From: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx> [ Upstream commit df7c8e3dde37a9d81c0613285b43600f3cc70f34 ] 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: Maxime Ripard <mripard@xxxxxxxxxx> Link: https://patchwork.freedesktop.org/patch/msgid/20241206-drm-connector-eld-mutex-v2-1-c9bce1ee8bea@xxxxxxxxxx Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/gpu/drm/drm_connector.c | 1 + drivers/gpu/drm/drm_edid.c | 6 ++++++ include/drm/drm_connector.h | 5 ++++- 3 files changed, 11 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c index 309aad5f0c808..35bed66214474 100644 --- a/drivers/gpu/drm/drm_connector.c +++ b/drivers/gpu/drm/drm_connector.c @@ -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); connector->edid_blob_ptr = NULL; connector->epoch_counter = 0; diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c index ee3fab115c4b5..ad872c61aac0e 100644 --- a/drivers/gpu/drm/drm_edid.c +++ b/drivers/gpu/drm/drm_edid.c @@ -5499,7 +5499,9 @@ 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; @@ -5530,6 +5532,8 @@ 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, @@ -5590,6 +5594,8 @@ 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, diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h index d300fde6c1a47..b2e9dc02fa349 100644 --- a/include/drm/drm_connector.h +++ b/include/drm/drm_connector.h @@ -1764,8 +1764,11 @@ 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]; /** -- 2.39.5
