mesa: fix invalid index_bo refcounting

If take_index_buffer_ownership is true, then we should reserve
enough references of index_bo or we'll get an underflow later.

Fixes: 819627041e7 ("mesa: set pipe_draw_info::index::resource directly and remove gl_bo")
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/8747
Reviewed-by: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22237>

diff --git a/src/mesa/main/draw.c b/src/mesa/main/draw.c
index e58e65d..8349243 100644 (file)
--- a/src/mesa/main/draw.c
+++ b/src/mesa/main/draw.c
@@ -2534,6 +2534,11 @@ _mesa_MultiDrawElementsIndirect(GLenum mode, GLenum type,
          /* Fast path for u_threaded_context to eliminate atomics. */
          info.index.resource = _mesa_get_bufferobj_reference(ctx, index_bo);
          info.take_index_buffer_ownership = true;
+         /* Increase refcount so be able to use take_index_buffer_ownership with
+          * multiple draws.
+          */
+         if (primcount > 1 && info.index.resource)
+            p_atomic_add(&info.index.resource->reference.count, primcount - 1);
       } else {
          info.index.resource = index_bo->buffer;
       }