From: Rob Herring <rob.herring@calxeda.com>
Date: Tue, 20 Sep 2011 18:02:54 +0000 (-0500)
Subject: of/irq: of_irq_find_parent: check for parent equal to child
X-Git-Tag: MMI-PSA29.97-13-9~18215^2~6^2~2
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=dc9372808412edb;p=GitHub%2FMotorolaMobilityLLC%2Fkernel-slsi.git

of/irq: of_irq_find_parent: check for parent equal to child

An interrupt controller may often implicitly inherit itself from a parent
node when in fact the controller is the interrupt root controller. Guard
against the case of child == parent and return NULL in this case.

This can also be fixed by adding an explicit "interrupt-parent;" to a root
interrupt controller node.

Based on code from Grant Likely.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
---

diff --git a/drivers/of/irq.c b/drivers/of/irq.c
index 9f689f1da0fc..6a5b5e777dd2 100644
--- a/drivers/of/irq.c
+++ b/drivers/of/irq.c
@@ -58,27 +58,27 @@ EXPORT_SYMBOL_GPL(irq_of_parse_and_map);
  */
 struct device_node *of_irq_find_parent(struct device_node *child)
 {
-	struct device_node *p;
+	struct device_node *p, *c = child;
 	const __be32 *parp;
 
-	if (!of_node_get(child))
+	if (!of_node_get(c))
 		return NULL;
 
 	do {
-		parp = of_get_property(child, "interrupt-parent", NULL);
+		parp = of_get_property(c, "interrupt-parent", NULL);
 		if (parp == NULL)
-			p = of_get_parent(child);
+			p = of_get_parent(c);
 		else {
 			if (of_irq_workarounds & OF_IMAP_NO_PHANDLE)
 				p = of_node_get(of_irq_dflt_pic);
 			else
 				p = of_find_node_by_phandle(be32_to_cpup(parp));
 		}
-		of_node_put(child);
-		child = p;
+		of_node_put(c);
+		c = p;
 	} while (p && of_get_property(p, "#interrupt-cells", NULL) == NULL);
 
-	return p;
+	return (p == child) ? NULL : p;
 }
 
 /**