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, 1 insertions, 2 deletions

diff --git a/src/gallium/drivers/softpipe/sp_context.c b/src/gallium/drivers/softpipe/sp_context.c
index ff5d1b54a4c..cc552c4915b 100644
--- a/src/gallium/drivers/softpipe/sp_context.c
+++ b/src/gallium/drivers/softpipe/sp_context.c
@@ -87,7 +87,6 @@ softpipe_unmap_transfers(struct softpipe_context *sp)
 static void softpipe_destroy( struct pipe_context *pipe )
 {
    struct softpipe_context *softpipe = softpipe_context( pipe );
-   struct pipe_screen *screen = pipe->screen;
    uint i;
 
    if (softpipe->draw)
@@ -116,7 +115,7 @@ static void softpipe_destroy( struct pipe_context *pipe )
 
    for (i = 0; i < Elements(softpipe->constants); i++) {
       if (softpipe->constants[i].buffer) {
-         pipe_buffer_reference(screen, &softpipe->constants[i].buffer, NULL);
+         pipe_buffer_reference(&softpipe->constants[i].buffer, NULL);
       }
    }