[alsa-devel] [PATCH v2] Fix possible codec_dai->ops NULL pointer problems

[Barry Song]

On Fri, Oct 16, 2009 at 6:13 PM, Barry Song <21cnbao at gmail.com> wrote:
> From: Barry Song <barry.song at gmail.com>
Sorry for the mis-operation while git commit, this mailbox is not mine.
>
> Some codec DAIs like stac9766, wm9712, wm9713, ad1980 don't register themselves
> then it loses to the chance to be given a null_dai_ops in snd_soc_register_dai
> if they have no ops. When functions like soc_pcm_open, soc_pcm_hw_params etc.
> access the ops field in these DAIs, panic will happen.
>
> Signed-off-by: Barry Song <21cnbao at gmail.com>
> ---
>  sound/soc/soc-core.c |   11 ++++++++---
>  1 files changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
> index fa0da3c..2d190df 100644
> --- a/sound/soc/soc-core.c
> +++ b/sound/soc/soc-core.c
> @@ -795,6 +795,9 @@ static int soc_resume(struct device *dev)
>  #define soc_resume     NULL
>  #endif
>
> +static struct snd_soc_dai_ops null_dai_ops = {
> +};
> +
>  static void snd_soc_instantiate_card(struct snd_soc_card *card)
>  {
>        struct platform_device *pdev = container_of(card->dev,
> @@ -838,6 +841,11 @@ static void snd_soc_instantiate_card(struct snd_soc_card *card)
>                        ac97 = 1;
>        }
>
> +       for (i = 0; i < card->num_links; i++) {
> +               if (!card->dai_link[i].codec_dai->ops)
> +                       card->dai_link[i].codec_dai->ops = &null_dai_ops;
> +       }
> +
>        /* If we have AC97 in the system then don't wait for the
>         * codec.  This will need revisiting if we have to handle
>         * systems with mixed AC97 and non-AC97 parts.  Only check for
> @@ -2332,9 +2340,6 @@ static int snd_soc_unregister_card(struct snd_soc_card *card)
>        return 0;
>  }
>
> -static struct snd_soc_dai_ops null_dai_ops = {
> -};
> -
>  /**
>  * snd_soc_register_dai - Register a DAI with the ASoC core
>  *
> --
> 1.5.6.3
>
>