Re: [RFC PATCH 1/3] procfs: check uniq proc_dir_entry subdir name

["Serge E. Hallyn" <serge@hallyn.com>]

Quoting Chen Hanxiao (chenhanxiao@cn.fujitsu.com):
> Check whether a proc dir has a subdir
> with a specific name.
> Will be used in a later patch.
> 
> Signed-off-by: Chen Hanxiao <chenhanxiao@cn.fujitsu.com>
> ---
>  fs/proc/generic.c       | 15 +++++++++++++++
>  include/linux/proc_fs.h |  3 +++
>  2 files changed, 18 insertions(+)
> 
> diff --git a/fs/proc/generic.c b/fs/proc/generic.c
> index b7f268e..4d576c2 100644
> --- a/fs/proc/generic.c
> +++ b/fs/proc/generic.c
> @@ -173,6 +173,21 @@ static const struct inode_operations proc_link_inode_operations = {
>  	.follow_link	= proc_follow_link,
>  };
>  
> +/* check whether dir has @name member */
> +struct proc_dir_entry *proc_uniq_dir(struct proc_dir_entry *de, char *name)
> +{
> +	spin_lock(&proc_subdir_lock);
> +	for (de = de->subdir; de ; de = de->next) {
> +		if (!strcmp(de->name, name)) {

Should you pde_get(de) here?

> +			spin_unlock(&proc_subdir_lock);
> +			return de;
> +		}
> +	}
> +	spin_unlock(&proc_subdir_lock);
> +	return NULL;
> +}
> +EXPORT_SYMBOL(proc_uniq_dir);
> +
>  /*
>   * Don't create negative dentries here, return -ENOENT by hand
>   * instead.
> diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
> index 9d117f6..38e87aa 100644
> --- a/include/linux/proc_fs.h
> +++ b/include/linux/proc_fs.h
> @@ -41,6 +41,7 @@ extern void *proc_get_parent_data(const struct inode *);
>  extern void proc_remove(struct proc_dir_entry *);
>  extern void remove_proc_entry(const char *, struct proc_dir_entry *);
>  extern int remove_proc_subtree(const char *, struct proc_dir_entry *);
> +extern struct proc_dir_entry *proc_uniq_dir(struct proc_dir_entry *, char *);
>  
>  #else /* CONFIG_PROC_FS */
>  
> @@ -71,6 +72,8 @@ static inline void *proc_get_parent_data(const struct inode *inode) { BUG(); ret
>  static inline void proc_remove(struct proc_dir_entry *de) {}
>  #define remove_proc_entry(name, parent) do {} while (0)
>  static inline int remove_proc_subtree(const char *name, struct proc_dir_entry *parent) { return 0; }
> +static inline struct proc_dir_entry *proc_uniq_dir(struct proc_dir_entry *,
> +	char *) {return 0; }
>  
>  #endif /* CONFIG_PROC_FS */
>  
> -- 
> 1.9.0
> 
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