#include <linux/proc_fs.h>
#include <linux/rcupdate.h>
#include <linux/sched.h>
- #include <linux/backing-dev.h>
#include <linux/slab.h>
- #include <linux/magic.h>
#include <linux/spinlock.h>
+ #include <linux/rwsem.h>
#include <linux/string.h>
#include <linux/sort.h>
#include <linux/kmod.h>
- #include <linux/module.h>
#include <linux/delayacct.h>
#include <linux/cgroupstats.h>
#include <linux/hashtable.h>
- #include <linux/namei.h>
#include <linux/pid_namespace.h>
#include <linux/idr.h>
#include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */
- #include <linux/flex_array.h> /* used in cgroup_attach_task */
#include <linux/kthread.h>
+ #include <linux/delay.h>
#include <linux/atomic.h>
*/
#define CGROUP_PIDLIST_DESTROY_DELAY HZ
+ #define CGROUP_FILE_NAME_MAX (MAX_CGROUP_TYPE_NAMELEN + \
+ MAX_CFTYPE_NAME + 2)
+
+ /*
+ * cgroup_tree_mutex nests above cgroup_mutex and protects cftypes, file
+ * creation/removal and hierarchy changing operations including cgroup
+ * creation, removal, css association and controller rebinding. This outer
+ * lock is needed mainly to resolve the circular dependency between kernfs
+ * active ref and cgroup_mutex. cgroup_tree_mutex nests above both.
+ */
+ static DEFINE_MUTEX(cgroup_tree_mutex);
+
/*
* cgroup_mutex is the master lock. Any modification to cgroup or its
* hierarchy must be performed while holding it.
*
- * cgroup_root_mutex nests inside cgroup_mutex and should be held to modify
- * cgroupfs_root of any cgroup hierarchy - subsys list, flags,
- * release_agent_path and so on. Modifying requires both cgroup_mutex and
- * cgroup_root_mutex. Readers can acquire either of the two. This is to
- * break the following locking order cycle.
+ * css_set_rwsem protects task->cgroups pointer, the list of css_set
+ * objects, and the chain of tasks off each css_set.
*
- * A. cgroup_mutex -> cred_guard_mutex -> s_type->i_mutex_key -> namespace_sem
- * B. namespace_sem -> cgroup_mutex
- *
- * B happens only through cgroup_show_options() and using cgroup_root_mutex
- * breaks it.
+ * These locks are exported if CONFIG_PROVE_RCU so that accessors in
+ * cgroup.h can use them for lockdep annotations.
*/
#ifdef CONFIG_PROVE_RCU
DEFINE_MUTEX(cgroup_mutex);
- EXPORT_SYMBOL_GPL(cgroup_mutex); /* only for lockdep */
+ DECLARE_RWSEM(css_set_rwsem);
+ EXPORT_SYMBOL_GPL(cgroup_mutex);
+ EXPORT_SYMBOL_GPL(css_set_rwsem);
#else
static DEFINE_MUTEX(cgroup_mutex);
+ static DECLARE_RWSEM(css_set_rwsem);
#endif
- static DEFINE_MUTEX(cgroup_root_mutex);
+ /*
+ * Protects cgroup_subsys->release_agent_path. Modifying it also requires
+ * cgroup_mutex. Reading requires either cgroup_mutex or this spinlock.
+ */
+ static DEFINE_SPINLOCK(release_agent_path_lock);
- #define cgroup_assert_mutex_or_rcu_locked() \
+ #define cgroup_assert_mutexes_or_rcu_locked() \
rcu_lockdep_assert(rcu_read_lock_held() || \
+ lockdep_is_held(&cgroup_tree_mutex) || \
lockdep_is_held(&cgroup_mutex), \
- "cgroup_mutex or RCU read lock required");
-
- #ifdef CONFIG_LOCKDEP
- #define cgroup_assert_mutex_or_root_locked() \
- WARN_ON_ONCE(debug_locks && (!lockdep_is_held(&cgroup_mutex) && \
- !lockdep_is_held(&cgroup_root_mutex)))
- #else
- #define cgroup_assert_mutex_or_root_locked() do { } while (0)
- #endif
+ "cgroup_[tree_]mutex or RCU read lock required");
/*
* cgroup destruction makes heavy use of work items and there can be a lot
*/
static struct workqueue_struct *cgroup_pidlist_destroy_wq;
- /*
- * Generate an array of cgroup subsystem pointers. At boot time, this is
- * populated with the built in subsystems, and modular subsystems are
- * registered after that. The mutable section of this array is protected by
- * cgroup_mutex.
- */
- #define SUBSYS(_x) [_x ## _subsys_id] = &_x ## _subsys,
- #define IS_SUBSYS_ENABLED(option) IS_BUILTIN(option)
- static struct cgroup_subsys *cgroup_subsys[CGROUP_SUBSYS_COUNT] = {
+ /* generate an array of cgroup subsystem pointers */
+ #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys,
+ static struct cgroup_subsys *cgroup_subsys[] = {
+ #include <linux/cgroup_subsys.h>
+ };
+ #undef SUBSYS
+
+ /* array of cgroup subsystem names */
+ #define SUBSYS(_x) [_x ## _cgrp_id] = #_x,
+ static const char *cgroup_subsys_name[] = {
#include <linux/cgroup_subsys.h>
};
+ #undef SUBSYS
/*
- * The dummy hierarchy, reserved for the subsystems that are otherwise
+ * The default hierarchy, reserved for the subsystems that are otherwise
* unattached - it never has more than a single cgroup, and all tasks are
* part of that cgroup.
*/
- static struct cgroupfs_root cgroup_dummy_root;
+ struct cgroup_root cgrp_dfl_root;
- /* dummy_top is a shorthand for the dummy hierarchy's top cgroup */
- static struct cgroup * const cgroup_dummy_top = &cgroup_dummy_root.top_cgroup;
+ /*
+ * The default hierarchy always exists but is hidden until mounted for the
+ * first time. This is for backward compatibility.
+ */
+ static bool cgrp_dfl_root_visible;
/* The list of hierarchy roots */
static LIST_HEAD(cgroup_roots);
static int cgroup_root_count;
- /*
- * Hierarchy ID allocation and mapping. It follows the same exclusion
- * rules as other root ops - both cgroup_mutex and cgroup_root_mutex for
- * writes, either for reads.
- */
+ /* hierarchy ID allocation and mapping, protected by cgroup_mutex */
static DEFINE_IDR(cgroup_hierarchy_idr);
- static struct cgroup_name root_cgroup_name = { .name = "/" };
-
/*
* Assign a monotonically increasing serial number to cgroups. It
* guarantees cgroups with bigger numbers are newer than those with smaller
static struct cftype cgroup_base_files[];
+ static void cgroup_put(struct cgroup *cgrp);
+ static int rebind_subsystems(struct cgroup_root *dst_root,
+ unsigned long ss_mask);
static void cgroup_destroy_css_killed(struct cgroup *cgrp);
static int cgroup_destroy_locked(struct cgroup *cgrp);
static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[],
bool is_add);
- static int cgroup_file_release(struct inode *inode, struct file *file);
static void cgroup_pidlist_destroy_all(struct cgroup *cgrp);
/**
struct cgroup_subsys *ss)
{
if (ss)
- return rcu_dereference_check(cgrp->subsys[ss->subsys_id],
- lockdep_is_held(&cgroup_mutex));
+ return rcu_dereference_check(cgrp->subsys[ss->id],
+ lockdep_is_held(&cgroup_tree_mutex) ||
+ lockdep_is_held(&cgroup_mutex));
else
return &cgrp->dummy_css;
}
return test_bit(CGRP_DEAD, &cgrp->flags);
}
+ struct cgroup_subsys_state *seq_css(struct seq_file *seq)
+ {
+ struct kernfs_open_file *of = seq->private;
+ struct cgroup *cgrp = of->kn->parent->priv;
+ struct cftype *cft = seq_cft(seq);
+
+ /*
+ * This is open and unprotected implementation of cgroup_css().
+ * seq_css() is only called from a kernfs file operation which has
+ * an active reference on the file. Because all the subsystem
+ * files are drained before a css is disassociated with a cgroup,
+ * the matching css from the cgroup's subsys table is guaranteed to
+ * be and stay valid until the enclosing operation is complete.
+ */
+ if (cft->ss)
+ return rcu_dereference_raw(cgrp->subsys[cft->ss->id]);
+ else
+ return &cgrp->dummy_css;
+ }
+ EXPORT_SYMBOL_GPL(seq_css);
+
/**
* cgroup_is_descendant - test ancestry
* @cgrp: the cgroup to be tested
}
return false;
}
- EXPORT_SYMBOL_GPL(cgroup_is_descendant);
static int cgroup_is_releasable(const struct cgroup *cgrp)
{
for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
if (!((css) = rcu_dereference_check( \
(cgrp)->subsys[(ssid)], \
+ lockdep_is_held(&cgroup_tree_mutex) || \
lockdep_is_held(&cgroup_mutex)))) { } \
else
/**
- * for_each_subsys - iterate all loaded cgroup subsystems
+ * for_each_subsys - iterate all enabled cgroup subsystems
* @ss: the iteration cursor
* @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
- *
- * Iterates through all loaded subsystems. Should be called under
- * cgroup_mutex or cgroup_root_mutex.
*/
#define for_each_subsys(ss, ssid) \
- for (({ cgroup_assert_mutex_or_root_locked(); (ssid) = 0; }); \
- (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
- if (!((ss) = cgroup_subsys[(ssid)])) { } \
- else
+ for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT && \
+ (((ss) = cgroup_subsys[ssid]) || true); (ssid)++)
- /**
- * for_each_builtin_subsys - iterate all built-in cgroup subsystems
- * @ss: the iteration cursor
- * @i: the index of @ss, CGROUP_BUILTIN_SUBSYS_COUNT after reaching the end
- *
- * Bulit-in subsystems are always present and iteration itself doesn't
- * require any synchronization.
- */
- #define for_each_builtin_subsys(ss, i) \
- for ((i) = 0; (i) < CGROUP_BUILTIN_SUBSYS_COUNT && \
- (((ss) = cgroup_subsys[i]) || true); (i)++)
-
- /* iterate across the active hierarchies */
- #define for_each_active_root(root) \
+ /* iterate across the hierarchies */
+ #define for_each_root(root) \
list_for_each_entry((root), &cgroup_roots, root_list)
- static inline struct cgroup *__d_cgrp(struct dentry *dentry)
- {
- return dentry->d_fsdata;
- }
-
- static inline struct cfent *__d_cfe(struct dentry *dentry)
- {
- return dentry->d_fsdata;
- }
-
- static inline struct cftype *__d_cft(struct dentry *dentry)
- {
- return __d_cfe(dentry)->type;
- }
-
/**
* cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive.
* @cgrp: the cgroup to be checked for liveness
struct list_head cgrp_link;
};
- /* The default css_set - used by init and its children prior to any
+ /*
+ * The default css_set - used by init and its children prior to any
* hierarchies being mounted. It contains a pointer to the root state
* for each subsystem. Also used to anchor the list of css_sets. Not
* reference-counted, to improve performance when child cgroups
* haven't been created.
*/
+ static struct css_set init_css_set = {
+ .refcount = ATOMIC_INIT(1),
+ .cgrp_links = LIST_HEAD_INIT(init_css_set.cgrp_links),
+ .tasks = LIST_HEAD_INIT(init_css_set.tasks),
+ .mg_tasks = LIST_HEAD_INIT(init_css_set.mg_tasks),
+ .mg_preload_node = LIST_HEAD_INIT(init_css_set.mg_preload_node),
+ .mg_node = LIST_HEAD_INIT(init_css_set.mg_node),
+ };
- static struct css_set init_css_set;
- static struct cgrp_cset_link init_cgrp_cset_link;
-
- /*
- * css_set_lock protects the list of css_set objects, and the chain of
- * tasks off each css_set. Nests outside task->alloc_lock due to
- * css_task_iter_start().
- */
- static DEFINE_RWLOCK(css_set_lock);
- static int css_set_count;
+ static int css_set_count = 1; /* 1 for init_css_set */
/*
* hash table for cgroup groups. This improves the performance to find
return key;
}
- /*
- * We don't maintain the lists running through each css_set to its task
- * until after the first call to css_task_iter_start(). This reduces the
- * fork()/exit() overhead for people who have cgroups compiled into their
- * kernel but not actually in use.
- */
- static int use_task_css_set_links __read_mostly;
-
- static void __put_css_set(struct css_set *cset, int taskexit)
+ static void put_css_set_locked(struct css_set *cset, bool taskexit)
{
struct cgrp_cset_link *link, *tmp_link;
- /*
- * Ensure that the refcount doesn't hit zero while any readers
- * can see it. Similar to atomic_dec_and_lock(), but for an
- * rwlock
- */
- if (atomic_add_unless(&cset->refcount, -1, 1))
- return;
- write_lock(&css_set_lock);
- if (!atomic_dec_and_test(&cset->refcount)) {
- write_unlock(&css_set_lock);
+ lockdep_assert_held(&css_set_rwsem);
+
+ if (!atomic_dec_and_test(&cset->refcount))
return;
- }
/* This css_set is dead. unlink it and release cgroup refcounts */
hash_del(&cset->hlist);
list_del(&link->cset_link);
list_del(&link->cgrp_link);
- /* @cgrp can't go away while we're holding css_set_lock */
+ /* @cgrp can't go away while we're holding css_set_rwsem */
if (list_empty(&cgrp->cset_links) && notify_on_release(cgrp)) {
if (taskexit)
set_bit(CGRP_RELEASABLE, &cgrp->flags);
kfree(link);
}
- write_unlock(&css_set_lock);
kfree_rcu(cset, rcu_head);
}
+ static void put_css_set(struct css_set *cset, bool taskexit)
+ {
+ /*
+ * Ensure that the refcount doesn't hit zero while any readers
+ * can see it. Similar to atomic_dec_and_lock(), but for an
+ * rwlock
+ */
+ if (atomic_add_unless(&cset->refcount, -1, 1))
+ return;
+
+ down_write(&css_set_rwsem);
+ put_css_set_locked(cset, taskexit);
+ up_write(&css_set_rwsem);
+ }
+
/*
* refcounted get/put for css_set objects
*/
atomic_inc(&cset->refcount);
}
- static inline void put_css_set(struct css_set *cset)
- {
- __put_css_set(cset, 0);
- }
-
- static inline void put_css_set_taskexit(struct css_set *cset)
- {
- __put_css_set(cset, 1);
- }
-
/**
* compare_css_sets - helper function for find_existing_css_set().
* @cset: candidate css_set being tested
struct cgroup *cgrp,
struct cgroup_subsys_state *template[])
{
- struct cgroupfs_root *root = cgrp->root;
+ struct cgroup_root *root = cgrp->root;
struct cgroup_subsys *ss;
struct css_set *cset;
unsigned long key;
* won't change, so no need for locking.
*/
for_each_subsys(ss, i) {
- if (root->subsys_mask & (1UL << i)) {
+ if (root->cgrp.subsys_mask & (1UL << i)) {
/* Subsystem is in this hierarchy. So we want
* the subsystem state from the new
* cgroup */
/* First see if we already have a cgroup group that matches
* the desired set */
- read_lock(&css_set_lock);
+ down_read(&css_set_rwsem);
cset = find_existing_css_set(old_cset, cgrp, template);
if (cset)
get_css_set(cset);
- read_unlock(&css_set_lock);
+ up_read(&css_set_rwsem);
if (cset)
return cset;
atomic_set(&cset->refcount, 1);
INIT_LIST_HEAD(&cset->cgrp_links);
INIT_LIST_HEAD(&cset->tasks);
+ INIT_LIST_HEAD(&cset->mg_tasks);
+ INIT_LIST_HEAD(&cset->mg_preload_node);
+ INIT_LIST_HEAD(&cset->mg_node);
INIT_HLIST_NODE(&cset->hlist);
/* Copy the set of subsystem state objects generated in
* find_existing_css_set() */
memcpy(cset->subsys, template, sizeof(cset->subsys));
- write_lock(&css_set_lock);
+ down_write(&css_set_rwsem);
/* Add reference counts and links from the new css_set. */
list_for_each_entry(link, &old_cset->cgrp_links, cgrp_link) {
struct cgroup *c = link->cgrp;
key = css_set_hash(cset->subsys);
hash_add(css_set_table, &cset->hlist, key);
- write_unlock(&css_set_lock);
+ up_write(&css_set_rwsem);
return cset;
}
- /*
- * Return the cgroup for "task" from the given hierarchy. Must be
- * called with cgroup_mutex held.
- */
- static struct cgroup *task_cgroup_from_root(struct task_struct *task,
- struct cgroupfs_root *root)
+ static struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root)
{
- struct css_set *cset;
- struct cgroup *res = NULL;
+ struct cgroup *root_cgrp = kf_root->kn->priv;
+
+ return root_cgrp->root;
+ }
+
+ static int cgroup_init_root_id(struct cgroup_root *root)
+ {
+ int id;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, 0, 0, GFP_KERNEL);
+ if (id < 0)
+ return id;
+
+ root->hierarchy_id = id;
+ return 0;
+ }
+
+ static void cgroup_exit_root_id(struct cgroup_root *root)
+ {
+ lockdep_assert_held(&cgroup_mutex);
+
+ if (root->hierarchy_id) {
+ idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id);
+ root->hierarchy_id = 0;
+ }
+ }
+
+ static void cgroup_free_root(struct cgroup_root *root)
+ {
+ if (root) {
+ /* hierarhcy ID shoulid already have been released */
+ WARN_ON_ONCE(root->hierarchy_id);
+
+ idr_destroy(&root->cgroup_idr);
+ kfree(root);
+ }
+ }
+
+ static void cgroup_destroy_root(struct cgroup_root *root)
+ {
+ struct cgroup *cgrp = &root->cgrp;
+ struct cgrp_cset_link *link, *tmp_link;
+
+ mutex_lock(&cgroup_tree_mutex);
+ mutex_lock(&cgroup_mutex);
+
+ BUG_ON(atomic_read(&root->nr_cgrps));
+ BUG_ON(!list_empty(&cgrp->children));
+
+ /* Rebind all subsystems back to the default hierarchy */
+ rebind_subsystems(&cgrp_dfl_root, cgrp->subsys_mask);
- BUG_ON(!mutex_is_locked(&cgroup_mutex));
- read_lock(&css_set_lock);
/*
- * No need to lock the task - since we hold cgroup_mutex the
- * task can't change groups, so the only thing that can happen
- * is that it exits and its css is set back to init_css_set.
