Re: [alsa-devel] [PATCH] ASoC: topology: fix soc_tplg_fe_link_create() - link->dobj initialization order

[Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>]

On 1/22/20 1:07 PM, Jaroslav Kysela wrote:
> The code which checks the return value for snd_soc_add_dai_link() call
> in soc_tplg_fe_link_create() moved the snd_soc_add_dai_link() call before
> link->dobj members initialization.
> 
> While it does not affect the latest kernels, the old soc-core.c code
> in the stable kernels is affected. The snd_soc_add_dai_link() function uses
> the link->dobj.type member to check, if the link structure is valid.
> 
> Reorder the link->dobj initialization to make things work again.
> It's harmless for the recent code (and the structure should be properly
> initialized before other calls anyway).
> 
> The problem is in stable linux-5.4.y since version 5.4.11 when the
> upstream commit 76d270364932 was applied.

I am not following. Is this a fix for linux-5.4-y only, or is it needed 
on Mark's tree? In the latter case, what is broken? We've been using 
Mark's tree without issues, wondering what we missed?

> 
> Fixes: 76d270364932 ("ASoC: topology: Check return value for snd_soc_add_dai_link()")
> Cc: Dragos Tarcatu <dragos_tarcatu@mentor.com>
> Cc: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
> Cc: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
> Cc: Mark Brown <broonie@kernel.org>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
> ---
>   sound/soc/soc-topology.c | 7 ++++---
>   1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/sound/soc/soc-topology.c b/sound/soc/soc-topology.c
> index 92e4f4d08bfa..4e1fe623c390 100644
> --- a/sound/soc/soc-topology.c
> +++ b/sound/soc/soc-topology.c
> @@ -1906,6 +1906,10 @@ static int soc_tplg_fe_link_create(struct soc_tplg *tplg,
>   	link->num_codecs = 1;
>   	link->num_platforms = 1;
>   
> +	link->dobj.index = tplg->index;
> +	link->dobj.ops = tplg->ops;
> +	link->dobj.type = SND_SOC_DOBJ_DAI_LINK;
> +
>   	if (strlen(pcm->pcm_name)) {
>   		link->name = kstrdup(pcm->pcm_name, GFP_KERNEL);
>   		link->stream_name = kstrdup(pcm->pcm_name, GFP_KERNEL);
> @@ -1942,9 +1946,6 @@ static int soc_tplg_fe_link_create(struct soc_tplg *tplg,
>   		goto err;
>   	}
>   
> -	link->dobj.index = tplg->index;
> -	link->dobj.ops = tplg->ops;
> -	link->dobj.type = SND_SOC_DOBJ_DAI_LINK;
>   	list_add(&link->dobj.list, &tplg->comp->dobj_list);
>   
>   	return 0;
> 
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