diff options
| -rw-r--r-- | include/linux/cgroup.h | 2 | ||||
| -rw-r--r-- | kernel/cgroup.c | 78 |
2 files changed, 66 insertions, 14 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 8d52c8e..5287f93 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -208,6 +208,8 @@ struct cgroup { * ->subtree_control is the one configured through * "cgroup.subtree_control" while ->child_subsys_mask is the * effective one which may have more subsystems enabled. + * Controller knobs are made available iff it's enabled in + * ->subtree_control. */ unsigned int subtree_control; unsigned int child_subsys_mask; diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 14a9d88..331fa296 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -186,7 +186,8 @@ static void cgroup_put(struct cgroup *cgrp); static int rebind_subsystems(struct cgroup_root *dst_root, unsigned int ss_mask); static int cgroup_destroy_locked(struct cgroup *cgrp); -static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss); +static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss, + bool visible); static void css_release(struct percpu_ref *ref); static void kill_css(struct cgroup_subsys_state *css); static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[], @@ -2577,6 +2578,7 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, loff_t off) { unsigned int enable = 0, disable = 0; + unsigned int css_enable, css_disable, old_ctrl, new_ctrl; struct cgroup *cgrp, *child; struct cgroup_subsys *ss; char *tok; @@ -2630,6 +2632,13 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, } /* + * @ss is already enabled through dependency and + * we'll just make it visible. Skip draining. + */ + if (cgrp->child_subsys_mask & (1 << ssid)) + continue; + + /* * Because css offlining is asynchronous, userland * might try to re-enable the same controller while * the previous instance is still around. In such @@ -2681,17 +2690,39 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, goto out_unlock; } + /* + * Update subsys masks and calculate what needs to be done. More + * subsystems than specified may need to be enabled or disabled + * depending on subsystem dependencies. + */ cgrp->subtree_control |= enable; cgrp->subtree_control &= ~disable; + + old_ctrl = cgrp->child_subsys_mask; cgroup_refresh_child_subsys_mask(cgrp); + new_ctrl = cgrp->child_subsys_mask; + + css_enable = ~old_ctrl & new_ctrl; + css_disable = old_ctrl & ~new_ctrl; + enable |= css_enable; + disable |= css_disable; - /* create new csses */ + /* + * Create new csses or make the existing ones visible. A css is + * created invisible if it's being implicitly enabled through + * dependency. An invisible css is made visible when the userland + * explicitly enables it. + */ for_each_subsys(ss, ssid) { if (!(enable & (1 << ssid))) continue; cgroup_for_each_live_child(child, cgrp) { - ret = create_css(child, ss); + if (css_enable & (1 << ssid)) + ret = create_css(child, ss, + cgrp->subtree_control & (1 << ssid)); + else + ret = cgroup_populate_dir(child, 1 << ssid); if (ret) goto err_undo_css; } @@ -2706,13 +2737,21 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, if (ret) goto err_undo_css; - /* all tasks are now migrated away from the old csses, kill them */ + /* + * 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. + */ for_each_subsys(ss, ssid) { if (!(disable & (1 << ssid))) continue; - cgroup_for_each_live_child(child, cgrp) - kill_css(cgroup_css(child, ss)); + cgroup_for_each_live_child(child, cgrp) { + if (css_disable & (1 << ssid)) + kill_css(cgroup_css(child, ss)); + else + cgroup_clear_dir(child, 1 << ssid); + } } kernfs_activate(cgrp->kn); @@ -2732,8 +2771,14 @@ err_undo_css: cgroup_for_each_live_child(child, cgrp) { struct cgroup_subsys_state *css = cgroup_css(child, ss); - if (css) + + if (!css) + continue; + + if (css_enable & (1 << ssid)) kill_css(css); + else + cgroup_clear_dir(child, 1 << ssid); } } goto out_unlock; @@ -4282,12 +4327,14 @@ static void offline_css(struct cgroup_subsys_state *css) * create_css - create a cgroup_subsys_state * @cgrp: the cgroup new css will be associated with * @ss: the subsys of new css + * @visible: whether to create control knobs for the new css or not * * Create a new css associated with @cgrp - @ss pair. On success, the new - * css is online and installed in @cgrp with all interface files created. - * Returns 0 on success, -errno on failure. + * css is online and installed in @cgrp with all interface files created if + * @visible. Returns 0 on success, -errno on failure. */ -static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss) +static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss, + bool visible) { struct cgroup *parent = cgroup_parent(cgrp); struct cgroup_subsys_state *parent_css = cgroup_css(parent, ss); @@ -4311,9 +4358,11 @@ static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss) goto err_free_percpu_ref; css->id = err; - err = cgroup_populate_dir(cgrp, 1 << ss->id); - if (err) - goto err_free_id; + if (visible) { + err = cgroup_populate_dir(cgrp, 1 << ss->id); + if (err) + goto err_free_id; + } /* @css is ready to be brought online now, make it visible */ list_add_tail_rcu(&css->sibling, &parent_css->children); @@ -4430,7 +4479,8 @@ static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, /* let's create and online css's */ for_each_subsys(ss, ssid) { if (parent->child_subsys_mask & (1 << ssid)) { - ret = create_css(cgrp, ss); + ret = create_css(cgrp, ss, + parent->subtree_control & (1 << ssid)); if (ret) goto out_destroy; } |
