[PATCH] of: Fix locking when calling of_get_next_available_child()

Grant Likely
2013-02-11T22:19:22Z

of_get_next_available_child() obtains the devtree_lock and then calls
of_device_is_available() which also attempts to claim the lock. This is
obviously incorrect and causes a deadlock on boot. Fix issue by adding
an variant of of_device_is_available() which doesn't obtain the lock.

Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: Rob Herring <robherring2@gmail.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
---
drivers/of/base.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index e8d65af..4af74b7 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -297,7 +297,7 @@ EXPORT_SYMBOL(of_machine_is_compatible);
* Returns 1 if the status property is absent or set to "okay" or "ok",
* 0 otherwise
*/
-int of_device_is_available(const struct device_node *device)
+int __of_device_is_available(const struct device_node *device)
{
const char *status;
int statlen;
@@ -313,6 +313,17 @@ int of_device_is_available(const struct device_node *device)

return 0;
}
+
+int of_device_is_available(const struct device_node *device)
+{
+ unsigned long flags;
+ int rc;
+
+ raw_spin_lock_irqsave(&devtree_lock, flags);
+ rc = __of_device_is_available(device);
+ raw_spin_unlock_irqrestore(&devtree_lock, flags);
+ return rc;
+}
EXPORT_SYMBOL(of_device_is_available);

/**
@@ -404,7 +415,7 @@ struct device_node *of_get_next_available_child(const struct device_node *node,
raw_spin_lock(&devtree_lock);
next = prev ? prev->sibling : node->child;
for (; next; next = next->sibling) {
- if (!of_device_is_available(next))
+ if (!__of_device_is_available(next))
continue;
if (of_node_get(next))
break;
--
1.7.10.4