/* some controllers are implicitly enabled on the default hierarchy */
static u16 cgrp_dfl_implicit_ss_mask;
+/* some controllers can be threaded on the default hierarchy */
+static u16 cgrp_dfl_threaded_ss_mask;
+
/* The list of hierarchy roots */
LIST_HEAD(cgroup_roots);
static int cgroup_root_count;
spin_unlock_bh(&cgroup_idr_lock);
}
-static struct cgroup *cgroup_parent(struct cgroup *cgrp)
+static bool cgroup_has_tasks(struct cgroup *cgrp)
{
- struct cgroup_subsys_state *parent_css = cgrp->self.parent;
+ return cgrp->nr_populated_csets;
+}
- if (parent_css)
- return container_of(parent_css, struct cgroup, self);
- return NULL;
+bool cgroup_is_threaded(struct cgroup *cgrp)
+{
+ return cgrp->dom_cgrp != cgrp;
+}
+
+/* can @cgrp host both domain and threaded children? */
+static bool cgroup_is_mixable(struct cgroup *cgrp)
+{
+ /*
+ * Root isn't under domain level resource control exempting it from
+ * the no-internal-process constraint, so it can serve as a thread
+ * root and a parent of resource domains at the same time.
+ */
+ return !cgroup_parent(cgrp);
+}
+
+/* can @cgrp become a thread root? should always be true for a thread root */
+static bool cgroup_can_be_thread_root(struct cgroup *cgrp)
+{
+ /* mixables don't care */
+ if (cgroup_is_mixable(cgrp))
+ return true;
+
+ /* domain roots can't be nested under threaded */
+ if (cgroup_is_threaded(cgrp))
+ return false;
+
+ /* can only have either domain or threaded children */
+ if (cgrp->nr_populated_domain_children)
+ return false;
+
+ /* and no domain controllers can be enabled */
+ if (cgrp->subtree_control & ~cgrp_dfl_threaded_ss_mask)
+ return false;
+
+ return true;
+}
+
+/* is @cgrp root of a threaded subtree? */
+bool cgroup_is_thread_root(struct cgroup *cgrp)
+{
+ /* thread root should be a domain */
+ if (cgroup_is_threaded(cgrp))
+ return false;
+
+ /* a domain w/ threaded children is a thread root */
+ if (cgrp->nr_threaded_children)
+ return true;
+
+ /*
+ * A domain which has tasks and explicit threaded controllers
+ * enabled is a thread root.
+ */
+ if (cgroup_has_tasks(cgrp) &&
+ (cgrp->subtree_control & cgrp_dfl_threaded_ss_mask))
+ return true;
+
+ return false;
+}
+
+/* a domain which isn't connected to the root w/o brekage can't be used */
+static bool cgroup_is_valid_domain(struct cgroup *cgrp)
+{
+ /* the cgroup itself can be a thread root */
+ if (cgroup_is_threaded(cgrp))
+ return false;
+
+ /* but the ancestors can't be unless mixable */
+ while ((cgrp = cgroup_parent(cgrp))) {
+ if (!cgroup_is_mixable(cgrp) && cgroup_is_thread_root(cgrp))
+ return false;
+ if (cgroup_is_threaded(cgrp))
+ return false;
+ }
+
+ return true;
}
/* subsystems visibly enabled on a cgroup */
struct cgroup *parent = cgroup_parent(cgrp);
u16 root_ss_mask = cgrp->root->subsys_mask;
- if (parent)
- return parent->subtree_control;
+ if (parent) {
+ u16 ss_mask = parent->subtree_control;
+
+ /* threaded cgroups can only have threaded controllers */
+ if (cgroup_is_threaded(cgrp))
+ ss_mask &= cgrp_dfl_threaded_ss_mask;
+ return ss_mask;
+ }
if (cgroup_on_dfl(cgrp))
root_ss_mask &= ~(cgrp_dfl_inhibit_ss_mask |
{
struct cgroup *parent = cgroup_parent(cgrp);
- if (parent)
- return parent->subtree_ss_mask;
+ if (parent) {
+ u16 ss_mask = parent->subtree_ss_mask;
+
+ /* threaded cgroups can only have threaded controllers */
+ if (cgroup_is_threaded(cgrp))
+ ss_mask &= cgrp_dfl_threaded_ss_mask;
+ return ss_mask;
+ }
return cgrp->root->subsys_mask;
}
return css;
}
-static void __maybe_unused cgroup_get(struct cgroup *cgrp)
-{
- css_get(&cgrp->self);
-}
-
static void cgroup_get_live(struct cgroup *cgrp)
{
WARN_ON_ONCE(cgroup_is_dead(cgrp));
css_get(&cgrp->self);
}
-static bool cgroup_tryget(struct cgroup *cgrp)
-{
- return css_tryget(&cgrp->self);
-}
-
struct cgroup_subsys_state *of_css(struct kernfs_open_file *of)
{
struct cgroup *cgrp = of->kn->parent->priv;
*/
struct css_set init_css_set = {
.refcount = REFCOUNT_INIT(1),
+ .dom_cset = &init_css_set,
.tasks = LIST_HEAD_INIT(init_css_set.tasks),
.mg_tasks = LIST_HEAD_INIT(init_css_set.mg_tasks),
.task_iters = LIST_HEAD_INIT(init_css_set.task_iters),
+ .threaded_csets = LIST_HEAD_INIT(init_css_set.threaded_csets),
.cgrp_links = LIST_HEAD_INIT(init_css_set.cgrp_links),
.mg_preload_node = LIST_HEAD_INIT(init_css_set.mg_preload_node),
.mg_node = LIST_HEAD_INIT(init_css_set.mg_node),
static int css_set_count = 1; /* 1 for init_css_set */
+static bool css_set_threaded(struct css_set *cset)
+{
+ return cset->dom_cset != cset;
+}
+
/**
* css_set_populated - does a css_set contain any tasks?
