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From:   "Rafael J. Wysocki" <rjw@rjwysocki.net>
To:     Linux PM <linux-pm@vger.kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Daniel Lezcano <daniel.lezcano@linaro.org>,
        Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
        Zhang Rui <rui.zhang@intel.com>
Subject: [PATCH v1 1/2] driver core: class: Clear private pointer on registration failures
Date:   Fri, 20 Jan 2023 20:46:57 +0100
Message-ID: <4463268.LvFx2qVVIh@kreacher>
In-Reply-To: <5905717.lOV4Wx5bFT@kreacher>
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From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Clear the class private pointer if __class_register() fails for it, so
as to allow its users to verify that the class is usable by checking
the value of that pointer.

For consistency, clear that pointer before freeing the object pointed
to by it in class_release().

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/base/class.c |   16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

Index: linux-pm/drivers/base/class.c
===================================================================
--- linux-pm.orig/drivers/base/class.c
+++ linux-pm/drivers/base/class.c
@@ -53,6 +53,8 @@ static void class_release(struct kobject
 
 	pr_debug("class '%s': release.\n", class->name);
 
+	class->p = NULL;
+
 	if (class->class_release)
 		class->class_release(class);
 	else
@@ -186,17 +188,21 @@ int __class_register(struct class *cls,
 	cls->p = cp;
 
 	error = kset_register(&cp->subsys);
-	if (error) {
-		kfree(cp);
-		return error;
-	}
+	if (error)
+		goto err_out;
+
 	error = class_add_groups(class_get(cls), cls->class_groups);
 	class_put(cls);
 	if (error) {
 		kobject_del(&cp->subsys.kobj);
 		kfree_const(cp->subsys.kobj.name);
-		kfree(cp);
+		goto err_out;
 	}
+	return 0;
+
+err_out:
+	kfree(cp);
+	cls->p = NULL;
 	return error;
 }
 EXPORT_SYMBOL_GPL(__class_register);