From 8592f8a2b4cae1320b7e152f4d3a68ac7b39bfa3 Mon Sep 17 00:00:00 2001
From: bunnei <bunneidev@gmail.com>
Date: Sat, 29 May 2021 01:06:04 -0700
Subject: [PATCH] video_core: gpu: WaitFence: Do not block threads during
 shutdown.

- Fixes a hang on shutdown when NVFlinger thread is waiting on a syncpoint that will never occur.
- Commonly observed when stopping emulation in Super Mario Odyssey.
---
 src/video_core/gpu.cpp | 12 +++++++++++-
 src/video_core/gpu.h   |  2 ++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/video_core/gpu.cpp b/src/video_core/gpu.cpp
index 37f7b24e1..35cc561be 100644
--- a/src/video_core/gpu.cpp
+++ b/src/video_core/gpu.cpp
@@ -104,7 +104,13 @@ void GPU::WaitFence(u32 syncpoint_id, u32 value) {
     }
     MICROPROFILE_SCOPE(GPU_wait);
     std::unique_lock lock{sync_mutex};
-    sync_cv.wait(lock, [=, this] { return syncpoints.at(syncpoint_id).load() >= value; });
+    sync_cv.wait(lock, [=, this] {
+        if (shutting_down.load(std::memory_order_relaxed)) {
+            // We're shutting down, ensure no threads continue to wait for the next syncpoint
+            return true;
+        }
+        return syncpoints.at(syncpoint_id).load() >= value;
+    });
 }
 
 void GPU::IncrementSyncPoint(const u32 syncpoint_id) {
@@ -523,6 +529,10 @@ void GPU::TriggerCpuInterrupt(const u32 syncpoint_id, const u32 value) const {
 }
 
 void GPU::ShutDown() {
+    // Signal that threads should no longer block on syncpoint fences
+    shutting_down.store(true, std::memory_order_relaxed);
+    sync_cv.notify_all();
+
     gpu_thread.ShutDown();
 }
 
diff --git a/src/video_core/gpu.h b/src/video_core/gpu.h
index 29a867863..a8e98e51b 100644
--- a/src/video_core/gpu.h
+++ b/src/video_core/gpu.h
@@ -389,6 +389,8 @@ private:
     std::unique_ptr<Engines::KeplerMemory> kepler_memory;
     /// Shader build notifier
     std::unique_ptr<VideoCore::ShaderNotify> shader_notify;
+    /// When true, we are about to shut down emulation session, so terminate outstanding tasks
+    std::atomic_bool shutting_down{};
 
     std::array<std::atomic<u32>, Service::Nvidia::MaxSyncPoints> syncpoints{};