scene: release shm buffers once uploaded

Once a shm buffer is uploaded there's no reason for wlr_scene_buffer
to keep it locked any further. Allow the compositor to re-use it.

include/wlr/types/wlr_scene.h

@@ -185,6 +185,12 @@ struct wlr_scene_buffer {
 	uint64_t active_outputs;
 	struct wlr_texture *texture;
 	struct wlr_linux_dmabuf_feedback_v1_init_options prev_feedback_options;
+
+	bool own_buffer;
+	int buffer_width, buffer_height;
+	bool buffer_is_opaque;
+
+	struct wl_listener buffer_release;
 };
 
 /** A viewport for an output in the scene-graph */

types/scene/wlr_scene.c

@@ -82,6 +82,9 @@ struct highlight_region {
 	struct wl_list link;
 };
 
+static void scene_buffer_set_buffer(struct wlr_scene_buffer *scene_buffer,
+	struct wlr_buffer *buffer);
+
 void wlr_scene_node_destroy(struct wlr_scene_node *node) {
 	if (node == NULL) {
 		return;
@@ -111,7 +114,7 @@ void wlr_scene_node_destroy(struct wlr_scene_node *node) {
 		}
 
 		wlr_texture_destroy(scene_buffer->texture);
-		wlr_buffer_unlock(scene_buffer->buffer);
+		scene_buffer_set_buffer(scene_buffer, NULL);
 		pixman_region32_fini(&scene_buffer->opaque_region);
 	} else if (node->type == WLR_SCENE_NODE_TREE) {
 		struct wlr_scene_tree *scene_tree = wlr_scene_tree_from_node(node);
@@ -249,7 +252,7 @@ static void scene_node_opaque_region(struct wlr_scene_node *node, int x, int y,
 			return;
 		}
 
-		if (!buffer_is_opaque(scene_buffer->buffer)) {
+		if (!scene_buffer->buffer_is_opaque) {
 			pixman_region32_copy(opaque, &scene_buffer->opaque_region);
 			pixman_region32_intersect_rect(opaque, opaque, 0, 0, width, height);
 			pixman_region32_translate(opaque, x, y);
@@ -600,6 +603,39 @@ void wlr_scene_rect_set_color(struct wlr_scene_rect *rect, const float color[sta
 	scene_node_update(&rect->node, NULL);
 }
 
+static void scene_buffer_handle_buffer_release(struct wl_listener *listener,
+		void *data) {
+	struct wlr_scene_buffer *scene_buffer =
+		wl_container_of(listener, scene_buffer, buffer_release);
+	scene_buffer_set_buffer(scene_buffer, NULL);
+}
+
+static void scene_buffer_set_buffer(struct wlr_scene_buffer *scene_buffer,
+		struct wlr_buffer *buffer) {
+	wl_list_remove(&scene_buffer->buffer_release.link);
+	wl_list_init(&scene_buffer->buffer_release.link);
+	if (scene_buffer->own_buffer) {
+		wlr_buffer_unlock(scene_buffer->buffer);
+	}
+	scene_buffer->buffer = NULL;
+	scene_buffer->own_buffer = false;
+	scene_buffer->buffer_width = scene_buffer->buffer_height = 0;
+	scene_buffer->buffer_is_opaque = false;
+
+	if (!buffer) {
+		return;
+	}
+
+	scene_buffer->own_buffer = true;
+	scene_buffer->buffer = wlr_buffer_lock(buffer);
+	scene_buffer->buffer_width = buffer->width;
+	scene_buffer->buffer_height = buffer->height;
+	scene_buffer->buffer_is_opaque = buffer_is_opaque(buffer);
+
+	scene_buffer->buffer_release.notify = scene_buffer_handle_buffer_release;
+	wl_signal_add(&buffer->events.release, &scene_buffer->buffer_release);
+}
+
 struct wlr_scene_buffer *wlr_scene_buffer_create(struct wlr_scene_tree *parent,
 		struct wlr_buffer *buffer) {
 	struct wlr_scene_buffer *scene_buffer = calloc(1, sizeof(*scene_buffer));
@@ -609,18 +645,16 @@ struct wlr_scene_buffer *wlr_scene_buffer_create(struct wlr_scene_tree *parent,
 	assert(parent);
 	scene_node_init(&scene_buffer->node, WLR_SCENE_NODE_BUFFER, parent);
 
-	if (buffer) {
-		scene_buffer->buffer = wlr_buffer_lock(buffer);
-	}
-
 	wl_signal_init(&scene_buffer->events.outputs_update);
 	wl_signal_init(&scene_buffer->events.output_enter);
 	wl_signal_init(&scene_buffer->events.output_leave);
 	wl_signal_init(&scene_buffer->events.output_sample);
 	wl_signal_init(&scene_buffer->events.frame_done);
 	pixman_region32_init(&scene_buffer->opaque_region);
+	wl_list_init(&scene_buffer->buffer_release.link);
 	scene_buffer->opacity = 1;
 
