From ab4a2e97a9ae8340f755193f8d0b4f8cfa929b23 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jos=C3=A9=20Exp=C3=B3sito?= <jexposit@redhat.com>
Date: Tue, 14 Nov 2023 09:23:23 +0100
Subject: [PATCH] egl/glx: fallback to software when Zink is forced and fails
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When `MESA_LOADER_DRIVER_OVERRIDE` is set to `zink` and the display
initialization fails, fallback to software rendering.

The error was reported in #10123 and it can be reproduced with:

    $ MESA_LOADER_DRIVER_OVERRIDE=zink eglinfo

`eglinfo` would crash in `dri2_display_release()` because of
`assert(dri2_dpy->ref_count > 0)`.

After bisecting the error to commit 8cd44b884387 ("egl/glx: add
autoloading for zink"), I found out that, before this change, the
display was set to initialized even when `_eglDriver.Initialize(disp)`
failed:

    disp->Options.Zink = env && !strcmp(env, "zink");
    // disp->Options.Zink is true

    if (!_eglDriver.Initialize(disp)) {
       [...]
       // Zink initialization has failed at this point
       // However, success is set to true:
       bool success = disp->Options.Zink;
       if (!disp->Options.Zink && !getenv("GALLIUM_DRIVER")) {
          [...]
       }
       // Software initialization is ignored because success is true
       if (!success) {
          [...]
       }
    }

    // The display is set as initialized even though it shouldn't
    disp->Initialized = EGL_TRUE;

Resolves: https://gitlab.freedesktop.org/mesa/mesa/-/issues/10123
Fixes: 8cd44b884387 ("egl/glx: add autoloading for zink")
Signed-off-by: José Expósito <jexposit@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/26184>
(cherry picked from commit d913927fe9201f0fea71ef0e614b9c400c122d49)
---
 .pick_status.json     | 2 +-
 src/egl/main/eglapi.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/.pick_status.json b/.pick_status.json
index 2056adad921..446acdb8812 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -234,7 +234,7 @@
         "description": "egl/glx: fallback to software when Zink is forced and fails",
         "nominated": true,
         "nomination_type": 1,
-        "resolution": 0,
+        "resolution": 1,
         "main_sha": null,
         "because_sha": "8cd44b8843877a2f7d559d123eb3694841f16fdc",
         "notes": null
diff --git a/src/egl/main/eglapi.c b/src/egl/main/eglapi.c
index b9f179c2ce3..d50be23e871 100644
--- a/src/egl/main/eglapi.c
+++ b/src/egl/main/eglapi.c
@@ -695,7 +695,7 @@ eglInitialize(EGLDisplay dpy, EGLint *major, EGLint *minor)
          if (disp->Options.ForceSoftware)
             RETURN_EGL_ERROR(disp, EGL_NOT_INITIALIZED, EGL_FALSE);
          else {
-            bool success = disp->Options.Zink;
+            bool success = false;
             if (!disp->Options.Zink && !getenv("GALLIUM_DRIVER")) {
                disp->Options.Zink = EGL_TRUE;
                success = _eglDriver.Initialize(disp);