diff options
| -rw-r--r-- | kernel/cgroup.c | 81 |
1 files changed, 58 insertions, 23 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 452a90e455fa..2adf0433a3cf 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -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) |