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Commit c29adf24 authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: reorganize cgroup_subtree_control_write() 



Make the following two reorganizations to
cgroup_subtree_control_write().  These are to prepare for future
changes and shouldn't cause any functional difference.

* Move availability above css offlining wait.

* Move cgrp->child_subsys_mask update above new css creation.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
parent a497c3ba

kernel/cgroup.c

+17 −17
Original line number Diff line number Diff line
@@ -2613,6 +2613,14 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, 
				continue;

			}



			/* unavailable or not enabled on the parent? */

			if (!(cgrp_dfl_root.subsys_mask & (1 << ssid)) ||

			    (cgroup_parent(cgrp) &&

			     !(cgroup_parent(cgrp)->child_subsys_mask & (1 << ssid)))) {

				ret = -ENOENT;

				goto out_unlock;

			}



			/*

			 * Because css offlining is asynchronous, userland

			 * might try to re-enable the same controller while
@@ -2635,14 +2643,6 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, 


				return restart_syscall();

			}



			/* unavailable or not enabled on the parent? */

			if (!(cgrp_dfl_root.subsys_mask & (1 << ssid)) ||

			    (cgroup_parent(cgrp) &&

			     !(cgroup_parent(cgrp)->child_subsys_mask & (1 << ssid)))) {

				ret = -ENOENT;

				goto out_unlock;

			}

		} else if (disable & (1 << ssid)) {

			if (!(cgrp->child_subsys_mask & (1 << ssid))) {

				disable &= ~(1 << ssid);
@@ -2673,12 +2673,10 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, 
		goto out_unlock;

	}



	/*

	 * Create csses for enables and update child_subsys_mask.  This

	 * changes cgroup_e_css() results which in turn makes the

	 * subsequent cgroup_update_dfl_csses() associate all tasks in the

	 * subtree to the updated csses.

	 */

	cgrp->child_subsys_mask |= enable;

	cgrp->child_subsys_mask &= ~disable;



	/* create new csses */

	for_each_subsys(ss, ssid) {

		if (!(enable & (1 << ssid)))

			continue;
@@ -2690,9 +2688,11 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, 
		}

	}



	cgrp->child_subsys_mask |= enable;

	cgrp->child_subsys_mask &= ~disable;



	/*

	 * 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;