From cf202f371862ebe92dd88924a9f7b8cfbc7ad738 Mon Sep 17 00:00:00 2001
From: Liam <byteslice@airmail.cc>
Date: Mon, 14 Nov 2022 21:00:32 -0500
Subject: [PATCH] nvnflinger: fix lost wakeup

---
 .../hle/service/nvflinger/buffer_queue_core.cpp    |  6 ++++--
 src/core/hle/service/nvflinger/buffer_queue_core.h |  5 +++--
 .../service/nvflinger/buffer_queue_producer.cpp    | 14 +++++++-------
 .../hle/service/nvflinger/buffer_queue_producer.h  |  3 ++-
 4 files changed, 16 insertions(+), 12 deletions(-)

diff --git a/src/core/hle/service/nvflinger/buffer_queue_core.cpp b/src/core/hle/service/nvflinger/buffer_queue_core.cpp
index ea4a14ea4e..3d1338e66d 100644
--- a/src/core/hle/service/nvflinger/buffer_queue_core.cpp
+++ b/src/core/hle/service/nvflinger/buffer_queue_core.cpp
@@ -23,15 +23,17 @@ void BufferQueueCore::NotifyShutdown() {
 }
 
 void BufferQueueCore::SignalDequeueCondition() {
+    dequeue_possible.store(true);
     dequeue_condition.notify_all();
 }
 
-bool BufferQueueCore::WaitForDequeueCondition() {
+bool BufferQueueCore::WaitForDequeueCondition(std::unique_lock<std::mutex>& lk) {
     if (is_shutting_down) {
         return false;
     }
 
-    dequeue_condition.wait(mutex);
+    dequeue_condition.wait(lk, [&] { return dequeue_possible.load(); });
+    dequeue_possible.store(false);
 
     return true;
 }
diff --git a/src/core/hle/service/nvflinger/buffer_queue_core.h b/src/core/hle/service/nvflinger/buffer_queue_core.h
index ca6baefaf2..85b3bc4c12 100644
--- a/src/core/hle/service/nvflinger/buffer_queue_core.h
+++ b/src/core/hle/service/nvflinger/buffer_queue_core.h
@@ -38,7 +38,7 @@ public:
 
 private:
     void SignalDequeueCondition();
-    bool WaitForDequeueCondition();
+    bool WaitForDequeueCondition(std::unique_lock<std::mutex>& lk);
 
     s32 GetMinUndequeuedBufferCountLocked(bool async) const;
     s32 GetMinMaxBufferCountLocked(bool async) const;
@@ -60,7 +60,8 @@ private:
     BufferQueueDefs::SlotsType slots{};
     std::vector<BufferItem> queue;
     s32 override_max_buffer_count{};
-    mutable std::condition_variable_any dequeue_condition;
+    std::condition_variable dequeue_condition;
+    std::atomic<bool> dequeue_possible{};
     const bool use_async_buffer{}; // This is always disabled on HOS
     bool dequeue_buffer_cannot_block{};
     PixelFormat default_buffer_format{PixelFormat::Rgba8888};
diff --git a/src/core/hle/service/nvflinger/buffer_queue_producer.cpp b/src/core/hle/service/nvflinger/buffer_queue_producer.cpp
index 41ba44b215..e601b5da1c 100644
--- a/src/core/hle/service/nvflinger/buffer_queue_producer.cpp
+++ b/src/core/hle/service/nvflinger/buffer_queue_producer.cpp
@@ -121,8 +121,8 @@ Status BufferQueueProducer::SetBufferCount(s32 buffer_count) {
     return Status::NoError;
 }
 
-Status BufferQueueProducer::WaitForFreeSlotThenRelock(bool async, s32* found,
-                                                      Status* return_flags) const {
+Status BufferQueueProducer::WaitForFreeSlotThenRelock(bool async, s32* found, Status* return_flags,
+                                                      std::unique_lock<std::mutex>& lk) const {
     bool try_again = true;
 
     while (try_again) {
@@ -214,7 +214,7 @@ Status BufferQueueProducer::WaitForFreeSlotThenRelock(bool async, s32* found,
                 return Status::WouldBlock;
             }
 
-            if (!core->WaitForDequeueCondition()) {
+            if (!core->WaitForDequeueCondition(lk)) {
                 // We are no longer running
                 return Status::NoError;
             }
@@ -237,7 +237,7 @@ Status BufferQueueProducer::DequeueBuffer(s32* out_slot, Fence* out_fence, bool
     Status return_flags = Status::NoError;
     bool attached_by_consumer = false;
     {
-        std::scoped_lock lock{core->mutex};
+        std::unique_lock lock{core->mutex};
         core->WaitWhileAllocatingLocked();
 
         if (format == PixelFormat::NoFormat) {
@@ -248,7 +248,7 @@ Status BufferQueueProducer::DequeueBuffer(s32* out_slot, Fence* out_fence, bool
         usage |= core->consumer_usage_bit;
 
         s32 found{};
-        Status status = WaitForFreeSlotThenRelock(async, &found, &return_flags);
+        Status status = WaitForFreeSlotThenRelock(async, &found, &return_flags, lock);
         if (status != Status::NoError) {
             return status;
         }
@@ -400,13 +400,13 @@ Status BufferQueueProducer::AttachBuffer(s32* out_slot,
         return Status::BadValue;
     }
 
-    std::scoped_lock lock{core->mutex};
+    std::unique_lock lock{core->mutex};
     core->WaitWhileAllocatingLocked();
 
     Status return_flags = Status::NoError;
     s32 found{};
 
-    const auto status = WaitForFreeSlotThenRelock(false, &found, &return_flags);
+    const auto status = WaitForFreeSlotThenRelock(false, &found, &return_flags, lock);
     if (status != Status::NoError) {
         return status;
     }
diff --git a/src/core/hle/service/nvflinger/buffer_queue_producer.h b/src/core/hle/service/nvflinger/buffer_queue_producer.h
index 7526bf8ece..1d380480f0 100644
--- a/src/core/hle/service/nvflinger/buffer_queue_producer.h
+++ b/src/core/hle/service/nvflinger/buffer_queue_producer.h
@@ -70,7 +70,8 @@ public:
 private:
     BufferQueueProducer(const BufferQueueProducer&) = delete;
 
-    Status WaitForFreeSlotThenRelock(bool async, s32* found, Status* return_flags) const;
+    Status WaitForFreeSlotThenRelock(bool async, s32* found, Status* return_flags,
+                                     std::unique_lock<std::mutex>& lk) const;
 
     Kernel::KEvent* buffer_wait_event{};
     Service::KernelHelpers::ServiceContext& service_context;