+ * Release all the links from cset_links to this hierarchy's
+ * root cgroup
*/
- cset = task_css_set(task);
+ down_write(&css_set_rwsem);
+
+ list_for_each_entry_safe(link, tmp_link, &cgrp->cset_links, cset_link) {
+ list_del(&link->cset_link);
+ list_del(&link->cgrp_link);
+ kfree(link);
+ }
+ up_write(&css_set_rwsem);
+
+ if (!list_empty(&root->root_list)) {
+ list_del(&root->root_list);
+ cgroup_root_count--;
+ }
+
+ cgroup_exit_root_id(root);
+
+ mutex_unlock(&cgroup_mutex);
+ mutex_unlock(&cgroup_tree_mutex);
+
+ kernfs_destroy_root(root->kf_root);
+ cgroup_free_root(root);
+ }
+
+ /* look up cgroup associated with given css_set on the specified hierarchy */
+ static struct cgroup *cset_cgroup_from_root(struct css_set *cset,
+ struct cgroup_root *root)
+ {
+ struct cgroup *res = NULL;
+
+ lockdep_assert_held(&cgroup_mutex);
+ lockdep_assert_held(&css_set_rwsem);
+
if (cset == &init_css_set) {
- res = &root->top_cgroup;
+ res = &root->cgrp;
} else {
struct cgrp_cset_link *link;
}
}
}
- read_unlock(&css_set_lock);
+
BUG_ON(!res);
return res;
}
/*
- * There is one global cgroup mutex. We also require taking
- * task_lock() when dereferencing a task's cgroup subsys pointers.
- * See "The task_lock() exception", at the end of this comment.
- *
+ * Return the cgroup for "task" from the given hierarchy. Must be
+ * called with cgroup_mutex and css_set_rwsem held.
+ */
+ static struct cgroup *task_cgroup_from_root(struct task_struct *task,
+ struct cgroup_root *root)
+ {
+ /*
+ * No need to lock the task - since we hold cgroup_mutex the
+ * task can't change groups, so the only thing that can happen
+ * is that it exits and its css is set back to init_css_set.
+ */
+ return cset_cgroup_from_root(task_css_set(task), root);
+ }
+
+ /*
* A task must hold cgroup_mutex to modify cgroups.
*
* Any task can increment and decrement the count field without lock.
* A cgroup can only be deleted if both its 'count' of using tasks
* is zero, and its list of 'children' cgroups is empty. Since all
* tasks in the system use _some_ cgroup, and since there is always at
- * least one task in the system (init, pid == 1), therefore, top_cgroup
+ * least one task in the system (init, pid == 1), therefore, root cgroup
* always has either children cgroups and/or using tasks. So we don't
- * need a special hack to ensure that top_cgroup cannot be deleted.
- *
- * The task_lock() exception
- *
- * The need for this exception arises from the action of
- * cgroup_attach_task(), which overwrites one task's cgroup pointer with
- * another. It does so using cgroup_mutex, however there are
- * several performance critical places that need to reference
- * task->cgroup without the expense of grabbing a system global
- * mutex. Therefore except as noted below, when dereferencing or, as
- * in cgroup_attach_task(), modifying a task's cgroup pointer we use
- * task_lock(), which acts on a spinlock (task->alloc_lock) already in
- * the task_struct routinely used for such matters.
+ * need a special hack to ensure that root cgroup cannot be deleted.
*
* P.S. One more locking exception. RCU is used to guard the
* update of a tasks cgroup pointer by cgroup_attach_task()
*/
- /*
- * A couple of forward declarations required, due to cyclic reference loop:
- * cgroup_mkdir -> cgroup_create -> cgroup_populate_dir ->
- * cgroup_add_file -> cgroup_create_file -> cgroup_dir_inode_operations
- * -> cgroup_mkdir.
- */
-
- static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode);
- static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry);
static int cgroup_populate_dir(struct cgroup *cgrp, unsigned long subsys_mask);
- static const struct inode_operations cgroup_dir_inode_operations;
+ static struct kernfs_syscall_ops cgroup_kf_syscall_ops;
static const struct file_operations proc_cgroupstats_operations;
- static struct backing_dev_info cgroup_backing_dev_info = {
- .name = "cgroup",
- .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
- };
-
- static struct inode *cgroup_new_inode(umode_t mode, struct super_block *sb)
+ static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft,
+ char *buf)
{
- struct inode *inode = new_inode(sb);
-
- if (inode) {
- inode->i_ino = get_next_ino();
- inode->i_mode = mode;
- inode->i_uid = current_fsuid();
- inode->i_gid = current_fsgid();
- inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
- inode->i_mapping->backing_dev_info = &cgroup_backing_dev_info;
- }
- return inode;
+ if (cft->ss && !(cft->flags & CFTYPE_NO_PREFIX) &&
+ !(cgrp->root->flags & CGRP_ROOT_NOPREFIX))
+ snprintf(buf, CGROUP_FILE_NAME_MAX, "%s.%s",
+ cft->ss->name, cft->name);
+ else
+ strncpy(buf, cft->name, CGROUP_FILE_NAME_MAX);
+ return buf;
}
- static struct cgroup_name *cgroup_alloc_name(struct dentry *dentry)
+ /**
+ * cgroup_file_mode - deduce file mode of a control file
+ * @cft: the control file in question
+ *
+ * returns cft->mode if ->mode is not 0
+ * returns S_IRUGO|S_IWUSR if it has both a read and a write handler
+ * returns S_IRUGO if it has only a read handler
+ * returns S_IWUSR if it has only a write hander
+ */
+ static umode_t cgroup_file_mode(const struct cftype *cft)
{
- struct cgroup_name *name;
+ umode_t mode = 0;
- name = kmalloc(sizeof(*name) + dentry->d_name.len + 1, GFP_KERNEL);
- if (!name)
- return NULL;
- strcpy(name->name, dentry->d_name.name);
- return name;
+ if (cft->mode)
+ return cft->mode;
+
+ if (cft->read_u64 || cft->read_s64 || cft->seq_show)
+ mode |= S_IRUGO;
+
+ if (cft->write_u64 || cft->write_s64 || cft->write_string ||
+ cft->trigger)
+ mode |= S_IWUSR;
+
+ return mode;
}
static void cgroup_free_fn(struct work_struct *work)
{
struct cgroup *cgrp = container_of(work, struct cgroup, destroy_work);
- mutex_lock(&cgroup_mutex);
- cgrp->root->number_of_cgroups--;
- mutex_unlock(&cgroup_mutex);
-
- /*
- * We get a ref to the parent's dentry, and put the ref when
- * this cgroup is being freed, so it's guaranteed that the
- * parent won't be destroyed before its children.
- */
- dput(cgrp->parent->dentry);
-
- /*
- * Drop the active superblock reference that we took when we
- * created the cgroup. This will free cgrp->root, if we are
- * holding the last reference to @sb.
- */
- deactivate_super(cgrp->root->sb);
-
+ atomic_dec(&cgrp->root->nr_cgrps);
cgroup_pidlist_destroy_all(cgrp);
- simple_xattrs_free(&cgrp->xattrs);
-
- kfree(rcu_dereference_raw(cgrp->name));
- kfree(cgrp);
+ if (cgrp->parent) {
+ /*
+ * We get a ref to the parent, and put the ref when this
+ * cgroup is being freed, so it's guaranteed that the
+ * parent won't be destroyed before its children.
+ */
+ cgroup_put(cgrp->parent);
+ kernfs_put(cgrp->kn);
+ kfree(cgrp);
+ } else {
+ /*
+ * This is root cgroup's refcnt reaching zero, which
+ * indicates that the root should be released.
+ */
+ cgroup_destroy_root(cgrp->root);
+ }
}
static void cgroup_free_rcu(struct rcu_head *head)
queue_work(cgroup_destroy_wq, &cgrp->destroy_work);
}
- static void cgroup_diput(struct dentry *dentry, struct inode *inode)
- {
- /* is dentry a directory ? if so, kfree() associated cgroup */
- if (S_ISDIR(inode->i_mode)) {
- struct cgroup *cgrp = dentry->d_fsdata;
-
- BUG_ON(!(cgroup_is_dead(cgrp)));
-
- /*
- * XXX: cgrp->id is only used to look up css's. As cgroup
- * and css's lifetimes will be decoupled, it should be made
- * per-subsystem and moved to css->id so that lookups are
- * successful until the target css is released.
- */
- mutex_lock(&cgroup_mutex);
- idr_remove(&cgrp->root->cgroup_idr, cgrp->id);
- mutex_unlock(&cgroup_mutex);
- cgrp->id = -1;
-
- call_rcu(&cgrp->rcu_head, cgroup_free_rcu);
- } else {
- struct cfent *cfe = __d_cfe(dentry);
- struct cgroup *cgrp = dentry->d_parent->d_fsdata;
-
- WARN_ONCE(!list_empty(&cfe->node) &&
- cgrp != &cgrp->root->top_cgroup,
- "cfe still linked for %s\n", cfe->type->name);
- simple_xattrs_free(&cfe->xattrs);
- kfree(cfe);
- }
- iput(inode);
- }
-
- static void remove_dir(struct dentry *d)
+ static void cgroup_get(struct cgroup *cgrp)
{
- struct dentry *parent = dget(d->d_parent);
-
- d_delete(d);
- simple_rmdir(parent->d_inode, d);
- dput(parent);
+ WARN_ON_ONCE(cgroup_is_dead(cgrp));
+ WARN_ON_ONCE(atomic_read(&cgrp->refcnt) <= 0);
+ atomic_inc(&cgrp->refcnt);
}
- static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
+ static void cgroup_put(struct cgroup *cgrp)
{
- struct cfent *cfe;
-
- lockdep_assert_held(&cgrp->dentry->d_inode->i_mutex);
- lockdep_assert_held(&cgroup_mutex);
+ if (!atomic_dec_and_test(&cgrp->refcnt))
+ return;
+ if (WARN_ON_ONCE(cgrp->parent && !cgroup_is_dead(cgrp)))
+ return;
/*
- * If we're doing cleanup due to failure of cgroup_create(),
- * the corresponding @cfe may not exist.
+ * XXX: cgrp->id is only used to look up css's. As cgroup and
+ * css's lifetimes will be decoupled, it should be made
+ * per-subsystem and moved to css->id so that lookups are
+ * successful until the target css is released.
*/
- list_for_each_entry(cfe, &cgrp->files, node) {
- struct dentry *d = cfe->dentry;
+ mutex_lock(&cgroup_mutex);
+ idr_remove(&cgrp->root->cgroup_idr, cgrp->id);
+ mutex_unlock(&cgroup_mutex);
+ cgrp->id = -1;
- if (cft && cfe->type != cft)
- continue;
+ call_rcu(&cgrp->rcu_head, cgroup_free_rcu);
+ }
- dget(d);
- d_delete(d);
- simple_unlink(cgrp->dentry->d_inode, d);
- list_del_init(&cfe->node);
- dput(d);
+ static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
+ {
+ char name[CGROUP_FILE_NAME_MAX];
- break;
- }
+ lockdep_assert_held(&cgroup_tree_mutex);
+ kernfs_remove_by_name(cgrp->kn, cgroup_file_name(cgrp, cft, name));
}
/**
int i;
for_each_subsys(ss, i) {
- struct cftype_set *set;
+ struct cftype *cfts;
if (!test_bit(i, &subsys_mask))
continue;
- list_for_each_entry(set, &ss->cftsets, node)
- cgroup_addrm_files(cgrp, set->cfts, false);
+ list_for_each_entry(cfts, &ss->cfts, node)
+ cgroup_addrm_files(cgrp, cfts, false);
}
}
- /*
- * NOTE : the dentry must have been dget()'ed
- */
- static void cgroup_d_remove_dir(struct dentry *dentry)
+ static int rebind_subsystems(struct cgroup_root *dst_root,
+ unsigned long ss_mask)
{
- struct dentry *parent;
+ struct cgroup_subsys *ss;
+ int ssid, ret;
- parent = dentry->d_parent;
- spin_lock(&parent->d_lock);
- spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
- list_del_init(&dentry->d_u.d_child);
- spin_unlock(&dentry->d_lock);
- spin_unlock(&parent->d_lock);
- remove_dir(dentry);
- }
+ lockdep_assert_held(&cgroup_tree_mutex);
+ lockdep_assert_held(&cgroup_mutex);
- /*
- * Call with cgroup_mutex held. Drops reference counts on modules, including
- * any duplicate ones that parse_cgroupfs_options took. If this function
- * returns an error, no reference counts are touched.
- */
- static int rebind_subsystems(struct cgroupfs_root *root,
- unsigned long added_mask, unsigned removed_mask)
- {
- struct cgroup *cgrp = &root->top_cgroup;
- struct cgroup_subsys *ss;
- unsigned long pinned = 0;
- int i, ret;
-
- BUG_ON(!mutex_is_locked(&cgroup_mutex));
- BUG_ON(!mutex_is_locked(&cgroup_root_mutex));
+ for_each_subsys(ss, ssid) {
+ if (!(ss_mask & (1 << ssid)))
+ continue;
- /* Check that any added subsystems are currently free */
- for_each_subsys(ss, i) {
- if (!(added_mask & (1 << i)))
+ /* if @ss is on the dummy_root, we can always move it */
+ if (ss->root == &cgrp_dfl_root)
continue;
- /* is the subsystem mounted elsewhere? */
- if (ss->root != &cgroup_dummy_root) {
- ret = -EBUSY;
- goto out_put;
- }
+ /* if @ss has non-root cgroups attached to it, can't move */
+ if (!list_empty(&ss->root->cgrp.children))
+ return -EBUSY;
- /* pin the module */
- if (!try_module_get(ss->module)) {
- ret = -ENOENT;
- goto out_put;
- }
- pinned |= 1 << i;
+ /* can't move between two non-dummy roots either */
+ if (dst_root != &cgrp_dfl_root)
+ return -EBUSY;
}
- /* subsys could be missing if unloaded between parsing and here */
- if (added_mask != pinned) {
- ret = -ENOENT;
- goto out_put;
- }
+ ret = cgroup_populate_dir(&dst_root->cgrp, ss_mask);
+ if (ret) {
+ if (dst_root != &cgrp_dfl_root)
+ return ret;
- ret = cgroup_populate_dir(cgrp, added_mask);
- if (ret)
- goto out_put;
+ /*
+ * Rebinding back to the default root is not allowed to
+ * fail. Using both default and non-default roots should
+ * be rare. Moving subsystems back and forth even more so.
+ * Just warn about it and continue.
+ */
+ if (cgrp_dfl_root_visible) {
+ pr_warning("cgroup: failed to create files (%d) while rebinding 0x%lx to default root\n",
+ ret, ss_mask);
+ pr_warning("cgroup: you may retry by moving them to a different hierarchy and unbinding\n");
+ }
+ }
/*
* Nothing can fail from this point on. Remove files for the
* removed subsystems and rebind each subsystem.
*/
- cgroup_clear_dir(cgrp, removed_mask);
-
- for_each_subsys(ss, i) {
- unsigned long bit = 1UL << i;
-
- if (bit & added_mask) {
- /* We're binding this subsystem to this hierarchy */
- BUG_ON(cgroup_css(cgrp, ss));
- BUG_ON(!cgroup_css(cgroup_dummy_top, ss));
- BUG_ON(cgroup_css(cgroup_dummy_top, ss)->cgroup != cgroup_dummy_top);
+ mutex_unlock(&cgroup_mutex);
+ for_each_subsys(ss, ssid)
+ if (ss_mask & (1 << ssid))
+ cgroup_clear_dir(&ss->root->cgrp, 1 << ssid);
+ mutex_lock(&cgroup_mutex);
- rcu_assign_pointer(cgrp->subsys[i],
- cgroup_css(cgroup_dummy_top, ss));
- cgroup_css(cgrp, ss)->cgroup = cgrp;
+ for_each_subsys(ss, ssid) {
+ struct cgroup_root *src_root;
+ struct cgroup_subsys_state *css;
- ss->root = root;
- if (ss->bind)
- ss->bind(cgroup_css(cgrp, ss));
+ if (!(ss_mask & (1 << ssid)))
+ continue;
- /* refcount was already taken, and we're keeping it */
- root->subsys_mask |= bit;
- } else if (bit & removed_mask) {
- /* We're removing this subsystem */
- BUG_ON(cgroup_css(cgrp, ss) != cgroup_css(cgroup_dummy_top, ss));
- BUG_ON(cgroup_css(cgrp, ss)->cgroup != cgrp);
+ src_root = ss->root;
+ css = cgroup_css(&src_root->cgrp, ss);
- if (ss->bind)
- ss->bind(cgroup_css(cgroup_dummy_top, ss));
+ WARN_ON(!css || cgroup_css(&dst_root->cgrp, ss));
- cgroup_css(cgroup_dummy_top, ss)->cgroup = cgroup_dummy_top;
- RCU_INIT_POINTER(cgrp->subsys[i], NULL);
+ RCU_INIT_POINTER(src_root->cgrp.subsys[ssid], NULL);
+ rcu_assign_pointer(dst_root->cgrp.subsys[ssid], css);
+ ss->root = dst_root;
+ css->cgroup = &dst_root->cgrp;
- cgroup_subsys[i]->root = &cgroup_dummy_root;
+ src_root->cgrp.subsys_mask &= ~(1 << ssid);
+ dst_root->cgrp.subsys_mask |= 1 << ssid;
- /* subsystem is now free - drop reference on module */
- module_put(ss->module);
- root->subsys_mask &= ~bit;
- }
+ if (ss->bind)
+ ss->bind(css);
}
- /*
- * Mark @root has finished binding subsystems. @root->subsys_mask
- * now matches the bound subsystems.
- */
- root->flags |= CGRP_ROOT_SUBSYS_BOUND;
-
+ kernfs_activate(dst_root->cgrp.kn);
return 0;
-
- out_put:
- for_each_subsys(ss, i)
- if (pinned & (1 << i))
- module_put(ss->module);
- return ret;
}
- static int cgroup_show_options(struct seq_file *seq, struct dentry *dentry)
+ static int cgroup_show_options(struct seq_file *seq,
+ struct kernfs_root *kf_root)
{
- struct cgroupfs_root *root = dentry->d_sb->s_fs_info;
+ struct cgroup_root *root = cgroup_root_from_kf(kf_root);
struct cgroup_subsys *ss;
int ssid;
- mutex_lock(&cgroup_root_mutex);
for_each_subsys(ss, ssid)
- if (root->subsys_mask & (1 << ssid))
+ if (root->cgrp.subsys_mask & (1 << ssid))
seq_printf(seq, ",%s", ss->name);
if (root->flags & CGRP_ROOT_SANE_BEHAVIOR)
seq_puts(seq, ",sane_behavior");
seq_puts(seq, ",noprefix");
if (root->flags & CGRP_ROOT_XATTR)
seq_puts(seq, ",xattr");
+
+ spin_lock(&release_agent_path_lock);
if (strlen(root->release_agent_path))
seq_printf(seq, ",release_agent=%s", root->release_agent_path);
- if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->top_cgroup.flags))
+ spin_unlock(&release_agent_path_lock);
+
+ if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags))
seq_puts(seq, ",clone_children");
if (strlen(root->name))
seq_printf(seq, ",name=%s", root->name);
- mutex_unlock(&cgroup_root_mutex);
return 0;
}
char *name;
/* User explicitly requested empty subsystem */
bool none;
-
- struct cgroupfs_root *new_root;
-
};
/*
BUG_ON(!mutex_is_locked(&cgroup_mutex));
#ifdef CONFIG_CPUSETS
- mask = ~(1UL << cpuset_subsys_id);
+ mask = ~(1UL << cpuset_cgrp_id);
#endif
memset(opts, 0, sizeof(*opts));
return -ENOENT;
}
- /*
- * If the 'all' option was specified select all the subsystems,
- * otherwise if 'none', 'name=' and a subsystem name options
- * were not specified, let's default to 'all'
- */
- if (all_ss || (!one_ss && !opts->none && !opts->name))
- for_each_subsys(ss, i)
- if (!ss->disabled)
- set_bit(i, &opts->subsys_mask);
-
/* Consistency checks */
if (opts->flags & CGRP_ROOT_SANE_BEHAVIOR) {
pr_warning("cgroup: sane_behavior: this is still under development and its behaviors will change, proceed at your own risk\n");
- if (opts->flags & CGRP_ROOT_NOPREFIX) {
- pr_err("cgroup: sane_behavior: noprefix is not allowed\n");
+ if ((opts->flags & (CGRP_ROOT_NOPREFIX | CGRP_ROOT_XATTR)) ||
+ opts->cpuset_clone_children || opts->release_agent ||
+ opts->name) {
+ pr_err("cgroup: sane_behavior: noprefix, xattr, clone_children, release_agent and name are not allowed\n");
return -EINVAL;
}
+ } else {
+ /*
+ * If the 'all' option was specified select all the
+ * subsystems, otherwise if 'none', 'name=' and a subsystem
+ * name options were not specified, let's default to 'all'
+ */
+ if (all_ss || (!one_ss && !opts->none && !opts->name))
+ for_each_subsys(ss, i)
+ if (!ss->disabled)
+ set_bit(i, &opts->subsys_mask);
- if (opts->cpuset_clone_children) {
- pr_err("cgroup: sane_behavior: clone_children is not allowed\n");
+ /*
+ * We either have to specify by name or by subsystems. (So
+ * all empty hierarchies must have a name).
