mesa: Enable true refcounting for NullBufferObj.

This object can be shared with another context, so we cannot just
delete it when the owning context is being destroyed.

Ensuring that buffer objects are properly refcounted guarantees
NullBufferObj is destroyed when all references to it are removed.

2 files changed, 22 insertions, 2 deletions

diff --git a/src/mesa/vbo/vbo_context.c b/src/mesa/vbo/vbo_context.c
index 75c32e0b9b..a5b0070bd3 100644
--- a/src/mesa/vbo/vbo_context.c
+++ b/src/mesa/vbo/vbo_context.c
@@ -249,17 +249,25 @@ void _vbo_InvalidateState( GLcontext *ctx, GLuint new_state )
 
 void _vbo_DestroyContext( GLcontext *ctx )
 {
+   struct vbo_context *vbo = vbo_context(ctx);
+
    if (ctx->aelt_context) {
       _ae_destroy_context( ctx );
       ctx->aelt_context = NULL;
    }
 
-   if (vbo_context(ctx)) {
+   if (vbo) {
+      GLuint i;
+
+      for (i = 0; i < VBO_ATTRIB_MAX; i++) {
+         _mesa_reference_buffer_object(ctx, &vbo->currval[i].BufferObj, NULL);
+      }
+
       vbo_exec_destroy(ctx);
 #if FEATURE_dlist
       vbo_save_destroy(ctx);
 #endif
-      FREE(vbo_context(ctx));
+      FREE(vbo);
       ctx->swtnl_im = NULL;
    }
 }
diff --git a/src/mesa/vbo/vbo_exec_api.c b/src/mesa/vbo/vbo_exec_api.c
index f0a7eeadd0..8ee14be261 100644
--- a/src/mesa/vbo/vbo_exec_api.c
+++ b/src/mesa/vbo/vbo_exec_api.c
@@ -759,6 +759,7 @@ void vbo_use_buffer_objects(GLcontext *ctx)
    }
 
    /* Allocate a real buffer object now */
+   _mesa_reference_buffer_object(ctx, &exec->vtx.bufferobj, NULL);
    exec->vtx.bufferobj = ctx->Driver.NewBufferObject(ctx, bufName, target);
    ctx->Driver.BufferData(ctx, target, size, NULL, usage, exec->vtx.bufferobj);
 }
@@ -803,8 +804,19 @@ void vbo_exec_vtx_init( struct vbo_exec_context *exec )
    
    {
       struct gl_client_array *arrays = exec->vtx.arrays;
+      unsigned i;
+
       memcpy(arrays,      vbo->legacy_currval,  16 * sizeof(arrays[0]));
       memcpy(arrays + 16, vbo->generic_currval, 16 * sizeof(arrays[0]));
+
+      for (i = 0; i < 16; ++i) {
+         arrays[i     ].BufferObj = NULL;
+         arrays[i + 16].BufferObj = NULL;
+         _mesa_reference_buffer_object(ctx, &arrays[i     ].BufferObj,
+                                       vbo->legacy_currval[i].BufferObj);
+         _mesa_reference_buffer_object(ctx, &arrays[i + 16].BufferObj,
+                                       vbo->generic_currval[i].BufferObj);
+      }
    }
 
    exec->vtx.vertex_size = 0;