[Mesa-dev] [PATCH] st/mesa: fix sampler view reference counting bug in glDraw/CopyPixels

[Ilia Mirkin]

On Wed, Feb 18, 2015 at 1:20 PM, Brian Paul <brianp at vmware.com> wrote:
> Use pipe_sampler_view_reference() instead of ordinary assignment.
> Also add a new sanity check assertion.
>
> Fixes piglit gl-1.0-drawpixels-color-index test crash.  But note
> that the test still fails.

Fails on nvc0 as well, for the record.

>
> Cc: "10.4, 10.5" <mesa-stable at lists.freedesktop.org>
> ---
>  src/mesa/state_tracker/st_cb_drawpixels.c | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/src/mesa/state_tracker/st_cb_drawpixels.c b/src/mesa/state_tracker/st_cb_drawpixels.c
> index 939fc20..3d13b5c 100644
> --- a/src/mesa/state_tracker/st_cb_drawpixels.c
> +++ b/src/mesa/state_tracker/st_cb_drawpixels.c
> @@ -1154,8 +1154,10 @@ st_DrawPixels(struct gl_context *ctx, GLint x, GLint y,
>
>        color = NULL;
>        if (st->pixel_xfer.pixelmap_enabled) {
> -         sv[1] = st->pixel_xfer.pixelmap_sampler_view;
> -         num_sampler_view++;
> +         sv[1] = NULL;
> +         pipe_sampler_view_reference(&sv[1],
> +                                     st->pixel_xfer.pixelmap_sampler_view);

I would *much* prefer a = {NULL} when sv is declared instead of
awkwardly before the reference (both here and in st_CopyPixels).

With that changed, Reviewed-by: Ilia Mirkin <imirkin at alum.mit.edu>

> +         num_sampler_view++;
>        }
>     }
>
> @@ -1176,7 +1178,8 @@ st_DrawPixels(struct gl_context *ctx, GLint x, GLint y,
>              if (write_stencil) {
>                 enum pipe_format stencil_format =
>                       util_format_stencil_only(pt->format);
> -
> +               /* we should not be doing pixel map/transfer (see above) */
> +               assert(num_sampler_view == 1);
>                 sv[1] = st_create_texture_sampler_view_format(st->pipe, pt,
>                                                               stencil_format);
>                 num_sampler_view++;
> @@ -1516,7 +1519,9 @@ st_CopyPixels(struct gl_context *ctx, GLint srcx, GLint srcy,
>        driver_vp = make_passthrough_vertex_shader(st, GL_FALSE);
>
>        if (st->pixel_xfer.pixelmap_enabled) {
> -         sv[1] = st->pixel_xfer.pixelmap_sampler_view;
> +         sv[1] = NULL;
> +         pipe_sampler_view_reference(&sv[1],
> +                                     st->pixel_xfer.pixelmap_sampler_view);
>           num_sampler_view++;
>        }
>     }
> --
> 1.9.1
>
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