> 2023年2月14日 11:13，Thomas Weißschuh <linux@xxxxxxxxxxxxxx> 写道：
>
> Since commit ee6d3dd4ed48 ("driver core: make kobj_type constant.")
> the driver core allows the usage of const struct kobj_type.
>
> Take advantage of this to constify the structure definitions to prevent
> modification at runtime.
>
How the const structure definition can prevent modification at run time?
Thanks.
Coly Li
> Signed-off-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx>
> ---
> drivers/md/bcache/bcache.h | 10 +++++-----
> drivers/md/bcache/sysfs.h | 2 +-
> 2 files changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
> index aebb7ef10e63..a522f4f1f992 100644
> --- a/drivers/md/bcache/bcache.h
> +++ b/drivers/md/bcache/bcache.h
> @@ -1004,11 +1004,11 @@ extern struct workqueue_struct *bch_flush_wq;
> extern struct mutex bch_register_lock;
> extern struct list_head bch_cache_sets;
>
> -extern struct kobj_type bch_cached_dev_ktype;
> -extern struct kobj_type bch_flash_dev_ktype;
> -extern struct kobj_type bch_cache_set_ktype;
> -extern struct kobj_type bch_cache_set_internal_ktype;
> -extern struct kobj_type bch_cache_ktype;
> +extern const struct kobj_type bch_cached_dev_ktype;
> +extern const struct kobj_type bch_flash_dev_ktype;
> +extern const struct kobj_type bch_cache_set_ktype;
> +extern const struct kobj_type bch_cache_set_internal_ktype;
> +extern const struct kobj_type bch_cache_ktype;
>
> void bch_cached_dev_release(struct kobject *kobj);
> void bch_flash_dev_release(struct kobject *kobj);
> diff --git a/drivers/md/bcache/sysfs.h b/drivers/md/bcache/sysfs.h
> index a2ff6447b699..65b8bd975ab1 100644
> --- a/drivers/md/bcache/sysfs.h
> +++ b/drivers/md/bcache/sysfs.h
> @@ -3,7 +3,7 @@
> #define _BCACHE_SYSFS_H_
>
> #define KTYPE(type) \
> -struct kobj_type type ## _ktype = { \
> +const struct kobj_type type ## _ktype = { \
> .release = type ## _release, \
> .sysfs_ops = &((const struct sysfs_ops) { \
> .show = type ## _show, \
>
> ---
> base-commit: f6feea56f66d34259c4222fa02e8171c4f2673d1
> change-id: 20230214-kobj_type-bcache-6d2bd129b0fa
>
> Best regards,
> --
> Thomas Weißschuh <linux@xxxxxxxxxxxxxx>
>