* @cset: target css_set
}
/**
- * cgroup_update_populated - updated populated count of a cgroup
+ * cgroup_update_populated - update the populated count of a cgroup
* @cgrp: the target cgroup
* @populated: inc or dec populated count
*
* One of the css_sets associated with @cgrp is either getting its first
- * task or losing the last. Update @cgrp->populated_cnt accordingly. The
- * count is propagated towards root so that a given cgroup's populated_cnt
- * is zero iff the cgroup and all its descendants don't contain any tasks.
+ * task or losing the last. Update @cgrp->nr_populated_* accordingly. The
+ * count is propagated towards root so that a given cgroup's
+ * nr_populated_children is zero iff none of its descendants contain any
+ * tasks.
*
- * @cgrp's interface file "cgroup.populated" is zero if
- * @cgrp->populated_cnt is zero and 1 otherwise. When @cgrp->populated_cnt
- * changes from or to zero, userland is notified that the content of the
- * interface file has changed. This can be used to detect when @cgrp and
- * its descendants become populated or empty.
+ * @cgrp's interface file "cgroup.populated" is zero if both
+ * @cgrp->nr_populated_csets and @cgrp->nr_populated_children are zero and
+ * 1 otherwise. When the sum changes from or to zero, userland is notified
+ * that the content of the interface file has changed. This can be used to
+ * detect when @cgrp and its descendants become populated or empty.
*/
static void cgroup_update_populated(struct cgroup *cgrp, bool populated)
{
+ struct cgroup *child = NULL;
+ int adj = populated ? 1 : -1;
+
lockdep_assert_held(&css_set_lock);
do {
- bool trigger;
+ bool was_populated = cgroup_is_populated(cgrp);
- if (populated)
- trigger = !cgrp->populated_cnt++;
- else
- trigger = !--cgrp->populated_cnt;
+ if (!child) {
+ cgrp->nr_populated_csets += adj;
+ } else {
+ if (cgroup_is_threaded(child))
+ cgrp->nr_populated_threaded_children += adj;
+ else
+ cgrp->nr_populated_domain_children += adj;
+ }
- if (!trigger)
+ if (was_populated == cgroup_is_populated(cgrp))
break;
cgroup1_check_for_release(cgrp);
cgroup_file_notify(&cgrp->events_file);
+ child = cgrp;
cgrp = cgroup_parent(cgrp);
} while (cgrp);
}
* @populated: whether @cset is populated or depopulated
*
* @cset is either getting the first task or losing the last. Update the
- * ->populated_cnt of all associated cgroups accordingly.
+ * populated counters of all associated cgroups accordingly.
*/
static void css_set_update_populated(struct css_set *cset, bool populated)
{
* css_set, @from_cset can be NULL. If @task is being disassociated
* instead of moved, @to_cset can be NULL.
*
- * This function automatically handles populated_cnt updates and
+ * This function automatically handles populated counter updates and
* css_task_iter adjustments but the caller is responsible for managing
* @from_cset and @to_cset's reference counts.
*/
if (!refcount_dec_and_test(&cset->refcount))
return;
+ WARN_ON_ONCE(!list_empty(&cset->threaded_csets));
+
/* This css_set is dead. unlink it and release cgroup and css refs */
for_each_subsys(ss, ssid) {
list_del(&cset->e_cset_node[ssid]);
kfree(link);
}
+ if (css_set_threaded(cset)) {
+ list_del(&cset->threaded_csets_node);
+ put_css_set_locked(cset->dom_cset);
+ }
+
kfree_rcu(cset, rcu_head);
}
struct cgroup *new_cgrp,
struct cgroup_subsys_state *template[])
{
+ struct cgroup *new_dfl_cgrp;
struct list_head *l1, *l2;
/*
if (memcmp(template, cset->subsys, sizeof(cset->subsys)))
return false;
+
+ /* @cset's domain should match the default cgroup's */
+ if (cgroup_on_dfl(new_cgrp))
+ new_dfl_cgrp = new_cgrp;
+ else
+ new_dfl_cgrp = old_cset->dfl_cgrp;
+
+ if (new_dfl_cgrp->dom_cgrp != cset->dom_cset->dfl_cgrp)
+ return false;
+
/*
* Compare cgroup pointers in order to distinguish between
* different cgroups in hierarchies. As different cgroups may
}
refcount_set(&cset->refcount, 1);
+ cset->dom_cset = cset;
INIT_LIST_HEAD(&cset->tasks);
INIT_LIST_HEAD(&cset->mg_tasks);
INIT_LIST_HEAD(&cset->task_iters);
+ INIT_LIST_HEAD(&cset->threaded_csets);
INIT_HLIST_NODE(&cset->hlist);
INIT_LIST_HEAD(&cset->cgrp_links);
INIT_LIST_HEAD(&cset->mg_preload_node);
spin_unlock_irq(&css_set_lock);
+ /*
+ * If @cset should be threaded, look up the matching dom_cset and
+ * link them up. We first fully initialize @cset then look for the
+ * dom_cset. It's simpler this way and safe as @cset is guaranteed
+ * to stay empty until we return.
