render/gbm_allocator: export to DMA-BUF on init

Instead of lazily exporting BOs to DMA-BUFs, do it on init. This is
the only way to use the buffer, so there's no point in deferring
that work.

This is preparatory work for the next commit.

render/gbm_allocator.c

@@ -16,6 +16,52 @@ static struct wlr_gbm_buffer *get_gbm_buffer_from_buffer(
 	return (struct wlr_gbm_buffer *)buffer;
 }
 
+static bool export_gbm_bo(struct gbm_bo *bo,
+		struct wlr_dmabuf_attributes *out) {
+	struct wlr_dmabuf_attributes attribs = {0};
+
+	attribs.n_planes = gbm_bo_get_plane_count(bo);
+	if (attribs.n_planes > WLR_DMABUF_MAX_PLANES) {
+		wlr_log(WLR_ERROR, "GBM BO contains too many planes (%d)",
+			attribs.n_planes);
+		return false;
+	}
+
+	attribs.width = gbm_bo_get_width(bo);
+	attribs.height = gbm_bo_get_height(bo);
+	attribs.format = gbm_bo_get_format(bo);
+	attribs.modifier = gbm_bo_get_modifier(bo);
+
+	int i;
+	for (i = 0; i < attribs.n_planes; ++i) {
+		union gbm_bo_handle handle = gbm_bo_get_handle_for_plane(bo, i);
+		if (handle.s32 < 0) {
+			wlr_log(WLR_ERROR, "gbm_bo_get_handle_for_plane failed");
+			goto error_fd;
+		}
+
+		int drm_fd = gbm_device_get_fd(gbm_bo_get_device(bo));
+		int ret = drmPrimeHandleToFD(drm_fd, handle.s32,
+			DRM_CLOEXEC, &attribs.fd[i]);
+		if (ret < 0 || attribs.fd[i] < 0) {
+			wlr_log_errno(WLR_ERROR, "drmPrimeHandleToFD failed");
+			goto error_fd;
+		}
+
+		attribs.offset[i] = gbm_bo_get_offset(bo, i);
+		attribs.stride[i] = gbm_bo_get_stride_for_plane(bo, i);
+	}
+
+	memcpy(out, &attribs, sizeof(attribs));
+	return true;
+
+error_fd:
+	for (int j = 0; j < i; ++j) {
+		close(attribs.fd[j]);
+	}
+	return false;
+}
+
 static struct wlr_gbm_buffer *create_buffer(struct wlr_gbm_allocator *alloc,
 		int width, int height, const struct wlr_drm_format *format) {
 	struct gbm_device *gbm_device = alloc->gbm_device;
@@ -47,6 +93,12 @@ static struct wlr_gbm_buffer *create_buffer(struct wlr_gbm_allocator *alloc,
 	buffer->gbm_bo = bo;
 	wl_list_insert(&alloc->buffers, &buffer->link);
 
+	if (!export_gbm_bo(bo, &buffer->dmabuf)) {
+		free(buffer);
+		gbm_bo_destroy(bo);
+		return NULL;
+	}
+
 	wlr_log(WLR_DEBUG, "Allocated %dx%d GBM buffer (format 0x%"PRIX32", "
 		"modifier 0x%"PRIX64")", buffer->base.width, buffer->base.height,
 		gbm_bo_get_format(bo), gbm_bo_get_modifier(bo));
@@ -65,72 +117,10 @@ static void buffer_destroy(struct wlr_buffer *wlr_buffer) {
 	free(buffer);
 }
 
-static bool buffer_create_dmabuf(struct wlr_gbm_buffer *buffer) {
-	assert(buffer->dmabuf.n_planes == 0);
-
-	struct gbm_bo *bo = buffer->gbm_bo;
-	if (bo == NULL) {
-		return false;
-	}
-
-	struct wlr_dmabuf_attributes attribs = {0};
-
-	attribs.n_planes = gbm_bo_get_plane_count(bo);
-	if (attribs.n_planes > WLR_DMABUF_MAX_PLANES) {
-		wlr_log(WLR_ERROR, "GBM BO contains too many planes (%d)",
-			attribs.n_planes);
-		return false;
-	}
-
-	attribs.width = gbm_bo_get_width(bo);
-	attribs.height = gbm_bo_get_height(bo);
-	attribs.format = gbm_bo_get_format(bo);
-	attribs.modifier = gbm_bo_get_modifier(bo);
-
-	int i;
-	for (i = 0; i < attribs.n_planes; ++i) {
-		union gbm_bo_handle handle = gbm_bo_get_handle_for_plane(bo, i);
-		if (handle.s32 < 0) {
-			wlr_log(WLR_ERROR, "gbm_bo_get_handle_for_plane failed");
-			goto error_fd;
-		}
-
-		int drm_fd = gbm_device_get_fd(gbm_bo_get_device(bo));
-		int ret = drmPrimeHandleToFD(drm_fd, handle.s32,
-			DRM_CLOEXEC, &attribs.fd[i]);
-		if (ret < 0 || attribs.fd[i] < 0) {
-			wlr_log_errno(WLR_ERROR, "drmPrimeHandleToFD failed");
-			goto error_fd;
-		}
-
-		attribs.offset[i] = gbm_bo_get_offset(bo, i);
-		attribs.stride[i] = gbm_bo_get_stride_for_plane(bo, i);
-	}
-
-	memcpy(&buffer->dmabuf, &attribs, sizeof(attribs));
-	return true;
-
-error_fd:
-	for (int j = 0; j < i; ++j) {
-		close(attribs.fd[j]);
-	}
-	return false;
-}
-
 static bool buffer_get_dmabuf(struct wlr_buffer *wlr_buffer,
 		struct wlr_dmabuf_attributes *attribs) {
 	struct wlr_gbm_buffer *buffer =
 		get_gbm_buffer_from_buffer(wlr_buffer);
-
-	memset(attribs, 0, sizeof(*attribs));
-
-	// Only export the buffer once
-	if (buffer->dmabuf.n_planes == 0) {
-		if (!buffer_create_dmabuf(buffer)) {
-			return false;
-		}
-	}
-
 	memcpy(attribs, &buffer->dmabuf, sizeof(buffer->dmabuf));
 	return true;
 }