Hello, On Wed, Sep 28, 2022 at 01:33:16PM +0200, Michal Koutný wrote: ... > I realized the pinning with reference taking won't really work > generally. The code would get the reference within RCU read section, so > it'd have to be cgroup_get_live() and if that fails there's not much to > do. Hmm... isn't current's root cgrp guaranteed to be alive? How would cgroup_get_live() fail? Also, shouldn't cgroup_get() enough for path walking? > @@ -6673,8 +6678,8 @@ struct cgroup *cgroup_get_from_path(const char *path) > > spin_lock_irq(&css_set_lock); > root_cgrp = current_cgns_cgroup_from_root(&cgrp_dfl_root); > - kn = kernfs_walk_and_get(root_cgrp->kn, path); > spin_unlock_irq(&css_set_lock); > + kn = kernfs_walk_and_get(root_cgrp->kn, path); If you really wanna do it this way, can you please add a detailed comment here why this is safe? But I'd prefer just doing a strightforward ref inc/dec around it. Thanks. -- tejun
