From 7887efa69f5db3e45cd76d7e33629ece6ed19eb0 Mon Sep 17 00:00:00 2001
From: "Herman S." <429230+has207@users.noreply.github.com>
Date: Fri, 17 Oct 2025 00:18:20 +0900
Subject: [PATCH] [APU] fix potential semaphore leak on invalid client index

---
 src/xenia/apu/audio_system.cc | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/xenia/apu/audio_system.cc b/src/xenia/apu/audio_system.cc
index e5c4fd3c9..ba53454b3 100644
--- a/src/xenia/apu/audio_system.cc
+++ b/src/xenia/apu/audio_system.cc
@@ -248,6 +248,14 @@ void AudioSystem::SubmitFrame(size_t index, float* samples) {
         "(in_use={}, driver={:p})",
         index, index < kMaximumClientCount ? clients_[index].in_use : false,
         index < kMaximumClientCount ? (void*)clients_[index].driver : nullptr);
+
+    // Submit silence instead of dropping the frame to maintain the callback
+    // chain.  If we don't submit anything, the audio driver's OnBufferEnd
+    // callback will never fire, causing the semaphore to leak.
+    if (index < kMaximumClientCount && clients_[index].driver) {
+      static float silence[apu::AudioDriver::kFrameSamplesMax] = {0};
+      (clients_[index].driver)->SubmitFrame(silence);
+    }
     return;
   }
   (clients_[index].driver)->SubmitFrame(samples);