Subject: Re: [PATCH v6 2/6] sysfs: wrap __compat_only_sysfs_link_entry_to_kobj function to change the symlink name

From: Michael Ellerman <[email-masked]>
Date: Mon, 10 Feb 2020 15:44:42 +1100

Sourabh Jain <[email-masked]> writes:
> The __compat_only_sysfs_link_entry_to_kobj function creates a symlink to a
> kobject but doesn't provide an option to change the symlink file name.
>
> This patch adds a wrapper function compat_only_sysfs_link_entry_to_kobj
> that extends the __compat_only_sysfs_link_entry_to_kobj functionality
> which allows function caller to customize the symlink name.
>
> Signed-off-by: Sourabh Jain <[email-masked]>
> ---
>  fs/sysfs/group.c      | 28 +++++++++++++++++++++++++---
>  include/linux/sysfs.h | 12 ++++++++++++
>  2 files changed, 37 insertions(+), 3 deletions(-)

I'll assume no one has any objections to this and merge it via the
powerpc tree with the rest of the series.

cheers

> diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
> index d41c21fef138..0993645f0b59 100644
> --- a/fs/sysfs/group.c
> +++ b/fs/sysfs/group.c
> @@ -424,6 +424,25 @@ EXPORT_SYMBOL_GPL(sysfs_remove_link_from_group);
>  int __compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
>  				      struct kobject *target_kobj,
>  				      const char *target_name)
> +{
> +	return compat_only_sysfs_link_entry_to_kobj(kobj, target_kobj,
> +						target_name, NULL);
> +}
> +EXPORT_SYMBOL_GPL(__compat_only_sysfs_link_entry_to_kobj);
> +
> +/**
> + * compat_only_sysfs_link_entry_to_kobj - add a symlink to a kobject pointing
> + * to a group or an attribute
> + * @kobj:		The kobject containing the group.
> + * @target_kobj:	The target kobject.
> + * @target_name:	The name of the target group or attribute.
> + * @symlink_name:	The name of the symlink file (target_name will be
> + *			considered if symlink_name is NULL).
> + */
> +int compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
> +					 struct kobject *target_kobj,
> +					 const char *target_name,
> +					 const char *symlink_name)
>  {
>  	struct kernfs_node *target;
>  	struct kernfs_node *entry;
> @@ -448,12 +467,15 @@ int __compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
>  		return -ENOENT;
>  	}
>  
> -	link = kernfs_create_link(kobj->sd, target_name, entry);
> +	if (!symlink_name)
> +		symlink_name = target_name;
> +
> +	link = kernfs_create_link(kobj->sd, symlink_name, entry);
>  	if (IS_ERR(link) && PTR_ERR(link) == -EEXIST)
> -		sysfs_warn_dup(kobj->sd, target_name);
> +		sysfs_warn_dup(kobj->sd, symlink_name);
>  
>  	kernfs_put(entry);
>  	kernfs_put(target);
>  	return PTR_ERR_OR_ZERO(link);
>  }
> -EXPORT_SYMBOL_GPL(__compat_only_sysfs_link_entry_to_kobj);
> +EXPORT_SYMBOL_GPL(compat_only_sysfs_link_entry_to_kobj);
> diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
> index 5420817ed317..15b195a4529d 100644
> --- a/include/linux/sysfs.h
> +++ b/include/linux/sysfs.h
> @@ -300,6 +300,10 @@ void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
>  int __compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
>  				      struct kobject *target_kobj,
>  				      const char *target_name);
> +int compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
> +					 struct kobject *target_kobj,
> +					 const char *target_name,
> +					 const char *symlink_name);
>  
>  void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr);
>  
> @@ -508,6 +512,14 @@ static inline int __compat_only_sysfs_link_entry_to_kobj(
>  	return 0;
>  }
>  
> +static int compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
> +						struct kobject *target_kobj,
> +						const char *target_name,
> +						const char *symlink_name)
> +{
> +	return 0;
> +}
> +
>  static inline void sysfs_notify(struct kobject *kobj, const char *dir,
>  				const char *attr)
>  {
> -- 
> 2.17.2