[Mesa-dev] [PATCH 7/8] glx: fix the refcounting of dri drawables

[Stéphane Marchesin]

On Mar 23, 2016 17:13, "Miklós Máté" <mtmkls at gmail.com> wrote:
>
> This fixes premature deallocation on unbind, and introduces
> support for deleting GLX drawables while they are current to a context.
>
> Note that in practice this also introduces a resource leak, because nobody
> uses the GLX 1.3 glXDestroyWindow and glXDestroyPixmap calls.
>
> This fixes disappearing characters in SW:KotOR when soft shadows are
enabled.
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=93955

Chrome has hit the same problem. There is no way to fix glx without
breaking glx 1.3. I think we should educate people still using glx 1.2 to
go to 1.3 instead. That's what we did for chrome.

Stéphane

>
> Signed-off-by: Miklós Máté <mtmkls at gmail.com>
> ---
>  src/glx/dri_common.c  | 3 ++-
>  src/glx/glx_pbuffer.c | 8 ++++++--
>  src/glx/glxcmds.c     | 8 ++++++--
>  3 files changed, 14 insertions(+), 5 deletions(-)
>
> diff --git a/src/glx/dri_common.c b/src/glx/dri_common.c
> index 6728d38..7051fa0 100644
> --- a/src/glx/dri_common.c
> +++ b/src/glx/dri_common.c
> @@ -420,7 +420,8 @@ driFetchDrawable(struct glx_context *gc, GLXDrawable
glxDrawable)
>        (*pdraw->destroyDrawable) (pdraw);
>        return NULL;
>     }
> -   pdraw->refcount = 1;
> +   /* created and bound */
> +   pdraw->refcount = 1 + 1;
>
>     return pdraw;
>  }
> diff --git a/src/glx/glx_pbuffer.c b/src/glx/glx_pbuffer.c
> index 231ab20..860c039 100644
> --- a/src/glx/glx_pbuffer.c
> +++ b/src/glx/glx_pbuffer.c
> @@ -217,6 +217,7 @@ CreateDRIDrawable(Display *dpy, struct glx_config
*config,
>        (*pdraw->destroyDrawable) (pdraw);
>        return GL_FALSE;
>     }
> +   pdraw->refcount = 1;
>
>     pdraw->textureTarget = determineTextureTarget(attrib_list,
num_attribs);
>     pdraw->textureFormat = determineTextureFormat(attrib_list,
num_attribs);
> @@ -233,8 +234,11 @@ DestroyDRIDrawable(Display *dpy, GLXDrawable
drawable, int destroy_xdrawable)
>
>     if (priv != NULL && pdraw != NULL) {
>        xid = pdraw->xDrawable;
> -      (*pdraw->destroyDrawable) (pdraw);
> -      __glxHashDelete(priv->drawHash, drawable);
> +      pdraw->refcount --;
> +      if (pdraw->refcount == 0) {
> +         (*pdraw->destroyDrawable) (pdraw);
> +         __glxHashDelete(priv->drawHash, drawable);
> +      }
>        if (destroy_xdrawable)
>           XFreePixmap(priv->dpy, xid);
>     }
> diff --git a/src/glx/glxcmds.c b/src/glx/glxcmds.c
> index 93e8db5..ce798c6 100644
> --- a/src/glx/glxcmds.c
> +++ b/src/glx/glxcmds.c
> @@ -753,6 +753,7 @@ glXCreateGLXPixmap(Display * dpy, XVisualInfo * vis,
Pixmap pixmap)
>           xid = None;
>           break;
>        }
> +      pdraw->refcount = 1;
>     } while (0);
>
>     if (xid == None) {
> @@ -806,8 +807,11 @@ glXDestroyGLXPixmap(Display * dpy, GLXPixmap
glxpixmap)
>        __GLXDRIdrawable *pdraw = GetGLXDRIDrawable(dpy, glxpixmap);
>
>        if (priv != NULL && pdraw != NULL) {
> -         (*pdraw->destroyDrawable) (pdraw);
> -         __glxHashDelete(priv->drawHash, glxpixmap);
> +         pdraw->refcount --;
> +         if (pdraw->refcount == 0) {
> +            (*pdraw->destroyDrawable) (pdraw);
> +            __glxHashDelete(priv->drawHash, glxpixmap);
> +         }
>        }
>     }
>  #endif
> --
> 2.8.0.rc3
>
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