTYPE_NONE) {
-        t->wait_type = WAITTYPE_NONE;
-    }
     ChangeThreadState(t, THREADSTATUS_READY);
 }
 
@@ -200,7 +181,6 @@ static void SwitchContext(Thread* t) {
         current_thread = t;
         ChangeReadyState(t, false);
         t->status = (t->status | THREADSTATUS_RUNNING) & ~THREADSTATUS_READY;
-        t->wait_type = WAITTYPE_NONE;
         Core::g_app_core->LoadContext(t->context);
     } else {
         current_thread = nullptr;
@@ -223,16 +203,27 @@ static Thread* NextThread() {
     return next;
 }
 
-void WaitCurrentThread(WaitType wait_type, Object* wait_object) {
+void WaitCurrentThread_Sleep() {
     Thread* thread = GetCurrentThread();
-    thread->wait_type = wait_type;
-    thread->wait_object = wait_object;
     ChangeThreadState(thread, ThreadStatus(THREADSTATUS_WAIT | (thread->status & THREADSTATUS_SUSPEND)));
 }
 
-void WaitCurrentThread(WaitType wait_type, Object* wait_object, VAddr wait_address) {
+void WaitCurrentThread_WaitSynchronization(SharedPtr<WaitObject> wait_object, bool wait_set_output, bool wait_all) {
-    WaitCurrentThread(wait_type, wait_object);
+    Thread* thread = GetCurrentThread();
-    GetCurrentThread()->wait_address = wait_address;
+    thread->wait_set_output = wait_set_output;
+    thread->wait_all = wait_all;
+
+    // It's possible to call WaitSynchronizationN without any objects passed in...
+    if (wait_object != nullptr)
+        thread->wait_objects.push_back(wait_object);
+
+    ChangeThreadState(thread, ThreadStatus(THREADSTATUS_WAIT | (thread->status & THREADSTATUS_SUSPEND)));
+}
+
+void WaitCurrentThread_ArbitrateAddress(VAddr wait_address) {
+    Thread* thread = GetCurrentThread();
+    thread->wait_address = wait_address;
+    ChangeThreadState(thread, ThreadStatus(THREADSTATUS_WAIT | (thread->status & THREADSTATUS_SUSPEND)));
 }
 
 /// Event type for the thread wake up event
@@ -247,6 +238,12 @@ static void ThreadWakeupCallback(u64 parameter, int cycles_late) {
         return;
     }
 
+    thread->SetWaitSynchronizationResult(ResultCode(ErrorDescription::Timeout, ErrorModule::OS,
+        ErrorSummary::StatusChanged, ErrorLevel::Info));
+
+    if (thread->wait_set_output)
+        thread->SetWaitSynchronizationOutput(-1);
+
     thread->ResumeFromWait();
 }
 
@@ -261,14 +258,63 @@ void WakeThreadAfterDelay(Thread* thread, s64 nanoseconds) {
     CoreTiming::ScheduleEvent(usToCycles(microseconds), ThreadWakeupEventType, thread->GetHandle());
 }
 
-/// Resumes a thread from waiting by marking it as "ready"
+void Thread::ReleaseWaitObject(WaitObject* wait_object) {
+    if (wait_objects.empty()) {
+        LOG_CRITICAL(Kernel, "thread is not waiting on any objects!");
+        return;
+    }
+
+    // Remove this thread from the waiting object's thread list
+    wait_object->RemoveWaitingThread(this);
+
+    unsigned index = 0;
+    bool wait_all_failed = false; // Will be set to true if any object is unavailable
+
+    // Iterate through all waiting objects to check availability...
+    for (auto itr = wait_objects.begin(); itr != wait_objects.end(); ++itr) {
+        if ((*itr)->ShouldWait())
+            wait_all_failed = true;
+
+        // The output should be the last index of wait_object
+        if (*itr == wait_object)
+            index = itr - wait_objects.begin();
+    }
+
+    // If we are waiting on all objects...
+    if (wait_all) {
+        // Resume the thread only if all are available...
+        if (!wait_all_failed) {
+            SetWaitSynchronizationResult(RESULT_SUCCESS);
+            SetWaitSynchronizationOutput(-1);
+
+            ResumeFromWait();
+        }
+    } else {
+        // Otherwise, resume
+        SetWaitSynchronizationResult(RESULT_SUCCESS);
+
+        if (wait_set_output)
+            SetWaitSynchronizationOutput(index);
+
+        ResumeFromWait();
+    }
+}
+
 void Thread::ResumeFromWait() {
     // Cancel any outstanding wakeup events
     CoreTiming::UnscheduleEvent(ThreadWakeupEventType, GetHandle());
 
