cgroup: separate out cgroup_calc_child_subsys_mask() from cgroup_refresh_child_subsys_mask()
cgroup_refresh_child_subsys_mask() calculates and updates the
effective @cgrp->child_subsys_maks according to the current
@cgrp->subtree_control. Separate out the calculation part into
cgroup_calc_child_subsys_mask(). This will be used to fix a bug in
the async css offline wait logic.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 136ecead..1dda601 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1019,31 +1019,30 @@
}
/**
- * cgroup_refresh_child_subsys_mask - update child_subsys_mask
+ * cgroup_calc_child_subsys_mask - calculate child_subsys_mask
* @cgrp: the target cgroup
+ * @subtree_control: the new subtree_control mask to consider
*
* 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.
+ * This function calculates which subsystems need to be enabled if
+ * @subtree_control is to be applied to @cgrp. The returned mask is always
+ * a superset of @subtree_control and follows the usual hierarchy rules.
*/
-static void cgroup_refresh_child_subsys_mask(struct cgroup *cgrp)
+static unsigned int cgroup_calc_child_subsys_mask(struct cgroup *cgrp,
+ unsigned int subtree_control)
{
struct cgroup *parent = cgroup_parent(cgrp);
- unsigned int cur_ss_mask = cgrp->subtree_control;
+ unsigned int cur_ss_mask = 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;
- }
+ if (!cgroup_on_dfl(cgrp))
+ return cur_ss_mask;
while (true) {
unsigned int new_ss_mask = cur_ss_mask;
@@ -1067,7 +1066,20 @@
cur_ss_mask = new_ss_mask;
}
- cgrp->child_subsys_mask = cur_ss_mask;
+ return cur_ss_mask;
+}
+
+/**
+ * cgroup_refresh_child_subsys_mask - update child_subsys_mask
+ * @cgrp: the target cgroup
+ *
+ * Update @cgrp->child_subsys_mask according to the current
+ * @cgrp->subtree_control using cgroup_calc_child_subsys_mask().
+ */
+static void cgroup_refresh_child_subsys_mask(struct cgroup *cgrp)
+{
+ cgrp->child_subsys_mask =
+ cgroup_calc_child_subsys_mask(cgrp, cgrp->subtree_control);
}
/**