From fab9961c4912f2ddd3e35ce9c6d66dd3851b8742 Mon Sep 17 00:00:00 2001
From: Geoffrey McRae <geoff@hostfission.com>
Date: Fri, 31 Jul 2026 14:15:17 +1000
Subject: [PATCH] [client] egl: fix streamed texture post-processing race

---
 client/renderers/EGL/desktop.c        | 18 +++++++++++-------
 client/renderers/EGL/egltypes.h       |  1 +
 client/renderers/EGL/texture_buffer.c |  2 +-
 3 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/client/renderers/EGL/desktop.c b/client/renderers/EGL/desktop.c
index 9f1d7415..ffaf36a3 100644
--- a/client/renderers/EGL/desktop.c
+++ b/client/renderers/EGL/desktop.c
@@ -431,12 +431,14 @@ bool egl_desktopUpdate(EGL_Desktop * desktop, const FrameBuffer * frame, int dma
       return false;
   }
 
+  /*
+   * Streamed textures trigger post-processing when the render context submits
+   * the upload. Signalling here can race with that submission and process the
+   * previous texture contents instead.
+   */
   if (likely(egl_textureUpdateFromFrame(desktop->texture, frame,
         damageRects, damageRectsCount)))
-  {
-    atomic_store(&desktop->processFrame, true);
     return true;
-  }
 
   return false;
 }
@@ -474,8 +476,9 @@ bool egl_desktopRender(EGL_Desktop * desktop, unsigned int outputWidth,
   if (unlikely(outputWidth == 0 || outputHeight == 0))
     DEBUG_FATAL("outputWidth || outputHeight == 0");
 
-  enum EGL_TexStatus status;
-  if (unlikely((status = egl_textureProcess(tex)) != EGL_TEX_STATUS_OK))
+  const enum EGL_TexStatus status = egl_textureProcess(tex);
+  const bool textureUpdated = status == EGL_TEX_STATUS_UPDATED;
+  if (unlikely(status != EGL_TEX_STATUS_OK && !textureUpdated))
   {
     if (status != EGL_TEX_STATUS_NOTREADY)
       DEBUG_ERROR("Failed to process the desktop texture");
@@ -501,8 +504,9 @@ bool egl_desktopRender(EGL_Desktop * desktop, unsigned int outputWidth,
           HDR_PEAK_LUMINANCE_MIN, HDR_PEAK_LUMINANCE_MAX);
   }
 
-  const bool processFrame = atomic_exchange(&desktop->processFrame, false) ||
-    egl_postProcessConfigModified(desktop->pp);
+  bool processFrame = textureUpdated;
+  processFrame |= atomic_exchange(&desktop->processFrame, false);
+  processFrame |= egl_postProcessConfigModified(desktop->pp);
   if (processFrame &&
       egl_postProcessRun(desktop->pp, tex, desktop->mesh,
         width, height, outputWidth, outputHeight, dma,
diff --git a/client/renderers/EGL/egltypes.h b/client/renderers/EGL/egltypes.h
index 7990e9ed..1967ecef 100644
--- a/client/renderers/EGL/egltypes.h
+++ b/client/renderers/EGL/egltypes.h
@@ -48,6 +48,7 @@ typedef enum EGL_TexStatus
 {
   EGL_TEX_STATUS_NOTREADY,
   EGL_TEX_STATUS_OK,
+  EGL_TEX_STATUS_UPDATED,
   EGL_TEX_STATUS_ERROR
 }
 EGL_TexStatus;
diff --git a/client/renderers/EGL/texture_buffer.c b/client/renderers/EGL/texture_buffer.c
index 11de3c2b..6d17d427 100644
--- a/client/renderers/EGL/texture_buffer.c
+++ b/client/renderers/EGL/texture_buffer.c
@@ -325,7 +325,7 @@ EGL_TexStatus egl_texBufferStreamProcess(EGL_Texture * texture)
   if (keepLocked)
     LG_UNLOCK(this->copyLock);
 
-  return EGL_TEX_STATUS_OK;
+  return EGL_TEX_STATUS_UPDATED;
 }
 
 EGL_TexStatus egl_texBufferStreamGet(EGL_Texture * texture, GLuint * tex,