2 files changed, 77 insertions, 0 deletions

diff --git a/src/core/CMakeLists.txt b/src/core/CMakeLists.txt
index 4de159119..2e60a8331 100644
--- a/src/core/CMakeLists.txt
+++ b/src/core/CMakeLists.txt
@@ -154,6 +154,7 @@ add_library(core STATIC
     hle/kernel/hle_ipc.h
     hle/kernel/k_affinity_mask.h
     hle/kernel/k_priority_queue.h
+    hle/kernel/k_scheduler_lock.h
     hle/kernel/kernel.cpp
     hle/kernel/kernel.h
     hle/kernel/memory/address_space_info.cpp
diff --git a/src/core/hle/kernel/k_scheduler_lock.h b/src/core/hle/kernel/k_scheduler_lock.h
new file mode 100644
index 000000000..d46f5fc04
--- /dev/null
+++ b/src/core/hle/kernel/k_scheduler_lock.h
@@ -0,0 +1,76 @@
+// Copyright 2020 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+// This file references various implementation details from Atmosphere, an open-source firmware for
+// the Nintendo Switch. Copyright 2018-2020 Atmosphere-NX.
+
+#pragma once
+
+#include "common/assert.h"
+#include "common/spin_lock.h"
+#include "core/hardware_properties.h"
+
+namespace Kernel {
+
+class KernelCore;
+
+template <typename SchedulerType>
+class KAbstractSchedulerLock {
+private:
+    KernelCore& kernel;
+    Common::SpinLock spin_lock;
+    s32 lock_count;
+    Core::EmuThreadHandle owner_thread;
+
+public:
+    KAbstractSchedulerLock(KernelCore& kernel)
+        : kernel{kernel}, spin_lock(), lock_count(0),
+          owner_thread(Core::EmuThreadHandle::InvalidHandle()) {}
+
+    bool IsLockedByCurrentThread() const {
+        return this->owner_thread == kernel.GetCurrentEmuThreadID();
+    }
+
+    void Lock() {
+        if (this->IsLockedByCurrentThread()) {
+            /* If we already own the lock, we can just increment the count. */
+            ASSERT(this->lock_count > 0);
+            this->lock_count++;
+        } else {
+            /* Otherwise, we want to disable scheduling and acquire the spinlock. */
+            SchedulerType::DisableScheduling(kernel);
+            this->spin_lock.lock();
+
+            /* For debug, ensure that our state is valid. */
+            ASSERT(this->lock_count == 0);
+            ASSERT(this->owner_thread == Core::EmuThreadHandle::InvalidHandle());
+
+            /* Increment count, take ownership. */
+            this->lock_count = 1;
+            this->owner_thread = kernel.GetCurrentEmuThreadID();
+        }
+    }
+
+    void Unlock() {
+        ASSERT(this->IsLockedByCurrentThread());
+        ASSERT(this->lock_count > 0);
+
+        /* Release an instance of the lock. */
+        if ((--this->lock_count) == 0) {
+            /* We're no longer going to hold the lock. Take note of what cores need scheduling. */
+            const u64 cores_needing_scheduling =
+                SchedulerType::UpdateHighestPriorityThreads(kernel);
+            Core::EmuThreadHandle leaving_thread = owner_thread;
+
+            /* Note that we no longer hold the lock, and unlock the spinlock. */
+            this->owner_thread = Core::EmuThreadHandle::InvalidHandle();
+            this->spin_lock.unlock();
+
+            /* Enable scheduling, and perform a rescheduling operation. */
+            SchedulerType::EnableScheduling(kernel, cores_needing_scheduling, leaving_thread);
+        }
+    }
+};
+
+} // namespace Kernel