[Mesa-dev] [PATCH v2] platform_android: prevent deadlock in droid_swap_buffers

[Haixia Shi]

To avoid blocking other EGL calls, release the display mutex before
we enqueue buffer to android frameworks and re-acquire the mutex
upon return.

v2: moved lock/unlock inside droid_window_enqueue_buffer().

TEST=verify pinch zoom in Photos app no longer causes hangs

Signed-off-by: Haixia Shi <hshi at chromium.org>
---
 src/egl/drivers/dri2/platform_android.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/src/egl/drivers/dri2/platform_android.c b/src/egl/drivers/dri2/platform_android.c
index 25d02f5..0c5550b 100644
--- a/src/egl/drivers/dri2/platform_android.c
+++ b/src/egl/drivers/dri2/platform_android.c
@@ -160,8 +160,14 @@ droid_window_dequeue_buffer(struct dri2_egl_surface *dri2_surf)
 }
 
 static EGLBoolean
-droid_window_enqueue_buffer(struct dri2_egl_surface *dri2_surf)
+droid_window_enqueue_buffer(_EGLDisplay *disp, struct dri2_egl_surface *dri2_surf)
 {
+   /* To avoid blocking other EGL calls, release the display mutex before
+    * we enter droid_window_enqueue_buffer() and re-acquire the mutex upon
+    * return.
+    */
+   mtx_unlock(&disp->Mutex);
+
 #if ANDROID_VERSION >= 0x0402
    /* Queue the buffer without a sync fence. This informs the ANativeWindow
     * that it may access the buffer immediately.
@@ -185,14 +191,15 @@ droid_window_enqueue_buffer(struct dri2_egl_surface *dri2_surf)
    dri2_surf->buffer->common.decRef(&dri2_surf->buffer->common);
    dri2_surf->buffer = NULL;
 
+   mtx_lock(&disp->Mutex);
    return EGL_TRUE;
 }
 
 static void
-droid_window_cancel_buffer(struct dri2_egl_surface *dri2_surf)
+droid_window_cancel_buffer(_EGLDisplay *disp, struct dri2_egl_surface *dri2_surf)
 {
    /* no cancel buffer? */
-   droid_window_enqueue_buffer(dri2_surf);
+   droid_window_enqueue_buffer(disp, dri2_surf);
 }
 
 static __DRIbuffer *
@@ -325,7 +332,7 @@ droid_destroy_surface(_EGLDriver *drv, _EGLDisplay *disp, _EGLSurface *surf)
 
    if (dri2_surf->base.Type == EGL_WINDOW_BIT) {
       if (dri2_surf->buffer)
-         droid_window_cancel_buffer(dri2_surf);
+         droid_window_cancel_buffer(disp, dri2_surf);
 
       dri2_surf->window->common.decRef(&dri2_surf->window->common);
    }
@@ -435,7 +442,7 @@ droid_swap_buffers(_EGLDriver *drv, _EGLDisplay *disp, _EGLSurface *draw)
    dri2_flush_drawable_for_swapbuffers(disp, draw);
 
    if (dri2_surf->buffer)
-      droid_window_enqueue_buffer(dri2_surf);
+      droid_window_enqueue_buffer(disp, dri2_surf);
 
    (*dri2_dpy->flush->invalidate)(dri2_surf->dri_drawable);
 
-- 
2.8.0.rc3.226.g39d4020