Re: [PATCH v2 2/2] cgroup, kernfs: Move cgroup to the RCU interface for name lookups

[Sebastian Andrzej Siewior]

On 2024-11-12 08:59:16 [-1000], Tejun Heo wrote:
> Hello,

Hi,

> On Tue, Nov 12, 2024 at 04:52:39PM +0100, Sebastian Andrzej Siewior wrote:
> ...
> >  /**
> > - * pr_cont_kernfs_name - pr_cont name of a kernfs_node
> > + * pr_cont_kernfs_name_rcu - pr_cont name of a kernfs_node
> >   * @kn: kernfs_node of interest
> >   *
> > - * This function can be called from any context.
> > + * This function can be called from any context. The root node must be with
> > + * KERNFS_ROOT_SAME_PARENT.
> >   */
> > -void pr_cont_kernfs_name(struct kernfs_node *kn)
> > +void pr_cont_kernfs_name_rcu(struct kernfs_node *kn)
> 
> Having to split the interface all the way up isn't great. While there are
> also downsides, I wonder whether a better approach here is just making the
> backend function (kernfs_path_from_node()) automatically use RCU locking if
> the flag is set rather than propagating the difference by splitting the
> interface. The distinction doesn't mean anything to most users after all.

Indeed.

> Thanks.
> 

Sebastian