linux-kernel - [RFC PATCH 4/5] kobject: Add kobject initialized predicate

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Date:   Thu,  2 May 2019 12:31:41 +1000
From:   "Tobin C. Harding" <tobin@...nel.org>
To:     Josh Poimboeuf <jpoimboe@...hat.com>,
        Jiri Kosina <jikos@...nel.org>,
        Miroslav Benes <mbenes@...e.cz>,
        Petr Mladek <pmladek@...e.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     "Tobin C. Harding" <tobin@...nel.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Joe Lawrence <joe.lawrence@...hat.com>,
        live-patching@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [RFC PATCH 4/5] kobject: Add kobject initialized predicate

A call to kobject_init() is required to be paired with a call to
kobject_put() in order to correctly free up the kobject.  During cleanup
functions it would be useful to know if a kobject was initialized in
order to correctly pair the call to kobject_put().  For example this is
necessary if we attempt to initialize multiple objects on a list and one
fails - in order to correctly do cleanup we need to know which objects
have been initialized.

Add a predicate kobject_is_initialized() to the kobject API.  This
function maintains the kobject layer of abstraction; simply returns
kobj->state_initialized.

Signed-off-by: Tobin C. Harding <tobin@...nel.org>
---
 include/linux/kobject.h |  2 ++
 lib/kobject.c           | 12 ++++++++++++
 2 files changed, 14 insertions(+)

diff --git a/include/linux/kobject.h b/include/linux/kobject.h
index 1ab0d624fb36..65a317b65d9c 100644
--- a/include/linux/kobject.h
+++ b/include/linux/kobject.h
@@ -100,6 +100,8 @@ int kobject_init_and_add(struct kobject *kobj,
 			 struct kobj_type *ktype, struct kobject *parent,
 			 const char *fmt, ...);
 
+extern bool kobject_is_initialized(struct kobject *kobj);
+
 extern void kobject_del(struct kobject *kobj);
 
 extern struct kobject * __must_check kobject_create(void);
diff --git a/lib/kobject.c b/lib/kobject.c
index 0181f102cd1c..ecddf417f452 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -366,6 +366,18 @@ void kobject_init(struct kobject *kobj, struct kobj_type *ktype)
 }
 EXPORT_SYMBOL(kobject_init);
 
+/**
+ * kobject_is_initialized() - Kobject initialized predicate.
+ * @kobj: The kobject to query
+ *
+ * Return: True if @kobj has been initialized.
+ */
+bool kobject_is_initialized(struct kobject *kobj)
+{
+	return kobj->state_initialized;
+}
+EXPORT_SYMBOL(kobject_is_initialized);
+
 static __printf(3, 0) int kobject_add_varg(struct kobject *kobj,
 					   struct kobject *parent,
 					   const char *fmt, va_list vargs)
-- 
2.21.0