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, 7 insertions, 18 deletions

diff --git a/src/gallium/auxiliary/pipebuffer/pb_buffer.h b/src/gallium/auxiliary/pipebuffer/pb_buffer.h
index e6b0b30ff4..be1654c654 100644
--- a/src/gallium/auxiliary/pipebuffer/pb_buffer.h
+++ b/src/gallium/auxiliary/pipebuffer/pb_buffer.h
@@ -159,7 +159,7 @@ pb_map(struct pb_buffer *buf,
    assert(buf);
    if(!buf)
       return NULL;
-   assert(buf->base.refcount > 0);
+   assert(buf->base.reference.count > 0);
    return buf->vtbl->map(buf, flags);
 }
 
@@ -170,7 +170,7 @@ pb_unmap(struct pb_buffer *buf)
    assert(buf);
    if(!buf)
       return;
-   assert(buf->base.refcount > 0);
+   assert(buf->base.reference.count > 0);
    buf->vtbl->unmap(buf);
 }
 
@@ -186,7 +186,7 @@ pb_get_base_buffer( struct pb_buffer *buf,
       offset = 0;
       return;
    }
-   assert(buf->base.refcount > 0);
+   assert(buf->base.reference.count > 0);
    assert(buf->vtbl->get_base_buffer);
    buf->vtbl->get_base_buffer(buf, base_buf, offset);
    assert(*base_buf);
@@ -222,29 +222,18 @@ pb_destroy(struct pb_buffer *buf)
    assert(buf);
    if(!buf)
       return;
-   assert(buf->base.refcount == 0);
+   assert(buf->base.reference.count == 0);
    buf->vtbl->destroy(buf);
 }
 
-
-/* XXX: thread safety issues!
- */
 static INLINE void
 pb_reference(struct pb_buffer **dst,
              struct pb_buffer *src)
 {
-   if (src) {
-      assert(src->base.refcount);
-      src->base.refcount++;
-   }
-
-   if (*dst) {
-      assert((*dst)->base.refcount);
-      if(--(*dst)->base.refcount == 0)
-         pb_destroy( *dst );
-   }
+   struct pb_buffer *old = *dst;
 
-   *dst = src;
+   if (pipe_reference((struct pipe_reference**)dst, &src->base.reference))
+      pb_destroy( old );
 }