Re: [bug report] ASoC: audio-graph-card2: add Codec2Codec support

[Kuninori Morimoto <kuninori.morimoto.gx@xxxxxxxxxxx>]

Hi Dan

> Hello Kuninori Morimoto,
> 
> Commit c3a15c92a67b ("ASoC: audio-graph-card2: add Codec2Codec
> support") from Oct 12, 2021 (linux-next), leads to the following
> Smatch static checker warning:
> 
> 	sound/soc/generic/audio-graph-card2.c:1206 graph_count_c2c()
> 	warn: already decremented on line 1206 'lnk->kobj.kref.refcount.refs.counter'
> 
> sound/soc/generic/audio-graph-card2.c
>     1194 static int graph_count_c2c(struct simple_util_priv *priv,
>     1195                            struct device_node *lnk,
>     1196                            struct link_info *li)
>     1197 {
>     1198         struct device_node *ports = of_get_parent(lnk);
>     1199         struct device_node *port0 = lnk;
>     1200         struct device_node *port1 = of_get_next_child(ports, lnk);
>                                                                       ^^^
> 
> This calls of_node_put() on lnk.
> 
>     1201         struct device_node *ep0 = port_to_endpoint(port0);
>     1202         struct device_node *ep1 = port_to_endpoint(port1);
>     1203         struct device_node *codec0 = of_graph_get_remote_port(ep0);
>     1204         struct device_node *codec1 = of_graph_get_remote_port(ep1);
>     1205 
> --> 1206         of_node_get(lnk);
> 
> So this of_node_get() undoes the put.  But if the reference count
> dropped to zero then this would be a use afer free.

Thank you for pointing it.

This "lnk" is used as "port0", and of_node_get(lnk) was for it,
but this function doesn't call of_node_put(port0).
So yes, indeed this of_node_get() is not needed.
Let's remove it. 
Thank you for your help !!

Best regards
---
Renesas Electronics
Ph.D. Kuninori Morimoto