From ac35358b3ffed74aaac56b0e99b09e81bb60d2e1 Mon Sep 17 00:00:00 2001
From: lizzie <lizzie@eden-emu.dev>
Date: Wed, 16 Sep 2026 15:35:13 +0200
Subject: [PATCH] [common] Replace `Common::SpinLock` with `std::mutex` (#4436)

`std::mutex` can be better than the spin-lock specially since we don't waste CPU cycles for no reason.

Test less stuttering/heat consumption.

Signed-off-by: lizzie <lizzie@eden-emu.dev>

- [x] I have read and followed the [Contribution Guidelines](https://git.eden-emu.dev/eden-emu/eden/src/branch/master/CONTRIBUTING.md#code-contributions).
- [x] I have read and followed the [AI Policy](https://git.eden-emu.dev/eden-emu/eden/src/branch/master/docs/policies/AI.md)
- [x] I have read and followed the [Coding Guidelines](https://git.eden-emu.dev/eden-emu/eden/src/branch/master/docs/policies/Coding.md) to the best of my ability.

-------------------

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/4436
Reviewed-by: CamilleLaVey <camillelavey99@gmail.com>
Reviewed-by: MaranBr <maranbr@eden-emu.dev>
---
 src/common/CMakeLists.txt         |  1 -
 src/common/spin_lock.h            | 50 -------------------------------
 src/core/hle/kernel/k_slab_heap.h |  7 ++---
 src/core/hle/kernel/k_thread.h    |  3 +-
 4 files changed, 4 insertions(+), 57 deletions(-)
 delete mode 100644 src/common/spin_lock.h

diff --git a/src/common/CMakeLists.txt b/src/common/CMakeLists.txt
index 61e0e64aa8..94da1724df 100644
--- a/src/common/CMakeLists.txt
+++ b/src/common/CMakeLists.txt
@@ -110,7 +110,6 @@ add_library(
     socket_types.h
     sparse_large_vector.cpp
     sparse_large_vector.h
-    spin_lock.h
     stb.cpp
     stb.h
     steady_clock.cpp
diff --git a/src/common/spin_lock.h b/src/common/spin_lock.h
deleted file mode 100644
index 93d507ae80..0000000000
--- a/src/common/spin_lock.h
+++ /dev/null
@@ -1,50 +0,0 @@
-// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
-// SPDX-License-Identifier: GPL-3.0-or-later
-
-// SPDX-FileCopyrightText: Copyright 2020 yuzu Emulator Project
-// SPDX-License-Identifier: GPL-2.0-or-later
-
-#pragma once
-
-#ifdef _MSC_VER
-#include <intrin.h>
-#elif defined(ARCHITECTURE_x86_64)
-#include <xmmintrin.h>
-#endif
-#include <atomic>
-
-namespace Common {
-
-/// @brief A lock similar to mutex that forces a thread to spin wait instead calling the
-/// supervisor. Should be used on short sequences of code.
-struct SpinLock {
-    SpinLock() noexcept = default;
-    SpinLock(const SpinLock&) noexcept = delete;
-    SpinLock& operator=(const SpinLock&) noexcept = delete;
-    SpinLock(SpinLock&&) noexcept = delete;
-    SpinLock& operator=(SpinLock&&) noexcept = delete;
-
-    inline void lock() noexcept {
-        while (lck.test_and_set(std::memory_order_acquire)) {
-#if defined(ARCHITECTURE_x86_64)
-            _mm_pause();
-#elif defined(ARCHITECTURE_arm64) && defined(_MSC_VER)
-            __yield();
-#elif defined(ARCHITECTURE_arm64)
-            asm("yield");
-#endif
-        }
-    }
-
-    inline void unlock() noexcept {
-        lck.clear(std::memory_order_release);
-    }
-
-    [[nodiscard]] inline bool try_lock() noexcept {
-        return !lck.test_and_set(std::memory_order_acquire);
-    }
-
-    std::atomic_flag lck = ATOMIC_FLAG_INIT;
-};
-
-} // namespace Common
diff --git a/src/core/hle/kernel/k_slab_heap.h b/src/core/hle/kernel/k_slab_heap.h
index c91e7969a2..a5dbab9571 100644
--- a/src/core/hle/kernel/k_slab_heap.h
+++ b/src/core/hle/kernel/k_slab_heap.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 // SPDX-FileCopyrightText: Copyright 2020 yuzu Emulator Project
@@ -12,7 +12,6 @@
 #include "common/atomic_ops.h"
 #include "common/common_funcs.h"
 #include "common/common_types.h"
-#include "common/spin_lock.h"
 
 namespace Kernel {
 
@@ -30,7 +29,7 @@ public:
     };
 
 public:
-    constexpr KSlabHeapImpl() = default;
+    KSlabHeapImpl() = default;
 
     void Initialize() {
         ASSERT(m_head == nullptr);
@@ -68,7 +67,7 @@ public:
 
 private:
     std::atomic<Node*> m_head{};
-    Common::SpinLock m_lock;
+    std::mutex m_lock;
 };
 
 } // namespace impl
diff --git a/src/core/hle/kernel/k_thread.h b/src/core/hle/kernel/k_thread.h
index 95ba1b4d76..0ee5f72c8e 100644
--- a/src/core/hle/kernel/k_thread.h
+++ b/src/core/hle/kernel/k_thread.h
@@ -19,7 +19,6 @@
 
 #include "common/intrusive_red_black_tree.h"
 #include "common/scratch_buffer.h"
-#include "common/spin_lock.h"
 #include "core/arm/arm_interface.h"
 #include "core/hle/kernel/k_affinity_mask.h"
 #include "core/hle/kernel/k_light_lock.h"
@@ -920,7 +919,7 @@ private:
     bool m_resource_limit_release_hint{};
     bool m_is_kernel_address_key{};
     StackParameters m_stack_parameters{};
-    Common::SpinLock m_context_guard{};
+    std::mutex m_context_guard{};
 
     // For emulation
     std::shared_ptr<Common::Fiber> m_host_context{};