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Commit f7b2814b authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: factor out cgroup_{apply|finalize}_control() from cgroup_subtree_control_write() 



Factor out cgroup_{apply|finalize}_control() so that control mask
update can be done in several simple steps.  This patch doesn't
introduce behavior changes.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarZefan Li <lizefan@huawei.com>
parent 15a27c36

kernel/cgroup.c

+58 −23
Original line number Diff line number Diff line
@@ -3169,6 +3169,62 @@ static void cgroup_apply_control_disable(struct cgroup *cgrp) 
	}

}



/**

 * cgroup_apply_control - apply control mask updates to the subtree

 * @cgrp: root of the target subtree

 *

 * subsystems can be enabled and disabled in a subtree using the following

 * steps.

 *

 * 1. Call cgroup_save_control() to stash the current state.

 * 2. Update ->subtree_control masks in the subtree as desired.

 * 3. Call cgroup_apply_control() to apply the changes.

 * 4. Optionally perform other related operations.

 * 5. Call cgroup_finalize_control() to finish up.

 *

 * This function implements step 3 and propagates the mask changes

 * throughout @cgrp's subtree, updates csses accordingly and perform

 * process migrations.

 */

static int cgroup_apply_control(struct cgroup *cgrp)

{

	int ret;



	cgroup_propagate_control(cgrp);



	ret = cgroup_apply_control_enable(cgrp);

	if (ret)

		return ret;



	/*

	 * At this point, cgroup_e_css() results reflect the new csses

	 * making the following cgroup_update_dfl_csses() properly update

	 * css associations of all tasks in the subtree.

	 */

	ret = cgroup_update_dfl_csses(cgrp);

	if (ret)

		return ret;



	return 0;

}



/**

 * cgroup_finalize_control - finalize control mask update

 * @cgrp: root of the target subtree

 * @ret: the result of the update

 *

 * Finalize control mask update.  See cgroup_apply_control() for more info.

 */

static void cgroup_finalize_control(struct cgroup *cgrp, int ret)

{

	if (ret) {

		cgroup_restore_control(cgrp);

		cgroup_propagate_control(cgrp);

	}



	cgroup_apply_control_disable(cgrp);

}



/* change the enabled child controllers for a cgroup in the default hierarchy */

static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,

					    char *buf, size_t nbytes,
@@ -3264,36 +3320,15 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, 
	cgrp->subtree_control |= enable;

	cgrp->subtree_control &= ~disable;



	cgroup_propagate_control(cgrp);

	ret = cgroup_apply_control(cgrp);



	ret = cgroup_apply_control_enable(cgrp);

	if (ret)

		goto err_undo_css;



	/*

	 * At this point, cgroup_e_css() results reflect the new csses

	 * making the following cgroup_update_dfl_csses() properly update

	 * css associations of all tasks in the subtree.

	 */

	ret = cgroup_update_dfl_csses(cgrp);

	if (ret)

		goto err_undo_css;



	/* all tasks are migrated out of disabled csses, commit disable */

	cgroup_apply_control_disable(cgrp);

	cgroup_finalize_control(cgrp, ret);



	kernfs_activate(cgrp->kn);

	ret = 0;

out_unlock:

	cgroup_kn_unlock(of->kn);

	return ret ?: nbytes;



err_undo_css:

	/* restore masks and shoot down new csses */

	cgroup_restore_control(cgrp);

	cgroup_apply_control_disable(cgrp);



	goto out_unlock;

}



static int cgroup_events_show(struct seq_file *seq, void *v)