     status &= ~THREADSTATUS_WAIT;
-    wait_object = nullptr;
+
-    wait_type = WAITTYPE_NONE;
+    // Remove this thread from all other WaitObjects
+    for (auto wait_object : wait_objects)
+        wait_object->RemoveWaitingThread(this);
+
+    wait_objects.clear();
+    wait_set_output = false;
+    wait_all = false;
+    wait_address = 0;
+
     if (!(status & (THREADSTATUS_WAITSUSPEND | THREADSTATUS_DORMANT | THREADSTATUS_DEAD))) {
         ChangeReadyState(this, true);
     }
@@ -334,8 +380,9 @@ ResultVal<SharedPtr<Thread>> Thread::Create(std::string name, VAddr entry_point,
     thread->stack_size = stack_size;
     thread->initial_priority = thread->current_priority = priority;
     thread->processor_id = processor_id;
-    thread->wait_type = WAITTYPE_NONE;
+    thread->wait_set_output = false;
-    thread->wait_object = nullptr;
+    thread->wait_all = false;
+    thread->wait_objects.clear();
     thread->wait_address = 0;
     thread->name = std::move(name);
 
@@ -419,13 +466,20 @@ void Reschedule() {
         LOG_TRACE(Kernel, "cannot context switch from 0x%08X, no higher priority thread!", prev->GetHandle());
 
         for (auto& thread : thread_list) {
-            LOG_TRACE(Kernel, "\thandle=0x%08X prio=0x%02X, status=0x%08X wait_type=0x%08X wait_handle=0x%08X",
+            LOG_TRACE(Kernel, "\thandle=0x%08X prio=0x%02X, status=0x%08X", thread->GetHandle(), 
-                thread->GetHandle(), thread->current_priority, thread->status, thread->wait_type,
+                      thread->current_priority, thread->status);
-                (thread->wait_object ? thread->wait_object->GetHandle() : INVALID_HANDLE));
         }
     }
 }
 
+void Thread::SetWaitSynchronizationResult(ResultCode result) {
+    context.cpu_registers[0] = result.raw;
+}
+
+void Thread::SetWaitSynchronizationOutput(s32 output) {
+    context.cpu_registers[1] = output;
+}
+
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
 void ThreadingInit() {

src/core/hle/kernel/thread.h

@@ -38,21 +38,9 @@ enum ThreadStatus {
     THREADSTATUS_WAITSUSPEND    = THREADSTATUS_WAIT | THREADSTATUS_SUSPEND
 };
 
-enum WaitType {
-    WAITTYPE_NONE,
-    WAITTYPE_SLEEP,
-    WAITTYPE_SEMA,
-    WAITTYPE_EVENT,
-    WAITTYPE_THREADEND,
-    WAITTYPE_MUTEX,
-    WAITTYPE_SYNCH,
-    WAITTYPE_ARB,
-    WAITTYPE_TIMER,
-};
-
 namespace Kernel {
 
-class Thread : public Kernel::Object {
+class Thread : public WaitObject {
 public:
     static ResultVal<SharedPtr<Thread>> Create(std::string name, VAddr entry_point, s32 priority,
         u32 arg, s32 processor_id, VAddr stack_top, u32 stack_size);
@@ -70,7 +58,8 @@ public:
     inline bool IsSuspended() const { return (status & THREADSTATUS_SUSPEND) != 0; }
     inline bool IsIdle() const { return idle; }
 
