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().

3 files changed, 20 insertions, 14 deletions

diff --git a/src/gallium/state_trackers/python/st_device.c b/src/gallium/state_trackers/python/st_device.c
index 20dd8d269d..a2cd25067d 100644
--- a/src/gallium/state_trackers/python/st_device.c
+++ b/src/gallium/state_trackers/python/st_device.c
@@ -51,11 +51,20 @@ st_device_really_destroy(struct st_device *st_dev)
 }
 
 
+static void
+st_device_reference(struct st_device **ptr, struct st_device *st_dev)
+{
+   struct st_device *old_dev = *ptr;
+
+   if (pipe_reference((struct pipe_reference **)ptr, &st_dev->reference))
+      st_device_really_destroy(old_dev);
+}
+
+
 void
 st_device_destroy(struct st_device *st_dev) 
 {
-   if(!--st_dev->refcount)
-      st_device_really_destroy(st_dev);
+   st_device_reference(&st_dev, NULL);
 }
 
 
@@ -72,7 +81,7 @@ st_device_create_from_st_winsys(const struct st_winsys *st_ws)
    if(!st_dev)
       return NULL;
    
-   st_dev->refcount = 1;
+   pipe_reference_init(&st_dev->reference, 1);
    st_dev->st_ws = st_ws;
    
    st_dev->real_screen = st_ws->screen_create();
@@ -124,8 +133,7 @@ st_context_destroy(struct st_context *st_ctx)
 
       FREE(st_ctx);
       
-      if(!--st_dev->refcount)
-         st_device_really_destroy(st_dev);
+      st_device_reference(&st_dev, NULL);
    }
 }
 
@@ -139,8 +147,7 @@ st_context_create(struct st_device *st_dev)
    if(!st_ctx)
       return NULL;
    
-   st_ctx->st_dev = st_dev;
-   ++st_dev->refcount;
+   st_device_reference(&st_ctx->st_dev, st_dev);
    
    st_ctx->real_pipe = st_dev->st_ws->context_create(st_dev->real_screen);
    if(!st_ctx->real_pipe) {
@@ -292,8 +299,7 @@ void
 st_buffer_destroy(struct st_buffer *st_buf)
 {
    if(st_buf) {
-      struct pipe_screen *screen = st_buf->st_dev->screen;
-      pipe_buffer_reference(screen, &st_buf->buffer, NULL);
+      pipe_buffer_reference(&st_buf->buffer, NULL);
       FREE(st_buf);
    }
 }
diff --git a/src/gallium/state_trackers/python/st_device.h b/src/gallium/state_trackers/python/st_device.h
index 7cfe6de9f6..0641aff149 100644
--- a/src/gallium/state_trackers/python/st_device.h
+++ b/src/gallium/state_trackers/python/st_device.h
@@ -68,13 +68,13 @@ struct st_context {
 
 
 struct st_device {
+   /* FIXME: we also need to refcount for textures and surfaces... */
+   struct pipe_reference reference;
+
    const struct st_winsys *st_ws; 
 
    struct pipe_screen *real_screen;
    struct pipe_screen *screen;
-   
-   /* FIXME: we also need to refcount for textures and surfaces... */
-   unsigned refcount;
 };
 
 
diff --git a/src/gallium/state_trackers/python/st_softpipe_winsys.c b/src/gallium/state_trackers/python/st_softpipe_winsys.c
index 4d798df99b..426f347d18 100644
--- a/src/gallium/state_trackers/python/st_softpipe_winsys.c
+++ b/src/gallium/state_trackers/python/st_softpipe_winsys.c
@@ -124,7 +124,7 @@ st_softpipe_buffer_create(struct pipe_winsys *winsys,
 {
    struct st_softpipe_buffer *buffer = CALLOC_STRUCT(st_softpipe_buffer);
 
-   buffer->base.refcount = 1;
+   pipe_reference_init(&buffer->base.reference, 1);
    buffer->base.alignment = alignment;
    buffer->base.usage = usage;
    buffer->base.size = size;
@@ -149,7 +149,7 @@ st_softpipe_user_buffer_create(struct pipe_winsys *winsys,
    if(!buffer)
       return NULL;
    
-   buffer->base.refcount = 1;
+   pipe_reference_init(&buffer->base.reference, 1);
    buffer->base.size = bytes;
    buffer->userBuffer = TRUE;
    buffer->data = ptr;