[PATCH 2/4] drm/fb-helper: Keep references for the current set of used connectors

[Chris Wilson]

On Wed, Oct 26, 2016 at 12:05:53PM +0300, ville.syrjala at linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> The fbdev helper code keeps around two lists of connectors. One is the
> list of all connectors it could use, and that list already holds
> references for all the connectors. However the other list, or rather
> lists, is the one actively being used. That list is tracked per-crtc
> and currently doesn't hold any extra references. Let's grab those
> extra references to avoid oopsing when the connector vanishes. The
> list of all possible connectors should get updated when the hpd happens,
> but the list of actively used connectors would not get updated until
> the next time the fb-helper picks through the set of possible connectors.
> And so we need to hang on to the connectors until that time.
> 
> Cc: stable at vger.kernel.org
> Cc: Carlos Santa <carlos.santa at intel.com>
> Cc: Kirill A. Shutemov <kirill at shutemov.name>
> Tested-by: Carlos Santa <carlos.santa at intel.com>
> Tested-by: Kirill A. Shutemov <kirill at shutemov.name>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=97666
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>  drivers/gpu/drm/drm_fb_helper.c | 25 ++++++++++++++++++-------
>  1 file changed, 18 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index db469d12d195..9ee1dacf97b8 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -2090,7 +2090,6 @@ static void drm_setup_crtcs(struct drm_fb_helper *fb_helper)
>  	struct drm_fb_helper_crtc **crtcs;
>  	struct drm_display_mode **modes;
>  	struct drm_fb_offset *offsets;
> -	struct drm_mode_set *modeset;
>  	bool *enabled;
>  	int width, height;
>  	int i;
> @@ -2139,7 +2138,14 @@ static void drm_setup_crtcs(struct drm_fb_helper *fb_helper)
>  	/* need to set the modesets up here for use later */
>  	/* fill out the connector<->crtc mappings into the modesets */
>  	for (i = 0; i < fb_helper->crtc_count; i++) {
> -		modeset = &fb_helper->crtc_info[i].mode_set;
> +		struct drm_mode_set *modeset = &fb_helper->crtc_info[i].mode_set;
> +		int j;
> +
> +		for (j = 0; j < modeset->num_connectors; j++) {
> +			drm_connector_unreference(modeset->connectors[j]);
> +			modeset->connectors[j] = NULL;
> +		}
> +

Don't we also need a similar cleanup loop in drm_fb_helper_crtc_free()?
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre