[Bf-blender-cvs] [4fbd00e04c0] blender-v3.1-release: Fix T94268: Closing SteamVR and restarting VR Session crashes Blender

[Peter Kim]

Commit: 4fbd00e04c00735fdcc135c588b884fbb9b71efc
Author: Peter Kim
Date:   Fri Feb 11 20:38:22 2022 +0900
Branches: blender-v3.1-release
https://developer.blender.org/rB4fbd00e04c00735fdcc135c588b884fbb9b71efc

Fix T94268: Closing SteamVR and restarting VR Session crashes Blender

Crash was caused since the function pointers
`s_xrGetOpenGLGraphicsRequirementsKHR_fn`/
`s_xrGetD3D11GraphicsRequirementsKHR_fn` were static and were not
updated with the correct proc address after being set the first time.

As stated in the OpenXR spec: "function pointers returned by
xrGetInstanceProcAddr using one XrInstance may not be valid when used
with objects related to a different XrInstance".

Although it would seem reasonable that the proc address would not
change if the instance was the same (hence the `static XrInstance s_instance;`),
in testing, repeated calls to `xrGetInstanceProcAddress()`
with the same instance still can result in changes (at least for the
SteamVR runtime) so the workaround is to simply set the function pointers
every time, essentially trivializing their `static` designations.

Reviewed By: Severin

Maniphest Tasks: T94268

Differential Revision: https://developer.blender.org/D14023

===================================================================

M	intern/ghost/intern/GHOST_XrGraphicsBinding.cpp

===================================================================

diff --git a/intern/ghost/intern/GHOST_XrGraphicsBinding.cpp b/intern/ghost/intern/GHOST_XrGraphicsBinding.cpp
index 936b973c97e..6eaf55afacd 100644
--- a/intern/ghost/intern/GHOST_XrGraphicsBinding.cpp
+++ b/intern/ghost/intern/GHOST_XrGraphicsBinding.cpp
@@ -84,16 +84,26 @@ class GHOST_XrGraphicsBindingOpenGL : public GHOST_IXrGraphicsBinding {
 #endif
     static PFN_xrGetOpenGLGraphicsRequirementsKHR s_xrGetOpenGLGraphicsRequirementsKHR_fn =
         nullptr;
+    // static XrInstance s_instance = XR_NULL_HANDLE;
     XrGraphicsRequirementsOpenGLKHR gpu_requirements = {XR_TYPE_GRAPHICS_REQUIREMENTS_OPENGL_KHR};
     const XrVersion gl_version = XR_MAKE_VERSION(
         ctx_gl.m_contextMajorVersion, ctx_gl.m_contextMinorVersion, 0);
 
+    /* Although it would seem reasonable that the proc address would not change if the instance was
+     * the same, in testing, repeated calls to #xrGetInstanceProcAddress() with the same instance
+     * can still result in changes so the workaround is to simply set the function pointer every
+     * time (trivializing its 'static' designation). */
+    // if (instance != s_instance) {
+    // s_instance = instance;
+    s_xrGetOpenGLGraphicsRequirementsKHR_fn = nullptr;
+    //}
     if (!s_xrGetOpenGLGraphicsRequirementsKHR_fn &&
         XR_FAILED(xrGetInstanceProcAddr(
             instance,
             "xrGetOpenGLGraphicsRequirementsKHR",
             (PFN_xrVoidFunction *)&s_xrGetOpenGLGraphicsRequirementsKHR_fn))) {
       s_xrGetOpenGLGraphicsRequirementsKHR_fn = nullptr;
+      return false;
     }
 
     s_xrGetOpenGLGraphicsRequirementsKHR_fn(instance, system_id, &gpu_requirements);
@@ -305,14 +315,24 @@ class GHOST_XrGraphicsBindingD3D : public GHOST_IXrGraphicsBinding {
       std::string *r_requirement_info) const override
   {
     static PFN_xrGetD3D11GraphicsRequirementsKHR s_xrGetD3D11GraphicsRequirementsKHR_fn = nullptr;
+    // static XrInstance s_instance = XR_NULL_HANDLE;
     XrGraphicsRequirementsD3D11KHR gpu_requirements = {XR_TYPE_GRAPHICS_REQUIREMENTS_D3D11_KHR};
 
+    /* Although it would seem reasonable that the proc address would not change if the instance was
+     * the same, in testing, repeated calls to #xrGetInstanceProcAddress() with the same instance
+     * can still result in changes so the workaround is to simply set the function pointer every
+     * time (trivializing its 'static' designation). */
+    // if (instance != s_instance) {
+    // s_instance = instance;
+    s_xrGetD3D11GraphicsRequirementsKHR_fn = nullptr;
+    //}
     if (!s_xrGetD3D11GraphicsRequirementsKHR_fn &&
         XR_FAILED(xrGetInstanceProcAddr(
             instance,
             "xrGetD3D11GraphicsRequirementsKHR",
             (PFN_xrVoidFunction *)&s_xrGetD3D11GraphicsRequirementsKHR_fn))) {
       s_xrGetD3D11GraphicsRequirementsKHR_fn = nullptr;
+      return false;
     }
 
     s_xrGetD3D11GraphicsRequirementsKHR_fn(instance, system_id, &gpu_requirements);