Commit 5ced2518 authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: make cgroup_calc_subtree_ss_mask() take @this_ss_mask 



cgroup_calc_subtree_ss_mask() currently takes @cgrp and
@subtree_control.  @cgrp is used for two purposes - to decide whether
it's for default hierarchy and the mask of available subsystems.  The
former doesn't matter as the results are the same regardless.  The
latter can be specified directly through a subsystem mask.

This patch makes cgroup_calc_subtree_ss_mask() perform the same
calculations for both default and legacy hierarchies and take
@this_ss_mask for available subsystems.  @cgrp is no longer used and
dropped.  This is to allow using the function in contexts where
available controllers can't be decided from the cgroup.

v2: cgroup_refres_subtree_ss_mask() is removed by a previous patch.
    Updated accordingly.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarZefan Li <lizefan@huawei.com>
parent 334c3679

kernel/cgroup.c

+7 −10
Original line number Diff line number Diff line
@@ -1309,18 +1309,17 @@ static umode_t cgroup_file_mode(const struct cftype *cft) 


/**

 * cgroup_calc_subtree_ss_mask - calculate subtree_ss_mask

 * @cgrp: the target cgroup

 * @subtree_control: the new subtree_control mask to consider

 * @this_ss_mask: available subsystems

 *

 * 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 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.

 * @subtree_control is to be applied while restricted to @this_ss_mask.

 */

static u16 cgroup_calc_subtree_ss_mask(struct cgroup *cgrp, u16 subtree_control)

static u16 cgroup_calc_subtree_ss_mask(u16 subtree_control, u16 this_ss_mask)

{

	u16 cur_ss_mask = subtree_control;

	struct cgroup_subsys *ss;
@@ -1328,9 +1327,6 @@ static u16 cgroup_calc_subtree_ss_mask(struct cgroup *cgrp, u16 subtree_control) 


	lockdep_assert_held(&cgroup_mutex);



	if (!cgroup_on_dfl(cgrp))

		return cur_ss_mask;



	while (true) {

		u16 new_ss_mask = cur_ss_mask;
@@ -1343,7 +1339,7 @@ static u16 cgroup_calc_subtree_ss_mask(struct cgroup *cgrp, u16 subtree_control) 
		 * happen only if some depended-upon subsystems were bound

		 * to non-default hierarchies.

		 */

		new_ss_mask &= cgroup_ss_mask(cgrp);

		new_ss_mask &= this_ss_mask;



		if (new_ss_mask == cur_ss_mask)

			break;
@@ -3012,8 +3008,9 @@ static void cgroup_propagate_control(struct cgroup *cgrp) 


	cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) {

		dsct->subtree_control &= cgroup_control(dsct);

		dsct->subtree_ss_mask = cgroup_calc_subtree_ss_mask(dsct,

							dsct->subtree_control);

		dsct->subtree_ss_mask =

			cgroup_calc_subtree_ss_mask(dsct->subtree_control,

						    cgroup_ss_mask(dsct));

	}

}

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