-    ResultVal<bool> WaitSynchronization() override;
+    bool ShouldWait() override;
+    void Acquire() override;
 
     s32 GetPriority() const { return current_priority; }
     void SetPriority(s32 priority);
@@ -78,9 +67,28 @@ public:
     u32 GetThreadId() const { return thread_id; }
 
     void Stop(const char* reason);
-    /// Resumes a thread from waiting by marking it as "ready".
+    
+    /**
+     * Release an acquired wait object
+     * @param wait_object WaitObject to release
+     */
+    void ReleaseWaitObject(WaitObject* wait_object);
+
+    /// Resumes a thread from waiting by marking it as "ready"
     void ResumeFromWait();
 
+    /**
+     * Sets the result after the thread awakens (from either WaitSynchronization SVC)
+     * @param result Value to set to the returned result
+     */
+    void SetWaitSynchronizationResult(ResultCode result);
+
+    /**
+     * Sets the output parameter value after the thread awakens (from WaitSynchronizationN SVC only)
+     * @param output Value to set to the output parameter
+     */
+    void SetWaitSynchronizationOutput(s32 output);
+
     Core::ThreadContext context;
 
     u32 thread_id;
@@ -95,11 +103,11 @@ public:
 
     s32 processor_id;
 
-    WaitType wait_type;
+    std::vector<SharedPtr<WaitObject>> wait_objects; ///< Objects that the thread is waiting on
-    Object* wait_object;
-    VAddr wait_address;
 
-    std::vector<SharedPtr<Thread>> waiting_threads;
+    VAddr wait_address;     ///< If waiting on an AddressArbiter, this is the arbitration address
+    bool wait_all;          ///< True if the thread is waiting on all objects before resuming
+    bool wait_set_output;   ///< True if the output parameter should be set on thread wakeup
 
     std::string name;
 
@@ -107,6 +115,7 @@ public:
     bool idle = false;
 
 private:
+
     Thread() = default;
 };
 
@@ -117,38 +126,38 @@ SharedPtr<Thread> SetupMainThread(s32 priority, u32 stack_size);
 void Reschedule();
 
 /// Arbitrate the highest priority thread that is waiting
-Thread* ArbitrateHighestPriorityThread(Object* arbiter, u32 address);
+Thread* ArbitrateHighestPriorityThread(u32 address);
 
 /// Arbitrate all threads currently waiting...
-void ArbitrateAllThreads(Object* arbiter, u32 address);
+void ArbitrateAllThreads(u32 address);
 
 /// Gets the current thread
 Thread* GetCurrentThread();
 
+/// Waits the current thread on a sleep
+void WaitCurrentThread_Sleep();
+
 /**
- * Puts the current thread in the wait state for the given type
+ * Waits the current thread from a WaitSynchronization call
- * @param wait_type Type of wait
+ * @param wait_object Kernel object that we are waiting on
- * @param wait_object Kernel object that we are waiting on, defaults to current thread
+ * @param wait_set_output If true, set the output parameter on thread wakeup (for WaitSynchronizationN only)
+ * @param wait_all If true, wait on all objects before resuming (for WaitSynchronizationN only)
  */
-void WaitCurrentThread(WaitType wait_type, Object* wait_object = GetCurrentThread());
+void WaitCurrentThread_WaitSynchronization(SharedPtr<WaitObject> wait_object, bool wait_set_output, bool wait_all);
+
+/**
+ * Waits the current thread from an ArbitrateAddress call
+ * @param wait_address Arbitration address used to resume from wait
+ */
+void WaitCurrentThread_ArbitrateAddress(VAddr wait_address);
 
 /**
  * Schedules an event to wake up the specified thread after the specified delay.
- * @param thread The thread to wake after the delay.
+ * @param handle The thread handle.
  * @param nanoseconds The time this thread will be allowed to sleep for.
  */
 void WakeThreadAfterDelay(Thread* thread, s64 nanoseconds);
 
