2023-03-22 17:03:28

by 李扬韬

Subject: [PATCH v3 01/10] kobject: introduce kobject_del_and_put()

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 <[email protected]>
---
v3:
-convert to inline helper
v2:
-add kobject_del_and_put() users
include/linux/kobject.h | 13 +++++++++++++
lib/kobject.c | 3 +--
2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/include/linux/kobject.h b/include/linux/kobject.h
index bdab370a24f4..e21b7c22e355 100644
--- a/include/linux/kobject.h
+++ b/include/linux/kobject.h
@@ -112,6 +112,19 @@ extern struct kobject * __must_check kobject_get_unless_zero(
struct kobject *kobj);
extern void kobject_put(struct kobject *kobj);

+/**
+ * kobject_del_and_put() - Delete kobject.
+ * @kobj: object.
+ *
+ * Unlink kobject from hierarchy and decrement the refcount.
+ * If refcount is 0, call kobject_cleanup().
+ */
+static inline void kobject_del_and_put(struct kobject *kobj)
+{
+ kobject_del(kobj);
+ kobject_put(kobj);
+}
+
extern const void *kobject_namespace(const struct kobject *kobj);
extern void kobject_get_ownership(const struct kobject *kobj,
kuid_t *uid, kgid_t *gid);
diff --git a/lib/kobject.c b/lib/kobject.c
index f79a434e1231..e6c5a3ff1c53 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -876,8 +876,7 @@ 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

2023-03-22 23:33:27

by Damien Le Moal

Subject: Re: [PATCH v3 01/10] kobject: introduce kobject_del_and_put()

On 3/23/23 01:58, 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 <[email protected]>
> ---
> v3:
> -convert to inline helper
> v2:
> -add kobject_del_and_put() users
> include/linux/kobject.h | 13 +++++++++++++
> lib/kobject.c | 3 +--
> 2 files changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/kobject.h b/include/linux/kobject.h
> index bdab370a24f4..e21b7c22e355 100644
> --- a/include/linux/kobject.h
> +++ b/include/linux/kobject.h
> @@ -112,6 +112,19 @@ extern struct kobject * __must_check kobject_get_unless_zero(
> struct kobject *kobj);
> extern void kobject_put(struct kobject *kobj);
>
> +/**
> + * kobject_del_and_put() - Delete kobject.
> + * @kobj: object.
> + *
> + * Unlink kobject from hierarchy and decrement the refcount.

Unlink kobject from hierarchy and decrement its refcount.

> + * If refcount is 0, call kobject_cleanup().

That is done by kobject_put() and not explicitly done directly in this helper.
So I would not mention this to avoid confusion as you otherwise have a
description that does not match the code we can see here.

With that fixed, this looks OK to me, so feel free to add:

Reviewed-by: Damien Le Moal <[email protected]>

> + */
> +static inline void kobject_del_and_put(struct kobject *kobj)
> +{
> + kobject_del(kobj);
> + kobject_put(kobj);
> +}
> +
> extern const void *kobject_namespace(const struct kobject *kobj);
> extern void kobject_get_ownership(const struct kobject *kobj,
> kuid_t *uid, kgid_t *gid);
> diff --git a/lib/kobject.c b/lib/kobject.c
> index f79a434e1231..e6c5a3ff1c53 100644
> --- a/lib/kobject.c
> +++ b/lib/kobject.c
> @@ -876,8 +876,7 @@ void kset_unregister(struct kset *k)
> {
> if (!k)
> return;
> - kobject_del(&k->kobj);
> - kobject_put(&k->kobj);
> + kobject_del_and_put(&k->kobj);

Nit: You could simplify this one to be:

if (k)
kobject_del_and_put(&k->kobj);

and drop the return line.

> }
> EXPORT_SYMBOL(kset_unregister);
>

--
Damien Le Moal
Western Digital Research

2023-03-23 05:24:22

by Ming Lei

Subject: Re: [PATCH v3 01/10] kobject: introduce kobject_del_and_put()

On Thu, Mar 23, 2023 at 12:58:30AM +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 <[email protected]>
> ---
> v3:
> -convert to inline helper
> v2:
> -add kobject_del_and_put() users
> include/linux/kobject.h | 13 +++++++++++++
> lib/kobject.c | 3 +--
> 2 files changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/kobject.h b/include/linux/kobject.h
> index bdab370a24f4..e21b7c22e355 100644
> --- a/include/linux/kobject.h
> +++ b/include/linux/kobject.h
> @@ -112,6 +112,19 @@ extern struct kobject * __must_check kobject_get_unless_zero(
> struct kobject *kobj);
> extern void kobject_put(struct kobject *kobj);
>
> +/**
> + * kobject_del_and_put() - Delete kobject.
> + * @kobj: object.
> + *
> + * Unlink kobject from hierarchy and decrement the refcount.
> + * If refcount is 0, call kobject_cleanup().
> + */
> +static inline void kobject_del_and_put(struct kobject *kobj)
> +{
> + kobject_del(kobj);
> + kobject_put(kobj);
> +}

kobject_put() actually covers kobject removal automatically, which is
single stage removal. So if you see the two called together, it is
safe to kill kobject_del() directly.


thanks,
Ming