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, 21 insertions, 7 deletions

diff --git a/src/gallium/auxiliary/util/u_simple_screen.c b/src/gallium/auxiliary/util/u_simple_screen.c
index 089bbbc48a..8114b53cd0 100644
--- a/src/gallium/auxiliary/util/u_simple_screen.c
+++ b/src/gallium/auxiliary/util/u_simple_screen.c
@@ -28,6 +28,7 @@
 #include "u_simple_screen.h"
 
 #include "pipe/p_screen.h"
+#include "pipe/p_state.h"
 #include "pipe/internal/p_winsys_screen.h"
 
 
@@ -37,8 +38,12 @@ pass_buffer_create(struct pipe_screen *screen,
                    unsigned usage,
                    unsigned size)
 {
-   return screen->winsys->buffer_create(screen->winsys,
-                                        alignment, usage, size);
+   struct pipe_buffer *buffer =
+      screen->winsys->buffer_create(screen->winsys, alignment, usage, size);
+
+   buffer->screen = screen;
+
+   return buffer;
 }
 
 static struct pipe_buffer *
@@ -46,8 +51,13 @@ pass_user_buffer_create(struct pipe_screen *screen,
                         void *ptr,
                         unsigned bytes)
 {
-   return screen->winsys->user_buffer_create(screen->winsys,
+   struct pipe_buffer *buffer =
+      screen->winsys->user_buffer_create(screen->winsys,
                                              ptr, bytes);
+
+   buffer->screen = screen;
+
+   return buffer;
 }
 
 static struct pipe_buffer *
@@ -57,9 +67,14 @@ pass_surface_buffer_create(struct pipe_screen *screen,
                            unsigned usage,
                            unsigned *stride)
 {
-   return screen->winsys->surface_buffer_create(screen->winsys,
+   struct pipe_buffer *buffer =
+      screen->winsys->surface_buffer_create(screen->winsys,
                                                 width, height,
                                                 format, usage, stride);
+
+   buffer->screen = screen;
+
+   return buffer;
 }
 
 static void *
@@ -79,10 +94,9 @@ pass_buffer_unmap(struct pipe_screen *screen,
 }
 
 static void
-pass_buffer_destroy(struct pipe_screen *screen,
-                    struct pipe_buffer *buf)
+pass_buffer_destroy(struct pipe_buffer *buf)
 {
-   screen->winsys->buffer_destroy(screen->winsys, buf);
+   buf->screen->winsys->buffer_destroy(buf);
 }