Thread (19 messages) 19 messages, 2 authors, 2014-05-23

Re: [PATCH 2/3] of: Make of_find_node_by_path() handle /aliases

From: Grant Likely <hidden>
Date: 2014-05-22 03:38:20
Also in: lkml
Subsystem: open firmware and flattened device tree, the rest · Maintainers: Rob Herring, Saravana Kannan, Linus Torvalds

On Tue, 20 May 2014 19:46:19 -0700, Frank Rowand [off-list ref] wrote:
quoted hunk ↗ jump to hunk
On 5/20/2014 7:41 PM, Frank Rowand wrote:
< snip >
quoted
I will reply to this email with an additional patch that restores the
original behavior.
< snip >
From: Frank Rowand <redacted>

If __of_find_node_by_path() returns parent when the remaining portion of the
path is "/" then the behavior of of_find_node_by_path() has changed.

Previously, adding an extraneous "/" on the end of a path would result
in of_find_node_by_path() not finding a match.

Signed-off-by: Frank Rowand <redacted>
---
 drivers/of/base.c |   13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

Index: b/drivers/of/base.c
===================================================================
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -778,7 +778,7 @@ static struct device_node *__of_find_nod
 	int len = strchrnul(path, '/') - path;
 
 	if (!len)
-		return parent;
+		return NULL;
 
 	for_each_child_of_node(parent, child) {
 		const char *name = strrchr(child->full_name, '/');
@@ -813,6 +813,17 @@ struct device_node *of_find_node_by_path
 	struct property *pp;
 	unsigned long flags;
 
+	if (strcmp(path, "/") == 0) {
+		raw_spin_lock_irqsave(&devtree_lock, flags);
+		for (; np; np = np->allnext) {
+			if (np->full_name && (of_node_cmp(np->full_name, path) == 0)
+			    && of_node_get(np))
+				break;
+		}
+		raw_spin_unlock_irqrestore(&devtree_lock, flags);
+		return np;
+	}
+
Special case for the root node? Could use a comment, and of_allnodes
will already point to the root node so this could simply be:

	if (strcmp(path, "/") == 0)
		return of_node_get(np);

Here's a complete patch:

commit adc96db6c39ef7b895e75d30dbc69781f6443f1d
Author: Grant Likely [off-list ref]
Date:   Thu May 22 11:55:31 2014 +0900

    fix trailing '/' case
diff --git a/drivers/of/base.c b/drivers/of/base.c
index c05a143b6a70..45ac44c8dfea 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -790,7 +790,7 @@ static struct device_node *__of_find_node_by_path(struct device_node *parent,
 	int len = strchrnul(path, '/') - path;
 
 	if (!len)
-		return parent;
+		return NULL;
 
 	__for_each_child_of_node(parent, child) {
 		const char *name = strrchr(child->full_name, '/');
@@ -820,10 +820,13 @@ static struct device_node *__of_find_node_by_path(struct device_node *parent,
  */
 struct device_node *of_find_node_by_path(const char *path)
 {
-	struct device_node *np = of_allnodes;
+	struct device_node *np = NULL;
 	struct property *pp;
 	unsigned long flags;
 
+	if (strcmp(path, "/") == 0)
+		return of_node_get(of_allnodes);
+
 	/* The path could begin with an alias */
 	if (*path != '/') {
 		char *p = strchrnul(path, '/');
@@ -833,7 +836,6 @@ struct device_node *of_find_node_by_path(const char *path)
 		if (!of_aliases)
 			return NULL;
 
-		np = NULL;
 		for_each_property_of_node(of_aliases, pp) {
 			if (strlen(pp->name) == len && !strncmp(pp->name, path, len)) {
 				np = of_find_node_by_path(pp->value);
@@ -847,6 +849,8 @@ struct device_node *of_find_node_by_path(const char *path)
 
 	/* Step down the tree matching path components */
 	raw_spin_lock_irqsave(&devtree_lock, flags);
+	if (!np)
+		np = of_node_get(of_allnodes);
 	while (np && *path == '/') {
 		path++; /* Increment past '/' delimiter */
 		np = __of_find_node_by_path(np, path);
diff --git a/drivers/of/selftest.c b/drivers/of/selftest.c
index 10900b18fc06..aeb0b5c8b21d 100644
--- a/drivers/of/selftest.c
+++ b/drivers/of/selftest.c
@@ -42,9 +42,7 @@ static void __init of_selftest_find_node_by_name(void)
 
 	/* Test if trailing '/' works */
 	np = of_find_node_by_path("/testcase-data/");
-	selftest(np && !strcmp("/testcase-data", np->full_name),
-		"find /testcase-data/ failed\n");
-	of_node_put(np);
+	selftest(!np, "trailing '/' on /testcase-data/ should fail\n");
 
 	np = of_find_node_by_path("/testcase-data/phandle-tests/consumer-a");
 	selftest(np && !strcmp("/testcase-data/phandle-tests/consumer-a", np->full_name),
@@ -58,9 +56,7 @@ static void __init of_selftest_find_node_by_name(void)
 
 	/* Test if trailing '/' works on aliases */
 	np = of_find_node_by_path("testcase-alias/");
-	selftest(np && !strcmp("/testcase-data", np->full_name),
-		"find testcase-alias/ failed\n");
-	of_node_put(np);
+	selftest(!np, "trailing '/' on testcase-alias/ should fail\n");
 
 	np = of_find_node_by_path("testcase-alias/phandle-tests/consumer-a");
 	selftest(np && !strcmp("/testcase-data/phandle-tests/consumer-a", np->full_name),
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