From 582b2d345abaa0e313cf16c902e602084ea59551 Mon Sep 17 00:00:00 2001

From: Erik Kurzinger <ekurzinger@nvidia.com>

Date: Tue, 23 Nov 2021 14:15:14 -0500

Subject: [PATCH] egl-wayland: retrieve DRM device name before acquiring API

 lock

wlEglBindDisplaysHook acquires the external API lock before calling

wl_eglstream_display_bind, which in turn calls wl_drm_display_bind. That

function calls back into EGL to query the DRM device associated with the

given EGLDisplay.

Normally this is not a problem since the EGLDisplay passed to

eglBindWaylandDisplayWL will be an internal EGL_PLATFORM_DEVICE handle.

However, some applications, notably anything WebKit-based, will instead

pass in an external EGL_PLATFORM_WAYLAND handle. This means that the

eglQueryDisplayAttrib call by wl_drm_display_bind will require EGL to

call back into the egl-wayland library to look up the internal handle.

This is done by wlEglGetInternalHandleExport, which will attempt to

acquire the external API lock a second time, which will fail.

To avoid this, add a new function to wayland-drm.c which will retrieve

the DRM device name for the given EGLDisplay. wlEglBindDisplaysHook will

call this *before* acquiring the external API lock, and then pass it to

wl_drm_display_bind via wl_eglstream_display_bind so it can be saved in

the wl_eglstream_display struct.

---

 include/wayland-drm.h              |  7 ++++++-

 include/wayland-eglstream-server.h |  3 ++-

 src/wayland-drm.c                  | 33 +++++++++++++++---------------

 src/wayland-egldisplay.c           |  8 +++++---

 src/wayland-eglstream-server.c     |  5 +++--

 5 files changed, 32 insertions(+), 24 deletions(-)

diff --git a/include/wayland-drm.h b/include/wayland-drm.h

index be363c6..84d0f11 100644

--- a/include/wayland-drm.h

+++ b/include/wayland-drm.h

@@ -23,9 +23,14 @@

 #ifndef WAYLAND_DRM_H

 #define WAYLAND_DRM_H

+extern const char *

+wl_drm_get_dev_name(const WlEglPlatformData *data,

+                    EGLDisplay dpy);

+

 extern EGLBoolean

 wl_drm_display_bind(struct wl_display *display,

-                    struct wl_eglstream_display *wlStreamDpy);

+                    struct wl_eglstream_display *wlStreamDpy,

+                    const char *dev_name);

 extern void

 wl_drm_display_unbind(struct wl_eglstream_display *wlStreamDpy);

diff --git a/include/wayland-eglstream-server.h b/include/wayland-eglstream-server.h

index 76e772c..0f7d477 100644

--- a/include/wayland-eglstream-server.h

+++ b/include/wayland-eglstream-server.h

@@ -49,7 +49,8 @@ EGLBoolean

 wl_eglstream_display_bind(WlEglPlatformData *data,

                           struct wl_display *wlDisplay,

                           EGLDisplay eglDisplay,

-                          const char *exts);

+                          const char *exts,

+                          const char *dev_name);

 /*

  * wl_eglstream_display_unbind()

diff --git a/src/wayland-drm.c b/src/wayland-drm.c

index aa6de23..a08d82f 100644

--- a/src/wayland-drm.c

+++ b/src/wayland-drm.c

@@ -152,37 +152,36 @@ bind(struct wl_client *client, void *data, uint32_t version, uint32_t id)

         wl_resource_post_event(resource, WL_DRM_CAPABILITIES, 0);

 }

-EGLBoolean

-wl_drm_display_bind(struct wl_display *display,

-                    struct wl_eglstream_display *wlStreamDpy)

+const char *

+wl_drm_get_dev_name(const WlEglPlatformData *data,

+                    EGLDisplay dpy)

 {

-    EGLDisplay dpy = wlStreamDpy->eglDisplay;

     EGLDeviceEXT egl_dev;

     const char *dev_exts;

-    const char *dev_name;

