i965g: add lots of error checks and early returns

Any allocation that may fail should be checked, and propogate the
error upwards.  At the highest level we will flush batch and retry.

This is an alternate strategy to what the original DRI driver did of
attempting to flush batch from the lowest levels (eg inside
BEGIN_BATCH).  The trouble with that strategy was that flushes could
occur at unexpected times, and additionally there was a need for a
wierd notification mechanism to propogate the 'lost context' state
back up to higher levels.

Propogating the errors directly gives us a lot of flexibility how to
deal with these states, at the expense of a lot more checking in the
code.

Will add some sanity checks later to make sure that out-of-memory
conditions are properly escalated and not lost halfway up the stack.

1 files changed, 18 insertions, 28 deletions

diff --git a/src/gallium/winsys/drm/i965/xlib/xlib_i965.c b/src/gallium/winsys/drm/i965/xlib/xlib_i965.c
index b1edca818a..fc465d7c14 100644
--- a/src/gallium/winsys/drm/i965/xlib/xlib_i965.c
+++ b/src/gallium/winsys/drm/i965/xlib/xlib_i965.c
@@ -134,11 +134,12 @@ const char *data_types[BRW_DATA_MAX] =
 };
 
 
-static struct brw_winsys_buffer *
+static enum pipe_error
 xlib_brw_bo_alloc( struct brw_winsys_screen *sws,
-		      enum brw_buffer_type type,
-		      unsigned size,
-		      unsigned alignment )
+                   enum brw_buffer_type type,
+                   unsigned size,
+                   unsigned alignment,
+                   struct brw_winsys_buffer **bo_out )
 {
    struct xlib_brw_winsys *xbw = xlib_brw_winsys(sws);
    struct xlib_brw_buffer *buf;
@@ -148,12 +149,13 @@ xlib_brw_bo_alloc( struct brw_winsys_screen *sws,
 
    buf = CALLOC_STRUCT(xlib_brw_buffer);
    if (!buf)
-      return NULL;
+      return PIPE_ERROR_OUT_OF_MEMORY;
+
+   pipe_reference_init(&buf->base.reference, 1);
 
    buf->offset = align(xbw->offset, alignment);
    buf->type = type;
    buf->virtual = MALLOC(size);
-   buf->cheesy_refcount = 1;
    buf->base.offset = &buf->offset; /* hmm, cheesy */
    buf->base.size = size;
 
@@ -161,36 +163,25 @@ xlib_brw_bo_alloc( struct brw_winsys_screen *sws,
    if (xbw->offset > MAX_VRAM)
       goto err;
 
-   return &buf->base;
+   /* XXX: possibly rentrant call to bo_destroy:
+    */
+   bo_reference(bo_out, &buf->base);
+   return PIPE_OK;
 
 err:
    assert(0);
+   FREE(buf->virtual);
    FREE(buf);
-   return NULL;
-}
-
-static void 
-xlib_brw_bo_reference( struct brw_winsys_buffer *buffer )
-{
-   struct xlib_brw_buffer *buf = xlib_brw_buffer(buffer);
-
-   buf->cheesy_refcount++;
+   return PIPE_ERROR_OUT_OF_MEMORY;
 }
 
 static void 
-xlib_brw_bo_unreference( struct brw_winsys_buffer *buffer )
+xlib_brw_bo_destroy( struct brw_winsys_buffer *buffer )
 {
    struct xlib_brw_buffer *buf = xlib_brw_buffer(buffer);
 
-   /* As a special favor in this call only, buffer is allowed to be
-    * NULL:
-    */
-   if (buffer == NULL)
-      return;
-
-   if (--buf->cheesy_refcount == 0) {
-      FREE(buffer);
-   }
+   FREE(buf->virtual);
+   FREE(buf);
 }
 
 static int 
@@ -378,8 +369,7 @@ xlib_create_brw_winsys_screen( void )
 
    ws->base.destroy              = xlib_brw_winsys_destroy;
    ws->base.bo_alloc             = xlib_brw_bo_alloc;
-   ws->base.bo_reference         = xlib_brw_bo_reference;
-   ws->base.bo_unreference       = xlib_brw_bo_unreference;
+   ws->base.bo_destroy           = xlib_brw_bo_destroy;
    ws->base.bo_emit_reloc        = xlib_brw_bo_emit_reloc;
    ws->base.bo_exec              = xlib_brw_bo_exec;
    ws->base.bo_subdata           = xlib_brw_bo_subdata;