+ */
+ if (!opts->subsys_mask && !opts->name)
return -EINVAL;
- }
}
/*
if (opts->subsys_mask && opts->none)
return -EINVAL;
- /*
- * We either have to specify by name or by subsystems. (So all
- * empty hierarchies must have a name).
- */
- if (!opts->subsys_mask && !opts->name)
- return -EINVAL;
-
return 0;
}
- static int cgroup_remount(struct super_block *sb, int *flags, char *data)
+ static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data)
{
int ret = 0;
- struct cgroupfs_root *root = sb->s_fs_info;
- struct cgroup *cgrp = &root->top_cgroup;
+ struct cgroup_root *root = cgroup_root_from_kf(kf_root);
struct cgroup_sb_opts opts;
unsigned long added_mask, removed_mask;
return -EINVAL;
}
- mutex_lock(&cgrp->dentry->d_inode->i_mutex);
+ mutex_lock(&cgroup_tree_mutex);
mutex_lock(&cgroup_mutex);
- mutex_lock(&cgroup_root_mutex);
/* See what subsystems are wanted */
ret = parse_cgroupfs_options(data, &opts);
if (ret)
goto out_unlock;
- if (opts.subsys_mask != root->subsys_mask || opts.release_agent)
+ if (opts.subsys_mask != root->cgrp.subsys_mask || opts.release_agent)
pr_warning("cgroup: option changes via remount are deprecated (pid=%d comm=%s)\n",
task_tgid_nr(current), current->comm);
- added_mask = opts.subsys_mask & ~root->subsys_mask;
- removed_mask = root->subsys_mask & ~opts.subsys_mask;
+ added_mask = opts.subsys_mask & ~root->cgrp.subsys_mask;
+ removed_mask = root->cgrp.subsys_mask & ~opts.subsys_mask;
/* Don't allow flags or name to change at remount */
if (((opts.flags ^ root->flags) & CGRP_ROOT_OPTION_MASK) ||
}
/* remounting is not allowed for populated hierarchies */
- if (root->number_of_cgroups > 1) {
+ if (!list_empty(&root->cgrp.children)) {
ret = -EBUSY;
goto out_unlock;
}
- ret = rebind_subsystems(root, added_mask, removed_mask);
+ ret = rebind_subsystems(root, added_mask);
if (ret)
goto out_unlock;
- if (opts.release_agent)
+ rebind_subsystems(&cgrp_dfl_root, removed_mask);
+
+ if (opts.release_agent) {
+ spin_lock(&release_agent_path_lock);
strcpy(root->release_agent_path, opts.release_agent);
+ spin_unlock(&release_agent_path_lock);
+ }
out_unlock:
kfree(opts.release_agent);
kfree(opts.name);
- mutex_unlock(&cgroup_root_mutex);
mutex_unlock(&cgroup_mutex);
- mutex_unlock(&cgrp->dentry->d_inode->i_mutex);
+ mutex_unlock(&cgroup_tree_mutex);
return ret;
}
- static const struct super_operations cgroup_ops = {
- .statfs = simple_statfs,
- .drop_inode = generic_delete_inode,
- .show_options = cgroup_show_options,
- .remount_fs = cgroup_remount,
- };
+ /*
+ * To reduce the fork() overhead for systems that are not actually using
+ * their cgroups capability, we don't maintain the lists running through
+ * each css_set to its tasks until we see the list actually used - in other
+ * words after the first mount.
+ */
+ static bool use_task_css_set_links __read_mostly;
+
+ static void cgroup_enable_task_cg_lists(void)
+ {
+ struct task_struct *p, *g;
+
+ down_write(&css_set_rwsem);
+
+ if (use_task_css_set_links)
+ goto out_unlock;
+
+ use_task_css_set_links = true;
+
+ /*
+ * We need tasklist_lock because RCU is not safe against
+ * while_each_thread(). Besides, a forking task that has passed
+ * cgroup_post_fork() without seeing use_task_css_set_links = 1
+ * is not guaranteed to have its child immediately visible in the
+ * tasklist if we walk through it with RCU.
+ */
+ read_lock(&tasklist_lock);
+ do_each_thread(g, p) {
+ WARN_ON_ONCE(!list_empty(&p->cg_list) ||
+ task_css_set(p) != &init_css_set);
+
+ /*
+ * We should check if the process is exiting, otherwise
+ * it will race with cgroup_exit() in that the list
+ * entry won't be deleted though the process has exited.
+ * Do it while holding siglock so that we don't end up
+ * racing against cgroup_exit().
+ */
+ spin_lock_irq(&p->sighand->siglock);
+ if (!(p->flags & PF_EXITING)) {
+ struct css_set *cset = task_css_set(p);
+
+ list_add(&p->cg_list, &cset->tasks);
+ get_css_set(cset);
+ }
+ spin_unlock_irq(&p->sighand->siglock);
+ } while_each_thread(g, p);
+ read_unlock(&tasklist_lock);
+ out_unlock:
+ up_write(&css_set_rwsem);
+ }
static void init_cgroup_housekeeping(struct cgroup *cgrp)
{
+ atomic_set(&cgrp->refcnt, 1);
INIT_LIST_HEAD(&cgrp->sibling);
INIT_LIST_HEAD(&cgrp->children);
- INIT_LIST_HEAD(&cgrp->files);
INIT_LIST_HEAD(&cgrp->cset_links);
INIT_LIST_HEAD(&cgrp->release_list);
INIT_LIST_HEAD(&cgrp->pidlists);
mutex_init(&cgrp->pidlist_mutex);
cgrp->dummy_css.cgroup = cgrp;
- simple_xattrs_init(&cgrp->xattrs);
}
- static void init_cgroup_root(struct cgroupfs_root *root)
+ static void init_cgroup_root(struct cgroup_root *root,
+ struct cgroup_sb_opts *opts)
{
- struct cgroup *cgrp = &root->top_cgroup;
+ struct cgroup *cgrp = &root->cgrp;
INIT_LIST_HEAD(&root->root_list);
- root->number_of_cgroups = 1;
+ atomic_set(&root->nr_cgrps, 1);
cgrp->root = root;
- RCU_INIT_POINTER(cgrp->name, &root_cgroup_name);
init_cgroup_housekeeping(cgrp);
idr_init(&root->cgroup_idr);
- }
-
- static int cgroup_init_root_id(struct cgroupfs_root *root, int start, int end)
- {
- int id;
-
- lockdep_assert_held(&cgroup_mutex);
- lockdep_assert_held(&cgroup_root_mutex);
-
- id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, start, end,
- GFP_KERNEL);
- if (id < 0)
- return id;
-
- root->hierarchy_id = id;
- return 0;
- }
-
- static void cgroup_exit_root_id(struct cgroupfs_root *root)
- {
- lockdep_assert_held(&cgroup_mutex);
- lockdep_assert_held(&cgroup_root_mutex);
-
- if (root->hierarchy_id) {
- idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id);
- root->hierarchy_id = 0;
- }
- }
-
- static int cgroup_test_super(struct super_block *sb, void *data)
- {
- struct cgroup_sb_opts *opts = data;
- struct cgroupfs_root *root = sb->s_fs_info;
-
- /* If we asked for a name then it must match */
- if (opts->name && strcmp(opts->name, root->name))
- return 0;
-
- /*
- * If we asked for subsystems (or explicitly for no
- * subsystems) then they must match
- */
- if ((opts->subsys_mask || opts->none)
- && (opts->subsys_mask != root->subsys_mask))
- return 0;
-
- return 1;
- }
-
- static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts)
- {
- struct cgroupfs_root *root;
-
- if (!opts->subsys_mask && !opts->none)
- return NULL;
-
- root = kzalloc(sizeof(*root), GFP_KERNEL);
- if (!root)
- return ERR_PTR(-ENOMEM);
- init_cgroup_root(root);
-
- /*
- * We need to set @root->subsys_mask now so that @root can be
- * matched by cgroup_test_super() before it finishes
- * initialization; otherwise, competing mounts with the same
- * options may try to bind the same subsystems instead of waiting
- * for the first one leading to unexpected mount errors.
- * SUBSYS_BOUND will be set once actual binding is complete.
- */
- root->subsys_mask = opts->subsys_mask;
root->flags = opts->flags;
if (opts->release_agent)
strcpy(root->release_agent_path, opts->release_agent);
if (opts->name)
strcpy(root->name, opts->name);
if (opts->cpuset_clone_children)
- set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->top_cgroup.flags);
- return root;
+ set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags);
}
- static void cgroup_free_root(struct cgroupfs_root *root)
+ static int cgroup_setup_root(struct cgroup_root *root, unsigned long ss_mask)
{
- if (root) {
- /* hierarhcy ID shoulid already have been released */
- WARN_ON_ONCE(root->hierarchy_id);
-
- idr_destroy(&root->cgroup_idr);
- kfree(root);
- }
- }
+ LIST_HEAD(tmp_links);
+ struct cgroup *root_cgrp = &root->cgrp;
+ struct css_set *cset;
+ int i, ret;
- static int cgroup_set_super(struct super_block *sb, void *data)
- {
- int ret;
- struct cgroup_sb_opts *opts = data;
+ lockdep_assert_held(&cgroup_tree_mutex);
+ lockdep_assert_held(&cgroup_mutex);
- /* If we don't have a new root, we can't set up a new sb */
- if (!opts->new_root)
- return -EINVAL;
+ ret = idr_alloc(&root->cgroup_idr, root_cgrp, 0, 1, GFP_KERNEL);
+ if (ret < 0)
+ goto out;
+ root_cgrp->id = ret;
- BUG_ON(!opts->subsys_mask && !opts->none);
+ /*
+ * We're accessing css_set_count without locking css_set_rwsem here,
+ * but that's OK - it can only be increased by someone holding
+ * cgroup_lock, and that's us. The worst that can happen is that we
+ * have some link structures left over
+ */
+ ret = allocate_cgrp_cset_links(css_set_count, &tmp_links);
+ if (ret)
+ goto out;
- ret = set_anon_super(sb, NULL);
+ ret = cgroup_init_root_id(root);
if (ret)
- return ret;
+ goto out;
- sb->s_fs_info = opts->new_root;
- opts->new_root->sb = sb;
+ root->kf_root = kernfs_create_root(&cgroup_kf_syscall_ops,
+ KERNFS_ROOT_CREATE_DEACTIVATED,
+ root_cgrp);
+ if (IS_ERR(root->kf_root)) {
+ ret = PTR_ERR(root->kf_root);
+ goto exit_root_id;
+ }
+ root_cgrp->kn = root->kf_root->kn;
- sb->s_blocksize = PAGE_CACHE_SIZE;
- sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
- sb->s_magic = CGROUP_SUPER_MAGIC;
- sb->s_op = &cgroup_ops;
+ ret = cgroup_addrm_files(root_cgrp, cgroup_base_files, true);
+ if (ret)
+ goto destroy_root;
- return 0;
- }
+ ret = rebind_subsystems(root, ss_mask);
+ if (ret)
+ goto destroy_root;
- static int cgroup_get_rootdir(struct super_block *sb)
- {
- static const struct dentry_operations cgroup_dops = {
- .d_iput = cgroup_diput,
- .d_delete = always_delete_dentry,
- };
+ /*
+ * There must be no failure case after here, since rebinding takes
+ * care of subsystems' refcounts, which are explicitly dropped in
+ * the failure exit path.
+ */
+ list_add(&root->root_list, &cgroup_roots);
+ cgroup_root_count++;
- struct inode *inode =
- cgroup_new_inode(S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR, sb);
+ /*
+ * Link the root cgroup in this hierarchy into all the css_set
+ * objects.
+ */
+ down_write(&css_set_rwsem);
+ hash_for_each(css_set_table, i, cset, hlist)
+ link_css_set(&tmp_links, cset, root_cgrp);
+ up_write(&css_set_rwsem);
- if (!inode)
- return -ENOMEM;
+ BUG_ON(!list_empty(&root_cgrp->children));
+ BUG_ON(atomic_read(&root->nr_cgrps) != 1);
- inode->i_fop = &simple_dir_operations;
- inode->i_op = &cgroup_dir_inode_operations;
- /* directories start off with i_nlink == 2 (for "." entry) */
- inc_nlink(inode);
- sb->s_root = d_make_root(inode);
- if (!sb->s_root)
- return -ENOMEM;
- /* for everything else we want ->d_op set */
- sb->s_d_op = &cgroup_dops;
- return 0;
+ kernfs_activate(root_cgrp->kn);
+ ret = 0;
+ goto out;
+
+ destroy_root:
+ kernfs_destroy_root(root->kf_root);
+ root->kf_root = NULL;
+ exit_root_id:
+ cgroup_exit_root_id(root);
+ out:
+ free_cgrp_cset_links(&tmp_links);
+ return ret;
}
static struct dentry *cgroup_mount(struct file_system_type *fs_type,
int flags, const char *unused_dev_name,
void *data)
{
+ struct cgroup_root *root;
struct cgroup_sb_opts opts;
- struct cgroupfs_root *root;
- int ret = 0;
- struct super_block *sb;
- struct cgroupfs_root *new_root;
- struct list_head tmp_links;
- struct inode *inode;
- const struct cred *cred;
+ struct dentry *dentry;
+ int ret;
- /* First find the desired set of subsystems */
+ /*
+ * The first time anyone tries to mount a cgroup, enable the list
+ * linking each css_set to its tasks and fix up all existing tasks.
+ */
+ if (!use_task_css_set_links)
+ cgroup_enable_task_cg_lists();
+ retry:
+ mutex_lock(&cgroup_tree_mutex);
mutex_lock(&cgroup_mutex);
+
+ /* First find the desired set of subsystems */
ret = parse_cgroupfs_options(data, &opts);
- mutex_unlock(&cgroup_mutex);
if (ret)
- goto out_err;
-
- /*
- * Allocate a new cgroup root. We may not need it if we're
- * reusing an existing hierarchy.
- */
- new_root = cgroup_root_from_opts(&opts);
- if (IS_ERR(new_root)) {
- ret = PTR_ERR(new_root);
- goto out_err;
- }
- opts.new_root = new_root;
+ goto out_unlock;
- /* Locate an existing or new sb for this hierarchy */
- sb = sget(fs_type, cgroup_test_super, cgroup_set_super, 0, &opts);
- if (IS_ERR(sb)) {
- ret = PTR_ERR(sb);
- cgroup_free_root(opts.new_root);
- goto out_err;
+ /* look for a matching existing root */
+ if (!opts.subsys_mask && !opts.none && !opts.name) {
+ cgrp_dfl_root_visible = true;
+ root = &cgrp_dfl_root;
+ cgroup_get(&root->cgrp);
+ ret = 0;
+ goto out_unlock;
}
- root = sb->s_fs_info;
- BUG_ON(!root);
- if (root == opts.new_root) {
- /* We used the new root structure, so this is a new hierarchy */
- struct cgroup *root_cgrp = &root->top_cgroup;
- struct cgroupfs_root *existing_root;
- int i;
- struct css_set *cset;
-
- BUG_ON(sb->s_root != NULL);
-
- ret = cgroup_get_rootdir(sb);
- if (ret)
- goto drop_new_super;
- inode = sb->s_root->d_inode;
-
- mutex_lock(&inode->i_mutex);
- mutex_lock(&cgroup_mutex);
- mutex_lock(&cgroup_root_mutex);
-
- ret = idr_alloc(&root->cgroup_idr, root_cgrp, 0, 1, GFP_KERNEL);
- if (ret < 0)
- goto unlock_drop;
- root_cgrp->id = ret;
-
- /* Check for name clashes with existing mounts */
- ret = -EBUSY;
- if (strlen(root->name))
- for_each_active_root(existing_root)
- if (!strcmp(existing_root->name, root->name))
- goto unlock_drop;
-
- /*
- * We're accessing css_set_count without locking
- * css_set_lock here, but that's OK - it can only be
- * increased by someone holding cgroup_lock, and
- * that's us. The worst that can happen is that we
- * have some link structures left over
- */
- ret = allocate_cgrp_cset_links(css_set_count, &tmp_links);
- if (ret)
- goto unlock_drop;
-
- /* ID 0 is reserved for dummy root, 1 for unified hierarchy */
- ret = cgroup_init_root_id(root, 2, 0);
- if (ret)
- goto unlock_drop;
-
- sb->s_root->d_fsdata = root_cgrp;
- root_cgrp->dentry = sb->s_root;
-
- /*
- * We're inside get_sb() and will call lookup_one_len() to
- * create the root files, which doesn't work if SELinux is
- * in use. The following cred dancing somehow works around
- * it. See 2ce9738ba ("cgroupfs: use init_cred when
- * populating new cgroupfs mount") for more details.
- */
- cred = override_creds(&init_cred);
-
- ret = cgroup_addrm_files(root_cgrp, cgroup_base_files, true);
- if (ret)
- goto rm_base_files;
+ for_each_root(root) {
+ bool name_match = false;
- ret = rebind_subsystems(root, root->subsys_mask, 0);
- if (ret)
- goto rm_base_files;
-
- revert_creds(cred);
+ if (root == &cgrp_dfl_root)
+ continue;
/*
- * There must be no failure case after here, since rebinding
- * takes care of subsystems' refcounts, which are explicitly
- * dropped in the failure exit path.
+ * If we asked for a name then it must match. Also, if
+ * name matches but sybsys_mask doesn't, we should fail.
