diff options
Diffstat (limited to 'src/core/hle/kernel/mutex.cpp')
-rw-r--r-- | src/core/hle/kernel/mutex.cpp | 39 |
1 files changed, 31 insertions, 8 deletions
diff --git a/src/core/hle/kernel/mutex.cpp b/src/core/hle/kernel/mutex.cpp index 5cc0bd266..63733ad79 100644 --- a/src/core/hle/kernel/mutex.cpp +++ b/src/core/hle/kernel/mutex.cpp @@ -18,13 +18,13 @@ namespace Kernel { /// Returns the number of threads that are waiting for a mutex, and the highest priority one among /// those. -static std::pair<SharedPtr<Thread>, u32> GetHighestPriorityMutexWaitingThread(VAddr mutex_addr) { - auto& thread_list = Core::System::GetInstance().Scheduler().GetThreadList(); +static std::pair<SharedPtr<Thread>, u32> GetHighestPriorityMutexWaitingThread( + SharedPtr<Thread> current_thread, VAddr mutex_addr) { SharedPtr<Thread> highest_priority_thread; u32 num_waiters = 0; - for (auto& thread : thread_list) { + for (auto& thread : current_thread->wait_mutex_threads) { if (thread->mutex_wait_address != mutex_addr) continue; @@ -40,6 +40,21 @@ static std::pair<SharedPtr<Thread>, u32> GetHighestPriorityMutexWaitingThread(VA return {highest_priority_thread, num_waiters}; } +/// Update the mutex owner field of all threads waiting on the mutex to point to the new owner. +static void TransferMutexOwnership(VAddr mutex_addr, SharedPtr<Thread> current_thread, + SharedPtr<Thread> new_owner) { + auto threads = current_thread->wait_mutex_threads; + for (auto& thread : threads) { + if (thread->mutex_wait_address != mutex_addr) + continue; + + ASSERT(thread->lock_owner == current_thread); + current_thread->RemoveMutexWaiter(thread); + if (new_owner != thread) + new_owner->AddMutexWaiter(thread); + } +} + ResultCode Mutex::TryAcquire(VAddr address, Handle holding_thread_handle, Handle requesting_thread_handle) { // The mutex address must be 4-byte aligned @@ -65,11 +80,14 @@ ResultCode Mutex::TryAcquire(VAddr address, Handle holding_thread_handle, return ERR_INVALID_HANDLE; // Wait until the mutex is released - requesting_thread->mutex_wait_address = address; - requesting_thread->wait_handle = requesting_thread_handle; + GetCurrentThread()->mutex_wait_address = address; + GetCurrentThread()->wait_handle = requesting_thread_handle; - requesting_thread->status = THREADSTATUS_WAIT_MUTEX; - requesting_thread->wakeup_callback = nullptr; + GetCurrentThread()->status = THREADSTATUS_WAIT_MUTEX; + GetCurrentThread()->wakeup_callback = nullptr; + + // Update the lock holder thread's priority to prevent priority inversion. + holding_thread->AddMutexWaiter(GetCurrentThread()); Core::System::GetInstance().PrepareReschedule(); @@ -82,14 +100,18 @@ ResultCode Mutex::Release(VAddr address) { return ResultCode(ErrorModule::Kernel, ErrCodes::MisalignedAddress); } - auto [thread, num_waiters] = GetHighestPriorityMutexWaitingThread(address); + auto [thread, num_waiters] = GetHighestPriorityMutexWaitingThread(GetCurrentThread(), address); // There are no more threads waiting for the mutex, release it completely. if (thread == nullptr) { + ASSERT(GetCurrentThread()->wait_mutex_threads.empty()); Memory::Write32(address, 0); return RESULT_SUCCESS; } + // Transfer the ownership of the mutex from the previous owner to the new one. + TransferMutexOwnership(address, GetCurrentThread(), thread); + u32 mutex_value = thread->wait_handle; if (num_waiters >= 2) { @@ -103,6 +125,7 @@ ResultCode Mutex::Release(VAddr address) { ASSERT(thread->status == THREADSTATUS_WAIT_MUTEX); thread->ResumeFromWait(); + thread->lock_owner = nullptr; thread->condvar_wait_address = 0; thread->mutex_wait_address = 0; thread->wait_handle = 0; |