From: Thomas Gleixner <tglx@linutronix.de>
Date: Thu, 13 Aug 2009 09:04:10 +0200
Subject: OF: Fixup resursive locking code paths

There is no real reason to use a rwlock for devtree_lock. It even
could be a mutex, but unfortunately it's locked from cpu hotplug
pathes which can't schedule :(

So it needs to become a raw lock on rt as well. devtree_lock would be
the only user of a raw_rw_lock, so we are better of cleaning the
recursive locking pathes which allows us to convert devtree_lock to a
read_lock.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
 drivers/of/base.c |   93 +++++++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 71 insertions(+), 22 deletions(-)

Index: linux-stable/drivers/of/base.c
===================================================================
--- linux-stable.orig/drivers/of/base.c
+++ linux-stable/drivers/of/base.c
@@ -163,16 +163,14 @@ void of_node_put(struct device_node *nod
 EXPORT_SYMBOL(of_node_put);
 #endif /* CONFIG_OF_DYNAMIC */
 
-struct property *of_find_property(const struct device_node *np,
-				  const char *name,
-				  int *lenp)
+static struct property *__of_find_property(const struct device_node *np,
+					   const char *name, int *lenp)
 {
 	struct property *pp;
 
 	if (!np)
 		return NULL;
 
-	read_lock(&devtree_lock);
 	for (pp = np->properties; pp; pp = pp->next) {
 		if (of_prop_cmp(pp->name, name) == 0) {
 			if (lenp)
@@ -180,6 +178,18 @@ struct property *of_find_property(const 
 			break;
 		}
 	}
+
+	return pp;
+}
+
+struct property *of_find_property(const struct device_node *np,
+				  const char *name,
+				  int *lenp)
+{
+	struct property *pp;
+
+	read_lock(&devtree_lock);
+	pp = __of_find_property(np, name, lenp);
 	read_unlock(&devtree_lock);
 
 	return pp;
@@ -213,8 +223,20 @@ EXPORT_SYMBOL(of_find_all_nodes);
  * Find a property with a given name for a given node
  * and return the value.
  */
+static const void *__of_get_property(const struct device_node *np,
+				     const char *name, int *lenp)
+{
+	struct property *pp = __of_find_property(np, name, lenp);
+
+	return pp ? pp->value : NULL;
+}
+
+/*
+ * Find a property with a given name for a given node
+ * and return the value.
+ */
 const void *of_get_property(const struct device_node *np, const char *name,
-			 int *lenp)
+			    int *lenp)
 {
 	struct property *pp = of_find_property(np, name, lenp);
 
@@ -225,13 +247,13 @@ EXPORT_SYMBOL(of_get_property);
 /** Checks if the given "compat" string matches one of the strings in
  * the device's "compatible" property
  */
-int of_device_is_compatible(const struct device_node *device,
-		const char *compat)
+static int __of_device_is_compatible(const struct device_node *device,
+				     const char *compat)
 {
 	const char* cp;
-	int cplen, l;
+	int uninitialized_var(cplen), l;
 
-	cp = of_get_property(device, "compatible", &cplen);
+	cp = __of_get_property(device, "compatible", &cplen);
 	if (cp == NULL)
 		return 0;
 	while (cplen > 0) {
@@ -244,6 +266,20 @@ int of_device_is_compatible(const struct
 
 	return 0;
 }
+
+/** Checks if the given "compat" string matches one of the strings in
+ * the device's "compatible" property
+ */
+int of_device_is_compatible(const struct device_node *device,
+		const char *compat)
+{
+	int res;
+
+	read_lock(&devtree_lock);
+	res = __of_device_is_compatible(device, compat);
+	read_unlock(&devtree_lock);
+	return res;
+}
 EXPORT_SYMBOL(of_device_is_compatible);
 
 /**
@@ -494,7 +530,8 @@ struct device_node *of_find_compatible_n
 		if (type
 		    && !(np->type && (of_node_cmp(np->type, type) == 0)))
 			continue;
-		if (of_device_is_compatible(np, compatible) && of_node_get(np))
+		if (__of_device_is_compatible(np, compatible) &&
+		    of_node_get(np))
 			break;
 	}
 	of_node_put(from);
@@ -538,15 +575,9 @@ out:
 }
 EXPORT_SYMBOL(of_find_node_with_property);
 
-/**
- * of_match_node - Tell if an device_node has a matching of_match structure
- *	@matches:	array of of device match structures to search in
- *	@node:		the of device structure to match against
- *
- *	Low level utility function used by device matching.
- */
-const struct of_device_id *of_match_node(const struct of_device_id *matches,
-					 const struct device_node *node)
+static
+const struct of_device_id *__of_match_node(const struct of_device_id *matches,
+					   const struct device_node *node)
 {
 	if (!matches)
 		return NULL;
@@ -560,14 +591,32 @@ const struct of_device_id *of_match_node
 			match &= node->type
 				&& !strcmp(matches->type, node->type);
 		if (matches->compatible[0])
-			match &= of_device_is_compatible(node,
-						matches->compatible);
+			match &= __of_device_is_compatible(node,
+							   matches->compatible);
 		if (match)
 			return matches;
 		matches++;
 	}
 	return NULL;
 }
+
+/**
+ * of_match_node - Tell if an device_node has a matching of_match structure
+ *	@matches:	array of of device match structures to search in
+ *	@node:		the of device structure to match against
+ *
+ *	Low level utility function used by device matching.
+ */
+const struct of_device_id *of_match_node(const struct of_device_id *matches,
+					 const struct device_node *node)
+{
+	const struct of_device_id *match;
+
+	read_lock(&devtree_lock);
+	match = __of_match_node(matches, node);
+	read_unlock(&devtree_lock);
+	return match;
+}
 EXPORT_SYMBOL(of_match_node);
 
 /**
@@ -590,7 +639,7 @@ struct device_node *of_find_matching_nod
 	read_lock(&devtree_lock);
 	np = from ? from->allnext : allnodes;
 	for (; np; np = np->allnext) {
-		if (of_match_node(matches, np) && of_node_get(np))
+		if (__of_match_node(matches, np) && of_node_get(np))
 			break;
 	}
 	of_node_put(from);