From c0a480d1acf7dc184f9f3e7cf724483b0d28dc2e Mon Sep 17 00:00:00 2001 From: Tony Lindgren Date: Fri, 28 Jul 2017 01:23:15 -0700 Subject: device property: Fix usecount for of_graph_get_port_parent() 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 also make sure the callers 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() except when we break out of the loop early. 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()") Signed-off-by: Tony Lindgren Reviewed-by: Rob Herring Tested-by: Antonio Borneo Tested-by: Kuninori Morimoto Signed-off-by: Mark Brown --- drivers/of/property.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) (limited to 'drivers/of') diff --git a/drivers/of/property.c b/drivers/of/property.c index eda50b4be934..067f9fab7b77 100644 --- 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); @@ -728,12 +737,16 @@ EXPORT_SYMBOL(of_graph_get_port_parent); struct device_node *of_graph_get_remote_port_parent( const struct device_node *node) { - struct device_node *np; + struct device_node *np, *pp; /* Get remote endpoint node. */ np = of_graph_get_remote_endpoint(node); - return of_graph_get_port_parent(np); + pp = of_graph_get_port_parent(np); + + of_node_put(np); + + return pp; } EXPORT_SYMBOL(of_graph_get_remote_port_parent); -- cgit v1.2.3-59-g8ed1b