On Thu, Jul 27, 2017 at 4:44 AM, Tony Lindgren <t...@atomide.com> wrote: > Fix inconsistent use of of_graph_get_port_parent() where > asoc_simple_card_parse_graph_dai() does of_node_get() before > calling it while other callers do not. We can fix this by > not trashing the node passed to of_graph_get_port_parent(). > > Let's make sure the users have correct refcounts and remove > related incorrect of_node_put() calls for of_for_each_phandle > as that's done by of_phandle_iterator_next(). > > Let's fix both issues with a single patch to avoid kobject > refcounts getting messed up more if two patches are merged > separately. > > Otherwise strange issues can happen caused by memory corruption > caused by too many kobject_del() calls such as: > > BUG: sleeping function called from invalid context at > kernel/locking/mutex.c:747 > ... > (___might_sleep) > (__mutex_lock) > (mutex_lock_nested) > (kernfs_remove) > (kobject_del) > (kobject_put) > (of_get_next_parent) > (of_graph_get_port_parent) > (asoc_simple_card_parse_graph_dai [snd_soc_simple_card_utils]) > (asoc_graph_card_probe [snd_soc_audio_graph_card]) > > Fixes: 0ef472a973eb ("of_graph: add of_graph_get_port_parent()") > Fixes: 2692c1c63c29 ("ASoC: add audio-graph-card support") > Fixes: 1689333f8311 ("ASoC: simple-card-utils: add > asoc_simple_card_parse_graph_dai()") > Cc: Mark Brown <broo...@kernel.org> > Cc: Takashi Iwai <ti...@suse.com> > Cc: Kuninori Morimoto <kuninori.morimoto...@renesas.com> > Cc: alsa-de...@alsa-project.org > Signed-off-by: Tony Lindgren <t...@atomide.com> > --- > drivers/of/property.c | 9 +++++++++ > sound/soc/generic/audio-graph-card.c | 5 +---- > sound/soc/generic/simple-card-utils.c | 5 ----- > 3 files changed, 10 insertions(+), 9 deletions(-) > > diff --git a/drivers/of/property.c b/drivers/of/property.c > --- a/drivers/of/property.c > +++ b/drivers/of/property.c > @@ -708,6 +708,15 @@ struct device_node *of_graph_get_port_parent(struct > device_node *node) > { > unsigned int depth; > > + if (!node) > + return NULL; > + > + /* > + * Preserve usecount for passed in node as of_get_next_parent() > + * will do of_node_put() on it. > + */ > + of_node_get(node);
I think this messes up of_graph_get_remote_port_parent(). First it calls of_graph_get_remote_endpoint which returns the endpoint node with ref count incremented. Then you are incrementing it again here. > + > /* Walk 3 levels up only if there is 'ports' node. */ > for (depth = 3; depth && node; depth--) { > node = of_get_next_parent(node); > diff --git a/sound/soc/generic/audio-graph-card.c > b/sound/soc/generic/audio-graph-card.c > --- a/sound/soc/generic/audio-graph-card.c > +++ b/sound/soc/generic/audio-graph-card.c > @@ -224,7 +224,6 @@ static int asoc_graph_card_parse_of(struct > graph_card_data *priv) > > of_for_each_phandle(&it, rc, node, "dais", NULL, 0) { > ret = asoc_graph_card_dai_link_of(it.node, priv, idx++); > - of_node_put(it.node); > if (ret < 0) > return ret; I think you need a put here. Rob