+ * Remember whether name matched.
*/
+ if (opts.name) {
+ if (strcmp(opts.name, root->name))
+ continue;
+ name_match = true;
+ }
- list_add(&root->root_list, &cgroup_roots);
- cgroup_root_count++;
-
- /* Link the top cgroup in this hierarchy into all
- * the css_set objects */
- write_lock(&css_set_lock);
- hash_for_each(css_set_table, i, cset, hlist)
- link_css_set(&tmp_links, cset, root_cgrp);
- write_unlock(&css_set_lock);
-
- free_cgrp_cset_links(&tmp_links);
-
- BUG_ON(!list_empty(&root_cgrp->children));
- BUG_ON(root->number_of_cgroups != 1);
-
- mutex_unlock(&cgroup_root_mutex);
- mutex_unlock(&cgroup_mutex);
- mutex_unlock(&inode->i_mutex);
- } else {
/*
- * We re-used an existing hierarchy - the new root (if
- * any) is not needed
+ * If we asked for subsystems (or explicitly for no
+ * subsystems) then they must match.
*/
- cgroup_free_root(opts.new_root);
+ if ((opts.subsys_mask || opts.none) &&
+ (opts.subsys_mask != root->cgrp.subsys_mask)) {
+ if (!name_match)
+ continue;
+ ret = -EBUSY;
+ goto out_unlock;
+ }
if ((root->flags ^ opts.flags) & CGRP_ROOT_OPTION_MASK) {
if ((root->flags | opts.flags) & CGRP_ROOT_SANE_BEHAVIOR) {
pr_err("cgroup: sane_behavior: new mount options should match the existing superblock\n");
ret = -EINVAL;
- goto drop_new_super;
+ goto out_unlock;
} else {
pr_warning("cgroup: new mount options do not match the existing superblock, will be ignored\n");
}
}
- }
-
- kfree(opts.release_agent);
- kfree(opts.name);
- return dget(sb->s_root);
-
- rm_base_files:
- free_cgrp_cset_links(&tmp_links);
- cgroup_addrm_files(&root->top_cgroup, cgroup_base_files, false);
- revert_creds(cred);
- unlock_drop:
- cgroup_exit_root_id(root);
- mutex_unlock(&cgroup_root_mutex);
- mutex_unlock(&cgroup_mutex);
- mutex_unlock(&inode->i_mutex);
- drop_new_super:
- deactivate_locked_super(sb);
- out_err:
- kfree(opts.release_agent);
- kfree(opts.name);
- return ERR_PTR(ret);
- }
- static void cgroup_kill_sb(struct super_block *sb)
- {
- struct cgroupfs_root *root = sb->s_fs_info;
- struct cgroup *cgrp = &root->top_cgroup;
- struct cgrp_cset_link *link, *tmp_link;
- int ret;
+ /*
+ * A root's lifetime is governed by its root cgroup. Zero
+ * ref indicate that the root is being destroyed. Wait for
+ * destruction to complete so that the subsystems are free.
+ * We can use wait_queue for the wait but this path is
+ * super cold. Let's just sleep for a bit and retry.
+ */
+ if (!atomic_inc_not_zero(&root->cgrp.refcnt)) {
+ mutex_unlock(&cgroup_mutex);
+ mutex_unlock(&cgroup_tree_mutex);
+ kfree(opts.release_agent);
+ kfree(opts.name);
+ msleep(10);
+ goto retry;
+ }
- BUG_ON(!root);
-
- BUG_ON(root->number_of_cgroups != 1);
- BUG_ON(!list_empty(&cgrp->children));
-
- mutex_lock(&cgrp->dentry->d_inode->i_mutex);
- mutex_lock(&cgroup_mutex);
- mutex_lock(&cgroup_root_mutex);
-
- /* Rebind all subsystems back to the default hierarchy */
- if (root->flags & CGRP_ROOT_SUBSYS_BOUND) {
- ret = rebind_subsystems(root, 0, root->subsys_mask);
- /* Shouldn't be able to fail ... */
- BUG_ON(ret);
- }
+ ret = 0;
+ goto out_unlock;
+ }
/*
- * Release all the links from cset_links to this hierarchy's
- * root cgroup
+ * No such thing, create a new one. name= matching without subsys
+ * specification is allowed for already existing hierarchies but we
+ * can't create new one without subsys specification.
*/
- write_lock(&css_set_lock);
-
- list_for_each_entry_safe(link, tmp_link, &cgrp->cset_links, cset_link) {
- list_del(&link->cset_link);
- list_del(&link->cgrp_link);
- kfree(link);
+ if (!opts.subsys_mask && !opts.none) {
+ ret = -EINVAL;
+ goto out_unlock;
}
- write_unlock(&css_set_lock);
- if (!list_empty(&root->root_list)) {
- list_del(&root->root_list);
- cgroup_root_count--;
+ root = kzalloc(sizeof(*root), GFP_KERNEL);
+ if (!root) {
+ ret = -ENOMEM;
+ goto out_unlock;
}
- cgroup_exit_root_id(root);
+ init_cgroup_root(root, &opts);
+
+ ret = cgroup_setup_root(root, opts.subsys_mask);
+ if (ret)
+ cgroup_free_root(root);
- mutex_unlock(&cgroup_root_mutex);
+ out_unlock:
mutex_unlock(&cgroup_mutex);
- mutex_unlock(&cgrp->dentry->d_inode->i_mutex);
+ mutex_unlock(&cgroup_tree_mutex);
- simple_xattrs_free(&cgrp->xattrs);
+ kfree(opts.release_agent);
+ kfree(opts.name);
- kill_litter_super(sb);
- cgroup_free_root(root);
+ if (ret)
+ return ERR_PTR(ret);
+
- dentry = kernfs_mount(fs_type, flags, root->kf_root);
++ dentry = kernfs_mount(fs_type, flags, root->kf_root, NULL);
+ if (IS_ERR(dentry))
+ cgroup_put(&root->cgrp);
+ return dentry;
+ }
+
+ static void cgroup_kill_sb(struct super_block *sb)
+ {
+ struct kernfs_root *kf_root = kernfs_root_from_sb(sb);
+ struct cgroup_root *root = cgroup_root_from_kf(kf_root);
+
+ cgroup_put(&root->cgrp);
+ kernfs_kill_sb(sb);
}
static struct file_system_type cgroup_fs_type = {
static struct kobject *cgroup_kobj;
- /**
- * cgroup_path - generate the path of a cgroup
- * @cgrp: the cgroup in question
- * @buf: the buffer to write the path into
- * @buflen: the length of the buffer
- *
- * Writes path of cgroup into buf. Returns 0 on success, -errno on error.
- *
- * We can't generate cgroup path using dentry->d_name, as accessing
- * dentry->name must be protected by irq-unsafe dentry->d_lock or parent
- * inode's i_mutex, while on the other hand cgroup_path() can be called
- * with some irq-safe spinlocks held.
- */
- int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen)
- {
- int ret = -ENAMETOOLONG;
- char *start;
-
- if (!cgrp->parent) {
- if (strlcpy(buf, "/", buflen) >= buflen)
- return -ENAMETOOLONG;
- return 0;
- }
-
- start = buf + buflen - 1;
- *start = '\0';
-
- rcu_read_lock();
- do {
- const char *name = cgroup_name(cgrp);
- int len;
-
- len = strlen(name);
- if ((start -= len) < buf)
- goto out;
- memcpy(start, name, len);
-
- if (--start < buf)
- goto out;
- *start = '/';
-
- cgrp = cgrp->parent;
- } while (cgrp->parent);
- ret = 0;
- memmove(buf, start, buf + buflen - start);
- out:
- rcu_read_unlock();
- return ret;
- }
- EXPORT_SYMBOL_GPL(cgroup_path);
-
/**
* task_cgroup_path - cgroup path of a task in the first cgroup hierarchy
* @task: target task
* function grabs cgroup_mutex and shouldn't be used inside locks used by
* cgroup controller callbacks.
*
- * Returns 0 on success, fails with -%ENAMETOOLONG if @buflen is too short.
+ * Return value is the same as kernfs_path().
*/
- int task_cgroup_path(struct task_struct *task, char *buf, size_t buflen)
+ char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen)
{
- struct cgroupfs_root *root;
+ struct cgroup_root *root;
struct cgroup *cgrp;
- int hierarchy_id = 1, ret = 0;
-
- if (buflen < 2)
- return -ENAMETOOLONG;
+ int hierarchy_id = 1;
+ char *path = NULL;
mutex_lock(&cgroup_mutex);
+ down_read(&css_set_rwsem);
root = idr_get_next(&cgroup_hierarchy_idr, &hierarchy_id);
if (root) {
cgrp = task_cgroup_from_root(task, root);
- ret = cgroup_path(cgrp, buf, buflen);
+ path = cgroup_path(cgrp, buf, buflen);
} else {
/* if no hierarchy exists, everyone is in "/" */
- memcpy(buf, "/", 2);
+ if (strlcpy(buf, "/", buflen) < buflen)
+ path = buf;
}
+ up_read(&css_set_rwsem);
mutex_unlock(&cgroup_mutex);
- return ret;
+ return path;
}
EXPORT_SYMBOL_GPL(task_cgroup_path);
- /*
- * Control Group taskset
- */
- struct task_and_cgroup {
- struct task_struct *task;
- struct cgroup *cgrp;
- struct css_set *cset;
- };
-
+ /* used to track tasks and other necessary states during migration */
struct cgroup_taskset {
- struct task_and_cgroup single;
- struct flex_array *tc_array;
- int tc_array_len;
- int idx;
- struct cgroup *cur_cgrp;
+ /* the src and dst cset list running through cset->mg_node */
+ struct list_head src_csets;
+ struct list_head dst_csets;
+
+ /*
+ * Fields for cgroup_taskset_*() iteration.
+ *
+ * Before migration is committed, the target migration tasks are on
+ * ->mg_tasks of the csets on ->src_csets. After, on ->mg_tasks of
+ * the csets on ->dst_csets. ->csets point to either ->src_csets
+ * or ->dst_csets depending on whether migration is committed.
+ *
+ * ->cur_csets and ->cur_task point to the current task position
+ * during iteration.
+ */
+ struct list_head *csets;
+ struct css_set *cur_cset;
+ struct task_struct *cur_task;
};
/**
*/
struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset)
{
- if (tset->tc_array) {
- tset->idx = 0;
- return cgroup_taskset_next(tset);
- } else {
- tset->cur_cgrp = tset->single.cgrp;
- return tset->single.task;
- }
+ tset->cur_cset = list_first_entry(tset->csets, struct css_set, mg_node);
+ tset->cur_task = NULL;
+
+ return cgroup_taskset_next(tset);
}
- EXPORT_SYMBOL_GPL(cgroup_taskset_first);
/**
* cgroup_taskset_next - iterate to the next task in taskset
*/
struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset)
{
- struct task_and_cgroup *tc;
+ struct css_set *cset = tset->cur_cset;
+ struct task_struct *task = tset->cur_task;
- if (!tset->tc_array || tset->idx >= tset->tc_array_len)
- return NULL;
+ while (&cset->mg_node != tset->csets) {
+ if (!task)
+ task = list_first_entry(&cset->mg_tasks,
+ struct task_struct, cg_list);
+ else
+ task = list_next_entry(task, cg_list);
- tc = flex_array_get(tset->tc_array, tset->idx++);
- tset->cur_cgrp = tc->cgrp;
- return tc->task;
- }
- EXPORT_SYMBOL_GPL(cgroup_taskset_next);
+ if (&task->cg_list != &cset->mg_tasks) {
+ tset->cur_cset = cset;
+ tset->cur_task = task;
+ return task;
+ }
- /**
- * cgroup_taskset_cur_css - return the matching css for the current task
- * @tset: taskset of interest
- * @subsys_id: the ID of the target subsystem
- *
- * Return the css for the current (last returned) task of @tset for
- * subsystem specified by @subsys_id. This function must be preceded by
- * either cgroup_taskset_first() or cgroup_taskset_next().
- */
- struct cgroup_subsys_state *cgroup_taskset_cur_css(struct cgroup_taskset *tset,
- int subsys_id)
- {
- return cgroup_css(tset->cur_cgrp, cgroup_subsys[subsys_id]);
- }
- EXPORT_SYMBOL_GPL(cgroup_taskset_cur_css);
+ cset = list_next_entry(cset, mg_node);
+ task = NULL;
+ }
- /**
- * cgroup_taskset_size - return the number of tasks in taskset
- * @tset: taskset of interest
- */
- int cgroup_taskset_size(struct cgroup_taskset *tset)
- {
- return tset->tc_array ? tset->tc_array_len : 1;
+ return NULL;
}
- EXPORT_SYMBOL_GPL(cgroup_taskset_size);
-
- /*
+ /**
* cgroup_task_migrate - move a task from one cgroup to another.
+ * @old_cgrp; the cgroup @tsk is being migrated from
+ * @tsk: the task being migrated
+ * @new_cset: the new css_set @tsk is being attached to
*
- * Must be called with cgroup_mutex and threadgroup locked.
+ * Must be called with cgroup_mutex, threadgroup and css_set_rwsem locked.
*/
static void cgroup_task_migrate(struct cgroup *old_cgrp,
struct task_struct *tsk,
{
struct css_set *old_cset;
+ lockdep_assert_held(&cgroup_mutex);
+ lockdep_assert_held(&css_set_rwsem);
+
/*
* We are synchronized through threadgroup_lock() against PF_EXITING
* setting such that we can't race against cgroup_exit() changing the
WARN_ON_ONCE(tsk->flags & PF_EXITING);
old_cset = task_css_set(tsk);
- task_lock(tsk);
+ get_css_set(new_cset);
rcu_assign_pointer(tsk->cgroups, new_cset);
- task_unlock(tsk);
- /* Update the css_set linked lists if we're using them */
- write_lock(&css_set_lock);
- if (!list_empty(&tsk->cg_list))
- list_move(&tsk->cg_list, &new_cset->tasks);
- write_unlock(&css_set_lock);
+ /*
+ * Use move_tail so that cgroup_taskset_first() still returns the
+ * leader after migration. This works because cgroup_migrate()
+ * ensures that the dst_cset of the leader is the first on the
+ * tset's dst_csets list.
+ */
+ list_move_tail(&tsk->cg_list, &new_cset->mg_tasks);
/*
* We just gained a reference on old_cset by taking it from the
* we're safe to drop it here; it will be freed under RCU.
*/
set_bit(CGRP_RELEASABLE, &old_cgrp->flags);
- put_css_set(old_cset);
+ put_css_set_locked(old_cset, false);
}
/**
- * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup
- * @cgrp: the cgroup to attach to
- * @tsk: the task or the leader of the threadgroup to be attached
- * @threadgroup: attach the whole threadgroup?
+ * cgroup_migrate_finish - cleanup after attach
+ * @preloaded_csets: list of preloaded css_sets
*
- * Call holding cgroup_mutex and the group_rwsem of the leader. Will take
- * task_lock of @tsk or each thread in the threadgroup individually in turn.
+ * Undo cgroup_migrate_add_src() and cgroup_migrate_prepare_dst(). See
+ * those functions for details.
*/
- static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk,
- bool threadgroup)
+ static void cgroup_migrate_finish(struct list_head *preloaded_csets)
{
- int retval, i, group_size;
- struct cgroupfs_root *root = cgrp->root;
- struct cgroup_subsys_state *css, *failed_css = NULL;
- /* threadgroup list cursor and array */
- struct task_struct *leader = tsk;
- struct task_and_cgroup *tc;
- struct flex_array *group;
- struct cgroup_taskset tset = { };
+ struct css_set *cset, *tmp_cset;
- /*
- * step 0: in order to do expensive, possibly blocking operations for
- * every thread, we cannot iterate the thread group list, since it needs
- * rcu or tasklist locked. instead, build an array of all threads in the
- * group - group_rwsem prevents new threads from appearing, and if
- * threads exit, this will just be an over-estimate.
- */
- if (threadgroup)
- group_size = get_nr_threads(tsk);
- else
- group_size = 1;
- /* flex_array supports very large thread-groups better than kmalloc. */
- group = flex_array_alloc(sizeof(*tc), group_size, GFP_KERNEL);
- if (!group)
- return -ENOMEM;
- /* pre-allocate to guarantee space while iterating in rcu read-side. */
- retval = flex_array_prealloc(group, 0, group_size, GFP_KERNEL);
- if (retval)
- goto out_free_group_list;
+ lockdep_assert_held(&cgroup_mutex);
+
+ down_write(&css_set_rwsem);
+ list_for_each_entry_safe(cset, tmp_cset, preloaded_csets, mg_preload_node) {
+ cset->mg_src_cgrp = NULL;
+ cset->mg_dst_cset = NULL;
+ list_del_init(&cset->mg_preload_node);
+ put_css_set_locked(cset, false);
+ }
+ up_write(&css_set_rwsem);
+ }
+
+ /**
+ * cgroup_migrate_add_src - add a migration source css_set
+ * @src_cset: the source css_set to add
+ * @dst_cgrp: the destination cgroup
+ * @preloaded_csets: list of preloaded css_sets
+ *
+ * Tasks belonging to @src_cset are about to be migrated to @dst_cgrp. Pin
+ * @src_cset and add it to @preloaded_csets, which should later be cleaned
+ * up by cgroup_migrate_finish().
+ *
+ * This function may be called without holding threadgroup_lock even if the
+ * target is a process. Threads may be created and destroyed but as long
+ * as cgroup_mutex is not dropped, no new css_set can be put into play and
+ * the preloaded css_sets are guaranteed to cover all migrations.
+ */
+ static void cgroup_migrate_add_src(struct css_set *src_cset,
+ struct cgroup *dst_cgrp,
+ struct list_head *preloaded_csets)
+ {
+ struct cgroup *src_cgrp;
+
+ lockdep_assert_held(&cgroup_mutex);
+ lockdep_assert_held(&css_set_rwsem);
+
+ src_cgrp = cset_cgroup_from_root(src_cset, dst_cgrp->root);
+
+ /* nothing to do if this cset already belongs to the cgroup */
+ if (src_cgrp == dst_cgrp)
+ return;
+
+ if (!list_empty(&src_cset->mg_preload_node))
+ return;
+
+ WARN_ON(src_cset->mg_src_cgrp);
+ WARN_ON(!list_empty(&src_cset->mg_tasks));
+ WARN_ON(!list_empty(&src_cset->mg_node));
+
+ src_cset->mg_src_cgrp = src_cgrp;
+ get_css_set(src_cset);
+ list_add(&src_cset->mg_preload_node, preloaded_csets);
+ }
+
+ /**
+ * cgroup_migrate_prepare_dst - prepare destination css_sets for migration
+ * @dst_cgrp: the destination cgroup
+ * @preloaded_csets: list of preloaded source css_sets
+ *
+ * Tasks are about to be moved to @dst_cgrp and all the source css_sets
+ * have been preloaded to @preloaded_csets. This function looks up and
+ * pins all destination css_sets, links each to its source, and put them on
+ * @preloaded_csets.