-/**
- * Puts the current thread in the wait state for the given type
- * @param wait_type Type of wait
- * @param wait_object Kernel object that we are waiting on
- * @param wait_address Arbitration address used to resume from wait
- */
-void WaitCurrentThread(WaitType wait_type, Object* wait_object, VAddr wait_address);
-
-
-
 /**
  * Sets up the idle thread, this is a thread that is intended to never execute instructions,
  * only to advance the timing. It is scheduled when there are no other ready threads in the thread queue
@@ -156,6 +165,7 @@ void WaitCurrentThread(WaitType wait_type, Object* wait_object, VAddr wait_addre
  * @returns The handle of the idle thread
  */
 Handle SetupIdleThread();
+
 /// Initialize threading
 void ThreadingInit();
 

src/core/hle/kernel/timer.cpp

@@ -13,7 +13,7 @@
 
 namespace Kernel {
 
-class Timer : public Object {
+class Timer : public WaitObject {
 public:
     std::string GetTypeName() const override { return "Timer"; }
     std::string GetName() const override { return name; }
@@ -24,19 +24,17 @@ public:
     ResetType reset_type;                   ///< The ResetType of this timer
 
     bool signaled;                          ///< Whether the timer has been signaled or not
-    std::set<Handle> waiting_threads;       ///< Threads that are waiting for the timer
     std::string name;                       ///< Name of timer (optional)
 
     u64 initial_delay;                      ///< The delay until the timer fires for the first time
     u64 interval_delay;                     ///< The delay until the timer fires after the first time
 
-    ResultVal<bool> WaitSynchronization() override {
+    bool ShouldWait() override {
-        bool wait = !signaled;
+        return !signaled;
-        if (wait) {
+    }
-            waiting_threads.insert(GetCurrentThread()->GetHandle());
+
-            Kernel::WaitCurrentThread(WAITTYPE_TIMER, this);
+    void Acquire() override {
-        }
+        _assert_msg_(Kernel, !ShouldWait(), "object unavailable!");
-        return MakeResult<bool>(wait);
     }
 };
 
@@ -92,12 +90,7 @@ static void TimerCallback(u64 timer_handle, int cycles_late) {
     timer->signaled = true;
 
     // Resume all waiting threads
-    for (Handle thread_handle : timer->waiting_threads) {
+    timer->WakeupAllWaitingThreads();
-        if (SharedPtr<Thread> thread = Kernel::g_handle_table.Get<Thread>(thread_handle))
-            thread->ResumeFromWait();
-    }
-
-    timer->waiting_threads.clear();
 
     if (timer->reset_type == RESETTYPE_ONESHOT)
         timer->signaled = false;

src/core/hle/service/apt_u.cpp

@@ -50,8 +50,8 @@ void Initialize(Service::Interface* self) {
     cmd_buff[3] = notification_event_handle;
     cmd_buff[4] = pause_event_handle;
 
-    Kernel::SetEventLocked(notification_event_handle, true);
+    Kernel::ClearEvent(notification_event_handle);
-    Kernel::SetEventLocked(pause_event_handle, false); // Fire start event
+    Kernel::SignalEvent(pause_event_handle); // Fire start event
 
     _assert_msg_(KERNEL, (0 != lock_handle), "Cannot initialize without lock");
     Kernel::ReleaseMutex(lock_handle);

src/core/hle/service/srv.cpp

@@ -24,7 +24,7 @@ static void GetProcSemaphore(Service::Interface* self) {
 
     // TODO(bunnei): Change to a semaphore once these have been implemented
     g_event_handle = Kernel::CreateEvent(RESETTYPE_ONESHOT, "SRV:Event");
-    Kernel::SetEventLocked(g_event_handle, false);
+    Kernel::ClearEvent(g_event_handle);
 
     cmd_buff[1] = 0; // No error
     cmd_buff[3] = g_event_handle;

src/core/hle/svc.cpp

@@ -29,6 +29,9 @@ using Kernel::SharedPtr;
 
 namespace SVC {
 
+/// An invalid result code that is meant to be overwritten when a thread resumes from waiting
+const ResultCode RESULT_INVALID(0xDEADC0DE);
+
 enum ControlMemoryOperation {
     MEMORY_OPERATION_HEAP       = 0x00000003,
     MEMORY_OPERATION_GSP_HEAP   = 0x00010003,
@@ -103,12 +106,7 @@ static Result SendSyncRequest(Handle handle) {
 
     LOG_TRACE(Kernel_SVC, "called handle=0x%08X(%s)", handle, session->GetName().c_str());
 