+ */
+ if (cgroup_is_threaded(cset->dfl_cgrp)) {
+ struct css_set *dcset;
+
+ dcset = find_css_set(cset, cset->dfl_cgrp->dom_cgrp);
+ if (!dcset) {
+ put_css_set(cset);
+ return NULL;
+ }
+
+ spin_lock_irq(&css_set_lock);
+ cset->dom_cset = dcset;
+ list_add_tail(&cset->threaded_csets_node,
+ &dcset->threaded_csets);
+ spin_unlock_irq(&css_set_lock);
+ }
+
return cset;
}
if (cset == &init_css_set) {
res = &root->cgrp;
+ } else if (root == &cgrp_dfl_root) {
+ res = cset->dfl_cgrp;
} else {
struct cgrp_cset_link *link;
mutex_init(&cgrp->pidlist_mutex);
cgrp->self.cgroup = cgrp;
cgrp->self.flags |= CSS_ONLINE;
+ cgrp->dom_cgrp = cgrp;
+ cgrp->max_descendants = INT_MAX;
+ cgrp->max_depth = INT_MAX;
for_each_subsys(ss, ssid)
INIT_LIST_HEAD(&cgrp->e_csets[ssid]);
if (!cset->mg_src_cgrp)
return;
+ mgctx->tset.nr_tasks++;
+
list_move_tail(&task->cg_list, &cset->mg_tasks);
if (list_empty(&cset->mg_node))
list_add_tail(&cset->mg_node,
struct css_set *cset, *tmp_cset;
int ssid, failed_ssid, ret;
- /* methods shouldn't be called if no task is actually migrating */
- if (list_empty(&tset->src_csets))
- return 0;
-
/* check that we can legitimately attach to the cgroup */
- do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {
- if (ss->can_attach) {
- tset->ssid = ssid;
- ret = ss->can_attach(tset);
- if (ret) {
- failed_ssid = ssid;
- goto out_cancel_attach;
+ if (tset->nr_tasks) {
+ do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {
+ if (ss->can_attach) {
+ tset->ssid = ssid;
+ ret = ss->can_attach(tset);
+ if (ret) {
+ failed_ssid = ssid;
+ goto out_cancel_attach;
+ }
}
- }
- } while_each_subsys_mask();
+ } while_each_subsys_mask();
+ }
/*
* Now that we're guaranteed success, proceed to move all tasks to
*/
tset->csets = &tset->dst_csets;
- do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {
- if (ss->attach) {
- tset->ssid = ssid;
- ss->attach(tset);
- }
- } while_each_subsys_mask();
+ if (tset->nr_tasks) {
+ do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {
+ if (ss->attach) {
+ tset->ssid = ssid;
+ ss->attach(tset);
+ }
+ } while_each_subsys_mask();
+ }
ret = 0;
goto out_release_tset;
out_cancel_attach:
- do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {
- if (ssid == failed_ssid)
- break;
- if (ss->cancel_attach) {
- tset->ssid = ssid;
- ss->cancel_attach(tset);
- }
- } while_each_subsys_mask();
+ if (tset->nr_tasks) {
+ do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {
+ if (ssid == failed_ssid)
+ break;
+ if (ss->cancel_attach) {
+ tset->ssid = ssid;
+ ss->cancel_attach(tset);
+ }
+ } while_each_subsys_mask();
+ }
out_release_tset:
spin_lock_irq(&css_set_lock);
list_splice_init(&tset->dst_csets, &tset->src_csets);
}
/**
- * cgroup_may_migrate_to - verify whether a cgroup can be migration destination
+ * cgroup_migrate_vet_dst - verify whether a cgroup can be migration destination
* @dst_cgrp: destination cgroup to test
*
- * On the default hierarchy, except for the root, subtree_control must be
- * zero for migration destination cgroups with tasks so that child cgroups
- * don't compete against tasks.
+ * On the default hierarchy, except for the mixable, (possible) thread root
+ * and threaded cgroups, subtree_control must be zero for migration
+ * destination cgroups with tasks so that child cgroups don't compete
+ * against tasks.
*/
-bool cgroup_may_migrate_to(struct cgroup *dst_cgrp)
+int cgroup_migrate_vet_dst(struct cgroup *dst_cgrp)
{
- return !cgroup_on_dfl(dst_cgrp) || !cgroup_parent(dst_cgrp) ||
- !dst_cgrp->subtree_control;
+ /* v1 doesn't have any restriction */
+ if (!cgroup_on_dfl(dst_cgrp))
+ return 0;
+
+ /* verify @dst_cgrp can host resources */
+ if (!cgroup_is_valid_domain(dst_cgrp->dom_cgrp))
+ return -EOPNOTSUPP;
+
+ /* mixables don't care */
+ if (cgroup_is_mixable(dst_cgrp))
+ return 0;
+
+ /*
+ * If @dst_cgrp is already or can become a thread root or is
+ * threaded, it doesn't matter.
+ */
+ if (cgroup_can_be_thread_root(dst_cgrp) || cgroup_is_threaded(dst_cgrp))
+ return 0;
+
+ /* apply no-internal-process constraint */
+ if (dst_cgrp->subtree_control)
+ return -EBUSY;
+
+ return 0;
}
/**
struct task_struct *task;
int ret;
- if (!cgroup_may_migrate_to(dst_cgrp))
- return -EBUSY;
+ ret = cgroup_migrate_vet_dst(dst_cgrp);
+ if (ret)
+ return ret;
/* look up all src csets */
spin_lock_irq(&css_set_lock);
return ret;
}
-static int cgroup_procs_write_permission(struct task_struct *task,
- struct cgroup *dst_cgrp,
- struct kernfs_open_file *of)
-{
- struct super_block *sb = of->file->f_path.dentry->d_sb;
- struct cgroup_namespace *ns = current->nsproxy->cgroup_ns;
- struct cgroup *root_cgrp = ns->root_cset->dfl_cgrp;
- struct cgroup *src_cgrp, *com_cgrp;
- struct inode *inode;
- int ret;
-
- if (!cgroup_on_dfl(dst_cgrp)) {
- const struct cred *cred = current_cred();
- const struct cred *tcred = get_task_cred(task);
-
- /*
- * even if we're attaching all tasks in the thread group,
- * we only need to check permissions on one of them.
