Re: [PATCH v2] ASoc: hdmi-codec: remove HDMI device unregister

[Philipp Zabel <p.zabel@pengutronix.de>]

On Wed, 2017-02-08 at 10:47 +0100, Vincent Abriou wrote:
> While unregistering the hdmi-codec, the hdmi device list must be
> cleaned up. It avoid kernel page fault when registering again the
> hdmi-codec.
> 
> Cc: Liam Girdwood <lgirdwood@gmail.com>
> Cc: Mark Brown <broonie@kernel.org>
> Cc: Jaroslav Kysela <perex@perex.cz>
> Cc: Takashi Iwai <tiwai@suse.com>
> Cc: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
> Cc: Jyri Sarha <jsarha@ti.com>
> Cc: Arnaud Pouliquen <arnaud.pouliquen@st.com>
> Cc: Philipp Zabel <p.zabel@pengutronix.de>
> 
> Signed-off-by: Vincent Abriou <vincent.abriou@st.com>
> ---
> v2:
>  - add mutex to protect hdmi_device_list from concurrent accesses
>  - use of internal dev variable in the hdmi_codec_remove function
> 
>  sound/soc/codecs/hdmi-codec.c | 25 ++++++++++++++++++++++---
>  1 file changed, 22 insertions(+), 3 deletions(-)
> 
> diff --git a/sound/soc/codecs/hdmi-codec.c b/sound/soc/codecs/hdmi-codec.c
> index dc6715a..8c5ae1f 100644
> --- a/sound/soc/codecs/hdmi-codec.c
> +++ b/sound/soc/codecs/hdmi-codec.c
> @@ -32,6 +32,7 @@ struct hdmi_device {
>  };
>  #define pos_to_hdmi_device(pos)	container_of((pos), struct hdmi_device, list)
>  LIST_HEAD(hdmi_device_list);
> +static DEFINE_MUTEX(hdmi_mutex);
>  
>  #define DAI_NAME_SIZE 16
>  
> @@ -794,6 +795,7 @@ static int hdmi_codec_probe(struct platform_device *pdev)
>  		return -ENOMEM;
>  
>  	hd = NULL;
> +	mutex_lock(&hdmi_mutex);
>  	list_for_each(pos, &hdmi_device_list) {
>  		struct hdmi_device *tmp = pos_to_hdmi_device(pos);
>  
> @@ -805,13 +807,16 @@ static int hdmi_codec_probe(struct platform_device *pdev)
>  
>  	if (!hd) {
>  		hd = devm_kzalloc(dev, sizeof(*hd), GFP_KERNEL);
> -		if (!hd)
> +		if (!hd) {
> +			mutex_unlock(&hdmi_mutex);
>  			return -ENOMEM;
> +		}
>  
>  		hd->dev = dev->parent;
>  
>  		list_add_tail(&hd->list, &hdmi_device_list);
>  	}
> +	mutex_unlock(&hdmi_mutex);
>  
>  	if (hd->cnt >= ARRAY_SIZE(hdmi_dai_name)) {
>  		dev_err(dev, "too many hdmi codec are deteced\n");
> @@ -853,11 +858,25 @@ static int hdmi_codec_probe(struct platform_device *pdev)
>  
>  static int hdmi_codec_remove(struct platform_device *pdev)
>  {
> +	struct device *dev = &pdev->dev;
> +	struct list_head *pos;
>  	struct hdmi_codec_priv *hcp;
>  
> -	hcp = dev_get_drvdata(&pdev->dev);
> +	mutex_lock(&hdmi_mutex);
> +	list_for_each(pos, &hdmi_device_list) {
> +		struct hdmi_device *tmp = pos_to_hdmi_device(pos);
> +
> +		if (tmp->dev == dev->parent) {
> +			list_del(pos);
> +			break;
> +		}
> +	}
> +	mutex_unlock(&hdmi_mutex);
> +
> +	hcp = dev_get_drvdata(dev);
>  	kfree(hcp->chmap_info);
> -	snd_soc_unregister_codec(&pdev->dev);
> +	snd_soc_unregister_codec(dev);
> +
>  	return 0;
>  }

Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>

regards
Philipp