[PATCH] kobject: introduce kobject_del_and_put()

[PATCH] kobject: introduce kobject_del_and_put()

[Yangtao Li]

There are plenty of using kobject_del() and kobject_put() together
in the kernel tree. This patch wraps these two calls in a single helper.

Signed-off-by: Yangtao Li <frank.li@vivo.com>
---
 include/linux/kobject.h |  1 +
 lib/kobject.c           | 17 +++++++++++++++--
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/include/linux/kobject.h b/include/linux/kobject.h
index bdab370a24f4..782d4bd119f8 100644
--- a/include/linux/kobject.h
+++ b/include/linux/kobject.h
@@ -111,6 +111,7 @@ extern struct kobject *kobject_get(struct kobject *kobj);
 extern struct kobject * __must_check kobject_get_unless_zero(
 						struct kobject *kobj);
 extern void kobject_put(struct kobject *kobj);
+extern void kobject_del_and_put(struct kobject *kobj);
 
 extern const void *kobject_namespace(const struct kobject *kobj);
 extern void kobject_get_ownership(const struct kobject *kobj,
diff --git a/lib/kobject.c b/lib/kobject.c
index 6e2f0bee3560..8c0293e37214 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -731,6 +731,20 @@ void kobject_put(struct kobject *kobj)
 }
 EXPORT_SYMBOL(kobject_put);
 
+/**
+ * kobject_del_and_put() - Delete kobject.
+ * @kobj: object.
+ *
+ * Unlink kobject from hierarchy and decrement the refcount.
+ * If refcount is 0, call kobject_cleanup().
+ */
+void kobject_del_and_put(struct kobject *kobj)
+{
+	kobject_del(kobj);
+	kobject_put(kobj);
+}
+EXPORT_SYMBOL_GPL(kobject_del_and_put);
+
 static void dynamic_kobj_release(struct kobject *kobj)
 {
 	pr_debug("kobject: (%p): %s\n", kobj, __func__);
@@ -874,8 +888,7 @@ void kset_unregister(struct kset *k)
 {
 	if (!k)
 		return;
-	kobject_del(&k->kobj);
-	kobject_put(&k->kobj);
+	kobject_del_and_put(&k->kobj);
 }
 EXPORT_SYMBOL(kset_unregister);
 
-- 
2.35.1

Re: [PATCH] kobject: introduce kobject_del_and_put()

[Greg Kroah-Hartman]

On Sun, Mar 19, 2023 at 04:16:39AM +0800, Yangtao Li wrote:
> There are plenty of using kobject_del() and kobject_put() together
> in the kernel tree. This patch wraps these two calls in a single helper.
> 
> Signed-off-by: Yangtao Li <frank.li@vivo.com>
> ---
>  include/linux/kobject.h |  1 +
>  lib/kobject.c           | 17 +++++++++++++++--
>  2 files changed, 16 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/kobject.h b/include/linux/kobject.h
> index bdab370a24f4..782d4bd119f8 100644
> --- a/include/linux/kobject.h
> +++ b/include/linux/kobject.h
> @@ -111,6 +111,7 @@ extern struct kobject *kobject_get(struct kobject *kobj);
>  extern struct kobject * __must_check kobject_get_unless_zero(
>  						struct kobject *kobj);
>  extern void kobject_put(struct kobject *kobj);
> +extern void kobject_del_and_put(struct kobject *kobj);
>  
>  extern const void *kobject_namespace(const struct kobject *kobj);
>  extern void kobject_get_ownership(const struct kobject *kobj,
> diff --git a/lib/kobject.c b/lib/kobject.c
> index 6e2f0bee3560..8c0293e37214 100644
> --- a/lib/kobject.c
> +++ b/lib/kobject.c
> @@ -731,6 +731,20 @@ void kobject_put(struct kobject *kobj)
>  }
>  EXPORT_SYMBOL(kobject_put);
>  
> +/**
> + * kobject_del_and_put() - Delete kobject.
> + * @kobj: object.
> + *
> + * Unlink kobject from hierarchy and decrement the refcount.
> + * If refcount is 0, call kobject_cleanup().
> + */
> +void kobject_del_and_put(struct kobject *kobj)
> +{
> +	kobject_del(kobj);
> +	kobject_put(kobj);
> +}
> +EXPORT_SYMBOL_GPL(kobject_del_and_put);

We can't add exports or new functions like this without real users at
the same time, otherwise the export will quickly be removed.

So can you submit this as part of a patch series that actually uses it
so we can see if it's really even needed?

thanks,

greg k-h

RE: [PATCH] kobject: introduce kobject_del_and_put()

[David Laight]

From: Yangtao Li <frank.li@vivo.com>
> Sent: 18 March 2023 20:17
> 
> There are plenty of using kobject_del() and kobject_put() together
> in the kernel tree. This patch wraps these two calls in a single helper.

But why?
You are adding an extra function call for no benefit.
At best, perhaps, a static inline function.

	David

...
> +void kobject_del_and_put(struct kobject *kobj)
> +{
> +	kobject_del(kobj);
> +	kobject_put(kobj);
> +}
> +EXPORT_SYMBOL_GPL(kobject_del_and_put);
> +
>  static void dynamic_kobj_release(struct kobject *kobj)
>  {
>  	pr_debug("kobject: (%p): %s\n", kobj, __func__);
> @@ -874,8 +888,7 @@ void kset_unregister(struct kset *k)
>  {
>  	if (!k)
>  		return;
> -	kobject_del(&k->kobj);
> -	kobject_put(&k->kobj);
> +	kobject_del_and_put(&k->kobj);
>  }
>  EXPORT_SYMBOL(kset_unregister);
> 
> --
> 2.35.1

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