From 7c1e8a85cd3d84965502e5f9f6bad609cbd52a07 Mon Sep 17 00:00:00 2001
From: Geoffrey McRae <geoff@hostfission.com>
Date: Sun, 4 Jul 2021 21:54:44 +1000
Subject: [PATCH] [client] egl: fix race on resolution change

A resolution switch could cause the renderer state to become invalid as
the texture format may change while it's being rendered. This fixes this
by adding a lock around the format change and render calls to the
renderer.
---
 client/src/main.c | 12 ++++++++++++
 client/src/main.h |  2 ++
 2 files changed, 14 insertions(+)

diff --git a/client/src/main.c b/client/src/main.c
index 671ede9a..b3a2e23d 100644
--- a/client/src/main.c
+++ b/client/src/main.c
@@ -106,6 +106,8 @@ static int renderThread(void * unused)
     return 1;
   }
 
+  LG_LOCK_INIT(g_state.lgrLock);
+
   g_state.lgr->on_show_fps(g_state.lgrData, g_state.showFPS);
 
   /* signal to other threads that the renderer is ready */
@@ -132,8 +134,13 @@ static int renderThread(void * unused)
       atomic_compare_exchange_weak(&g_state.lgrResize, &resize, 0);
     }
 
+    LG_LOCK(g_state.lgrLock);
     if (!g_state.lgr->render(g_state.lgrData, g_params.winRotate))
+    {
+      LG_UNLOCK(g_state.lgrLock);
       break;
+    }
+    LG_UNLOCK(g_state.lgrLock);
 
     if (g_state.showFPS)
     {
@@ -184,6 +191,8 @@ static int renderThread(void * unused)
 
   g_state.lgr->deinitialize(g_state.lgrData);
   g_state.lgr = NULL;
+  LG_LOCK_FREE(g_state.lgrLock);
+
   return 0;
 }
 
@@ -492,12 +501,15 @@ int main_frameThread(void * unused)
           frame->stride, frame->pitch,
           frame->rotation);
 
+      LG_LOCK(g_state.lgrLock);
       if (!g_state.lgr->on_frame_format(g_state.lgrData, lgrFormat, useDMA))
       {
         DEBUG_ERROR("renderer failed to configure format");
         g_state.state = APP_STATE_SHUTDOWN;
+        LG_UNLOCK(g_state.lgrLock);
         break;
       }
+      LG_UNLOCK(g_state.lgrLock);
 
       g_state.srcSize.x = lgrFormat.width;
       g_state.srcSize.y = lgrFormat.height;
diff --git a/client/src/main.h b/client/src/main.h
index 856c32cf..20938f8f 100644
--- a/client/src/main.h
+++ b/client/src/main.h
@@ -28,6 +28,7 @@
 #include "common/thread.h"
 #include "common/types.h"
 #include "common/ivshmem.h"
+#include "common/locking.h"
 
 #include "spice/spice.h"
 #include <lgmp/client.h>
@@ -73,6 +74,7 @@ struct AppState
   const LG_Renderer  * lgr;
   void               * lgrData;
   atomic_int           lgrResize;
+  LG_Lock              lgrLock;
 
   bool                 cbAvailable;
   SpiceDataType        cbType;