- */
- if (uid_eq(cred->euid, GLOBAL_ROOT_UID) ||
- uid_eq(cred->euid, tcred->uid) ||
- uid_eq(cred->euid, tcred->suid))
- ret = 0;
- else
- ret = -EACCES;
-
- put_cred(tcred);
- return ret;
- }
-
- /* find the source cgroup */
- spin_lock_irq(&css_set_lock);
- src_cgrp = task_cgroup_from_root(task, &cgrp_dfl_root);
- spin_unlock_irq(&css_set_lock);
-
- /* and the common ancestor */
- com_cgrp = src_cgrp;
- while (!cgroup_is_descendant(dst_cgrp, com_cgrp))
- com_cgrp = cgroup_parent(com_cgrp);
-
- /* %current should be authorized to migrate to the common ancestor */
- inode = kernfs_get_inode(sb, com_cgrp->procs_file.kn);
- if (!inode)
- return -ENOMEM;
-
- ret = inode_permission(inode, MAY_WRITE);
- iput(inode);
- if (ret)
- return ret;
-
- /*
- * If namespaces are delegation boundaries, %current must be able
- * to see both source and destination cgroups from its namespace.
- */
- if ((cgrp_dfl_root.flags & CGRP_ROOT_NS_DELEGATE) &&
- (!cgroup_is_descendant(src_cgrp, root_cgrp) ||
- !cgroup_is_descendant(dst_cgrp, root_cgrp)))
- return -ENOENT;
-
- return 0;
-}
-
-/*
- * Find the task_struct of the task to attach by vpid and pass it along to the
- * function to attach either it or all tasks in its threadgroup. Will lock
- * cgroup_mutex and threadgroup.
- */
-ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf,
- size_t nbytes, loff_t off, bool threadgroup)
+struct task_struct *cgroup_procs_write_start(char *buf, bool threadgroup)
+ __acquires(&cgroup_threadgroup_rwsem)
{
struct task_struct *tsk;
- struct cgroup_subsys *ss;
- struct cgroup *cgrp;
pid_t pid;
- int ssid, ret;
if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0)
- return -EINVAL;
-
- cgrp = cgroup_kn_lock_live(of->kn, false);
- if (!cgrp)
- return -ENODEV;
+ return ERR_PTR(-EINVAL);
percpu_down_write(&cgroup_threadgroup_rwsem);
+
rcu_read_lock();
if (pid) {
tsk = find_task_by_vpid(pid);
if (!tsk) {
- ret = -ESRCH;
- goto out_unlock_rcu;
+ tsk = ERR_PTR(-ESRCH);
+ goto out_unlock_threadgroup;
}
} else {
tsk = current;
* cgroup with no rt_runtime allocated. Just say no.
*/
if (tsk->no_cgroup_migration || (tsk->flags & PF_NO_SETAFFINITY)) {
- ret = -EINVAL;
- goto out_unlock_rcu;
+ tsk = ERR_PTR(-EINVAL);
+ goto out_unlock_threadgroup;
}
get_task_struct(tsk);
+ goto out_unlock_rcu;
+
+out_unlock_threadgroup:
+ percpu_up_write(&cgroup_threadgroup_rwsem);
+out_unlock_rcu:
rcu_read_unlock();
+ return tsk;
+}
- ret = cgroup_procs_write_permission(tsk, cgrp, of);
- if (!ret)
- ret = cgroup_attach_task(cgrp, tsk, threadgroup);
+void cgroup_procs_write_finish(struct task_struct *task)
+ __releases(&cgroup_threadgroup_rwsem)
+{
+ struct cgroup_subsys *ss;
+ int ssid;
- put_task_struct(tsk);
- goto out_unlock_threadgroup;
+ /* release reference from cgroup_procs_write_start() */
+ put_task_struct(task);
-out_unlock_rcu:
- rcu_read_unlock();
-out_unlock_threadgroup:
percpu_up_write(&cgroup_threadgroup_rwsem);
for_each_subsys(ss, ssid)
if (ss->post_attach)
ss->post_attach();
- cgroup_kn_unlock(of->kn);
- return ret ?: nbytes;
-}
-
-ssize_t cgroup_procs_write(struct kernfs_open_file *of, char *buf, size_t nbytes,
- loff_t off)
-{
- return __cgroup_procs_write(of, buf, nbytes, off, true);
}
static void cgroup_print_ss_mask(struct seq_file *seq, u16 ss_mask)
cgroup_apply_control_disable(cgrp);
}
+static int cgroup_vet_subtree_control_enable(struct cgroup *cgrp, u16 enable)
+{
+ u16 domain_enable = enable & ~cgrp_dfl_threaded_ss_mask;
+
+ /* if nothing is getting enabled, nothing to worry about */
+ if (!enable)
+ return 0;
+
+ /* can @cgrp host any resources? */
+ if (!cgroup_is_valid_domain(cgrp->dom_cgrp))
+ return -EOPNOTSUPP;
+
+ /* mixables don't care */
+ if (cgroup_is_mixable(cgrp))
+ return 0;
+
+ if (domain_enable) {
+ /* can't enable domain controllers inside a thread subtree */
+ if (cgroup_is_thread_root(cgrp) || cgroup_is_threaded(cgrp))
+ return -EOPNOTSUPP;
+ } else {
+ /*
+ * Threaded controllers can handle internal competitions
+ * and are always allowed inside a (prospective) thread
+ * subtree.
