[Mesa-dev] [PATCH 10/30] egl/dri2: rework dri2_make_current code flow

[Eric Engestrom]

On Thu, Aug 25, 2016 at 05:18:32PM +0100, Emil Velikov wrote:
> From: Emil Velikov <emil.velikov at collabora.com>
> 
> Duplicate a few lines at the expense of making the code-flow clearer
> while adding a few extra comments ;-)
> 
> Signed-off-by: Emil Velikov <emil.velikov at collabora.com>
> ---
> 
> It makes things clearer the way on this end, but if people have better
> suggestions I would love to hear them.
> 
> Emil
> ---
>  src/egl/drivers/dri2/egl_dri2.c | 43 ++++++++++++++++++++++-------------------
>  1 file changed, 23 insertions(+), 20 deletions(-)
> 
> diff --git a/src/egl/drivers/dri2/egl_dri2.c b/src/egl/drivers/dri2/egl_dri2.c
> index a481236..d53c9b9 100644
> --- a/src/egl/drivers/dri2/egl_dri2.c
> +++ b/src/egl/drivers/dri2/egl_dri2.c
> @@ -1248,11 +1248,12 @@ dri2_make_current(_EGLDriver *drv, _EGLDisplay *disp, _EGLSurface *dsurf,
>     struct dri2_egl_display *dri2_dpy = dri2_egl_display(disp);
>     struct dri2_egl_context *dri2_ctx = dri2_egl_context(ctx);
>     _EGLContext *old_ctx;
> +   _EGLDisplay *old_disp = NULL;
>     _EGLSurface *old_dsurf, *old_rsurf;
>     _EGLSurface *tmp_dsurf, *tmp_rsurf;
> -   __DRIdrawable *ddraw, *rdraw;
> -   __DRIcontext *cctx;
> -   EGLBoolean unbind;
> +   __DRIdrawable *ddraw = (dsurf) ? dri2_dpy->vtbl->get_dri_drawable(dsurf) : NULL;
> +   __DRIdrawable *rdraw = (rsurf) ? dri2_dpy->vtbl->get_dri_drawable(rsurf) : NULL;
> +   __DRIcontext *cctx = (dri2_ctx) ? dri2_ctx->dri_context : NULL;
>  
>     if (!dri2_dpy)
>        return _eglError(EGL_NOT_INITIALIZED, "eglMakeCurrent");
> @@ -1263,32 +1264,34 @@ dri2_make_current(_EGLDriver *drv, _EGLDisplay *disp, _EGLSurface *dsurf,
>        return EGL_FALSE;
>     }
>  
> -   /* flush before context switch */
> -   if (old_ctx)
> -      dri2_drv->glFlush();
> -
> -   ddraw = (dsurf) ? dri2_dpy->vtbl->get_dri_drawable(dsurf) : NULL;
> -   rdraw = (rsurf) ? dri2_dpy->vtbl->get_dri_drawable(rsurf) : NULL;
> -   cctx = (dri2_ctx) ? dri2_ctx->dri_context : NULL;
> -
>     if (old_ctx) {
>        __DRIcontext *old_cctx = dri2_egl_context(old_ctx)->dri_context;
> +
> +      /* flush before context switch */
> +      dri2_drv->glFlush();
>        dri2_dpy->core->unbindContext(old_cctx);
> +
> +      /* Keep track of the old dpy as we'll need it for resource cleanup */
> +      old_disp = old_ctx->Resource.Display;
>     }
>  
> -   unbind = (cctx == NULL && ddraw == NULL && rdraw == NULL);
> +    /* There's no new ctx to bind, so just destroy the old resources */
> +   if (cctx == NULL) {
> +      dri2_destroy_surface(drv, disp, old_dsurf);
> +      dri2_destroy_surface(drv, disp, old_rsurf);
> +      dri2_destroy_context(drv, disp, old_ctx);
> +      dri2_display_release(old_disp);
>  
> -   if (unbind || dri2_dpy->core->bindContext(cctx, ddraw, rdraw)) {
> +      return EGL_TRUE;
> +   }
> +   if (dri2_dpy->core->bindContext(cctx, ddraw, rdraw)) {

I'm pretty sure dropping `unbind` changes the behaviour, which means
this isn't just a refactor.

(Also, nit: the grouping on that diff would have been better if you had
left an empty line between the two `if` :)

>        dri2_destroy_surface(drv, disp, old_dsurf);
>        dri2_destroy_surface(drv, disp, old_rsurf);
> +      dri2_destroy_context(drv, disp, old_ctx);
> +      dri2_display_release(old_disp);

I think `dri2_display_release()` needs to be in an `if (old_disp)` (or
`if (old_ctx)`, they're equivalent at this point), as it will
dereference old_disp.

Cheers,
  Eric

>  
> -      if (!unbind)
> -         dri2_dpy->ref_count++;
> -      if (old_ctx) {
> -         EGLDisplay old_disp = _eglGetDisplayHandle(old_ctx->Resource.Display);
> -         dri2_destroy_context(drv, disp, old_ctx);
> -         dri2_display_release(old_disp);
> -      }
> +      /* Refcount the new dpy */
> +      dri2_dpy->ref_count++;
>  
>        return EGL_TRUE;
>     } else {
> -- 
> 2.9.0