-    ResultVal<bool> wait = session->SyncRequest();
+    return session->SyncRequest().Code().raw;
-    if (wait.Succeeded() && *wait) {
-        Kernel::WaitCurrentThread(WAITTYPE_SYNCH); // TODO(bunnei): Is this correct?
-    }
-
-    return wait.Code().raw;
 }
 
 /// Close a handle
@@ -120,64 +118,122 @@ static Result CloseHandle(Handle handle) {
 
 /// Wait for a handle to synchronize, timeout after the specified nanoseconds
 static Result WaitSynchronization1(Handle handle, s64 nano_seconds) {
-    SharedPtr<Kernel::Object> object = Kernel::g_handle_table.GetGeneric(handle);
+    auto object = Kernel::g_handle_table.GetWaitObject(handle);
     if (object == nullptr)
         return InvalidHandle(ErrorModule::Kernel).raw;
 
     LOG_TRACE(Kernel_SVC, "called handle=0x%08X(%s:%s), nanoseconds=%lld", handle,
             object->GetTypeName().c_str(), object->GetName().c_str(), nano_seconds);
 
-    ResultVal<bool> wait = object->WaitSynchronization();
-
     // Check for next thread to schedule
-    if (wait.Succeeded() && *wait) {
+    if (object->ShouldWait()) {
+
+        object->AddWaitingThread(Kernel::GetCurrentThread());
+        Kernel::WaitCurrentThread_WaitSynchronization(object, false, false);
+
         // Create an event to wake the thread up after the specified nanosecond delay has passed
         Kernel::WakeThreadAfterDelay(Kernel::GetCurrentThread(), nano_seconds);
+
         HLE::Reschedule(__func__);
+
+        // NOTE: output of this SVC will be set later depending on how the thread resumes
+        return RESULT_INVALID.raw;
     }
 
-    return wait.Code().raw;
+    object->Acquire();
+
+    return RESULT_SUCCESS.raw;
 }
 
 /// Wait for the given handles to synchronize, timeout after the specified nanoseconds
-static Result WaitSynchronizationN(s32* out, Handle* handles, s32 handle_count, bool wait_all,
+static Result WaitSynchronizationN(s32* out, Handle* handles, s32 handle_count, bool wait_all, s64 nano_seconds) {
-    s64 nano_seconds) {
+    bool wait_thread = !wait_all;
+    int handle_index = 0;
 
-    // TODO(bunnei): Do something with nano_seconds, currently ignoring this
+    // Check if 'handles' is invalid
-    bool unlock_all = true;
+    if (handles == nullptr)
-    bool wait_infinite = (nano_seconds == -1); // Used to wait until a thread has terminated
+        return ResultCode(ErrorDescription::InvalidPointer, ErrorModule::Kernel, ErrorSummary::InvalidArgument, ErrorLevel::Permanent).raw;
 
-    LOG_TRACE(Kernel_SVC, "called handle_count=%d, wait_all=%s, nanoseconds=%lld",
+    // NOTE: on real hardware, there is no nullptr check for 'out' (tested with firmware 4.4). If
-        handle_count, (wait_all ? "true" : "false"), nano_seconds);
+    // this happens, the running application will crash.
+    _assert_msg_(Kernel, out != nullptr, "invalid output pointer specified!");
 
-    // Iterate through each handle, synchronize kernel object
+    // Check if 'handle_count' is invalid
-    for (s32 i = 0; i < handle_count; i++) {
+    if (handle_count < 0)
-        SharedPtr<Kernel::Object> object = Kernel::g_handle_table.GetGeneric(handles[i]);
+        return ResultCode(ErrorDescription::OutOfRange, ErrorModule::OS, ErrorSummary::InvalidArgument, ErrorLevel::Usage).raw;
-        if (object == nullptr)
-            return InvalidHandle(ErrorModule::Kernel).raw;
 
-        LOG_TRACE(Kernel_SVC, "\thandle[%d] = 0x%08X(%s:%s)", i, handles[i],
+    // If 'handle_count' is non-zero, iterate through each handle and wait the current thread if
-                object->GetTypeName().c_str(), object->GetName().c_str());
+    // necessary
+    if (handle_count != 0) {
+        bool selected = false; // True once an object has been selected
+        for (int i = 0; i < handle_count; ++i) {
+            auto object = Kernel::g_handle_table.GetWaitObject(handles[i]);
+            if (object == nullptr)
+                return InvalidHandle(ErrorModule::Kernel).raw;
 
