gallium: Unify reference counting.

The core reference counting code is centralized in p_refcnt.h.

This has some consequences related to struct pipe_buffer:

* The screen member of struct pipe_buffer must be initialized, or
  pipe_buffer_reference() will crash trying to destroy a buffer with reference
  count 0. u_simple_screen takes care of this, but I may have missed some of
  the drivers not using it.
* Except for rare exceptions deep in winsys code, buffers must always be
  allocated via pipe_buffer_create() or via screen->*buffer_create() rather
  than via winsys->*buffer_create().

1 files changed, 3 insertions, 5 deletions

diff --git a/src/mesa/state_tracker/st_cb_clear.c b/src/mesa/state_tracker/st_cb_clear.c
index c6fc7cec27..7d4948a64e 100644
--- a/src/mesa/state_tracker/st_cb_clear.c
+++ b/src/mesa/state_tracker/st_cb_clear.c
@@ -95,8 +95,6 @@ st_init_clear(struct st_context *st)
 void
 st_destroy_clear(struct st_context *st)
 {
-   struct pipe_context *pipe = st->pipe;
-
    if (st->clear.vert_shader.tokens) {
       util_free_shader(&st->clear.vert_shader);
       st->clear.vert_shader.tokens = NULL;
@@ -116,7 +114,7 @@ st_destroy_clear(struct st_context *st)
       st->clear.vs = NULL;
    }
    if (st->clear.vbuf) {
-      pipe_buffer_reference(pipe->screen, &st->clear.vbuf, NULL);
+      pipe_buffer_reference(&st->clear.vbuf, NULL);
       st->clear.vbuf = NULL;
    }
 }
@@ -152,7 +150,7 @@ draw_quad(GLcontext *ctx,
    GLuint i;
 
    if (st->clear.vbuf_slot >= max_slots) {
-      pipe_buffer_reference(pipe->screen, &st->clear.vbuf, NULL);
+      pipe_buffer_reference(&st->clear.vbuf, NULL);
       st->clear.vbuf_slot = 0;
    }
 
@@ -524,7 +522,7 @@ void st_flush_clear( struct st_context *st )
    /* Release vertex buffer to avoid synchronous rendering if we were
     * to map it in the next frame.
     */
-   pipe_buffer_reference(st->pipe->screen, &st->clear.vbuf, NULL);
+   pipe_buffer_reference(&st->clear.vbuf, NULL);
    st->clear.vbuf_slot = 0;
 }