linux-kernel - Re: [PATCH v5 2/9] drm/bridge-connector: switch to using drmm allocations

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Message-ID: <CAA8EJpogi2qm0bhCwumY4zj-xMUkF4zbK-NAPqCeDbLcybFciw@mail.gmail.com>
Date: Mon, 10 Jun 2024 14:46:03 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Maxime Ripard <mripard@...nel.org>
Cc: Andrzej Hajda <andrzej.hajda@...el.com>, Neil Armstrong <neil.armstrong@...aro.org>, 
	Robert Foss <rfoss@...nel.org>, Laurent Pinchart <Laurent.pinchart@...asonboard.com>, 
	Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Thomas Zimmermann <tzimmermann@...e.de>, 
	David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>, Rob Clark <robdclark@...il.com>, 
	Abhinav Kumar <quic_abhinavk@...cinc.com>, Sean Paul <sean@...rly.run>, 
	Marijn Suijten <marijn.suijten@...ainline.org>, dri-devel@...ts.freedesktop.org, 
	linux-arm-msm@...r.kernel.org, freedreno@...ts.freedesktop.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 2/9] drm/bridge-connector: switch to using drmm allocations

On Mon, 10 Jun 2024 at 11:04, Maxime Ripard <mripard@...nel.org> wrote:
>
> Hi,
>
> On Fri, Jun 07, 2024 at 04:22:59PM GMT, Dmitry Baryshkov wrote:
> > Turn drm_bridge_connector to using drmm_kzalloc() and
> > drmm_connector_init() and drop the custom destroy function. The
> > drm_connector_unregister() and fwnode_handle_put() are already handled
> > by the drm_connector_cleanup() and so are safe to be dropped.
> >
> > Acked-by: Maxime Ripard <mripard@...nel.org>
> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> > ---
> >  drivers/gpu/drm/drm_bridge_connector.c | 23 +++++------------------
> >  1 file changed, 5 insertions(+), 18 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_bridge_connector.c b/drivers/gpu/drm/drm_bridge_connector.c
> > index 982552c9f92c..e093fc8928dc 100644
> > --- a/drivers/gpu/drm/drm_bridge_connector.c
> > +++ b/drivers/gpu/drm/drm_bridge_connector.c
> > @@ -15,6 +15,7 @@
> >  #include <drm/drm_connector.h>
> >  #include <drm/drm_device.h>
> >  #include <drm/drm_edid.h>
> > +#include <drm/drm_managed.h>
> >  #include <drm/drm_modeset_helper_vtables.h>
> >  #include <drm/drm_probe_helper.h>
> >
> > @@ -193,19 +194,6 @@ drm_bridge_connector_detect(struct drm_connector *connector, bool force)
> >       return status;
> >  }
> >
> > -static void drm_bridge_connector_destroy(struct drm_connector *connector)
> > -{
> > -     struct drm_bridge_connector *bridge_connector =
> > -             to_drm_bridge_connector(connector);
> > -
> > -     drm_connector_unregister(connector);
> > -     drm_connector_cleanup(connector);
> > -
> > -     fwnode_handle_put(connector->fwnode);
> > -
> > -     kfree(bridge_connector);
> > -}
> > -
> >  static void drm_bridge_connector_debugfs_init(struct drm_connector *connector,
> >                                             struct dentry *root)
> >  {
> > @@ -224,7 +212,6 @@ static const struct drm_connector_funcs drm_bridge_connector_funcs = {
> >       .reset = drm_atomic_helper_connector_reset,
> >       .detect = drm_bridge_connector_detect,
> >       .fill_modes = drm_helper_probe_single_connector_modes,
> > -     .destroy = drm_bridge_connector_destroy,
> >       .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
> >       .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
> >       .debugfs_init = drm_bridge_connector_debugfs_init,
> > @@ -328,7 +315,7 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
> >       int connector_type;
> >       int ret;
> >
> > -     bridge_connector = kzalloc(sizeof(*bridge_connector), GFP_KERNEL);
> > +     bridge_connector = drmm_kzalloc(drm, sizeof(*bridge_connector), GFP_KERNEL);
>
> So you make destroy's kfree call unnecessary here ...
>
> >       if (!bridge_connector)
> >               return ERR_PTR(-ENOMEM);
> >
> > @@ -383,9 +370,9 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
> >               return ERR_PTR(-EINVAL);
> >       }
> >
> > -     ret = drm_connector_init_with_ddc(drm, connector,
> > -                                       &drm_bridge_connector_funcs,
> > -                                       connector_type, ddc);
> > +     ret = drmm_connector_init(drm, connector,
> > +                               &drm_bridge_connector_funcs,
> > +                               connector_type, ddc);
>
> ... and here of drm_connector_cleanup.
>
> drm_connector_unregister wasn't needed, so can ignore it, but you leak a reference to
> connector->fwnode since you don't call fwnode_handle_put anymore.
>
> We should register a drmm action right below the call to fwnode_handle_get too.

But drm_connector_cleanup() already contains
fwnode_handle_put(connector->fwnode). Isn't that enough?


-- 
With best wishes
Dmitry