Re: [PATCH v1 2/3] cgroup: allow for unprivileged subtree management

[Aleksa Sarai]

> > +static int cgroup_permission(struct inode *inode, struct kernfs_node *kn,
> > +			     int mask)
> > +{
> > +	int ret;
> > +	struct cgroup *cgroup;
> > +	struct cgroup_namespace *cgroupns;
> > +
> > +	/*
> > +	 * First, compute the generic_permission return value. In most cases
> > +	 * this will succeed and we can also avoid duplicating this code.
> > +	 */
> > +
> > +	cgroup = kn->priv;
> > +	cgroup_get(cgroup);
>
> This pattern which is repated for cgroupns doesn't make sense.  The
> code is already assuming that the cgroup is safe to deref.  Getting
> its reference doesn't do anything.  Getting it here would only make
> sense if the pointer is passed to an asynchronous context.

I'll send out a fixed patchset once we figure out the 
cgroups_proc_write_permission() stuff.

--
Aleksa Sarai
Software Engineer (Containers)
SUSE Linux GmbH
https://www.cyphar.com/