On Sun, 01 Dec 2024, Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx> wrote:
> 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.
Missed clear_eld().
BR,
Jani.
>
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> ---
> drivers/gpu/drm/drm_connector.c | 1 +
> drivers/gpu/drm/drm_edid.c | 4 ++++
> include/drm/drm_connector.h | 5 ++++-
> 3 files changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
> index fc35f47e2849ed6786d6223ac9c69e1c359fc648..bbdaaf7022b62d84594a29f1b60144920903a99a 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);
> mutex_init(&connector->hdmi.infoframes.lock);
> connector->edid_blob_ptr = NULL;
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 855beafb76ffbecf5c08d58e2f54bfb76f30b930..f0ca77bd42fd518d505d0db78557e0c8d83efb29 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -5657,6 +5657,8 @@ 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 +5719,8 @@ 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 e3fa43291f449d70f3b92a00985336c4f2237bc6..1e2b25e204cb523d61d30f5409faa059bf2b86eb 100644
> --- a/include/drm/drm_connector.h
> +++ b/include/drm/drm_connector.h
> @@ -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];
> /**
--
Jani Nikula, Intel
