[Devel] [PATCH RHEL7 v20 02/14] cgroup: added rcu node string wrapper for in-cgroup usage.

[Vasily Averin]

On 6/25/20 5:29 PM, Valeriy Vdovin wrote:
> This will be used in further patches in same patchset.

See below

> Signed-off-by: Valeriy Vdovin <valeriy.vdovin at virtuozzo.com>
> Reviewed-by: Kirill Tkhai <ktkhai at virtuozzo.com>
> ---
>  include/linux/cgroup.h |  7 +++++++
>  kernel/cgroup.c        | 15 +++++++++++++++
>  2 files changed, 22 insertions(+)
> 
> diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
> index 919cddd..ce46ee8 100644
> --- a/include/linux/cgroup.h
> +++ b/include/linux/cgroup.h
> @@ -239,6 +239,13 @@ struct cgroup_name {
>  	char name[];
>  };
>  
> +struct cgroup_rcu_string {
> +	struct rcu_head rcu_head;
> +	char val[];
> +};
> +
> +struct cgroup_rcu_string *cgroup_rcu_strdup(const char *str, int len);
> +
>  struct cgroup {
>  	unsigned long flags;		/* "unsigned long" so bitops work */
>  
> diff --git a/kernel/cgroup.c b/kernel/cgroup.c
> index 9fdba79..e703927 100644
> --- a/kernel/cgroup.c
> +++ b/kernel/cgroup.c
> @@ -774,6 +774,21 @@ static struct inode *cgroup_new_inode(umode_t mode, struct super_block *sb)
>  	return inode;
>  }
>  
> +struct cgroup_rcu_string *cgroup_rcu_strdup(const char *str, int len)
> +{
> +	struct cgroup_rcu_string *result;
> +	size_t buflen = len + 1;
> +
> +	result = kmalloc(sizeof(*result) + buflen, GFP_KERNEL);
> +	if (!result)
> +		return ERR_PTR(-ENOMEM);
> +	if (strlcpy(result->val, str, buflen) >= buflen) {

Is it better to make this check before allocation? 

> +		kfree(result);
> +		return ERR_PTR(-ENAMETOOLONG);
> +	}
> +	return result;
> +}
> +
>  static struct cgroup_name *cgroup_alloc_name(struct dentry *dentry)
>  {
>  	struct cgroup_name *name;
>