Commit c31a0c05 authored by Stephen Warren's avatar Stephen Warren Committed by Grant Likely
Browse files

of: fix recursive locking in of_get_next_available_child() 



of_get_next_available_child() acquires devtree_lock, then calls
of_device_is_available() which calls of_get_property() which calls
of_find_property() which tries to re-acquire devtree_lock, thus causing
deadlock.

To avoid this, create a new __of_device_is_available() which calls
__of_get_property() instead, which calls __of_find_property(), which
does not take the lock,. Update of_get_next_available_child() to call
the new __of_device_is_available() since it already owns the lock.

Signed-off-by: default avatarStephen Warren <swarren@nvidia.com>
Signed-off-by: default avatarGrant Likely <grant.likely@secretlab.ca>
parent bfc4a589

drivers/of/base.c

+25 −5
Original line number Diff line number Diff line
@@ -290,19 +290,19 @@ int of_machine_is_compatible(const char *compat) 
EXPORT_SYMBOL(of_machine_is_compatible);



/**

 *  of_device_is_available - check if a device is available for use

 *  __of_device_is_available - check if a device is available for use

 *

 *  @device: Node to check for availability

 *  @device: Node to check for availability, with locks already held

 *

 *  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)

static int __of_device_is_available(const struct device_node *device)

{

	const char *status;

	int statlen;



	status = of_get_property(device, "status", &statlen);

	status = __of_get_property(device, "status", &statlen);

	if (status == NULL)

		return 1;
@@ -313,6 +313,26 @@ int of_device_is_available(const struct device_node *device) 


	return 0;

}



/**

 *  of_device_is_available - check if a device is available for use

 *

 *  @device: Node to check for availability

 *

 *  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)

{

	unsigned long flags;

	int res;



	raw_spin_lock_irqsave(&devtree_lock, flags);

	res = __of_device_is_available(device);

	raw_spin_unlock_irqrestore(&devtree_lock, flags);

	return res;



}

EXPORT_SYMBOL(of_device_is_available);



/**
@@ -404,7 +424,7 @@ 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;

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