+ */
+ if (cgroup_can_be_thread_root(cgrp) || cgroup_is_threaded(cgrp))
+ return 0;
+ }
+
+ /*
+ * Controllers can't be enabled for a cgroup with tasks to avoid
+ * child cgroups competing against tasks.
+ */
+ if (cgroup_has_tasks(cgrp))
+ return -EBUSY;
+
+ return 0;
+}
+
/* 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,
goto out_unlock;
}
- /*
- * 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)) {
- struct cgrp_cset_link *link;
-
- /*
- * Because namespaces pin csets too, @cgrp->cset_links
- * might not be empty even when @cgrp is empty. Walk and
- * verify each cset.
- */
- spin_lock_irq(&css_set_lock);
-
- ret = 0;
- list_for_each_entry(link, &cgrp->cset_links, cset_link) {
- if (css_set_populated(link->cset)) {
- ret = -EBUSY;
- break;
- }
- }
-
- spin_unlock_irq(&css_set_lock);
-
- if (ret)
- goto out_unlock;
- }
+ ret = cgroup_vet_subtree_control_enable(cgrp, enable);
+ if (ret)
+ goto out_unlock;
/* save and update control masks and prepare csses */
cgroup_save_control(cgrp);
cgrp->subtree_control &= ~disable;
ret = cgroup_apply_control(cgrp);
-
cgroup_finalize_control(cgrp, ret);
+ if (ret)
+ goto out_unlock;
kernfs_activate(cgrp->kn);
- ret = 0;
out_unlock:
cgroup_kn_unlock(of->kn);
return ret ?: nbytes;
}
+/**
+ * cgroup_enable_threaded - make @cgrp threaded
+ * @cgrp: the target cgroup
+ *
+ * Called when "threaded" is written to the cgroup.type interface file and
+ * tries to make @cgrp threaded and join the parent's resource domain.
+ * This function is never called on the root cgroup as cgroup.type doesn't
+ * exist on it.
+ */
+static int cgroup_enable_threaded(struct cgroup *cgrp)
+{
+ struct cgroup *parent = cgroup_parent(cgrp);
+ struct cgroup *dom_cgrp = parent->dom_cgrp;
+ int ret;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ /* noop if already threaded */
+ if (cgroup_is_threaded(cgrp))
+ return 0;
+
+ /* we're joining the parent's domain, ensure its validity */
+ if (!cgroup_is_valid_domain(dom_cgrp) ||
+ !cgroup_can_be_thread_root(dom_cgrp))
+ return -EOPNOTSUPP;
+
+ /*
+ * The following shouldn't cause actual migrations and should
+ * always succeed.
+ */
+ cgroup_save_control(cgrp);
+
+ cgrp->dom_cgrp = dom_cgrp;
+ ret = cgroup_apply_control(cgrp);
+ if (!ret)
+ parent->nr_threaded_children++;
+ else
+ cgrp->dom_cgrp = cgrp;
+
+ cgroup_finalize_control(cgrp, ret);
+ return ret;
+}
+
+static int cgroup_type_show(struct seq_file *seq, void *v)
+{
+ struct cgroup *cgrp = seq_css(seq)->cgroup;
+
+ if (cgroup_is_threaded(cgrp))
+ seq_puts(seq, "threaded\n");
+ else if (!cgroup_is_valid_domain(cgrp))
+ seq_puts(seq, "domain invalid\n");
+ else if (cgroup_is_thread_root(cgrp))
+ seq_puts(seq, "domain threaded\n");
+ else
+ seq_puts(seq, "domain\n");
+
+ return 0;
+}
+
+static ssize_t cgroup_type_write(struct kernfs_open_file *of, char *buf,
+ size_t nbytes, loff_t off)
+{
+ struct cgroup *cgrp;
+ int ret;
+
+ /* only switching to threaded mode is supported */
+ if (strcmp(strstrip(buf), "threaded"))
+ return -EINVAL;
+
+ cgrp = cgroup_kn_lock_live(of->kn, false);
+ if (!cgrp)
+ return -ENOENT;
+
+ /* threaded can only be enabled */
+ ret = cgroup_enable_threaded(cgrp);
+
+ cgroup_kn_unlock(of->kn);
+ return ret ?: nbytes;
+}
+
+static int cgroup_max_descendants_show(struct seq_file *seq, void *v)
+{
+ struct cgroup *cgrp = seq_css(seq)->cgroup;
+ int descendants = READ_ONCE(cgrp->max_descendants);
+
+ if (descendants == INT_MAX)
+ seq_puts(seq, "max\n");
+ else
+ seq_printf(seq, "%d\n", descendants);
+
+ return 0;
+}
+
+static ssize_t cgroup_max_descendants_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ struct cgroup *cgrp;
+ int descendants;
+ ssize_t ret;
+
+ buf = strstrip(buf);
+ if (!strcmp(buf, "max")) {
+ descendants = INT_MAX;
+ } else {
+ ret = kstrtoint(buf, 0, &descendants);
+ if (ret)
+ return ret;
+ }
+
+ if (descendants < 0)
+ return -ERANGE;
+
+ cgrp = cgroup_kn_lock_live(of->kn, false);
+ if (!cgrp)
+ return -ENOENT;
+
+ cgrp->max_descendants = descendants;
+
+ cgroup_kn_unlock(of->kn);
+
+ return nbytes;
+}
+
+static int cgroup_max_depth_show(struct seq_file *seq, void *v)
