[PATCH 0/2] add kobject/of_node read() function

[PATCH 0/2] add kobject/of_node read() function

[Kuninori Morimoto]

Hi Greg, Rob, Frank

We are using {kobject_/of_node_}get/put() for increment/decrement
counter. But, because we don't have counter read() function,
confirming it (mainly for debug purpose) is a little bit difficult.
These patches add read() function for it.

Kuninori Morimoto (2):
  kobject: add kobject_read()
  of: add of_node_read()

 drivers/of/dynamic.c    | 14 ++++++++++++++
 include/linux/kobject.h |  1 +
 include/linux/of.h      |  5 +++++
 lib/kobject.c           | 18 ++++++++++++++++++
 4 files changed, 38 insertions(+)

-- 
1.9.1

[PATCH 1/2] kobject: add kobject_read()

[Kuninori Morimoto]

From: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>

We are counting kobject by using kobject_get/put(), but
not have kobject_read() which can be used to check count.
Let's add

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
---
 include/linux/kobject.h |  1 +
 lib/kobject.c           | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/include/linux/kobject.h b/include/linux/kobject.h
index 7f6f93c..6f74d4b 100644
--- a/include/linux/kobject.h
+++ b/include/linux/kobject.h
@@ -108,6 +108,7 @@ extern struct kobject * __must_check kobject_create_and_add(const char *name,
 extern int __must_check kobject_rename(struct kobject *, const char *new_name);
 extern int __must_check kobject_move(struct kobject *, struct kobject *);
 
+extern unsigned int kobject_read(struct kobject *kobj);
 extern struct kobject *kobject_get(struct kobject *kobj);
 extern struct kobject * __must_check kobject_get_unless_zero(
 						struct kobject *kobj);
diff --git a/lib/kobject.c b/lib/kobject.c
index afd5a3f..103c8c8 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -561,6 +561,24 @@ int kobject_move(struct kobject *kobj, struct kobject *new_parent)
 EXPORT_SYMBOL_GPL(kobject_move);
 
 /**
+ * kobject_read - read refcount count for object.
+ * @kobj: object.
+ */
+unsigned int kobject_read(struct kobject *kobj)
+{
+	if (kobj) {
+		if (!kobj->state_initialized)
+			WARN(1, KERN_WARNING "kobject: '%s' (%p): is not "
+			     "initialized, yet kobject_put() is being "
+			     "called.\n", kobject_name(kobj), kobj);
+		return kref_read(&kobj->kref);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(kobject_read);
+
+/**
  * kobject_del - unlink kobject from hierarchy.
  * @kobj: object.
  */
-- 
1.9.1

[PATCH 2/2] of: add of_node_read()

[Kuninori Morimoto]

From: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>

We are counting of node by using of_node_get/put(), but
not have of_node_read() which can be used to check count.
Let's add it

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
---
 drivers/of/dynamic.c | 14 ++++++++++++++
 include/linux/of.h   |  5 +++++
 2 files changed, 19 insertions(+)

diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
index f4f8ed9..db5fdf3 100644
--- a/drivers/of/dynamic.c
+++ b/drivers/of/dynamic.c
@@ -49,6 +49,20 @@ void of_node_put(struct device_node *node)
 }
 EXPORT_SYMBOL(of_node_put);
 
+/**
+ * of_node_read() - read refcount of a node
+ * @node:	Node to dec refcount, NULL is supported to simplify writing of
+ *		callers
+ */
+unsigned int of_node_read(struct device_node *node)
+{
+	if (node)
+		return kobject_read(&node->kobj);
+
+	return 0;
+}
+EXPORT_SYMBOL(of_node_read);
+
 static BLOCKING_NOTIFIER_HEAD(of_reconfig_chain);
 
 int of_reconfig_notifier_register(struct notifier_block *nb)
diff --git a/include/linux/of.h b/include/linux/of.h
index 4d25e4f..8be0ca8 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -122,6 +122,7 @@ static inline void of_node_init(struct device_node *node)
 #ifdef CONFIG_OF_DYNAMIC
 extern struct device_node *of_node_get(struct device_node *node);
 extern void of_node_put(struct device_node *node);
+unsigned int of_node_read(struct device_node *node);
 #else /* CONFIG_OF_DYNAMIC */
 /* Dummy ref counting routines - to be implemented later */
 static inline struct device_node *of_node_get(struct device_node *node)
@@ -129,6 +130,10 @@ static inline struct device_node *of_node_get(struct device_node *node)
 	return node;
 }
 static inline void of_node_put(struct device_node *node) { }
+static inline unsigned int of_node_read(struct device_node *node)
+{
+	return 0;
+}
 #endif /* !CONFIG_OF_DYNAMIC */
 
 /* Pointer for first entry in chain of all nodes. */
-- 
1.9.1

Re: [PATCH 1/2] kobject: add kobject_read()

[Greg Kroah-Hartman]

On Tue, Apr 10, 2018 at 06:53:50AM +0000, Kuninori Morimoto wrote:
> 
> From: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
> 
> We are counting kobject by using kobject_get/put(), but
> not have kobject_read() which can be used to check count.
> Let's add

No, please do not.  You should never care about this "count", and if we
do provide this, people will abuse it.

I understand that this might make some debugging harder, but if you
really need to write custom debugging code, then just use the internal
values.

sorry,

greg k-h

Re: [PATCH 2/2] of: add of_node_read()

[Greg Kroah-Hartman]

On Tue, Apr 10, 2018 at 06:54:13AM +0000, Kuninori Morimoto wrote:
> 
> From: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
> 
> We are counting of node by using of_node_get/put(), but
> not have of_node_read() which can be used to check count.
> Let's add it

Same objection as previous patch, please no.

thanks,

greg k-h