+ *
+ * This function must be called after cgroup_migrate_add_src() has been
+ * called on each migration source css_set. After migration is performed
+ * using cgroup_migrate(), cgroup_migrate_finish() must be called on
+ * @preloaded_csets.
+ */
+ static int cgroup_migrate_prepare_dst(struct cgroup *dst_cgrp,
+ struct list_head *preloaded_csets)
+ {
+ LIST_HEAD(csets);
+ struct css_set *src_cset;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ /* look up the dst cset for each src cset and link it to src */
+ list_for_each_entry(src_cset, preloaded_csets, mg_preload_node) {
+ struct css_set *dst_cset;
+
+ dst_cset = find_css_set(src_cset, dst_cgrp);
+ if (!dst_cset)
+ goto err;
+
+ WARN_ON_ONCE(src_cset->mg_dst_cset || dst_cset->mg_dst_cset);
+ src_cset->mg_dst_cset = dst_cset;
+
+ if (list_empty(&dst_cset->mg_preload_node))
+ list_add(&dst_cset->mg_preload_node, &csets);
+ else
+ put_css_set(dst_cset, false);
+ }
+
+ list_splice(&csets, preloaded_csets);
+ return 0;
+ err:
+ cgroup_migrate_finish(&csets);
+ return -ENOMEM;
+ }
+
+ /**
+ * cgroup_migrate - migrate a process or task to a cgroup
+ * @cgrp: the destination cgroup
+ * @leader: the leader of the process or the task to migrate
+ * @threadgroup: whether @leader points to the whole process or a single task
+ *
+ * Migrate a process or task denoted by @leader to @cgrp. If migrating a
+ * process, the caller must be holding threadgroup_lock of @leader. The
+ * caller is also responsible for invoking cgroup_migrate_add_src() and
+ * cgroup_migrate_prepare_dst() on the targets before invoking this
+ * function and following up with cgroup_migrate_finish().
+ *
+ * As long as a controller's ->can_attach() doesn't fail, this function is
+ * guaranteed to succeed. This means that, excluding ->can_attach()
+ * failure, when migrating multiple targets, the success or failure can be
+ * decided for all targets by invoking group_migrate_prepare_dst() before
+ * actually starting migrating.
+ */
+ static int cgroup_migrate(struct cgroup *cgrp, struct task_struct *leader,
+ bool threadgroup)
+ {
+ struct cgroup_taskset tset = {
+ .src_csets = LIST_HEAD_INIT(tset.src_csets),
+ .dst_csets = LIST_HEAD_INIT(tset.dst_csets),
+ .csets = &tset.src_csets,
+ };
+ struct cgroup_subsys_state *css, *failed_css = NULL;
+ struct css_set *cset, *tmp_cset;
+ struct task_struct *task, *tmp_task;
+ int i, ret;
- i = 0;
/*
* Prevent freeing of tasks while we take a snapshot. Tasks that are
* already PF_EXITING could be freed from underneath us unless we
* take an rcu_read_lock.
*/
+ down_write(&css_set_rwsem);
rcu_read_lock();
+ task = leader;
do {
- struct task_and_cgroup ent;
+ /* @task either already exited or can't exit until the end */
+ if (task->flags & PF_EXITING)
+ goto next;
- /* @tsk either already exited or can't exit until the end */
- if (tsk->flags & PF_EXITING)
+ /* leave @task alone if post_fork() hasn't linked it yet */
+ if (list_empty(&task->cg_list))
goto next;
- /* as per above, nr_threads may decrease, but not increase. */
- BUG_ON(i >= group_size);
- ent.task = tsk;
- ent.cgrp = task_cgroup_from_root(tsk, root);
- /* nothing to do if this task is already in the cgroup */
- if (ent.cgrp == cgrp)
+ cset = task_css_set(task);
+ if (!cset->mg_src_cgrp)
goto next;
+
/*
- * saying GFP_ATOMIC has no effect here because we did prealloc
- * earlier, but it's good form to communicate our expectations.
+ * cgroup_taskset_first() must always return the leader.
+ * Take care to avoid disturbing the ordering.
*/
- retval = flex_array_put(group, i, &ent, GFP_ATOMIC);
- BUG_ON(retval != 0);
- i++;
+ list_move_tail(&task->cg_list, &cset->mg_tasks);
+ if (list_empty(&cset->mg_node))
+ list_add_tail(&cset->mg_node, &tset.src_csets);
+ if (list_empty(&cset->mg_dst_cset->mg_node))
+ list_move_tail(&cset->mg_dst_cset->mg_node,
+ &tset.dst_csets);
next:
if (!threadgroup)
break;
- } while_each_thread(leader, tsk);
+ } while_each_thread(leader, task);
rcu_read_unlock();
- /* remember the number of threads in the array for later. */
- group_size = i;
- tset.tc_array = group;
- tset.tc_array_len = group_size;
+ up_write(&css_set_rwsem);
/* methods shouldn't be called if no task is actually migrating */
- retval = 0;
- if (!group_size)
- goto out_free_group_list;
+ if (list_empty(&tset.src_csets))
+ return 0;
- /*
- * step 1: check that we can legitimately attach to the cgroup.
- */
+ /* check that we can legitimately attach to the cgroup */
for_each_css(css, i, cgrp) {
if (css->ss->can_attach) {
- retval = css->ss->can_attach(css, &tset);
- if (retval) {
+ ret = css->ss->can_attach(css, &tset);
+ if (ret) {
failed_css = css;
goto out_cancel_attach;
}
}
/*
- * step 2: make sure css_sets exist for all threads to be migrated.
- * we use find_css_set, which allocates a new one if necessary.
+ * Now that we're guaranteed success, proceed to move all tasks to
+ * the new cgroup. There are no failure cases after here, so this
+ * is the commit point.
*/
- for (i = 0; i < group_size; i++) {
- struct css_set *old_cset;
-
- tc = flex_array_get(group, i);
- old_cset = task_css_set(tc->task);
- tc->cset = find_css_set(old_cset, cgrp);
- if (!tc->cset) {
- retval = -ENOMEM;
- goto out_put_css_set_refs;
- }
+ down_write(&css_set_rwsem);
+ list_for_each_entry(cset, &tset.src_csets, mg_node) {
+ list_for_each_entry_safe(task, tmp_task, &cset->mg_tasks, cg_list)
+ cgroup_task_migrate(cset->mg_src_cgrp, task,
+ cset->mg_dst_cset);
}
+ up_write(&css_set_rwsem);
/*
- * step 3: now that we're guaranteed success wrt the css_sets,
- * proceed to move all tasks to the new cgroup. There are no
- * failure cases after here, so this is the commit point.
+ * Migration is committed, all target tasks are now on dst_csets.
+ * Nothing is sensitive to fork() after this point. Notify
+ * controllers that migration is complete.
*/
- for (i = 0; i < group_size; i++) {
- tc = flex_array_get(group, i);
- cgroup_task_migrate(tc->cgrp, tc->task, tc->cset);
- }
- /* nothing is sensitive to fork() after this point. */
+ tset.csets = &tset.dst_csets;
- /*
- * step 4: do subsystem attach callbacks.
- */
for_each_css(css, i, cgrp)
if (css->ss->attach)
css->ss->attach(css, &tset);
- /*
- * step 5: success! and cleanup
- */
- retval = 0;
- out_put_css_set_refs:
- if (retval) {
- for (i = 0; i < group_size; i++) {
- tc = flex_array_get(group, i);
- if (!tc->cset)
- break;
- put_css_set(tc->cset);
- }
- }
+ ret = 0;
+ goto out_release_tset;
+
out_cancel_attach:
- if (retval) {
- for_each_css(css, i, cgrp) {
- if (css == failed_css)
- break;
- if (css->ss->cancel_attach)
- css->ss->cancel_attach(css, &tset);
- }
+ for_each_css(css, i, cgrp) {
+ if (css == failed_css)
+ break;
+ if (css->ss->cancel_attach)
+ css->ss->cancel_attach(css, &tset);
}
- out_free_group_list:
- flex_array_free(group);
- return retval;
+ out_release_tset:
+ down_write(&css_set_rwsem);
+ list_splice_init(&tset.dst_csets, &tset.src_csets);
+ list_for_each_entry_safe(cset, tmp_cset, &tset.src_csets, mg_node) {
+ list_splice_tail_init(&cset->mg_tasks, &cset->tasks);
+ list_del_init(&cset->mg_node);
+ }
+ up_write(&css_set_rwsem);
+ return ret;
+ }
+
+ /**
+ * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup
+ * @dst_cgrp: the cgroup to attach to
+ * @leader: the task or the leader of the threadgroup to be attached
+ * @threadgroup: attach the whole threadgroup?
+ *
+ * Call holding cgroup_mutex and threadgroup_lock of @leader.
+ */
+ static int cgroup_attach_task(struct cgroup *dst_cgrp,
+ struct task_struct *leader, bool threadgroup)
+ {
+ LIST_HEAD(preloaded_csets);
+ struct task_struct *task;
+ int ret;
+
+ /* look up all src csets */
+ down_read(&css_set_rwsem);
+ rcu_read_lock();
+ task = leader;
+ do {
+ cgroup_migrate_add_src(task_css_set(task), dst_cgrp,
+ &preloaded_csets);
+ if (!threadgroup)
+ break;
+ } while_each_thread(leader, task);
+ rcu_read_unlock();
+ up_read(&css_set_rwsem);
+
+ /* prepare dst csets and commit */
+ ret = cgroup_migrate_prepare_dst(dst_cgrp, &preloaded_csets);
+ if (!ret)
+ ret = cgroup_migrate(dst_cgrp, leader, threadgroup);
+
+ cgroup_migrate_finish(&preloaded_csets);
+ return ret;
}
/*
* 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; may take task_lock of task.
+ * cgroup_mutex and threadgroup.
*/
static int attach_task_by_pid(struct cgroup *cgrp, u64 pid, bool threadgroup)
{
*/
int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
{
- struct cgroupfs_root *root;
+ struct cgroup_root *root;
int retval = 0;
mutex_lock(&cgroup_mutex);
- for_each_active_root(root) {
- struct cgroup *from_cgrp = task_cgroup_from_root(from, root);
+ for_each_root(root) {
+ struct cgroup *from_cgrp;
+
+ if (root == &cgrp_dfl_root)
+ continue;
+
+ down_read(&css_set_rwsem);
+ from_cgrp = task_cgroup_from_root(from, root);
+ up_read(&css_set_rwsem);
retval = cgroup_attach_task(from_cgrp, tsk, false);
if (retval)
}
static int cgroup_release_agent_write(struct cgroup_subsys_state *css,
- struct cftype *cft, const char *buffer)
+ struct cftype *cft, char *buffer)
{
- BUILD_BUG_ON(sizeof(css->cgroup->root->release_agent_path) < PATH_MAX);
- if (strlen(buffer) >= PATH_MAX)
- return -EINVAL;
+ struct cgroup_root *root = css->cgroup->root;
+
+ BUILD_BUG_ON(sizeof(root->release_agent_path) < PATH_MAX);
if (!cgroup_lock_live_group(css->cgroup))
return -ENODEV;
- mutex_lock(&cgroup_root_mutex);
- strcpy(css->cgroup->root->release_agent_path, buffer);
- mutex_unlock(&cgroup_root_mutex);
+ spin_lock(&release_agent_path_lock);
+ strlcpy(root->release_agent_path, buffer,
+ sizeof(root->release_agent_path));
+ spin_unlock(&release_agent_path_lock);
mutex_unlock(&cgroup_mutex);
return 0;
}
return 0;
}
- /* A buffer size big enough for numbers or short strings */
- #define CGROUP_LOCAL_BUFFER_SIZE 64
-
- static ssize_t cgroup_file_write(struct file *file, const char __user *userbuf,
- size_t nbytes, loff_t *ppos)
+ static ssize_t cgroup_file_write(struct kernfs_open_file *of, char *buf,
+ size_t nbytes, loff_t off)
{
- struct cfent *cfe = __d_cfe(file->f_dentry);
- struct cftype *cft = __d_cft(file->f_dentry);
- struct cgroup_subsys_state *css = cfe->css;
- size_t max_bytes = cft->max_write_len ?: CGROUP_LOCAL_BUFFER_SIZE - 1;
- char *buf;
+ struct cgroup *cgrp = of->kn->parent->priv;
+ struct cftype *cft = of->kn->priv;
+ struct cgroup_subsys_state *css;
int ret;
- if (nbytes >= max_bytes)
- return -E2BIG;
-
- buf = kmalloc(nbytes + 1, GFP_KERNEL);
- if (!buf)
- return -ENOMEM;
-
- if (copy_from_user(buf, userbuf, nbytes)) {
- ret = -EFAULT;
- goto out_free;
- }
-
- buf[nbytes] = '\0';
+ /*
+ * kernfs guarantees that a file isn't deleted with operations in
+ * flight, which means that the matching css is and stays alive and
+ * doesn't need to be pinned. The RCU locking is not necessary
+ * either. It's just for the convenience of using cgroup_css().
+ */
+ rcu_read_lock();
+ css = cgroup_css(cgrp, cft->ss);
+ rcu_read_unlock();
if (cft->write_string) {
ret = cft->write_string(css, cft, strstrip(buf));
} else {
ret = -EINVAL;
}
- out_free:
- kfree(buf);
+
return ret ?: nbytes;
}
- /*
- * seqfile ops/methods for returning structured data. Currently just
- * supports string->u64 maps, but can be extended in future.
- */
-
static void *cgroup_seqfile_start(struct seq_file *seq, loff_t *ppos)
{
- struct cftype *cft = seq_cft(seq);
-
- if (cft->seq_start) {
- return cft->seq_start(seq, ppos);
- } else {
- /*
- * The same behavior and code as single_open(). Returns
- * !NULL if pos is at the beginning; otherwise, NULL.
- */
- return NULL + !*ppos;
- }
+ return seq_cft(seq)->seq_start(seq, ppos);
}
static void *cgroup_seqfile_next(struct seq_file *seq, void *v, loff_t *ppos)
{
- struct cftype *cft = seq_cft(seq);
-
- if (cft->seq_next) {
- return cft->seq_next(seq, v, ppos);
- } else {
- /*
- * The same behavior and code as single_open(), always
- * terminate after the initial read.
- */
- ++*ppos;
- return NULL;
- }
+ return seq_cft(seq)->seq_next(seq, v, ppos);
}
static void cgroup_seqfile_stop(struct seq_file *seq, void *v)
{
- struct cftype *cft = seq_cft(seq);
-
- if (cft->seq_stop)
- cft->seq_stop(seq, v);
+ seq_cft(seq)->seq_stop(seq, v);
}
static int cgroup_seqfile_show(struct seq_file *m, void *arg)
return 0;
}
- static struct seq_operations cgroup_seq_operations = {
- .start = cgroup_seqfile_start,
- .next = cgroup_seqfile_next,
- .stop = cgroup_seqfile_stop,
- .show = cgroup_seqfile_show,
+ static struct kernfs_ops cgroup_kf_single_ops = {
+ .atomic_write_len = PAGE_SIZE,
+ .write = cgroup_file_write,
+ .seq_show = cgroup_seqfile_show,
};
- static int cgroup_file_open(struct inode *inode, struct file *file)
- {
- struct cfent *cfe = __d_cfe(file->f_dentry);
- struct cftype *cft = __d_cft(file->f_dentry);
- struct cgroup *cgrp = __d_cgrp(cfe->dentry->d_parent);
- struct cgroup_subsys_state *css;
- struct cgroup_open_file *of;
- int err;
-
- err = generic_file_open(inode, file);
- if (err)
- return err;
-
- /*
- * If the file belongs to a subsystem, pin the css. Will be
- * unpinned either on open failure or release. This ensures that
- * @css stays alive for all file operations.
- */
- rcu_read_lock();
- css = cgroup_css(cgrp, cft->ss);
- if (cft->ss && !css_tryget(css))
- css = NULL;
- rcu_read_unlock();
-
- if (!css)
- return -ENODEV;
-
- /*
- * @cfe->css is used by read/write/close to determine the
- * associated css. @file->private_data would be a better place but
- * that's already used by seqfile. Multiple accessors may use it
- * simultaneously which is okay as the association never changes.
- */
- WARN_ON_ONCE(cfe->css && cfe->css != css);
- cfe->css = css;
-
- of = __seq_open_private(file, &cgroup_seq_operations,
- sizeof(struct cgroup_open_file));
- if (of) {
- of->cfe = cfe;
- return 0;
- }
-
- if (css->ss)
- css_put(css);
- return -ENOMEM;
- }
-
- static int cgroup_file_release(struct inode *inode, struct file *file)
- {
- struct cfent *cfe = __d_cfe(file->f_dentry);
- struct cgroup_subsys_state *css = cfe->css;
-
- if (css->ss)
- css_put(css);
- return seq_release_private(inode, file);
- }
+ static struct kernfs_ops cgroup_kf_ops = {
+ .atomic_write_len = PAGE_SIZE,
+ .write = cgroup_file_write,
+ .seq_start = cgroup_seqfile_start,
+ .seq_next = cgroup_seqfile_next,
+ .seq_stop = cgroup_seqfile_stop,
+ .seq_show = cgroup_seqfile_show,
+ };
/*
* cgroup_rename - Only allow simple rename of directories in place.
*/
- static int cgroup_rename(struct inode *old_dir, struct dentry *old_dentry,
- struct inode *new_dir, struct dentry *new_dentry)
+ static int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
+ const char *new_name_str)
{
+ struct cgroup *cgrp = kn->priv;
int ret;
- struct cgroup_name *name, *old_name;
- struct cgroup *cgrp;
-
- /*
- * It's convinient to use parent dir's i_mutex to protected
- * cgrp->name.
- */
- lockdep_assert_held(&old_dir->i_mutex);
- if (!S_ISDIR(old_dentry->d_inode->i_mode))
+ if (kernfs_type(kn) != KERNFS_DIR)
return -ENOTDIR;
- if (new_dentry->d_inode)
- return -EEXIST;
- if (old_dir != new_dir)
+ if (kn->parent != new_parent)
return -EIO;
- cgrp = __d_cgrp(old_dentry);
-
/*
* This isn't a proper migration and its usefulness is very
* limited. Disallow if sane_behavior.