+{
+ struct cgroup *cgrp = seq_css(seq)->cgroup;
+ int depth = READ_ONCE(cgrp->max_depth);
+
+ if (depth == INT_MAX)
+ seq_puts(seq, "max\n");
+ else
+ seq_printf(seq, "%d\n", depth);
+
+ return 0;
+}
+
+static ssize_t cgroup_max_depth_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ struct cgroup *cgrp;
+ ssize_t ret;
+ int depth;
+
+ buf = strstrip(buf);
+ if (!strcmp(buf, "max")) {
+ depth = INT_MAX;
+ } else {
+ ret = kstrtoint(buf, 0, &depth);
+ if (ret)
+ return ret;
+ }
+
+ if (depth < 0)
+ return -ERANGE;
+
+ cgrp = cgroup_kn_lock_live(of->kn, false);
+ if (!cgrp)
+ return -ENOENT;
+
+ cgrp->max_depth = depth;
+
+ cgroup_kn_unlock(of->kn);
+
+ return nbytes;
+}
+
static int cgroup_events_show(struct seq_file *seq, void *v)
{
seq_printf(seq, "populated %d\n",
return 0;
}
+static int cgroup_stat_show(struct seq_file *seq, void *v)
+{
+ struct cgroup *cgroup = seq_css(seq)->cgroup;
+
+ seq_printf(seq, "nr_descendants %d\n",
+ cgroup->nr_descendants);
+ seq_printf(seq, "nr_dying_descendants %d\n",
+ cgroup->nr_dying_descendants);
+
+ return 0;
+}
+
static int cgroup_file_open(struct kernfs_open_file *of)
{
struct cftype *cft = of->kn->priv;
static int cgroup_apply_cftypes(struct cftype *cfts, bool is_add)
{
- LIST_HEAD(pending);
struct cgroup_subsys *ss = cfts[0].ss;
struct cgroup *root = &ss->root->cgrp;
struct cgroup_subsys_state *css;
return ret;
}
+static struct css_set *css_task_iter_next_css_set(struct css_task_iter *it)
+{
+ struct list_head *l;
+ struct cgrp_cset_link *link;
+ struct css_set *cset;
+
+ lockdep_assert_held(&css_set_lock);
+
+ /* find the next threaded cset */
+ if (it->tcset_pos) {
+ l = it->tcset_pos->next;
+
+ if (l != it->tcset_head) {
+ it->tcset_pos = l;
+ return container_of(l, struct css_set,
+ threaded_csets_node);
+ }
+
+ it->tcset_pos = NULL;
+ }
+
+ /* find the next cset */
+ l = it->cset_pos;
+ l = l->next;
+ if (l == it->cset_head) {
+ it->cset_pos = NULL;
+ return NULL;
+ }
+
+ if (it->ss) {
+ cset = container_of(l, struct css_set, e_cset_node[it->ss->id]);
+ } else {
+ link = list_entry(l, struct cgrp_cset_link, cset_link);
+ cset = link->cset;
+ }
+
+ it->cset_pos = l;
+
+ /* initialize threaded css_set walking */
+ if (it->flags & CSS_TASK_ITER_THREADED) {
+ if (it->cur_dcset)
+ put_css_set_locked(it->cur_dcset);
+ it->cur_dcset = cset;
+ get_css_set(cset);
+
+ it->tcset_head = &cset->threaded_csets;
+ it->tcset_pos = &cset->threaded_csets;
+ }
+
+ return cset;
+}
+
/**
* css_task_iter_advance_css_set - advance a task itererator to the next css_set
* @it: the iterator to advance
*/
static void css_task_iter_advance_css_set(struct css_task_iter *it)
{
- struct list_head *l = it->cset_pos;
- struct cgrp_cset_link *link;
struct css_set *cset;
lockdep_assert_held(&css_set_lock);
/* Advance to the next non-empty css_set */
do {
- l = l->next;
- if (l == it->cset_head) {
- it->cset_pos = NULL;
+ cset = css_task_iter_next_css_set(it);
+ if (!cset) {
it->task_pos = NULL;
return;
}
-
- if (it->ss) {
- cset = container_of(l, struct css_set,
- e_cset_node[it->ss->id]);
- } else {
- link = list_entry(l, struct cgrp_cset_link, cset_link);
- cset = link->cset;
- }
} while (!css_set_populated(cset));
- it->cset_pos = l;
-
if (!list_empty(&cset->tasks))
it->task_pos = cset->tasks.next;
else
lockdep_assert_held(&css_set_lock);
WARN_ON_ONCE(!l);
+repeat:
/*
* Advance iterator to find next entry. cset->tasks is consumed
* first and then ->mg_tasks. After ->mg_tasks, we move onto the
css_task_iter_advance_css_set(it);
else
it->task_pos = l;
+
+ /* if PROCS, skip over tasks which aren't group leaders */
+ if ((it->flags & CSS_TASK_ITER_PROCS) && it->task_pos &&
+ !thread_group_leader(list_entry(it->task_pos, struct task_struct,
+ cg_list)))
+ goto repeat;
}
/**
* css_task_iter_start - initiate task iteration
* @css: the css to walk tasks of
+ * @flags: CSS_TASK_ITER_* flags
* @it: the task iterator to use
*
* Initiate iteration through the tasks of @css. The caller can call
* returns NULL. On completion of iteration, css_task_iter_end() must be
* called.
