Hi,
On Tue, Nov 02, 2021 at 04:46:28AM -0400, He Ying wrote:
> From the comments of drm_for_each_connector_iter(), we know
> that "connector is only valid within the list body, if you
> want to use connector after calling drm_connector_list_iter_end()
> then you need to grab your own reference first using
> drm_connector_get()". So fix the wrong use of connector
> according to the comments and then call drm_connector_put()
> after using connector finishes.
>
> Signed-off-by: He Ying <heying24@xxxxxxxxxx>
> ---
>
> V2:
> Use proper subject prefix
>
> drivers/gpu/drm/sun4i/sun4i_tcon.c | 18 +++++++++++++-----
> 1 file changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> index 9f06dec0fc61..24fa6784ee5f 100644
> --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
> +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> @@ -47,12 +47,12 @@ static struct drm_connector *sun4i_tcon_get_connector(const struct drm_encoder *
> drm_connector_list_iter_begin(encoder->dev, &iter);
> drm_for_each_connector_iter(connector, &iter)
> if (connector->encoder == encoder) {
> - drm_connector_list_iter_end(&iter);
> - return connector;
> + drm_connector_get(connector);
> + break;
> }
> drm_connector_list_iter_end(&iter);
>
> - return NULL;
> + return connector;
Connector might be uninitialized if we don't find one here
> }
>
> static int sun4i_tcon_get_pixel_depth(const struct drm_encoder *encoder)
> @@ -65,6 +65,7 @@ static int sun4i_tcon_get_pixel_depth(const struct drm_encoder *encoder)
> return -EINVAL;
>
> info = &connector->display_info;
> + drm_connector_put(connector);
> if (info->num_bus_formats != 1)
We're still accessing connector->display_info here, but it might have been
freed already.
Maxime
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