-        // TODO(yuriks): Verify how the real function behaves when an error happens here
+            // Check if the current thread should wait on this object...
-        ResultVal<bool> wait_result = object->WaitSynchronization();
+            if (object->ShouldWait()) {
-        bool wait = wait_result.Succeeded() && *wait_result;
 
-        if (!wait && !wait_all) {
+                // Check we are waiting on all objects...
-            *out = i;
+                if (wait_all)
-            return RESULT_SUCCESS.raw;
+                    // Wait the thread
-        } else {
+                    wait_thread = true;
-            unlock_all = false;
+            } else {
+                // Do not wait on this object, check if this object should be selected...
+                if (!wait_all && !selected) {
+                    // Do not wait the thread
+                    wait_thread = false;
+                    handle_index = i;
+                    selected = true;
+                }
+            }
+        }
+    } else {
+        // If no handles were passed in, put the thread to sleep only when 'wait_all' is false
+        // NOTE: This should deadlock the current thread if no timeout was specified
+        if (!wait_all) {
+            wait_thread = true;
+            Kernel::WaitCurrentThread_WaitSynchronization(nullptr, true, wait_all);
         }
     }
 
-    if (wait_all && unlock_all) {
+    // If thread should wait, then set its state to waiting and then reschedule...
-        *out = handle_count;
+    if (wait_thread) {
-        return RESULT_SUCCESS.raw;
+
+        // Actually wait the current thread on each object if we decided to wait...
+        for (int i = 0; i < handle_count; ++i) {
+            auto object = Kernel::g_handle_table.GetWaitObject(handles[i]);
+            object->AddWaitingThread(Kernel::GetCurrentThread());
+            Kernel::WaitCurrentThread_WaitSynchronization(object, true, wait_all);
+        }
+
+        // Create an event to wake the thread up after the specified nanosecond delay has passed
+        Kernel::WakeThreadAfterDelay(Kernel::GetCurrentThread(), nano_seconds);
+
+        HLE::Reschedule(__func__);
+
+        // NOTE: output of this SVC will be set later depending on how the thread resumes
+        return RESULT_INVALID.raw;
     }
 
-    // Check for next thread to schedule
+    // Acquire objects if we did not wait...
-    HLE::Reschedule(__func__);
+    for (int i = 0; i < handle_count; ++i) {
+        auto object = Kernel::g_handle_table.GetWaitObject(handles[i]);
+
+        // Acquire the object if it is not waiting...
+        if (!object->ShouldWait()) {
+            object->Acquire();
+
+            // If this was the first non-waiting object and 'wait_all' is false, don't acquire
+            // any other objects
+            if (!wait_all)
+                break;
+        }
+    }
+
+    // TODO(bunnei): If 'wait_all' is true, this is probably wrong. However, real hardware does
+    // not seem to set it to any meaningful value.
+    *out = wait_all ? 0 : handle_index;
 
     return RESULT_SUCCESS.raw;
 }
@@ -351,6 +407,7 @@ static Result DuplicateHandle(Handle* out, Handle handle) {
 /// Signals an event
 static Result SignalEvent(Handle evt) {
     LOG_TRACE(Kernel_SVC, "called event=0x%08X", evt);
+    HLE::Reschedule(__func__);
     return Kernel::SignalEvent(evt).raw;
 }
 
@@ -391,7 +448,7 @@ static void SleepThread(s64 nanoseconds) {
     LOG_TRACE(Kernel_SVC, "called nanoseconds=%lld", nanoseconds);
 
     // Sleep current thread and check for next thread to schedule
-    Kernel::WaitCurrentThread(WAITTYPE_SLEEP);
+    Kernel::WaitCurrentThread_Sleep();
 
     // Create an event to wake the thread up after the specified nanosecond delay has passed
     Kernel::WakeThreadAfterDelay(Kernel::GetCurrentThread(), nanoseconds);