+	scene_buffer_set_buffer(scene_buffer, buffer);
 	scene_node_update(&scene_buffer->node, NULL);
 
 	return scene_buffer;
@@ -642,19 +676,15 @@ void wlr_scene_buffer_set_buffer_with_damage(struct wlr_scene_buffer *scene_buff
 		// if this node used to not be mapped or its previous displayed
 		// buffer region will be different from what the new buffer would
 		// produce we need to update the node.
-		update = !scene_buffer->buffer ||
-			(scene_buffer->dst_width == 0 && scene_buffer->dst_height == 0 &&
-				(scene_buffer->buffer->width != buffer->width ||
-				scene_buffer->buffer->height != buffer->height));
-
-		wlr_buffer_unlock(scene_buffer->buffer);
-		scene_buffer->buffer = wlr_buffer_lock(buffer);
+		update = scene_buffer->dst_width == 0 && scene_buffer->dst_height == 0 &&
+			(scene_buffer->buffer_width != buffer->width ||
+				scene_buffer->buffer_height != buffer->height);
 	} else {
-		wlr_buffer_unlock(scene_buffer->buffer);
 		update = true;
-		scene_buffer->buffer = NULL;
 	}
 
+	scene_buffer_set_buffer(scene_buffer, buffer);
+
 	if (update) {
 		scene_node_update(&scene_buffer->node, NULL);
 		// updating the node will already damage the whole node for us. Return
@@ -842,18 +872,22 @@ void wlr_scene_buffer_set_filter_mode(struct wlr_scene_buffer *scene_buffer,
 
 static struct wlr_texture *scene_buffer_get_texture(
 		struct wlr_scene_buffer *scene_buffer, struct wlr_renderer *renderer) {
+	if (scene_buffer->buffer == NULL || scene_buffer->texture != NULL) {
+		return scene_buffer->texture;
+	}
+
 	struct wlr_client_buffer *client_buffer =
 		wlr_client_buffer_get(scene_buffer->buffer);
 	if (client_buffer != NULL) {
 		return client_buffer->texture;
 	}
 
-	if (scene_buffer->texture != NULL) {
-		return scene_buffer->texture;
-	}
-
 	scene_buffer->texture =
 		wlr_texture_from_buffer(renderer, scene_buffer->buffer);
+	if (scene_buffer->texture != NULL && scene_buffer->own_buffer) {
+		scene_buffer->own_buffer = false;
+		wlr_buffer_unlock(scene_buffer->buffer);
+	}
 	return scene_buffer->texture;
 }
 
@@ -875,9 +909,9 @@ static void scene_node_get_size(struct wlr_scene_node *node,
 		if (scene_buffer->dst_width > 0 && scene_buffer->dst_height > 0) {
 			*width = scene_buffer->dst_width;
 			*height = scene_buffer->dst_height;
-		} else if (scene_buffer->buffer) {
-			*width = scene_buffer->buffer->width;
-			*height = scene_buffer->buffer->height;
+		} else {
+			*width = scene_buffer->buffer_width;
+			*height = scene_buffer->buffer_height;
 			wlr_output_transform_coords(scene_buffer->transform, width, height);
 		}
 		break;
@@ -1155,7 +1189,6 @@ static void scene_entry_render(struct render_list_entry *entry, const struct ren
 		break;
 	case WLR_SCENE_NODE_BUFFER:;
 		struct wlr_scene_buffer *scene_buffer = wlr_scene_buffer_from_node(node);
-		assert(scene_buffer->buffer);
 
 		struct wlr_texture *texture = scene_buffer_get_texture(scene_buffer,
 			data->output->output->renderer);
@@ -1403,7 +1436,7 @@ static bool scene_node_invisible(struct wlr_scene_node *node) {
 	} else if (node->type == WLR_SCENE_NODE_BUFFER) {
 		struct wlr_scene_buffer *buffer = wlr_scene_buffer_from_node(node);
 
-		return buffer->buffer == NULL;
+		return buffer->buffer == NULL && buffer->texture == NULL;
 	}
 
 	return false;
@@ -1539,6 +1572,9 @@ static bool scene_entry_try_direct_scanout(struct render_list_entry *entry,
 	}
 
 	struct wlr_scene_buffer *buffer = wlr_scene_buffer_from_node(node);
+	if (buffer->buffer == NULL) {
+		return false;
+	}
 
 	int default_width = buffer->buffer->width;
 	int default_height = buffer->buffer->height;