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device property: Fix usecount for of_graph_get_port_parent()

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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: 0ef472a973 ("of_graph: add of_graph_get_port_parent()")
Fixes: 2692c1c63c ("ASoC: add audio-graph-card support")
Fixes: 1689333f83 ("ASoC: simple-card-utils: add asoc_simple_card_parse_graph_dai()")
Signed-off-by: Tony Lindgren <[email protected]>
Reviewed-by: Rob Herring <[email protected]>
Tested-by: Antonio Borneo <[email protected]>
Tested-by: Kuninori Morimoto <[email protected]>
Signed-off-by: Mark Brown <[email protected]>
This commit is contained in:
Tony Lindgren 2017-07-28 01:23:15 -07:00 • committed by Mark Brown
commit c0a480d1ac
5 changed files with 34 additions and 18 deletions
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17
drivers/of/property.c
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@ -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);