-    if (!wlStreamDpy->data->egl.queryDisplayAttrib(dpy,

-                                                   EGL_DEVICE_EXT,

-                                                   (EGLAttribKHR*)&egl_dev)) {

-        return EGL_FALSE;

+    if (!data->egl.queryDisplayAttrib(dpy, EGL_DEVICE_EXT,

+                                      (EGLAttribKHR*)&egl_dev)) {

+        return NULL;

     }

-

-    dev_exts = wlStreamDpy->data->egl.queryDeviceString(egl_dev,

-                                                        EGL_EXTENSIONS);

+    dev_exts = data->egl.queryDeviceString(egl_dev, EGL_EXTENSIONS);

     if (!dev_exts) {

-        return EGL_FALSE;

+        return NULL;

     }

     if (!wlEglFindExtension("EGL_EXT_device_drm_render_node", dev_exts)) {

-        return EGL_FALSE;

+        return NULL;

     }

-    dev_name =

-        wlStreamDpy->data->egl.queryDeviceString(egl_dev,

-                                                 EGL_DRM_RENDER_NODE_FILE_EXT);

+    return data->egl.queryDeviceString(egl_dev, EGL_DRM_RENDER_NODE_FILE_EXT);

+}

+EGLBoolean

+wl_drm_display_bind(struct wl_display *display,

+                    struct wl_eglstream_display *wlStreamDpy,

+                    const char *dev_name)

+{

     if (!dev_name) {

         return EGL_FALSE;

     }

diff --git a/src/wayland-egldisplay.c b/src/wayland-egldisplay.c

index 8b7394a..d285bf7 100644

--- a/src/wayland-egldisplay.c

+++ b/src/wayland-egldisplay.c

@@ -30,6 +30,7 @@

 #include "wayland-eglhandle.h"

 #include "wayland-eglutils.h"

 #include "wayland-drm-client-protocol.h"

+#include "wayland-drm.h"

 #include <string.h>

 #include <stdlib.h>

 #include <assert.h>

@@ -70,15 +71,16 @@ EGLBoolean wlEglIsValidNativeDisplayExport(void *data, void *nativeDpy)

 EGLBoolean wlEglBindDisplaysHook(void *data, EGLDisplay dpy, void *nativeDpy)

 {

-    /* Retrieve extension string before taking external API lock */

-    const char *exts = ((WlEglPlatformData *)data)->egl.queryString(dpy, EGL_EXTENSIONS);

+    /* Retrieve extension string and device name before taking external API lock */

+    const char *exts = ((WlEglPlatformData *)data)->egl.queryString(dpy, EGL_EXTENSIONS),

+               *dev_name = wl_drm_get_dev_name(data, dpy);

     EGLBoolean res = EGL_FALSE;

     wlExternalApiLock();

     res = wl_eglstream_display_bind((WlEglPlatformData *)data,

                                     (struct wl_display *)nativeDpy,

-                                    dpy, exts);

+                                    dpy, exts, dev_name);

     wlExternalApiUnlock();

diff --git a/src/wayland-eglstream-server.c b/src/wayland-eglstream-server.c

index b1baa08..1dfd7ce 100644

--- a/src/wayland-eglstream-server.c

+++ b/src/wayland-eglstream-server.c

@@ -289,7 +289,8 @@ EGLBoolean

 wl_eglstream_display_bind(WlEglPlatformData *data,

                           struct wl_display *wlDisplay,

                           EGLDisplay eglDisplay,

-                          const char *exts)

+                          const char *exts,

+                          const char *dev_name)

 {

     struct wl_eglstream_display *wlStreamDpy = NULL;

     char                        *env         = NULL;

@@ -355,7 +356,7 @@ wl_eglstream_display_bind(WlEglPlatformData *data,

                                            wl_eglstream_display_global_bind);

     /* Failure is not fatal */

-    wl_drm_display_bind(wlDisplay, wlStreamDpy);

+    wl_drm_display_bind(wlDisplay, wlStreamDpy, dev_name);

     wl_list_insert(&wlStreamDpyList, &wlStreamDpy->link);