*/
-void css_task_iter_start(struct cgroup_subsys_state *css,
+void css_task_iter_start(struct cgroup_subsys_state *css, unsigned int flags,
struct css_task_iter *it)
{
/* no one should try to iterate before mounting cgroups */
spin_lock_irq(&css_set_lock);
it->ss = css->ss;
+ it->flags = flags;
if (it->ss)
it->cset_pos = &css->cgroup->e_csets[css->ss->id];
spin_unlock_irq(&css_set_lock);
}
+ if (it->cur_dcset)
+ put_css_set(it->cur_dcset);
+
if (it->cur_task)
put_task_struct(it->cur_task);
}
{
struct kernfs_open_file *of = s->private;
struct css_task_iter *it = of->priv;
- struct task_struct *task;
- do {
- task = css_task_iter_next(it);
- } while (task && !thread_group_leader(task));
-
- return task;
+ return css_task_iter_next(it);
}
-static void *cgroup_procs_start(struct seq_file *s, loff_t *pos)
+static void *__cgroup_procs_start(struct seq_file *s, loff_t *pos,
+ unsigned int iter_flags)
{
struct kernfs_open_file *of = s->private;
struct cgroup *cgrp = seq_css(s)->cgroup;
if (!it)
return ERR_PTR(-ENOMEM);
of->priv = it;
- css_task_iter_start(&cgrp->self, it);
+ css_task_iter_start(&cgrp->self, iter_flags, it);
} else if (!(*pos)++) {
css_task_iter_end(it);
- css_task_iter_start(&cgrp->self, it);
+ css_task_iter_start(&cgrp->self, iter_flags, it);
}
return cgroup_procs_next(s, NULL, NULL);
}
+static void *cgroup_procs_start(struct seq_file *s, loff_t *pos)
+{
+ struct cgroup *cgrp = seq_css(s)->cgroup;
+
+ /*
+ * All processes of a threaded subtree belong to the domain cgroup
+ * of the subtree. Only threads can be distributed across the
+ * subtree. Reject reads on cgroup.procs in the subtree proper.
+ * They're always empty anyway.
+ */
+ if (cgroup_is_threaded(cgrp))
+ return ERR_PTR(-EOPNOTSUPP);
+
+ return __cgroup_procs_start(s, pos, CSS_TASK_ITER_PROCS |
+ CSS_TASK_ITER_THREADED);
+}
+
static int cgroup_procs_show(struct seq_file *s, void *v)
{
- seq_printf(s, "%d\n", task_tgid_vnr(v));
+ seq_printf(s, "%d\n", task_pid_vnr(v));
return 0;
}
+static int cgroup_procs_write_permission(struct cgroup *src_cgrp,
+ struct cgroup *dst_cgrp,
+ struct super_block *sb)
+{
+ struct cgroup_namespace *ns = current->nsproxy->cgroup_ns;
+ struct cgroup *com_cgrp = src_cgrp;
+ struct inode *inode;
+ int ret;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ /* find the common ancestor */
+ while (!cgroup_is_descendant(dst_cgrp, com_cgrp))
+ com_cgrp = cgroup_parent(com_cgrp);
+
+ /* %current should be authorized to migrate to the common ancestor */
+ inode = kernfs_get_inode(sb, com_cgrp->procs_file.kn);
+ if (!inode)
+ return -ENOMEM;
+
+ ret = inode_permission(inode, MAY_WRITE);
+ iput(inode);
+ if (ret)
+ return ret;
+
+ /*
+ * If namespaces are delegation boundaries, %current must be able
+ * to see both source and destination cgroups from its namespace.
+ */
+ if ((cgrp_dfl_root.flags & CGRP_ROOT_NS_DELEGATE) &&
+ (!cgroup_is_descendant(src_cgrp, ns->root_cset->dfl_cgrp) ||
+ !cgroup_is_descendant(dst_cgrp, ns->root_cset->dfl_cgrp)))
+ return -ENOENT;
+
+ return 0;
+}
+
+static ssize_t cgroup_procs_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ struct cgroup *src_cgrp, *dst_cgrp;
+ struct task_struct *task;
+ ssize_t ret;
+
+ dst_cgrp = cgroup_kn_lock_live(of->kn, false);
+ if (!dst_cgrp)
+ return -ENODEV;
+
+ task = cgroup_procs_write_start(buf, true);
+ ret = PTR_ERR_OR_ZERO(task);
+ if (ret)
+ goto out_unlock;
+
+ /* find the source cgroup */
+ spin_lock_irq(&css_set_lock);
+ src_cgrp = task_cgroup_from_root(task, &cgrp_dfl_root);
+ spin_unlock_irq(&css_set_lock);
+
+ ret = cgroup_procs_write_permission(src_cgrp, dst_cgrp,
+ of->file->f_path.dentry->d_sb);
+ if (ret)
+ goto out_finish;
+
+ ret = cgroup_attach_task(dst_cgrp, task, true);
+
+out_finish:
+ cgroup_procs_write_finish(task);
+out_unlock:
+ cgroup_kn_unlock(of->kn);
+
+ return ret ?: nbytes;
+}
+
+static void *cgroup_threads_start(struct seq_file *s, loff_t *pos)
+{
+ return __cgroup_procs_start(s, pos, 0);
+}
+
+static ssize_t cgroup_threads_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ struct cgroup *src_cgrp, *dst_cgrp;
+ struct task_struct *task;
+ ssize_t ret;
+
+ buf = strstrip(buf);
+
+ dst_cgrp = cgroup_kn_lock_live(of->kn, false);
+ if (!dst_cgrp)
+ return -ENODEV;
+
+ task = cgroup_procs_write_start(buf, false);
+ ret = PTR_ERR_OR_ZERO(task);
+ if (ret)
+ goto out_unlock;
+
+ /* find the source cgroup */
+ spin_lock_irq(&css_set_lock);
+ src_cgrp = task_cgroup_from_root(task, &cgrp_dfl_root);
