Merge pull request #551 from bunnei/mutex-fixes

Mutex/synch fixes

src/core/hle/kernel/mutex.cpp

@@ -21,7 +21,7 @@ namespace Kernel {
  */
 static void ResumeWaitingThread(Mutex* mutex) {
     // Reset mutex lock thread handle, nothing is waiting
-    mutex->locked = false;
+    mutex->lock_count = 0;
     mutex->holding_thread = nullptr;
 
     // Find the next waiting thread for the mutex...
@@ -44,8 +44,7 @@ Mutex::~Mutex() {}
 SharedPtr<Mutex> Mutex::Create(bool initial_locked, std::string name) {
     SharedPtr<Mutex> mutex(new Mutex);
 
-    mutex->initial_locked = initial_locked;
-    mutex->locked = false;
+    mutex->lock_count = 0;
     mutex->name = std::move(name);
     mutex->holding_thread = nullptr;
 
@@ -57,7 +56,7 @@ SharedPtr<Mutex> Mutex::Create(bool initial_locked, std::string name) {
 }
 
 bool Mutex::ShouldWait() {
-    return locked && holding_thread != GetCurrentThread();
+    return lock_count > 0 && holding_thread != GetCurrentThread();;
 }
 
 void Mutex::Acquire() {
@@ -66,21 +65,27 @@ void Mutex::Acquire() {
 
 void Mutex::Acquire(SharedPtr<Thread> thread) {
     _assert_msg_(Kernel, !ShouldWait(), "object unavailable!");
-    if (locked)
-        return;
-
-    locked = true;
 
+    // Actually "acquire" the mutex only if we don't already have it...
+    if (lock_count == 0) {
         thread->held_mutexes.insert(this);
         holding_thread = std::move(thread);
+    }
+
+    lock_count++;
 }
 
 void Mutex::Release() {
-    if (!locked)
-        return;
+    // Only release if the mutex is held...
+    if (lock_count > 0) {
+        lock_count--;
 
+        // Yield to the next thread only if we've fully released the mutex...
+        if (lock_count == 0) {
             holding_thread->held_mutexes.erase(this);
             ResumeWaitingThread(this);
+        }
+    }
 }
 
 } // namespace

src/core/hle/kernel/mutex.h

@@ -30,8 +30,7 @@ public:
     static const HandleType HANDLE_TYPE = HandleType::Mutex;
     HandleType GetHandleType() const override { return HANDLE_TYPE; }
 
-    bool initial_locked;                        ///< Initial lock state when mutex was created
-    bool locked;                                ///< Current locked state
+    int lock_count;                             ///< Number of times the mutex has been acquired
     std::string name;                           ///< Name of mutex (optional)
     SharedPtr<Thread> holding_thread;           ///< Thread that has acquired the mutex
 

src/core/hle/svc.cpp

@@ -144,6 +144,8 @@ static ResultCode WaitSynchronization1(Handle handle, s64 nano_seconds) {
     LOG_TRACE(Kernel_SVC, "called handle=0x%08X(%s:%s), nanoseconds=%lld", handle,
             object->GetTypeName().c_str(), object->GetName().c_str(), nano_seconds);
 
+    HLE::Reschedule(__func__);
+
     // Check for next thread to schedule
     if (object->ShouldWait()) {
 
@@ -153,8 +155,6 @@ static ResultCode WaitSynchronization1(Handle handle, s64 nano_seconds) {
         // Create an event to wake the thread up after the specified nanosecond delay has passed
         Kernel::GetCurrentThread()->WakeAfterDelay(nano_seconds);
 
-        HLE::Reschedule(__func__);
-
         // NOTE: output of this SVC will be set later depending on how the thread resumes
         return RESULT_INVALID;
     }
@@ -216,6 +216,8 @@ static ResultCode WaitSynchronizationN(s32* out, Handle* handles, s32 handle_cou
         }
     }
 
+    HLE::Reschedule(__func__);
+
     // If thread should wait, then set its state to waiting and then reschedule...
     if (wait_thread) {
 
@@ -229,8 +231,6 @@ static ResultCode WaitSynchronizationN(s32* out, Handle* handles, s32 handle_cou
         // Create an event to wake the thread up after the specified nanosecond delay has passed
         Kernel::GetCurrentThread()->WakeAfterDelay(nano_seconds);
 
-        HLE::Reschedule(__func__);
-
         // NOTE: output of this SVC will be set later depending on how the thread resumes
         return RESULT_INVALID;
     }