From: Ian Romanick <ian.d.romanick@intel.com>
Date: Tue, 3 Nov 2015 01:04:41 +0000 (-0800)
Subject: i965: Don't pollute the buffer object namespace in brw_meta_fast_clear
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=4e6b9c11fc545cc570ea0042af93e61bfb525d34;p=mesa.git

i965: Don't pollute the buffer object namespace in brw_meta_fast_clear

tl;dr: For many types of GL object, we can *NEVER* use the Gen function.

In OpenGL ES (all versions!) and OpenGL compatibility profile,
applications don't have to call Gen functions.  The GL spec is very
clear about how you can mix-and-match generated names and non-generated
names: you can use any name you want for a particular object type until
you call the Gen function for that object type.

Here's the problem scenario:

 - Application calls a meta function that generates a name.  The first
   Gen will probably return 1.

 - Application decides to use the same name for an object of the same
   type without calling Gen.  Many demo programs use names 1, 2, 3,
   etc. without calling Gen.

 - Application calls the meta function again, and the meta function
   replaces the data.  The application's data is lost, and the app
   fails.  Have fun debugging that.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=92363
Reviewed-by: Abdiel Janulgue <abdiel.janulgue@linux.intel.com>
Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com>
---

diff --git a/src/mesa/drivers/dri/i965/brw_meta_fast_clear.c b/src/mesa/drivers/dri/i965/brw_meta_fast_clear.c
index 1b5479d0315..cd3503508f9 100644
--- a/src/mesa/drivers/dri/i965/brw_meta_fast_clear.c
+++ b/src/mesa/drivers/dri/i965/brw_meta_fast_clear.c
@@ -57,7 +57,6 @@ struct brw_fast_clear_state {
    struct gl_buffer_object *buf_obj;
    struct gl_vertex_array_object *array_obj;
    GLuint vao;
-   GLuint vbo;
    GLuint shader_prog;
    GLint color_location;
 };
@@ -81,10 +80,11 @@ brw_fast_clear_init(struct brw_context *brw)
    memset(clear, 0, sizeof *clear);
    _mesa_GenVertexArrays(1, &clear->vao);
    _mesa_BindVertexArray(clear->vao);
-   _mesa_CreateBuffers(1, &clear->vbo);
 
-   clear->buf_obj = _mesa_lookup_bufferobj(ctx, clear->vbo);
-   assert(clear->buf_obj != NULL);
+   clear->buf_obj = ctx->Driver.NewBufferObject(ctx, 0xDEADBEEF);
+   if (clear->buf_obj == NULL)
+      return false;
+
    clear->array_obj = _mesa_lookup_vao(ctx, clear->vao);
    assert(clear->array_obj != NULL);
 
@@ -162,7 +162,7 @@ brw_meta_fast_clear_free(struct brw_context *brw)
    _mesa_make_current(&brw->ctx, NULL, NULL);
 
    _mesa_DeleteVertexArrays(1, &clear->vao);
-   _mesa_DeleteBuffers(1, &clear->vbo);
+   _mesa_reference_buffer_object(&brw->ctx, &clear->buf_obj, NULL);
    _mesa_DeleteProgram(clear->shader_prog);
    free(clear);