- */
- if (cgroup_sane_behavior(cgrp))
- return -EPERM;
-
- name = cgroup_alloc_name(new_dentry);
- if (!name)
- return -ENOMEM;
-
- ret = simple_rename(old_dir, old_dentry, new_dir, new_dentry);
- if (ret) {
- kfree(name);
- return ret;
- }
-
- old_name = rcu_dereference_protected(cgrp->name, true);
- rcu_assign_pointer(cgrp->name, name);
-
- kfree_rcu(old_name, rcu_head);
- return 0;
- }
-
- static struct simple_xattrs *__d_xattrs(struct dentry *dentry)
- {
- if (S_ISDIR(dentry->d_inode->i_mode))
- return &__d_cgrp(dentry)->xattrs;
- else
- return &__d_cfe(dentry)->xattrs;
- }
-
- static inline int xattr_enabled(struct dentry *dentry)
- {
- struct cgroupfs_root *root = dentry->d_sb->s_fs_info;
- return root->flags & CGRP_ROOT_XATTR;
- }
-
- static bool is_valid_xattr(const char *name)
- {
- if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) ||
- !strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN))
- return true;
- return false;
- }
-
- static int cgroup_setxattr(struct dentry *dentry, const char *name,
- const void *val, size_t size, int flags)
- {
- if (!xattr_enabled(dentry))
- return -EOPNOTSUPP;
- if (!is_valid_xattr(name))
- return -EINVAL;
- return simple_xattr_set(__d_xattrs(dentry), name, val, size, flags);
- }
-
- static int cgroup_removexattr(struct dentry *dentry, const char *name)
- {
- if (!xattr_enabled(dentry))
- return -EOPNOTSUPP;
- if (!is_valid_xattr(name))
- return -EINVAL;
- return simple_xattr_remove(__d_xattrs(dentry), name);
- }
-
- static ssize_t cgroup_getxattr(struct dentry *dentry, const char *name,
- void *buf, size_t size)
- {
- if (!xattr_enabled(dentry))
- return -EOPNOTSUPP;
- if (!is_valid_xattr(name))
- return -EINVAL;
- return simple_xattr_get(__d_xattrs(dentry), name, buf, size);
- }
-
- static ssize_t cgroup_listxattr(struct dentry *dentry, char *buf, size_t size)
- {
- if (!xattr_enabled(dentry))
- return -EOPNOTSUPP;
- return simple_xattr_list(__d_xattrs(dentry), buf, size);
- }
-
- static const struct file_operations cgroup_file_operations = {
- .read = seq_read,
- .write = cgroup_file_write,
- .llseek = generic_file_llseek,
- .open = cgroup_file_open,
- .release = cgroup_file_release,
- };
-
- static const struct inode_operations cgroup_file_inode_operations = {
- .setxattr = cgroup_setxattr,
- .getxattr = cgroup_getxattr,
- .listxattr = cgroup_listxattr,
- .removexattr = cgroup_removexattr,
- };
-
- static const struct inode_operations cgroup_dir_inode_operations = {
- .lookup = simple_lookup,
- .mkdir = cgroup_mkdir,
- .rmdir = cgroup_rmdir,
- .rename = cgroup_rename,
- .setxattr = cgroup_setxattr,
- .getxattr = cgroup_getxattr,
- .listxattr = cgroup_listxattr,
- .removexattr = cgroup_removexattr,
- };
-
- static int cgroup_create_file(struct dentry *dentry, umode_t mode,
- struct super_block *sb)
- {
- struct inode *inode;
-
- if (!dentry)
- return -ENOENT;
- if (dentry->d_inode)
- return -EEXIST;
-
- inode = cgroup_new_inode(mode, sb);
- if (!inode)
- return -ENOMEM;
-
- if (S_ISDIR(mode)) {
- inode->i_op = &cgroup_dir_inode_operations;
- inode->i_fop = &simple_dir_operations;
-
- /* start off with i_nlink == 2 (for "." entry) */
- inc_nlink(inode);
- inc_nlink(dentry->d_parent->d_inode);
-
- /*
- * Control reaches here with cgroup_mutex held.
- * @inode->i_mutex should nest outside cgroup_mutex but we
- * want to populate it immediately without releasing
- * cgroup_mutex. As @inode isn't visible to anyone else
- * yet, trylock will always succeed without affecting
- * lockdep checks.
- */
- WARN_ON_ONCE(!mutex_trylock(&inode->i_mutex));
- } else if (S_ISREG(mode)) {
- inode->i_size = 0;
- inode->i_fop = &cgroup_file_operations;
- inode->i_op = &cgroup_file_inode_operations;
- }
- d_instantiate(dentry, inode);
- dget(dentry); /* Extra count - pin the dentry in core */
- return 0;
- }
-
- /**
- * cgroup_file_mode - deduce file mode of a control file
- * @cft: the control file in question
- *
- * returns cft->mode if ->mode is not 0
- * returns S_IRUGO|S_IWUSR if it has both a read and a write handler
- * returns S_IRUGO if it has only a read handler
- * returns S_IWUSR if it has only a write hander
- */
- static umode_t cgroup_file_mode(const struct cftype *cft)
- {
- umode_t mode = 0;
+ */
+ if (cgroup_sane_behavior(cgrp))
+ return -EPERM;
- if (cft->mode)
- return cft->mode;
+ /*
+ * We're gonna grab cgroup_tree_mutex which nests outside kernfs
+ * active_ref. kernfs_rename() doesn't require active_ref
+ * protection. Break them before grabbing cgroup_tree_mutex.
+ */
+ kernfs_break_active_protection(new_parent);
+ kernfs_break_active_protection(kn);
- if (cft->read_u64 || cft->read_s64 || cft->seq_show)
- mode |= S_IRUGO;
+ mutex_lock(&cgroup_tree_mutex);
+ mutex_lock(&cgroup_mutex);
- if (cft->write_u64 || cft->write_s64 || cft->write_string ||
- cft->trigger)
- mode |= S_IWUSR;
+ ret = kernfs_rename(kn, new_parent, new_name_str);
- return mode;
+ mutex_unlock(&cgroup_mutex);
+ mutex_unlock(&cgroup_tree_mutex);
+
+ kernfs_unbreak_active_protection(kn);
+ kernfs_unbreak_active_protection(new_parent);
+ return ret;
}
static int cgroup_add_file(struct cgroup *cgrp, struct cftype *cft)
{
- struct dentry *dir = cgrp->dentry;
- struct cgroup *parent = __d_cgrp(dir);
- struct dentry *dentry;
- struct cfent *cfe;
- int error;
- umode_t mode;
- char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 };
-
- if (cft->ss && !(cft->flags & CFTYPE_NO_PREFIX) &&
- !(cgrp->root->flags & CGRP_ROOT_NOPREFIX)) {
- strcpy(name, cft->ss->name);
- strcat(name, ".");
- }
- strcat(name, cft->name);
-
- BUG_ON(!mutex_is_locked(&dir->d_inode->i_mutex));
-
- cfe = kzalloc(sizeof(*cfe), GFP_KERNEL);
- if (!cfe)
- return -ENOMEM;
+ char name[CGROUP_FILE_NAME_MAX];
+ struct kernfs_node *kn;
+ struct lock_class_key *key = NULL;
- dentry = lookup_one_len(name, dir, strlen(name));
- if (IS_ERR(dentry)) {
- error = PTR_ERR(dentry);
- goto out;
- }
-
- cfe->type = (void *)cft;
- cfe->dentry = dentry;
- dentry->d_fsdata = cfe;
- simple_xattrs_init(&cfe->xattrs);
-
- mode = cgroup_file_mode(cft);
- error = cgroup_create_file(dentry, mode | S_IFREG, cgrp->root->sb);
- if (!error) {
- list_add_tail(&cfe->node, &parent->files);
- cfe = NULL;
- }
- dput(dentry);
- out:
- kfree(cfe);
- return error;
+ #ifdef CONFIG_DEBUG_LOCK_ALLOC
+ key = &cft->lockdep_key;
+ #endif
+ kn = __kernfs_create_file(cgrp->kn, cgroup_file_name(cgrp, cft, name),
+ cgroup_file_mode(cft), 0, cft->kf_ops, cft,
+ NULL, false, key);
+ return PTR_ERR_OR_ZERO(kn);
}
/**
struct cftype *cft;
int ret;
- lockdep_assert_held(&cgrp->dentry->d_inode->i_mutex);
- lockdep_assert_held(&cgroup_mutex);
+ lockdep_assert_held(&cgroup_tree_mutex);
for (cft = cfts; cft->name[0] != '\0'; cft++) {
/* does cft->flags tell us to skip this file on @cgrp? */
+ if ((cft->flags & CFTYPE_ONLY_ON_DFL) && !cgroup_on_dfl(cgrp))
+ continue;
if ((cft->flags & CFTYPE_INSANE) && cgroup_sane_behavior(cgrp))
continue;
if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgrp->parent)
return 0;
}
- static void cgroup_cfts_prepare(void)
- __acquires(&cgroup_mutex)
- {
- /*
- * Thanks to the entanglement with vfs inode locking, we can't walk
- * the existing cgroups under cgroup_mutex and create files.
- * Instead, we use css_for_each_descendant_pre() and drop RCU read
- * lock before calling cgroup_addrm_files().
- */
- mutex_lock(&cgroup_mutex);
- }
-
- static int cgroup_cfts_commit(struct cftype *cfts, bool is_add)
- __releases(&cgroup_mutex)
+ 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->top_cgroup;
- struct super_block *sb = ss->root->sb;
- struct dentry *prev = NULL;
- struct inode *inode;
+ struct cgroup *root = &ss->root->cgrp;
struct cgroup_subsys_state *css;
- u64 update_before;
int ret = 0;
- /* %NULL @cfts indicates abort and don't bother if @ss isn't attached */
- if (!cfts || ss->root == &cgroup_dummy_root ||
- !atomic_inc_not_zero(&sb->s_active)) {
- mutex_unlock(&cgroup_mutex);
- return 0;
- }
+ lockdep_assert_held(&cgroup_tree_mutex);
- /*
- * All cgroups which are created after we drop cgroup_mutex will
- * have the updated set of files, so we only need to update the
- * cgroups created before the current @cgroup_serial_nr_next.
- */
- update_before = cgroup_serial_nr_next;
+ /* don't bother if @ss isn't attached */
+ if (ss->root == &cgrp_dfl_root)
+ return 0;
/* add/rm files for all cgroups created before */
css_for_each_descendant_pre(css, cgroup_css(root, ss)) {
if (cgroup_is_dead(cgrp))
continue;
- inode = cgrp->dentry->d_inode;
- dget(cgrp->dentry);
- dput(prev);
- prev = cgrp->dentry;
-
- mutex_unlock(&cgroup_mutex);
- mutex_lock(&inode->i_mutex);
- mutex_lock(&cgroup_mutex);
- if (cgrp->serial_nr < update_before && !cgroup_is_dead(cgrp))
- ret = cgroup_addrm_files(cgrp, cfts, is_add);
- mutex_unlock(&inode->i_mutex);
+ ret = cgroup_addrm_files(cgrp, cfts, is_add);
if (ret)
break;
}
- mutex_unlock(&cgroup_mutex);
- dput(prev);
- deactivate_super(sb);
+
+ if (is_add && !ret)
+ kernfs_activate(root->kn);
return ret;
}
- /**
- * cgroup_add_cftypes - add an array of cftypes to a subsystem
- * @ss: target cgroup subsystem
- * @cfts: zero-length name terminated array of cftypes
- *
- * Register @cfts to @ss. Files described by @cfts are created for all
- * existing cgroups to which @ss is attached and all future cgroups will
- * have them too. This function can be called anytime whether @ss is
- * attached or not.
- *
- * Returns 0 on successful registration, -errno on failure. Note that this
- * function currently returns 0 as long as @cfts registration is successful
- * even if some file creation attempts on existing cgroups fail.
- */
- int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
+ static void cgroup_exit_cftypes(struct cftype *cfts)
{
- struct cftype_set *set;
struct cftype *cft;
- int ret;
- set = kzalloc(sizeof(*set), GFP_KERNEL);
- if (!set)
- return -ENOMEM;
+ for (cft = cfts; cft->name[0] != '\0'; cft++) {
+ /* free copy for custom atomic_write_len, see init_cftypes() */
+ if (cft->max_write_len && cft->max_write_len != PAGE_SIZE)
+ kfree(cft->kf_ops);
+ cft->kf_ops = NULL;
+ cft->ss = NULL;
+ }
+ }
+
+ static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
+ {
+ struct cftype *cft;
+
+ for (cft = cfts; cft->name[0] != '\0'; cft++) {
+ struct kernfs_ops *kf_ops;
+
+ WARN_ON(cft->ss || cft->kf_ops);
+
+ if (cft->seq_start)
+ kf_ops = &cgroup_kf_ops;
+ else
+ kf_ops = &cgroup_kf_single_ops;
+
+ /*
+ * Ugh... if @cft wants a custom max_write_len, we need to
+ * make a copy of kf_ops to set its atomic_write_len.
+ */
+ if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) {
+ kf_ops = kmemdup(kf_ops, sizeof(*kf_ops), GFP_KERNEL);
+ if (!kf_ops) {
+ cgroup_exit_cftypes(cfts);
+ return -ENOMEM;
+ }
+ kf_ops->atomic_write_len = cft->max_write_len;
+ }
- for (cft = cfts; cft->name[0] != '\0'; cft++)
+ cft->kf_ops = kf_ops;
cft->ss = ss;
+ }
- cgroup_cfts_prepare();
- set->cfts = cfts;
- list_add_tail(&set->node, &ss->cftsets);
- ret = cgroup_cfts_commit(cfts, true);
- if (ret)
- cgroup_rm_cftypes(cfts);
- return ret;
+ return 0;
+ }
+
+ static int cgroup_rm_cftypes_locked(struct cftype *cfts)
+ {
+ lockdep_assert_held(&cgroup_tree_mutex);
+
+ if (!cfts || !cfts[0].ss)
+ return -ENOENT;
+
+ list_del(&cfts->node);
+ cgroup_apply_cftypes(cfts, false);
+ cgroup_exit_cftypes(cfts);
+ return 0;
}
- EXPORT_SYMBOL_GPL(cgroup_add_cftypes);
/**
* cgroup_rm_cftypes - remove an array of cftypes from a subsystem
*/
int cgroup_rm_cftypes(struct cftype *cfts)
{
- struct cftype_set *set;
+ int ret;
- if (!cfts || !cfts[0].ss)
- return -ENOENT;
+ mutex_lock(&cgroup_tree_mutex);
+ ret = cgroup_rm_cftypes_locked(cfts);
+ mutex_unlock(&cgroup_tree_mutex);
+ return ret;
+ }
+
+ /**
+ * cgroup_add_cftypes - add an array of cftypes to a subsystem
+ * @ss: target cgroup subsystem
+ * @cfts: zero-length name terminated array of cftypes
+ *
+ * Register @cfts to @ss. Files described by @cfts are created for all
+ * existing cgroups to which @ss is attached and all future cgroups will
+ * have them too. This function can be called anytime whether @ss is
+ * attached or not.
+ *
+ * Returns 0 on successful registration, -errno on failure. Note that this
+ * function currently returns 0 as long as @cfts registration is successful
+ * even if some file creation attempts on existing cgroups fail.
+ */
+ int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
+ {
+ int ret;
+
+ if (!cfts || cfts[0].name[0] == '\0')
+ return 0;
- cgroup_cfts_prepare();
+ ret = cgroup_init_cftypes(ss, cfts);
+ if (ret)
+ return ret;
- list_for_each_entry(set, &cfts[0].ss->cftsets, node) {
- if (set->cfts == cfts) {
- list_del(&set->node);
- kfree(set);
- cgroup_cfts_commit(cfts, false);
- return 0;
- }
- }
+ mutex_lock(&cgroup_tree_mutex);
+
+ list_add_tail(&cfts->node, &ss->cfts);
+ ret = cgroup_apply_cftypes(cfts, true);
+ if (ret)
+ cgroup_rm_cftypes_locked(cfts);
- cgroup_cfts_commit(NULL, false);
- return -ENOENT;
+ mutex_unlock(&cgroup_tree_mutex);
+ return ret;
}
/**
*
* Return the number of tasks in the cgroup.
*/
- int cgroup_task_count(const struct cgroup *cgrp)
+ static int cgroup_task_count(const struct cgroup *cgrp)
{
int count = 0;
struct cgrp_cset_link *link;
- read_lock(&css_set_lock);
+ down_read(&css_set_rwsem);
list_for_each_entry(link, &cgrp->cset_links, cset_link)
count += atomic_read(&link->cset->refcount);
- read_unlock(&css_set_lock);
+ up_read(&css_set_rwsem);
return count;
}
- /*
- * To reduce the fork() overhead for systems that are not actually using
- * their cgroups capability, we don't maintain the lists running through
- * each css_set to its tasks until we see the list actually used - in other
- * words after the first call to css_task_iter_start().
- */
- static void cgroup_enable_task_cg_lists(void)
- {
- struct task_struct *p, *g;
- write_lock(&css_set_lock);
- use_task_css_set_links = 1;
- /*
- * We need tasklist_lock because RCU is not safe against
- * while_each_thread(). Besides, a forking task that has passed
- * cgroup_post_fork() without seeing use_task_css_set_links = 1
- * is not guaranteed to have its child immediately visible in the
- * tasklist if we walk through it with RCU.
- */
- read_lock(&tasklist_lock);
- do_each_thread(g, p) {
- task_lock(p);
- /*
- * We should check if the process is exiting, otherwise
- * it will race with cgroup_exit() in that the list
- * entry won't be deleted though the process has exited.
- * Do it while holding siglock so that we don't end up
- * racing against cgroup_exit().
- */
- spin_lock_irq(&p->sighand->siglock);
- if (!(p->flags & PF_EXITING) && list_empty(&p->cg_list))
- list_add(&p->cg_list, &task_css_set(p)->tasks);
- spin_unlock_irq(&p->sighand->siglock);
-
- task_unlock(p);
- } while_each_thread(g, p);
- read_unlock(&tasklist_lock);
- write_unlock(&css_set_lock);
- }
-
/**
* css_next_child - find the next child of a given css
* @pos_css: the current position (%NULL to initiate traversal)
struct cgroup *cgrp = parent_css->cgroup;
struct cgroup *next;
- cgroup_assert_mutex_or_rcu_locked();
+ cgroup_assert_mutexes_or_rcu_locked();
/*
* @pos could already have been removed. Once a cgroup is removed,
return cgroup_css(next, parent_css->ss);
}
- EXPORT_SYMBOL_GPL(css_next_child);
/**
* css_next_descendant_pre - find the next descendant for pre-order walk
{
struct cgroup_subsys_state *next;
- cgroup_assert_mutex_or_rcu_locked();
+ cgroup_assert_mutexes_or_rcu_locked();
/* if first iteration, visit @root */
if (!pos)
return NULL;
}
- EXPORT_SYMBOL_GPL(css_next_descendant_pre);
/**
* css_rightmost_descendant - return the rightmost descendant of a css
{
struct cgroup_subsys_state *last, *tmp;
- cgroup_assert_mutex_or_rcu_locked();
+ cgroup_assert_mutexes_or_rcu_locked();
do {
last = pos;
return last;
}
- EXPORT_SYMBOL_GPL(css_rightmost_descendant);
static struct cgroup_subsys_state *
css_leftmost_descendant(struct cgroup_subsys_state *pos)
{
struct cgroup_subsys_state *next;
- cgroup_assert_mutex_or_rcu_locked();
+ cgroup_assert_mutexes_or_rcu_locked();
/* if first iteration, visit leftmost descendant which may be @root */
if (!pos)
/* no sibling left, visit parent */
return css_parent(pos);
}
- EXPORT_SYMBOL_GPL(css_next_descendant_post);
/**
* css_advance_task_iter - advance a task itererator to the next css_set
}
link = list_entry(l, struct cgrp_cset_link, cset_link);
cset = link->cset;
- } while (list_empty(&cset->tasks));
+ } while (list_empty(&cset->tasks) && list_empty(&cset->mg_tasks));
+
it->cset_link = l;
- it->task = cset->tasks.next;
+
+ if (!list_empty(&cset->tasks))
+ it->task = cset->tasks.next;
+ else
+ it->task = cset->mg_tasks.next;
}
/**
*/
void css_task_iter_start(struct cgroup_subsys_state *css,
struct css_task_iter *it)
- __acquires(css_set_lock)
+ __acquires(css_set_rwsem)
{
- /*
- * The first time anyone tries to iterate across a css, we need to
- * enable the list linking each css_set to its tasks, and fix up
- * all existing tasks.
