Commit 0f060deb authored by Tejun Heo's avatar Tejun Heo
Browse files

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: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarZefan Li <lizefan@huawei.com>
parent cea74465

kernel/cgroup.c

+24 −12
Original line number Diff line number Diff line
@@ -1019,31 +1019,30 @@ static void cgroup_put(struct cgroup *cgrp) 
}



/**

 * 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 @@ static void cgroup_refresh_child_subsys_mask(struct cgroup *cgrp) 
		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);

}



/**

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