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[],
css_put(&cgrp->self);
}
+/**
+ * cgroup_refresh_child_subsys_mask - update child_subsys_mask
+ * @cgrp: the target cgroup
+ *
+ * On the default hierarchy, a subsystem may request other subsystems to be
+ * enabled together through its ->depends_on mask. In such cases, more
+ * subsystems than specified in "cgroup.subtree_control" may be enabled.
+ *
+ * This function determines which subsystems need to be enabled given the
+ * current @cgrp->subtree_control and records it in
+ * @cgrp->child_subsys_mask. The resulting mask is always a superset of
+ * @cgrp->subtree_control and follows the usual hierarchy rules.
+ */
+static void cgroup_refresh_child_subsys_mask(struct cgroup *cgrp)
+{
+ struct cgroup *parent = cgroup_parent(cgrp);
+ unsigned int cur_ss_mask = cgrp->subtree_control;
+ struct cgroup_subsys *ss;
+ int ssid;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ if (!cgroup_on_dfl(cgrp)) {
+ cgrp->child_subsys_mask = cur_ss_mask;
+ return;
+ }
+
+ while (true) {
+ unsigned int new_ss_mask = cur_ss_mask;
+
+ for_each_subsys(ss, ssid)
+ if (cur_ss_mask & (1 << ssid))
+ new_ss_mask |= ss->depends_on;
+
+ /*
+ * Mask out subsystems which aren't available. This can
+ * happen only if some depended-upon subsystems were bound
+ * to non-default hierarchies.
+ */
+ if (parent)
+ new_ss_mask &= parent->child_subsys_mask;
+ else
+ new_ss_mask &= cgrp->root->subsys_mask;
+
+ if (new_ss_mask == cur_ss_mask)
+ break;
+ cur_ss_mask = new_ss_mask;
+ }
+
+ cgrp->child_subsys_mask = cur_ss_mask;
+}
+
/**
* cgroup_kn_unlock - unlocking helper for cgroup kernfs methods
* @kn: the kernfs_node being serviced
up_write(&css_set_rwsem);
src_root->subsys_mask &= ~(1 << ssid);
- src_root->cgrp.child_subsys_mask &= ~(1 << ssid);
+ src_root->cgrp.subtree_control &= ~(1 << ssid);
+ cgroup_refresh_child_subsys_mask(&src_root->cgrp);
/* default hierarchy doesn't enable controllers by default */
dst_root->subsys_mask |= 1 << ssid;
- if (dst_root != &cgrp_dfl_root)
- dst_root->cgrp.child_subsys_mask |= 1 << ssid;
+ if (dst_root != &cgrp_dfl_root) {
+ dst_root->cgrp.subtree_control |= 1 << ssid;
+ cgroup_refresh_child_subsys_mask(&dst_root->cgrp);
+ }
if (ss->bind)
ss->bind(css);
removed_mask = root->subsys_mask & ~opts.subsys_mask;
/* Don't allow flags or name to change at remount */
- if (((opts.flags ^ root->flags) & CGRP_ROOT_OPTION_MASK) ||
+ if ((opts.flags ^ root->flags) ||
(opts.name && strcmp(opts.name, root->name))) {
pr_err("option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"\n",
- opts.flags & CGRP_ROOT_OPTION_MASK, opts.name ?: "",
- root->flags & CGRP_ROOT_OPTION_MASK, root->name);
+ opts.flags, opts.name ?: "", root->flags, root->name);
ret = -EINVAL;
goto out_unlock;
}
goto out_unlock;
}
- if ((root->flags ^ opts.flags) & CGRP_ROOT_OPTION_MASK) {
+ if (root->flags ^ opts.flags) {
if ((root->flags | opts.flags) & CGRP_ROOT_SANE_BEHAVIOR) {
pr_err("sane_behavior: new mount options should match the existing superblock\n");
ret = -EINVAL;
static int cgroup_sane_behavior_show(struct seq_file *seq, void *v)
{
- struct cgroup *cgrp = seq_css(seq)->cgroup;
-
- seq_printf(seq, "%d\n", cgroup_sane_behavior(cgrp));
+ seq_puts(seq, "0\n");
return 0;
}
{
struct cgroup *cgrp = seq_css(seq)->cgroup;
