[PATCH AUTOSEL 5.19 13/36] drm: hide unregistered connectors from GETCONNECTOR IOCTL

Sasha Levin
2022-10-10T00:18:51Z

From: Simon Ser <contact@emersion.fr>

[ Upstream commit 981f09295687f856d5345e19c7084aca481c1395 ]

When registering a connector, the kernel sends a hotplug uevent in
drm_connector_register(). When unregistering a connector, drivers
are expected to send a uevent as well. However, user-space has no way
to figure out that the connector isn't registered anymore: it'll still
be reported in GETCONNECTOR IOCTLs.

The documentation for DRM_CONNECTOR_UNREGISTERED states:

> The connector […] has since been unregistered and removed from
> userspace, or the connector was unregistered before it had a chance
> to be exposed to userspace

Signed-off-by: Simon Ser <contact@emersion.fr>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220801133754.461037-1-contact@emersion.fr
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/drm_mode_config.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
index 37b4b9f0e468..6a326b41d193 100644
--- a/drivers/gpu/drm/drm_mode_config.c
+++ b/drivers/gpu/drm/drm_mode_config.c
@@ -150,6 +150,9 @@ int drm_mode_getresources(struct drm_device *dev, void *data,
count = 0;
connector_id = u64_to_user_ptr(card_res->connector_id_ptr);
drm_for_each_connector_iter(connector, &conn_iter) {
+ if (connector->registration_state != DRM_CONNECTOR_REGISTERED)
+ continue;
+
/* only expose writeback connectors if userspace understands them */
if (!file_priv->writeback_connectors &&
(connector->connector_type == DRM_MODE_CONNECTOR_WRITEBACK))
--
2.35.1