Commit df7c8e3d authored by Dmitry Baryshkov's avatar Dmitry Baryshkov
Browse files

drm/connector: add mutex to protect ELD from concurrent access 



The connector->eld is accessed by the .get_eld() callback. This access
can collide with the drm_edid_to_eld() updating the data at the same
time. Add drm_connector.eld_mutex to protect the data from concurrenct
access. Individual drivers are not updated (to reduce possible issues
while applying the patch), maintainers are to find a best suitable way
to lock that mutex while accessing the ELD data.

Reviewed-by: default avatarMaxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20241206-drm-connector-eld-mutex-v2-1-c9bce1ee8bea@linaro.org


Signed-off-by: default avatarDmitry Baryshkov <dmitry.baryshkov@linaro.org>
parent 67a615c5

drivers/gpu/drm/drm_connector.c

+1 −0
Original line number Diff line number Diff line
@@ -277,6 +277,7 @@ static int __drm_connector_init(struct drm_device *dev, 
	INIT_LIST_HEAD(&connector->probed_modes);

	INIT_LIST_HEAD(&connector->modes);

	mutex_init(&connector->mutex);

	mutex_init(&connector->eld_mutex);

	mutex_init(&connector->edid_override_mutex);

	mutex_init(&connector->hdmi.infoframes.lock);

	connector->edid_blob_ptr = NULL;

drivers/gpu/drm/drm_edid.c

+6 −0
Original line number Diff line number Diff line
@@ -5605,7 +5605,9 @@ EXPORT_SYMBOL(drm_edid_get_monitor_name); 


static void clear_eld(struct drm_connector *connector)

{

	mutex_lock(&connector->eld_mutex);

	memset(connector->eld, 0, sizeof(connector->eld));

	mutex_unlock(&connector->eld_mutex);



	connector->latency_present[0] = false;

	connector->latency_present[1] = false;
@@ -5657,6 +5659,8 @@ static void drm_edid_to_eld(struct drm_connector *connector, 
	if (!drm_edid)

		return;



	mutex_lock(&connector->eld_mutex);



	mnl = get_monitor_name(drm_edid, &eld[DRM_ELD_MONITOR_NAME_STRING]);

	drm_dbg_kms(connector->dev, "[CONNECTOR:%d:%s] ELD monitor %s\n",

		    connector->base.id, connector->name,
@@ -5717,6 +5721,8 @@ static void drm_edid_to_eld(struct drm_connector *connector, 
	drm_dbg_kms(connector->dev, "[CONNECTOR:%d:%s] ELD size %d, SAD count %d\n",

		    connector->base.id, connector->name,

		    drm_eld_size(eld), total_sad_count);



	mutex_unlock(&connector->eld_mutex);

}



static int _drm_edid_to_sad(const struct drm_edid *drm_edid,

include/drm/drm_connector.h

+4 −1
Original line number Diff line number Diff line
@@ -2001,8 +2001,11 @@ struct drm_connector { 
	struct drm_encoder *encoder;



#define MAX_ELD_BYTES	128

	/** @eld: EDID-like data, if present */

	/** @eld: EDID-like data, if present, protected by @eld_mutex */

	uint8_t eld[MAX_ELD_BYTES];

	/** @eld_mutex: protection for concurrenct access to @eld */

	struct mutex eld_mutex;



	/** @latency_present: AV delay info from ELD, if found */

	bool latency_present[2];

	/**