- */
- if (!use_task_css_set_links)
- cgroup_enable_task_cg_lists();
+ /* no one should try to iterate before mounting cgroups */
+ WARN_ON_ONCE(!use_task_css_set_links);
- read_lock(&css_set_lock);
+ down_read(&css_set_rwsem);
it->origin_css = css;
it->cset_link = &css->cgroup->cset_links;
{
struct task_struct *res;
struct list_head *l = it->task;
- struct cgrp_cset_link *link;
+ struct cgrp_cset_link *link = list_entry(it->cset_link,
+ struct cgrp_cset_link, cset_link);
/* If the iterator cg is NULL, we have no tasks */
if (!it->cset_link)
return NULL;
res = list_entry(l, struct task_struct, cg_list);
- /* Advance iterator to find next entry */
+
+ /*
+ * Advance iterator to find next entry. cset->tasks is consumed
+ * first and then ->mg_tasks. After ->mg_tasks, we move onto the
+ * next cset.
+ */
l = l->next;
- link = list_entry(it->cset_link, struct cgrp_cset_link, cset_link);
- if (l == &link->cset->tasks) {
- /*
- * We reached the end of this task list - move on to the
- * next cgrp_cset_link.
- */
+
+ if (l == &link->cset->tasks)
+ l = link->cset->mg_tasks.next;
+
+ if (l == &link->cset->mg_tasks)
css_advance_task_iter(it);
- } else {
+ else
it->task = l;
- }
+
return res;
}
* Finish task iteration started by css_task_iter_start().
*/
void css_task_iter_end(struct css_task_iter *it)
- __releases(css_set_lock)
- {
- read_unlock(&css_set_lock);
- }
-
- static inline int started_after_time(struct task_struct *t1,
- struct timespec *time,
- struct task_struct *t2)
- {
- int start_diff = timespec_compare(&t1->start_time, time);
- if (start_diff > 0) {
- return 1;
- } else if (start_diff < 0) {
- return 0;
- } else {
- /*
- * Arbitrarily, if two processes started at the same
- * time, we'll say that the lower pointer value
- * started first. Note that t2 may have exited by now
- * so this may not be a valid pointer any longer, but
- * that's fine - it still serves to distinguish
- * between two tasks started (effectively) simultaneously.
- */
- return t1 > t2;
- }
- }
-
- /*
- * This function is a callback from heap_insert() and is used to order
- * the heap.
- * In this case we order the heap in descending task start time.
- */
- static inline int started_after(void *p1, void *p2)
+ __releases(css_set_rwsem)
{
- struct task_struct *t1 = p1;
- struct task_struct *t2 = p2;
- return started_after_time(t1, &t2->start_time, t2);
+ up_read(&css_set_rwsem);
}
/**
- * css_scan_tasks - iterate though all the tasks in a css
- * @css: the css to iterate tasks of
- * @test: optional test callback
- * @process: process callback
- * @data: data passed to @test and @process
- * @heap: optional pre-allocated heap used for task iteration
- *
- * Iterate through all the tasks in @css, calling @test for each, and if it
- * returns %true, call @process for it also.
- *
- * @test may be NULL, meaning always true (select all tasks), which
- * effectively duplicates css_task_iter_{start,next,end}() but does not
- * lock css_set_lock for the call to @process.
- *
- * It is guaranteed that @process will act on every task that is a member
- * of @css for the duration of this call. This function may or may not
- * call @process for tasks that exit or move to a different css during the
- * call, or are forked or move into the css during the call.
- *
- * Note that @test may be called with locks held, and may in some
- * situations be called multiple times for the same task, so it should be
- * cheap.
+ * cgroup_trasnsfer_tasks - move tasks from one cgroup to another
+ * @to: cgroup to which the tasks will be moved
+ * @from: cgroup in which the tasks currently reside
*
- * If @heap is non-NULL, a heap has been pre-allocated and will be used for
- * heap operations (and its "gt" member will be overwritten), else a
- * temporary heap will be used (allocation of which may cause this function
- * to fail).
+ * Locking rules between cgroup_post_fork() and the migration path
+ * guarantee that, if a task is forking while being migrated, the new child
+ * is guaranteed to be either visible in the source cgroup after the
+ * parent's migration is complete or put into the target cgroup. No task
+ * can slip out of migration through forking.
*/
- int css_scan_tasks(struct cgroup_subsys_state *css,
- bool (*test)(struct task_struct *, void *),
- void (*process)(struct task_struct *, void *),
- void *data, struct ptr_heap *heap)
+ int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
{
- int retval, i;
+ LIST_HEAD(preloaded_csets);
+ struct cgrp_cset_link *link;
struct css_task_iter it;
- struct task_struct *p, *dropped;
- /* Never dereference latest_task, since it's not refcounted */
- struct task_struct *latest_task = NULL;
- struct ptr_heap tmp_heap;
- struct timespec latest_time = { 0, 0 };
-
- if (heap) {
- /* The caller supplied our heap and pre-allocated its memory */
- heap->gt = &started_after;
- } else {
- /* We need to allocate our own heap memory */
- heap = &tmp_heap;
- retval = heap_init(heap, PAGE_SIZE, GFP_KERNEL, &started_after);
- if (retval)
- /* cannot allocate the heap */
- return retval;
- }
+ struct task_struct *task;
+ int ret;
- again:
- /*
- * Scan tasks in the css, using the @test callback to determine
- * which are of interest, and invoking @process callback on the
- * ones which need an update. Since we don't want to hold any
- * locks during the task updates, gather tasks to be processed in a
- * heap structure. The heap is sorted by descending task start
- * time. If the statically-sized heap fills up, we overflow tasks
- * that started later, and in future iterations only consider tasks
- * that started after the latest task in the previous pass. This
- * guarantees forward progress and that we don't miss any tasks.
- */
- heap->size = 0;
- css_task_iter_start(css, &it);
- while ((p = css_task_iter_next(&it))) {
- /*
- * Only affect tasks that qualify per the caller's callback,
- * if he provided one
- */
- if (test && !test(p, data))
- continue;
- /*
- * Only process tasks that started after the last task
- * we processed
- */
- if (!started_after_time(p, &latest_time, latest_task))
- continue;
- dropped = heap_insert(heap, p);
- if (dropped == NULL) {
- /*
- * The new task was inserted; the heap wasn't
- * previously full
- */
- get_task_struct(p);
- } else if (dropped != p) {
- /*
- * The new task was inserted, and pushed out a
- * different task
- */
- get_task_struct(p);
- put_task_struct(dropped);
- }
- /*
- * Else the new task was newer than anything already in
- * the heap and wasn't inserted
- */
- }
- css_task_iter_end(&it);
+ mutex_lock(&cgroup_mutex);
- if (heap->size) {
- for (i = 0; i < heap->size; i++) {
- struct task_struct *q = heap->ptrs[i];
- if (i == 0) {
- latest_time = q->start_time;
- latest_task = q;
- }
- /* Process the task per the caller's callback */
- process(q, data);
- put_task_struct(q);
- }
- /*
- * If we had to process any tasks at all, scan again
- * in case some of them were in the middle of forking
- * children that didn't get processed.
- * Not the most efficient way to do it, but it avoids
- * having to take callback_mutex in the fork path
- */
- goto again;
- }
- if (heap == &tmp_heap)
- heap_free(&tmp_heap);
- return 0;
- }
+ /* all tasks in @from are being moved, all csets are source */
+ down_read(&css_set_rwsem);
+ list_for_each_entry(link, &from->cset_links, cset_link)
+ cgroup_migrate_add_src(link->cset, to, &preloaded_csets);
+ up_read(&css_set_rwsem);
- static void cgroup_transfer_one_task(struct task_struct *task, void *data)
- {
- struct cgroup *new_cgroup = data;
+ ret = cgroup_migrate_prepare_dst(to, &preloaded_csets);
+ if (ret)
+ goto out_err;
- mutex_lock(&cgroup_mutex);
- cgroup_attach_task(new_cgroup, task, false);
+ /*
+ * Migrate tasks one-by-one until @form is empty. This fails iff
+ * ->can_attach() fails.
+ */
+ do {
+ css_task_iter_start(&from->dummy_css, &it);
+ task = css_task_iter_next(&it);
+ if (task)
+ get_task_struct(task);
+ css_task_iter_end(&it);
+
+ if (task) {
+ ret = cgroup_migrate(to, task, false);
+ put_task_struct(task);
+ }
+ } while (task && !ret);
+ out_err:
+ cgroup_migrate_finish(&preloaded_csets);
mutex_unlock(&cgroup_mutex);
- }
-
- /**
- * cgroup_trasnsfer_tasks - move tasks from one cgroup to another
- * @to: cgroup to which the tasks will be moved
- * @from: cgroup in which the tasks currently reside
- */
- int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
- {
- return css_scan_tasks(&from->dummy_css, NULL, cgroup_transfer_one_task,
- to, NULL);
+ return ret;
}
/*
*/
int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
{
- int ret = -EINVAL;
+ struct kernfs_node *kn = kernfs_node_from_dentry(dentry);
struct cgroup *cgrp;
struct css_task_iter it;
struct task_struct *tsk;
+ /* it should be kernfs_node belonging to cgroupfs and is a directory */
+ if (dentry->d_sb->s_type != &cgroup_fs_type || !kn ||
+ kernfs_type(kn) != KERNFS_DIR)
+ return -EINVAL;
+
+ mutex_lock(&cgroup_mutex);
+
/*
- * Validate dentry by checking the superblock operations,
- * and make sure it's a directory.
+ * We aren't being called from kernfs and there's no guarantee on
+ * @kn->priv's validity. For this and css_tryget_from_dir(),
+ * @kn->priv is RCU safe. Let's do the RCU dancing.
*/
- if (dentry->d_sb->s_op != &cgroup_ops ||
- !S_ISDIR(dentry->d_inode->i_mode))
- goto err;
-
- ret = 0;
- cgrp = dentry->d_fsdata;
+ rcu_read_lock();
+ cgrp = rcu_dereference(kn->priv);
+ if (!cgrp || cgroup_is_dead(cgrp)) {
+ rcu_read_unlock();
+ mutex_unlock(&cgroup_mutex);
+ return -ENOENT;
+ }
+ rcu_read_unlock();
css_task_iter_start(&cgrp->dummy_css, &it);
while ((tsk = css_task_iter_next(&it))) {
}
css_task_iter_end(&it);
- err:
- return ret;
+ mutex_unlock(&cgroup_mutex);
+ return 0;
}
* after a seek to the start). Use a binary-search to find the
* next pid to display, if any
*/
- struct cgroup_open_file *of = s->private;
+ struct kernfs_open_file *of = s->private;
struct cgroup *cgrp = seq_css(s)->cgroup;
struct cgroup_pidlist *l;
enum cgroup_filetype type = seq_cft(s)->private;
static void cgroup_pidlist_stop(struct seq_file *s, void *v)
{
- struct cgroup_open_file *of = s->private;
+ struct kernfs_open_file *of = s->private;
struct cgroup_pidlist *l = of->priv;
if (l)
static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos)
{
- struct cgroup_open_file *of = s->private;
+ struct kernfs_open_file *of = s->private;
struct cgroup_pidlist *l = of->priv;
pid_t *p = v;
pid_t *end = l->list + l->length;
return 0;
}
- /*
- * When dput() is called asynchronously, if umount has been done and
- * then deactivate_super() in cgroup_free_fn() kills the superblock,
- * there's a small window that vfs will see the root dentry with non-zero
- * refcnt and trigger BUG().
- *
- * That's why we hold a reference before dput() and drop it right after.
- */
- static void cgroup_dput(struct cgroup *cgrp)
- {
- struct super_block *sb = cgrp->root->sb;
-
- atomic_inc(&sb->s_active);
- dput(cgrp->dentry);
- deactivate_super(sb);
- }
-
static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css,
struct cftype *cft)
{
.flags = CFTYPE_INSANE | CFTYPE_ONLY_ON_ROOT,
.seq_show = cgroup_release_agent_show,
.write_string = cgroup_release_agent_write,
- .max_write_len = PATH_MAX,
+ .max_write_len = PATH_MAX - 1,
},
{ } /* terminate */
};
/* process cftsets of each subsystem */
for_each_subsys(ss, i) {
- struct cftype_set *set;
+ struct cftype *cfts;
if (!test_bit(i, &subsys_mask))
continue;
- list_for_each_entry(set, &ss->cftsets, node) {
- ret = cgroup_addrm_files(cgrp, set->cfts, true);
+ list_for_each_entry(cfts, &ss->cfts, node) {
+ ret = cgroup_addrm_files(cgrp, cfts, true);
if (ret < 0)
goto err;
}
css_put(css->parent);
css->ss->css_free(css);
- cgroup_dput(cgrp);
+ cgroup_put(cgrp);
}
static void css_free_rcu_fn(struct rcu_head *rcu_head)
struct cgroup_subsys_state *css =
container_of(rcu_head, struct cgroup_subsys_state, rcu_head);
- /*
- * css holds an extra ref to @cgrp->dentry which is put on the last
- * css_put(). dput() requires process context which we don't have.
- */
INIT_WORK(&css->destroy_work, css_free_work_fn);
queue_work(cgroup_destroy_wq, &css->destroy_work);
}
struct cgroup_subsys_state *css =
container_of(ref, struct cgroup_subsys_state, refcnt);
- rcu_assign_pointer(css->cgroup->subsys[css->ss->subsys_id], NULL);
+ RCU_INIT_POINTER(css->cgroup->subsys[css->ss->id], NULL);
call_rcu(&css->rcu_head, css_free_rcu_fn);
}
struct cgroup_subsys *ss = css->ss;
int ret = 0;
+ lockdep_assert_held(&cgroup_tree_mutex);
lockdep_assert_held(&cgroup_mutex);
if (ss->css_online)
if (!ret) {
css->flags |= CSS_ONLINE;
css->cgroup->nr_css++;
- rcu_assign_pointer(css->cgroup->subsys[ss->subsys_id], css);
+ rcu_assign_pointer(css->cgroup->subsys[ss->id], css);
}
return ret;
}
{
struct cgroup_subsys *ss = css->ss;
+ lockdep_assert_held(&cgroup_tree_mutex);
lockdep_assert_held(&cgroup_mutex);
if (!(css->flags & CSS_ONLINE))
css->flags &= ~CSS_ONLINE;
css->cgroup->nr_css--;
- RCU_INIT_POINTER(css->cgroup->subsys[ss->subsys_id], css);
+ RCU_INIT_POINTER(css->cgroup->subsys[ss->id], css);
}
/**
struct cgroup_subsys_state *css;
int err;
- lockdep_assert_held(&cgrp->dentry->d_inode->i_mutex);
lockdep_assert_held(&cgroup_mutex);
css = ss->css_alloc(cgroup_css(parent, ss));
err = percpu_ref_init(&css->refcnt, css_release);
if (err)
- goto err_free;
+ goto err_free_css;
init_css(css, ss, cgrp);
- err = cgroup_populate_dir(cgrp, 1 << ss->subsys_id);
+ err = cgroup_populate_dir(cgrp, 1 << ss->id);
if (err)
- goto err_free;
+ goto err_free_percpu_ref;
err = online_css(css);
if (err)
- goto err_free;
+ goto err_clear_dir;
- dget(cgrp->dentry);
+ cgroup_get(cgrp);
css_get(css->parent);
+ cgrp->subsys_mask |= 1 << ss->id;
+
if (ss->broken_hierarchy && !ss->warned_broken_hierarchy &&
parent->parent) {
pr_warning("cgroup: %s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n",
return 0;
-err_free:
+err_clear_dir:
- cgroup_clear_dir(css->cgroup, 1 << css->ss->subsys_id);
++ cgroup_clear_dir(css->cgroup, 1 << css->ss->id);
+err_free_percpu_ref:
percpu_ref_cancel_init(&css->refcnt);
+err_free_css:
ss->css_free(css);
return err;
}
- /*
+ /**
* cgroup_create - create a cgroup
* @parent: cgroup that will be parent of the new cgroup
- * @dentry: dentry of the new cgroup
- * @mode: mode to set on new inode
- *
- * Must be called with the mutex on the parent inode held
+ * @name: name of the new cgroup
+ * @mode: mode to set on new cgroup
*/
- static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
- umode_t mode)
+ static long cgroup_create(struct cgroup *parent, const char *name,
+ umode_t mode)
{
struct cgroup *cgrp;
- struct cgroup_name *name;
- struct cgroupfs_root *root = parent->root;
+ struct cgroup_root *root = parent->root;
int ssid, err;
struct cgroup_subsys *ss;
- struct super_block *sb = root->sb;
+ struct kernfs_node *kn;
+
+ /*
+ * XXX: The default hierarchy isn't fully implemented yet. Block
+ * !root cgroup creation on it for now.
+ */
+ if (root == &cgrp_dfl_root)
+ return -EINVAL;
/* allocate the cgroup and its ID, 0 is reserved for the root */
cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL);
if (!cgrp)
return -ENOMEM;
- name = cgroup_alloc_name(dentry);
- if (!name) {
- err = -ENOMEM;
- goto err_free_cgrp;
- }
- rcu_assign_pointer(cgrp->name, name);
+ mutex_lock(&cgroup_tree_mutex);
/*
* Only live parents can have children. Note that the liveliness
*/
if (!cgroup_lock_live_group(parent)) {
err = -ENODEV;
- goto err_free_name;
+ goto err_unlock_tree;
}
/*
goto err_unlock;
}
- /* Grab a reference on the superblock so the hierarchy doesn't
- * get deleted on unmount if there are child cgroups. This
- * can be done outside cgroup_mutex, since the sb can't
- * disappear while someone has an open control file on the
- * fs */
- atomic_inc(&sb->s_active);
-
init_cgroup_housekeeping(cgrp);
- dentry->d_fsdata = cgrp;
- cgrp->dentry = dentry;
-
cgrp->parent = parent;
cgrp->dummy_css.parent = &parent->dummy_css;
cgrp->root = parent->root;
if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags))
set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags);
+ /* create the directory */
+ kn = kernfs_create_dir(parent->kn, name, mode, cgrp);
+ if (IS_ERR(kn)) {
+ err = PTR_ERR(kn);
+ goto err_free_id;
+ }
+ cgrp->kn = kn;
+
/*
- * Create directory. cgroup_create_file() returns with the new
- * directory locked on success so that it can be populated without
- * dropping cgroup_mutex.
+ * This extra ref will be put in cgroup_free_fn() and guarantees
+ * that @cgrp->kn is always accessible.
