From: Maxime Ripard <maxime@cerno.tech>
To: He Ying <heying24@huawei.com>
Cc: wens@csie.org, airlied@linux.ie, daniel@ffwll.ch,
jernej.skrabec@gmail.com, dri-devel@lists.freedesktop.org,
linux-arm-kernel@lists.infradead.org,
linux-sunxi@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH -V2] drm/sun4i: Grab reference of connector before return connector from sun4i_tcon_get_connector
Date: Tue, 2 Nov 2021 16:03:31 +0100 [thread overview]
Message-ID: <20211102150331.526nn2e6oqjbf6ur@gilmour> (raw)
In-Reply-To: <20211102084628.149070-1-heying24@huawei.com>
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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@huawei.com>
> ---
>
> 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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next prev parent reply other threads:[~2021-11-02 15:03 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-01 6:29 [PATCH] drm: Grab reference of connector before return connector from sun4i_tcon_get_connector He Ying
2021-11-01 13:02 ` Jani Nikula
2021-11-02 2:48 ` He Ying
2021-11-02 8:37 ` Jani Nikula
2021-11-02 8:46 ` [PATCH -V2] drm/sun4i: " He Ying
2021-11-02 15:03 ` Maxime Ripard [this message]
2021-11-03 2:26 ` He Ying
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