| Message ID | 20170727094405.19778-1-tony@atomide.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Jul 27, 2017 at 02:44:05AM -0700, Tony Lindgren 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(). This looks like it gives a much less surprising API so hopefully helps avoid issues in callers: Reviewed-by: Mark Brown <broonie@kernel.org>
On Thu, Jul 27, 2017 at 4:44 AM, Tony Lindgren <tony@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 <broonie@kernel.org> > Cc: Takashi Iwai <tiwai@suse.com> > Cc: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com> > Cc: alsa-devel@alsa-project.org > Signed-off-by: Tony Lindgren <tony@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
* Rob Herring <robh+dt@kernel.org> [170727 15:19]: > On Thu, Jul 27, 2017 at 4:44 AM, Tony Lindgren <tony@atomide.com> wrote: > > --- 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. Hmm OK looks like I missed that one. If we want to have of_graph_get_port_parent not trash the node passed to it, we should just change things there too: struct device_node *of_graph_get_remote_port_parent( const struct device_node *node) { struct device_node *np, *pp; /* Get remote endpoint node. */ np = of_graph_get_remote_endpoint(node); pp = of_graph_get_port_parent(np); of_node_put(np); return pp; } EXPORT_SYMBOL(of_graph_get_remote_port_parent); Does that make sense to you? > > 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. Do you mean on error it should be as below, right? ret = asoc_graph_card_dai_link_of(it.node, priv, idx++); if (ret < 0) { of_node_put(it.node); return ret; } Regards, Tony
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); + /* 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; } @@ -239,10 +238,8 @@ static int asoc_graph_get_dais_count(struct device *dev) int count = 0; int rc; - of_for_each_phandle(&it, rc, node, "dais", NULL, 0) { + of_for_each_phandle(&it, rc, node, "dais", NULL, 0) count++; - of_node_put(it.node); - } return count; } diff --git a/sound/soc/generic/simple-card-utils.c b/sound/soc/generic/simple-card-utils.c --- a/sound/soc/generic/simple-card-utils.c +++ b/sound/soc/generic/simple-card-utils.c @@ -282,11 +282,6 @@ int asoc_simple_card_parse_graph_dai(struct device_node *ep, if (!dai_name) return 0; - /* - * of_graph_get_port_parent() will call - * of_node_put(). So, call of_node_get() here - */ - of_node_get(ep); node = of_graph_get_port_parent(ep); /* Get dai->name */
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 <broonie@kernel.org> Cc: Takashi Iwai <tiwai@suse.com> Cc: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com> Cc: alsa-devel@alsa-project.org Signed-off-by: Tony Lindgren <tony@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(-)