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drm/debugfs: show lingering bridges

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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: Maxime Ripard <mripard@kernel.org>
Link: https://lore.kernel.org/r/20250915-drm-bridge-debugfs-removed-v9-2-6e5c0aff5de9@bootlin.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
This commit is contained in:
Luca Ceresoli 2025-09-15 12:12:47 +02:00
parent 17805a15d1
commit 27312a8f24
1 changed files with 11 additions and 5 deletions
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16
drivers/gpu/drm/drm_bridge.c
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@ -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;
}