Mutex: Locks should be recursive.
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@ -21,7 +21,7 @@ namespace Kernel {
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*/
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static void ResumeWaitingThread(Mutex* mutex) {
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// Reset mutex lock thread handle, nothing is waiting
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mutex->locked = false;
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mutex->lock_count = 0;
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mutex->holding_thread = nullptr;
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// Find the next waiting thread for the mutex...
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@ -44,8 +44,7 @@ Mutex::~Mutex() {}
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SharedPtr<Mutex> Mutex::Create(bool initial_locked, std::string name) {
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SharedPtr<Mutex> mutex(new Mutex);
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mutex->initial_locked = initial_locked;
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mutex->locked = false;
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mutex->lock_count = 0;
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mutex->name = std::move(name);
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mutex->holding_thread = nullptr;
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@ -57,7 +56,7 @@ SharedPtr<Mutex> Mutex::Create(bool initial_locked, std::string name) {
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}
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bool Mutex::ShouldWait() {
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return locked && holding_thread != GetCurrentThread();
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return lock_count > 0 && holding_thread != GetCurrentThread();;
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}
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void Mutex::Acquire() {
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@ -66,21 +65,27 @@ void Mutex::Acquire() {
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void Mutex::Acquire(SharedPtr<Thread> thread) {
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_assert_msg_(Kernel, !ShouldWait(), "object unavailable!");
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if (locked)
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return;
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locked = true;
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// Actually "acquire" the mutex only if we don't already have it...
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if (lock_count == 0) {
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thread->held_mutexes.insert(this);
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holding_thread = std::move(thread);
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}
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thread->held_mutexes.insert(this);
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holding_thread = std::move(thread);
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lock_count++;
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}
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void Mutex::Release() {
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if (!locked)
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return;
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// Only release if the mutex is held...
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if (lock_count > 0) {
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lock_count--;
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holding_thread->held_mutexes.erase(this);
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ResumeWaitingThread(this);
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// Yield to the next thread only if we've fully released the mutex...
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if (lock_count == 0) {
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holding_thread->held_mutexes.erase(this);
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ResumeWaitingThread(this);
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}
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}
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}
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} // namespace
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@ -30,8 +30,7 @@ public:
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static const HandleType HANDLE_TYPE = HandleType::Mutex;
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HandleType GetHandleType() const override { return HANDLE_TYPE; }
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bool initial_locked; ///< Initial lock state when mutex was created
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bool locked; ///< Current locked state
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int lock_count; ///< Number of times the mutex has been acquired
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std::string name; ///< Name of mutex (optional)
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SharedPtr<Thread> holding_thread; ///< Thread that has acquired the mutex
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