patches/0001-of-fix-recursive-locking-in-of_get_next_available_ch.patch

From c31a0c052205e3ec24efc3fe18ef70c3e913f2d4 Mon Sep 17 00:00:00 2001
From: Stephen Warren <swarren@nvidia.com>
Date: Mon, 11 Feb 2013 14:15:32 -0700
Subject: [PATCH] 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: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
---
 drivers/of/base.c |   30 +++++++++++++++++++++++++-----
 1 file changed, 25 insertions(+), 5 deletions(-)

--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -307,19 +307,19 @@ int of_machine_is_compatible(const char
 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;
 
@@ -330,6 +330,26 @@ int of_device_is_available(const struct
 
 	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);
 
 /**
@@ -421,7 +441,7 @@ struct device_node *of_get_next_availabl
 	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;