diff options
Diffstat (limited to 'kernel/cgroup.c')
| -rw-r--r-- | kernel/cgroup.c | 49 |
1 files changed, 48 insertions, 1 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 3a6b77d7ba4a..cd02e99d5d3b 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -1037,9 +1037,56 @@ static void cgroup_put(struct cgroup *cgrp) css_put(&cgrp->self); } +/** + * cgroup_refresh_child_subsys_mask - update child_subsys_mask + * @cgrp: the target cgroup + * + * On the default hierarchy, a subsystem may request other subsystems to be + * enabled together through its ->depends_on mask. In such cases, more + * subsystems than specified in "cgroup.subtree_control" may be enabled. + * + * This function determines which subsystems need to be enabled given the + * current @cgrp->subtree_control and records it in + * @cgrp->child_subsys_mask. The resulting mask is always a superset of + * @cgrp->subtree_control and follows the usual hierarchy rules. + */ static void cgroup_refresh_child_subsys_mask(struct cgroup *cgrp) { - cgrp->child_subsys_mask = cgrp->subtree_control; + struct cgroup *parent = cgroup_parent(cgrp); + unsigned int cur_ss_mask = cgrp->subtree_control; + struct cgroup_subsys *ss; + int ssid; + + lockdep_assert_held(&cgroup_mutex); + + if (!cgroup_on_dfl(cgrp)) { + cgrp->child_subsys_mask = cur_ss_mask; + return; + } + + while (true) { + unsigned int new_ss_mask = cur_ss_mask; + + for_each_subsys(ss, ssid) + if (cur_ss_mask & (1 << ssid)) + new_ss_mask |= ss->depends_on; + + /* + * Mask out subsystems which aren't available. This can + * happen only if some depended-upon subsystems were bound + * to non-default hierarchies. + */ + if (parent) + new_ss_mask &= parent->child_subsys_mask; + else + new_ss_mask &= cgrp->root->subsys_mask; + + if (new_ss_mask == cur_ss_mask) + break; + cur_ss_mask = new_ss_mask; + } + + cgrp->child_subsys_mask = cur_ss_mask; } /** |