Commit 27312a8f authored by Luca Ceresoli's avatar Luca Ceresoli
Browse files

drm/debugfs: show lingering bridges 



The usefulness of /sys/kernel/debug/dri/bridges is limited as it only shows
bridges between drm_bridge_add() and drm_bridge_remove(). However
refcounted bridges can stay allocated and lingering for a long time after
drm_bridge_remove(), and a memory leak due to a missing drm_bridge_put()
would not be visible in this debugfs file.

Add lingering bridges to the /sys/kernel/debug/dri/bridges output.

Reviewed-by: default avatarMaxime Ripard <mripard@kernel.org>
Link: https://lore.kernel.org/r/20250915-drm-bridge-debugfs-removed-v9-2-6e5c0aff5de9@bootlin.com


Signed-off-by: default avatarLuca Ceresoli <luca.ceresoli@bootlin.com>
parent 17805a15

drivers/gpu/drm/drm_bridge.c

+11 −5
Original line number Diff line number Diff line
@@ -1447,17 +1447,20 @@ EXPORT_SYMBOL(devm_drm_put_bridge); 


static void drm_bridge_debugfs_show_bridge(struct drm_printer *p,

					   struct drm_bridge *bridge,

					   unsigned int idx)

					   unsigned int idx,

					   bool lingering)

{

	drm_printf(p, "bridge[%u]: %ps\n", idx, bridge->funcs);



	drm_printf(p, "\trefcount: %u\n", kref_read(&bridge->refcount));

	drm_printf(p, "\trefcount: %u%s\n", kref_read(&bridge->refcount),

		   lingering ? " [lingering]" : "");



	drm_printf(p, "\ttype: [%d] %s\n",

		   bridge->type,

		   drm_get_connector_type_name(bridge->type));



	if (bridge->of_node)

	/* The OF node could be freed after drm_bridge_remove() */

	if (bridge->of_node && !lingering)

		drm_printf(p, "\tOF: %pOFfc\n", bridge->of_node);



	drm_printf(p, "\tops: [0x%x]", bridge->ops);
@@ -1483,7 +1486,10 @@ static int allbridges_show(struct seq_file *m, void *data) 
	mutex_lock(&bridge_lock);



	list_for_each_entry(bridge, &bridge_list, list)

		drm_bridge_debugfs_show_bridge(&p, bridge, idx++);

		drm_bridge_debugfs_show_bridge(&p, bridge, idx++, false);



	list_for_each_entry(bridge, &bridge_lingering_list, list)

		drm_bridge_debugfs_show_bridge(&p, bridge, idx++, true);



	mutex_unlock(&bridge_lock);
@@ -1498,7 +1504,7 @@ static int encoder_bridges_show(struct seq_file *m, void *data) 
	unsigned int idx = 0;



	drm_for_each_bridge_in_chain_scoped(encoder, bridge)

		drm_bridge_debugfs_show_bridge(&p, bridge, idx++);

		drm_bridge_debugfs_show_bridge(&p, bridge, idx++, false);



	return 0;

}