- cgroup_print_ss_mask(seq, cgroup_parent(cgrp)->child_subsys_mask);
+ cgroup_print_ss_mask(seq, cgroup_parent(cgrp)->subtree_control);
return 0;
}
{
struct cgroup *cgrp = seq_css(seq)->cgroup;
- cgroup_print_ss_mask(seq, cgrp->child_subsys_mask);
+ cgroup_print_ss_mask(seq, cgrp->subtree_control);
return 0;
}
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;
for_each_subsys(ss, ssid) {
if (enable & (1 << ssid)) {
- if (cgrp->child_subsys_mask & (1 << ssid)) {
+ if (cgrp->subtree_control & (1 << ssid)) {
enable &= ~(1 << ssid);
continue;
}
+ /* unavailable or not enabled on the parent? */
+ if (!(cgrp_dfl_root.subsys_mask & (1 << ssid)) ||
+ (cgroup_parent(cgrp) &&
+ !(cgroup_parent(cgrp)->subtree_control & (1 << ssid)))) {
+ ret = -ENOENT;
+ goto out_unlock;
+ }
+
+ /*
+ * @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
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))) {
+ if (!(cgrp->subtree_control & (1 << ssid))) {
disable &= ~(1 << ssid);
continue;
}
/* a child has it enabled? */
cgroup_for_each_live_child(child, cgrp) {
- if (child->child_subsys_mask & (1 << ssid)) {
+ if (child->subtree_control & (1 << ssid)) {
ret = -EBUSY;
goto out_unlock;
}
}
/*
- * Except for the root, child_subsys_mask must be zero for a cgroup
+ * Except for the root, subtree_control must be zero for a cgroup
* with tasks so that child cgroups don't compete against tasks.
*/
if (enable && cgroup_parent(cgrp) && !list_empty(&cgrp->cset_links)) {
}
/*
- * 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.
+ * 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 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;
}
}
- 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;
- /* 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. 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.
+ */
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) {
+ struct cgroup_subsys_state *css = cgroup_css(child, ss);
+
+ if (css_disable & (1 << ssid)) {
+ kill_css(css);
+ } else {
+ cgroup_clear_dir(child, 1 << ssid);
+ if (ss->css_reset)
+ ss->css_reset(css);
+ }
+ }
}
kernfs_activate(cgrp->kn);
return ret ?: nbytes;
err_undo_css:
- cgrp->child_subsys_mask &= ~enable;
- cgrp->child_subsys_mask |= disable;
+ cgrp->subtree_control &= ~enable;
+ cgrp->subtree_control |= disable;
+ cgroup_refresh_child_subsys_mask(cgrp);
for_each_subsys(ss, ssid) {
if (!(enable & (1 << ssid)))
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;
},
{
.name = "cgroup.sane_behavior",
- .flags = CFTYPE_ONLY_ON_ROOT,
+ .flags = CFTYPE_INSANE | CFTYPE_ONLY_ON_ROOT,
.seq_show = cgroup_sane_behavior_show,
},
{
* 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);
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);
/* 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;
}
/*
* On the default hierarchy, a child doesn't automatically inherit
- * child_subsys_mask from the parent. Each is configured manually.
+ * subtree_control from the parent. Each is configured manually.
*/
- if (!cgroup_on_dfl(cgrp))
- cgrp->child_subsys_mask = parent->child_subsys_mask;
+ if (!cgroup_on_dfl(cgrp)) {
+ cgrp->subtree_control = parent->subtree_control;
+ cgroup_refresh_child_subsys_mask(cgrp);
+ }
kernfs_activate(kn);
projects / mirror_ubuntu-zesty-kernel.git / blobdiff