+ spin_unlock_irq(&css_set_lock);
+
+ /* thread migrations follow the cgroup.procs delegation rule */
+ ret = cgroup_procs_write_permission(src_cgrp, dst_cgrp,
+ of->file->f_path.dentry->d_sb);
+ if (ret)
+ goto out_finish;
+
+ /* and must be contained in the same domain */
+ ret = -EOPNOTSUPP;
+ if (src_cgrp->dom_cgrp != dst_cgrp->dom_cgrp)
+ goto out_finish;
+
+ ret = cgroup_attach_task(dst_cgrp, task, false);
+
+out_finish:
+ cgroup_procs_write_finish(task);
+out_unlock:
+ cgroup_kn_unlock(of->kn);
+
+ return ret ?: nbytes;
+}
+
/* cgroup core interface files for the default hierarchy */
static struct cftype cgroup_base_files[] = {
+ {
+ .name = "cgroup.type",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .seq_show = cgroup_type_show,
+ .write = cgroup_type_write,
+ },
{
.name = "cgroup.procs",
.flags = CFTYPE_NS_DELEGATABLE,
.seq_show = cgroup_procs_show,
.write = cgroup_procs_write,
},
+ {
+ .name = "cgroup.threads",
+ .release = cgroup_procs_release,
+ .seq_start = cgroup_threads_start,
+ .seq_next = cgroup_procs_next,
+ .seq_show = cgroup_procs_show,
+ .write = cgroup_threads_write,
+ },
{
.name = "cgroup.controllers",
.seq_show = cgroup_controllers_show,
.file_offset = offsetof(struct cgroup, events_file),
.seq_show = cgroup_events_show,
},
+ {
+ .name = "cgroup.max.descendants",
+ .seq_show = cgroup_max_descendants_show,
+ .write = cgroup_max_descendants_write,
+ },
+ {
+ .name = "cgroup.max.depth",
+ .seq_show = cgroup_max_depth_show,
+ .write = cgroup_max_depth_write,
+ },
+ {
+ .name = "cgroup.stat",
+ .seq_show = cgroup_stat_show,
+ },
{ } /* terminate */
};
if (ss->css_released)
ss->css_released(css);
} else {
+ struct cgroup *tcgrp;
+
/* cgroup release path */
trace_cgroup_release(cgrp);
+ for (tcgrp = cgroup_parent(cgrp); tcgrp;
+ tcgrp = cgroup_parent(tcgrp))
+ tcgrp->nr_dying_descendants--;
+
cgroup_idr_remove(&cgrp->root->cgroup_idr, cgrp->id);
cgrp->id = -1;
if (!(css->flags & CSS_ONLINE))
return;
- if (ss->css_reset)
- ss->css_reset(css);
-
if (ss->css_offline)
ss->css_offline(css);
cgrp->root = root;
cgrp->level = level;
- for (tcgrp = cgrp; tcgrp; tcgrp = cgroup_parent(tcgrp))
+ for (tcgrp = cgrp; tcgrp; tcgrp = cgroup_parent(tcgrp)) {
cgrp->ancestor_ids[tcgrp->level] = tcgrp->id;
+ if (tcgrp != cgrp)
+ tcgrp->nr_descendants++;
+ }
+
if (notify_on_release(parent))
set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
return ERR_PTR(ret);
}
+static bool cgroup_check_hierarchy_limits(struct cgroup *parent)
+{
+ struct cgroup *cgroup;
+ int ret = false;
+ int level = 1;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ for (cgroup = parent; cgroup; cgroup = cgroup_parent(cgroup)) {
+ if (cgroup->nr_descendants >= cgroup->max_descendants)
+ goto fail;
+
+ if (level > cgroup->max_depth)
+ goto fail;
+
+ level++;
+ }
+
+ ret = true;
+fail:
+ return ret;
+}
+
int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode)
{
struct cgroup *parent, *cgrp;
if (!parent)
return -ENODEV;
+ if (!cgroup_check_hierarchy_limits(parent)) {
+ ret = -EAGAIN;
+ goto out_unlock;
+ }
+
cgrp = cgroup_create(parent);
if (IS_ERR(cgrp)) {
ret = PTR_ERR(cgrp);
static int cgroup_destroy_locked(struct cgroup *cgrp)
__releases(&cgroup_mutex) __acquires(&cgroup_mutex)
{
+ struct cgroup *tcgrp, *parent = cgroup_parent(cgrp);
struct cgroup_subsys_state *css;
struct cgrp_cset_link *link;
int ssid;
*/
kernfs_remove(cgrp->kn);
- cgroup1_check_for_release(cgroup_parent(cgrp));
+ if (parent && cgroup_is_threaded(cgrp))
+ parent->nr_threaded_children--;
+
+ for (tcgrp = cgroup_parent(cgrp); tcgrp; tcgrp = cgroup_parent(tcgrp)) {
+ tcgrp->nr_descendants--;
+ tcgrp->nr_dying_descendants++;
+ }
+
+ cgroup1_check_for_release(parent);
/* put the base reference */
percpu_ref_kill(&cgrp->self.refcnt);
cgrp_dfl_root.subsys_mask |= 1 << ss->id;
+ /* implicit controllers must be threaded too */
+ WARN_ON(ss->implicit_on_dfl && !ss->threaded);
+
if (ss->implicit_on_dfl)
cgrp_dfl_implicit_ss_mask |= 1 << ss->id;
else if (!ss->dfl_cftypes)
cgrp_dfl_inhibit_ss_mask |= 1 << ss->id;
+ if (ss->threaded)
+ cgrp_dfl_threaded_ss_mask |= 1 << ss->id;
+
if (ss->dfl_cftypes == ss->legacy_cftypes) {
WARN_ON(cgroup_add_cftypes(ss, ss->dfl_cftypes));
} else {
if (ss->bind)
ss->bind(init_css_set.subsys[ssid]);
+
+ mutex_lock(&cgroup_mutex);
+ css_populate_dir(init_css_set.subsys[ssid]);
+ mutex_unlock(&cgroup_mutex);
}
/* init_css_set.subsys[] has been updated, re-hash */
projects / linux.git / blobdiff