From 12b3bb6af862477f96e1adac51b201a143a8f3c4 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 3 Mar 2016 09:57:59 -0500 Subject: [PATCH] cgroup: factor out cgroup_apply_control_disable() from cgroup_subtree_control_write() Factor out css disabling and hiding into cgroup_apply_control_disable(). * Nest subsystem walk inside child walk. The child walk will later be converted to subtree walk which is a bit more expensive. * Instead of operating on the differential masks @css_enable and @css_disable, simply disable or hide csses according to the current cgroup_control() and cgroup_ss_mask(). This leads to the same result and is simpler and more robust. * This allows error handling path to share the same code. Signed-off-by: Tejun Heo Acked-by: Zefan Li --- kernel/cgroup.c | 74 +++++++++++++++++++++++++++---------------------- 1 file changed, 41 insertions(+), 33 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index d295e6a91cdc..97cb1315bcac 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -3012,6 +3012,43 @@ static bool cgroup_drain_offline(struct cgroup *cgrp) return false; } +/** + * cgroup_apply_control_disable - kill or hide csses according to control + * @cgrp: parent of the target cgroups + * + * Walk @cgrp's children and kill and hide csses so that they match + * cgroup_ss_mask() and cgroup_visible_mask(). + * + * A css is hidden when the userland requests it to be disabled while other + * subsystems are still depending on it. The css must not actively control + * resources and be in the vanilla state if it's made visible again later. + * Controllers which may be depended upon should provide ->css_reset() for + * this purpose. + */ +static void cgroup_apply_control_disable(struct cgroup *cgrp) +{ + struct cgroup *dsct; + struct cgroup_subsys *ss; + int ssid; + + cgroup_for_each_live_child(dsct, cgrp) { + for_each_subsys(ss, ssid) { + struct cgroup_subsys_state *css = cgroup_css(dsct, ss); + + if (!css) + continue; + + if (!(cgroup_ss_mask(dsct) & (1 << ss->id))) { + kill_css(css); + } else if (!(cgroup_control(dsct) & (1 << ss->id))) { + css_clear_dir(css, NULL); + if (ss->css_reset) + ss->css_reset(css); + } + } + } +} + /* 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, @@ -3160,27 +3197,8 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, if (ret) goto err_undo_css; - /* - * All tasks are migrated out of disabled csses. Kill or hide - * them. A css is hidden when the userland requests it to be - * disabled while other subsystems are still depending on it. The - * css must not actively control resources and be in the vanilla - * state if it's made visible again later. Controllers which may - * be depended upon should provide ->css_reset() for this purpose. - */ - do_each_subsys_mask(ss, ssid, disable) { - cgroup_for_each_live_child(child, cgrp) { - struct cgroup_subsys_state *css = cgroup_css(child, ss); - - if (css_disable & (1 << ssid)) { - kill_css(css); - } else { - css_clear_dir(css, NULL); - if (ss->css_reset) - ss->css_reset(css); - } - } - } while_each_subsys_mask(); + /* all tasks are migrated out of disabled csses, commit disable */ + cgroup_apply_control_disable(cgrp); kernfs_activate(cgrp->kn); ret = 0; @@ -3189,22 +3207,12 @@ out_unlock: return ret ?: nbytes; err_undo_css: + /* restore masks and shoot down new csses */ cgrp->subtree_control = old_sc; cgrp->subtree_ss_mask = old_ss; - do_each_subsys_mask(ss, ssid, enable) { - cgroup_for_each_live_child(child, cgrp) { - struct cgroup_subsys_state *css = cgroup_css(child, ss); - - if (!css) - continue; + cgroup_apply_control_disable(cgrp); - if (css_enable & (1 << ssid)) - kill_css(css); - else - css_clear_dir(css, NULL); - } - } while_each_subsys_mask(); goto out_unlock; } -- 2.20.1