*/
- err = cgroup_create_file(dentry, S_IFDIR | mode, sb);
- if (err < 0)
- goto err_free_id;
- lockdep_assert_held(&dentry->d_inode->i_mutex);
+ kernfs_get(kn);
cgrp->serial_nr = cgroup_serial_nr_next++;
/* allocation complete, commit to creation */
list_add_tail_rcu(&cgrp->sibling, &cgrp->parent->children);
- root->number_of_cgroups++;
-
- /* hold a ref to the parent's dentry */
- dget(parent->dentry);
+ atomic_inc(&root->nr_cgrps);
+ cgroup_get(parent);
/*
* @cgrp is now fully operational. If something fails after this
/* let's create and online css's */
for_each_subsys(ss, ssid) {
- if (root->subsys_mask & (1 << ssid)) {
+ if (root->cgrp.subsys_mask & (1 << ssid)) {
err = create_css(cgrp, ss);
if (err)
goto err_destroy;
}
}
+ kernfs_activate(kn);
+
mutex_unlock(&cgroup_mutex);
- mutex_unlock(&cgrp->dentry->d_inode->i_mutex);
+ mutex_unlock(&cgroup_tree_mutex);
return 0;
err_free_id:
idr_remove(&root->cgroup_idr, cgrp->id);
- /* Release the reference count that we took on the superblock */
- deactivate_super(sb);
err_unlock:
mutex_unlock(&cgroup_mutex);
- err_free_name:
- kfree(rcu_dereference_raw(cgrp->name));
- err_free_cgrp:
+ err_unlock_tree:
+ mutex_unlock(&cgroup_tree_mutex);
kfree(cgrp);
return err;
err_destroy:
cgroup_destroy_locked(cgrp);
mutex_unlock(&cgroup_mutex);
- mutex_unlock(&dentry->d_inode->i_mutex);
+ mutex_unlock(&cgroup_tree_mutex);
return err;
}
- static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
+ static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
+ umode_t mode)
{
- struct cgroup *c_parent = dentry->d_parent->d_fsdata;
+ struct cgroup *parent = parent_kn->priv;
+ int ret;
+
+ /*
+ * cgroup_create() grabs cgroup_tree_mutex which nests outside
+ * kernfs active_ref and cgroup_create() already synchronizes
+ * properly against removal through cgroup_lock_live_group().
+ * Break it before calling cgroup_create().
+ */
+ cgroup_get(parent);
+ kernfs_break_active_protection(parent_kn);
- /* the vfs holds inode->i_mutex already */
- return cgroup_create(c_parent, dentry, mode | S_IFDIR);
+ ret = cgroup_create(parent, name, mode);
+
+ kernfs_unbreak_active_protection(parent_kn);
+ cgroup_put(parent);
+ return ret;
}
/*
container_of(work, struct cgroup_subsys_state, destroy_work);
struct cgroup *cgrp = css->cgroup;
+ mutex_lock(&cgroup_tree_mutex);
mutex_lock(&cgroup_mutex);
/*
cgroup_destroy_css_killed(cgrp);
mutex_unlock(&cgroup_mutex);
+ mutex_unlock(&cgroup_tree_mutex);
/*
* Put the css refs from kill_css(). Each css holds an extra
queue_work(cgroup_destroy_wq, &css->destroy_work);
}
- /**
- * kill_css - destroy a css
- * @css: css to destroy
- *
- * This function initiates destruction of @css by removing cgroup interface
- * files and putting its base reference. ->css_offline() will be invoked
- * asynchronously once css_tryget() is guaranteed to fail and when the
- * reference count reaches zero, @css will be released.
- */
- static void kill_css(struct cgroup_subsys_state *css)
+ static void __kill_css(struct cgroup_subsys_state *css)
{
- cgroup_clear_dir(css->cgroup, 1 << css->ss->subsys_id);
+ lockdep_assert_held(&cgroup_tree_mutex);
+
+ /*
+ * This must happen before css is disassociated with its cgroup.
+ * See seq_css() for details.
+ */
+ cgroup_clear_dir(css->cgroup, 1 << css->ss->id);
/*
* Killing would put the base ref, but we need to keep it alive
percpu_ref_kill_and_confirm(&css->refcnt, css_killed_ref_fn);
}
+ /**
+ * kill_css - destroy a css
+ * @css: css to destroy
+ *
+ * This function initiates destruction of @css by removing cgroup interface
+ * files and putting its base reference. ->css_offline() will be invoked
+ * asynchronously once css_tryget() is guaranteed to fail and when the
+ * reference count reaches zero, @css will be released.
+ */
+ static void kill_css(struct cgroup_subsys_state *css)
+ {
+ struct cgroup *cgrp = css->cgroup;
+
+ lockdep_assert_held(&cgroup_tree_mutex);
+
+ /* if already killed, noop */
+ if (cgrp->subsys_mask & (1 << css->ss->id)) {
+ cgrp->subsys_mask &= ~(1 << css->ss->id);
+ __kill_css(css);
+ }
+ }
+
/**
* cgroup_destroy_locked - the first stage of cgroup destruction
* @cgrp: cgroup to be destroyed
static int cgroup_destroy_locked(struct cgroup *cgrp)
__releases(&cgroup_mutex) __acquires(&cgroup_mutex)
{
- struct dentry *d = cgrp->dentry;
- struct cgroup_subsys_state *css;
struct cgroup *child;
+ struct cgroup_subsys_state *css;
bool empty;
int ssid;
- lockdep_assert_held(&d->d_inode->i_mutex);
+ lockdep_assert_held(&cgroup_tree_mutex);
lockdep_assert_held(&cgroup_mutex);
/*
- * css_set_lock synchronizes access to ->cset_links and prevents
- * @cgrp from being removed while __put_css_set() is in progress.
+ * css_set_rwsem synchronizes access to ->cset_links and prevents
+ * @cgrp from being removed while put_css_set() is in progress.
*/
- read_lock(&css_set_lock);
+ down_read(&css_set_rwsem);
empty = list_empty(&cgrp->cset_links);
- read_unlock(&css_set_lock);
+ up_read(&css_set_rwsem);
if (!empty)
return -EBUSY;
if (!empty)
return -EBUSY;
- /*
- * Initiate massacre of all css's. cgroup_destroy_css_killed()
- * will be invoked to perform the rest of destruction once the
- * percpu refs of all css's are confirmed to be killed.
- */
- for_each_css(css, ssid, cgrp)
- kill_css(css);
-
/*
* Mark @cgrp dead. This prevents further task migration and child
* creation by disabling cgroup_lock_live_group(). Note that
*/
set_bit(CGRP_DEAD, &cgrp->flags);
+ /*
+ * Initiate massacre of all css's. cgroup_destroy_css_killed()
+ * will be invoked to perform the rest of destruction once the
+ * percpu refs of all css's are confirmed to be killed. This
+ * involves removing the subsystem's files, drop cgroup_mutex.
+ */
+ mutex_unlock(&cgroup_mutex);
+ for_each_css(css, ssid, cgrp)
+ kill_css(css);
+ mutex_lock(&cgroup_mutex);
+
/* CGRP_DEAD is set, remove from ->release_list for the last time */
raw_spin_lock(&release_list_lock);
if (!list_empty(&cgrp->release_list))
if (!cgrp->nr_css)
cgroup_destroy_css_killed(cgrp);
+ /* remove @cgrp directory along with the base files */
+ mutex_unlock(&cgroup_mutex);
+
/*
- * Clear the base files and remove @cgrp directory. The removal
- * puts the base ref but we aren't quite done with @cgrp yet, so
- * hold onto it.
+ * There are two control paths which try to determine cgroup from
+ * dentry without going through kernfs - cgroupstats_build() and
+ * css_tryget_from_dir(). Those are supported by RCU protecting
+ * clearing of cgrp->kn->priv backpointer, which should happen
+ * after all files under it have been removed.
*/
- cgroup_addrm_files(cgrp, cgroup_base_files, false);
- dget(d);
- cgroup_d_remove_dir(d);
+ kernfs_remove(cgrp->kn); /* @cgrp has an extra ref on its kn */
+ RCU_INIT_POINTER(*(void __rcu __force **)&cgrp->kn->priv, NULL);
+
+ mutex_lock(&cgroup_mutex);
return 0;
};
static void cgroup_destroy_css_killed(struct cgroup *cgrp)
{
struct cgroup *parent = cgrp->parent;
- struct dentry *d = cgrp->dentry;
+ lockdep_assert_held(&cgroup_tree_mutex);
lockdep_assert_held(&cgroup_mutex);
/* delete this cgroup from parent->children */
list_del_rcu(&cgrp->sibling);
- dput(d);
+ cgroup_put(cgrp);
set_bit(CGRP_RELEASABLE, &parent->flags);
check_for_release(parent);
}
- static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry)
+ static int cgroup_rmdir(struct kernfs_node *kn)
{
- int ret;
-
- mutex_lock(&cgroup_mutex);
- ret = cgroup_destroy_locked(dentry->d_fsdata);
- mutex_unlock(&cgroup_mutex);
+ struct cgroup *cgrp = kn->priv;
+ int ret = 0;
- return ret;
- }
+ /*
+ * This is self-destruction but @kn can't be removed while this
+ * callback is in progress. Let's break active protection. Once
+ * the protection is broken, @cgrp can be destroyed at any point.
+ * Pin it so that it stays accessible.
+ */
+ cgroup_get(cgrp);
+ kernfs_break_active_protection(kn);
- static void __init_or_module cgroup_init_cftsets(struct cgroup_subsys *ss)
- {
- INIT_LIST_HEAD(&ss->cftsets);
+ mutex_lock(&cgroup_tree_mutex);
+ mutex_lock(&cgroup_mutex);
/*
- * base_cftset is embedded in subsys itself, no need to worry about
- * deregistration.
+ * @cgrp might already have been destroyed while we're trying to
+ * grab the mutexes.
*/
- if (ss->base_cftypes) {
- struct cftype *cft;
+ if (!cgroup_is_dead(cgrp))
+ ret = cgroup_destroy_locked(cgrp);
- for (cft = ss->base_cftypes; cft->name[0] != '\0'; cft++)
- cft->ss = ss;
+ mutex_unlock(&cgroup_mutex);
+ mutex_unlock(&cgroup_tree_mutex);
- ss->base_cftset.cfts = ss->base_cftypes;
- list_add_tail(&ss->base_cftset.node, &ss->cftsets);
- }
+ kernfs_unbreak_active_protection(kn);
+ cgroup_put(cgrp);
+ return ret;
}
+ static struct kernfs_syscall_ops cgroup_kf_syscall_ops = {
+ .remount_fs = cgroup_remount,
+ .show_options = cgroup_show_options,
+ .mkdir = cgroup_mkdir,
+ .rmdir = cgroup_rmdir,
+ .rename = cgroup_rename,
+ };
+
static void __init cgroup_init_subsys(struct cgroup_subsys *ss)
{
struct cgroup_subsys_state *css;
printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name);
+ mutex_lock(&cgroup_tree_mutex);
mutex_lock(&cgroup_mutex);
- /* init base cftset */
- cgroup_init_cftsets(ss);
+ INIT_LIST_HEAD(&ss->cfts);
- /* Create the top cgroup state for this subsystem */
- ss->root = &cgroup_dummy_root;
- css = ss->css_alloc(cgroup_css(cgroup_dummy_top, ss));
+ /* Create the root cgroup state for this subsystem */
+ ss->root = &cgrp_dfl_root;
+ css = ss->css_alloc(cgroup_css(&cgrp_dfl_root.cgrp, ss));
/* We don't handle early failures gracefully */
BUG_ON(IS_ERR(css));
- init_css(css, ss, cgroup_dummy_top);
+ init_css(css, ss, &cgrp_dfl_root.cgrp);
/* Update the init_css_set to contain a subsys
* pointer to this state - since the subsystem is
* newly registered, all tasks and hence the
- * init_css_set is in the subsystem's top cgroup. */
- init_css_set.subsys[ss->subsys_id] = css;
+ * init_css_set is in the subsystem's root cgroup. */
+ init_css_set.subsys[ss->id] = css;
need_forkexit_callback |= ss->fork || ss->exit;
BUG_ON(online_css(css));
- mutex_unlock(&cgroup_mutex);
-
- /* this function shouldn't be used with modular subsystems, since they
- * need to register a subsys_id, among other things */
- BUG_ON(ss->module);
- }
-
- /**
- * cgroup_load_subsys: load and register a modular subsystem at runtime
- * @ss: the subsystem to load
- *
- * This function should be called in a modular subsystem's initcall. If the
- * subsystem is built as a module, it will be assigned a new subsys_id and set
- * up for use. If the subsystem is built-in anyway, work is delegated to the
- * simpler cgroup_init_subsys.
- */
- int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
- {
- struct cgroup_subsys_state *css;
- int i, ret;
- struct hlist_node *tmp;
- struct css_set *cset;
- unsigned long key;
-
- /* check name and function validity */
- if (ss->name == NULL || strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN ||
- ss->css_alloc == NULL || ss->css_free == NULL)
- return -EINVAL;
-
- /*
- * we don't support callbacks in modular subsystems. this check is
- * before the ss->module check for consistency; a subsystem that could
- * be a module should still have no callbacks even if the user isn't
- * compiling it as one.
- */
- if (ss->fork || ss->exit)
- return -EINVAL;
-
- /*
- * an optionally modular subsystem is built-in: we want to do nothing,
- * since cgroup_init_subsys will have already taken care of it.
- */
- if (ss->module == NULL) {
- /* a sanity check */
- BUG_ON(cgroup_subsys[ss->subsys_id] != ss);
- return 0;
- }
-
- /* init base cftset */
- cgroup_init_cftsets(ss);
-
- mutex_lock(&cgroup_mutex);
- mutex_lock(&cgroup_root_mutex);
- cgroup_subsys[ss->subsys_id] = ss;
-
- /*
- * no ss->css_alloc seems to need anything important in the ss
- * struct, so this can happen first (i.e. before the dummy root
- * attachment).
- */
- css = ss->css_alloc(cgroup_css(cgroup_dummy_top, ss));
- if (IS_ERR(css)) {
- /* failure case - need to deassign the cgroup_subsys[] slot. */
- cgroup_subsys[ss->subsys_id] = NULL;
- mutex_unlock(&cgroup_root_mutex);
- mutex_unlock(&cgroup_mutex);
- return PTR_ERR(css);
- }
-
- ss->root = &cgroup_dummy_root;
-
- /* our new subsystem will be attached to the dummy hierarchy. */
- init_css(css, ss, cgroup_dummy_top);
-
- /*
- * Now we need to entangle the css into the existing css_sets. unlike
- * in cgroup_init_subsys, there are now multiple css_sets, so each one
- * will need a new pointer to it; done by iterating the css_set_table.
- * furthermore, modifying the existing css_sets will corrupt the hash
- * table state, so each changed css_set will need its hash recomputed.
- * this is all done under the css_set_lock.
- */
- write_lock(&css_set_lock);
- hash_for_each_safe(css_set_table, i, tmp, cset, hlist) {
- /* skip entries that we already rehashed */
- if (cset->subsys[ss->subsys_id])
- continue;
- /* remove existing entry */
- hash_del(&cset->hlist);
- /* set new value */
- cset->subsys[ss->subsys_id] = css;
- /* recompute hash and restore entry */
- key = css_set_hash(cset->subsys);
- hash_add(css_set_table, &cset->hlist, key);
- }
- write_unlock(&css_set_lock);
-
- ret = online_css(css);
- if (ret) {
- ss->css_free(css);
- goto err_unload;
- }
-
- /* success! */
- mutex_unlock(&cgroup_root_mutex);
- mutex_unlock(&cgroup_mutex);
- return 0;
-
- err_unload:
- mutex_unlock(&cgroup_root_mutex);
- mutex_unlock(&cgroup_mutex);
- /* @ss can't be mounted here as try_module_get() would fail */
- cgroup_unload_subsys(ss);
- return ret;
- }
- EXPORT_SYMBOL_GPL(cgroup_load_subsys);
-
- /**
- * cgroup_unload_subsys: unload a modular subsystem
- * @ss: the subsystem to unload
- *
- * This function should be called in a modular subsystem's exitcall. When this
- * function is invoked, the refcount on the subsystem's module will be 0, so
- * the subsystem will not be attached to any hierarchy.
- */
- void cgroup_unload_subsys(struct cgroup_subsys *ss)
- {
- struct cgrp_cset_link *link;
- struct cgroup_subsys_state *css;
-
- BUG_ON(ss->module == NULL);
-
- /*
- * we shouldn't be called if the subsystem is in use, and the use of
- * try_module_get() in rebind_subsystems() should ensure that it
- * doesn't start being used while we're killing it off.
- */
- BUG_ON(ss->root != &cgroup_dummy_root);
-
- mutex_lock(&cgroup_mutex);
- mutex_lock(&cgroup_root_mutex);
-
- css = cgroup_css(cgroup_dummy_top, ss);
- if (css)
- offline_css(css);
-
- /* deassign the subsys_id */
- cgroup_subsys[ss->subsys_id] = NULL;
-
- /*
- * disentangle the css from all css_sets attached to the dummy
- * top. as in loading, we need to pay our respects to the hashtable
- * gods.
- */
- write_lock(&css_set_lock);
- list_for_each_entry(link, &cgroup_dummy_top->cset_links, cset_link) {
- struct css_set *cset = link->cset;
- unsigned long key;
-
- hash_del(&cset->hlist);
- cset->subsys[ss->subsys_id] = NULL;
- key = css_set_hash(cset->subsys);
- hash_add(css_set_table, &cset->hlist, key);
- }
- write_unlock(&css_set_lock);
-
- /*
- * remove subsystem's css from the cgroup_dummy_top and free it -
- * need to free before marking as null because ss->css_free needs
- * the cgrp->subsys pointer to find their state.
- */
- if (css)
- ss->css_free(css);
- RCU_INIT_POINTER(cgroup_dummy_top->subsys[ss->subsys_id], NULL);
+ cgrp_dfl_root.cgrp.subsys_mask |= 1 << ss->id;
- mutex_unlock(&cgroup_root_mutex);
mutex_unlock(&cgroup_mutex);
+ mutex_unlock(&cgroup_tree_mutex);
}
- EXPORT_SYMBOL_GPL(cgroup_unload_subsys);
/**
* cgroup_init_early - cgroup initialization at system boot
*/
int __init cgroup_init_early(void)
{
+ static struct cgroup_sb_opts __initdata opts =
+ { .flags = CGRP_ROOT_SANE_BEHAVIOR };
struct cgroup_subsys *ss;
int i;
- atomic_set(&init_css_set.refcount, 1);
- INIT_LIST_HEAD(&init_css_set.cgrp_links);
- INIT_LIST_HEAD(&init_css_set.tasks);
- INIT_HLIST_NODE(&init_css_set.hlist);
- css_set_count = 1;
- init_cgroup_root(&cgroup_dummy_root);
- cgroup_root_count = 1;
+ init_cgroup_root(&cgrp_dfl_root, &opts);
RCU_INIT_POINTER(init_task.cgroups, &init_css_set);
- init_cgrp_cset_link.cset = &init_css_set;
- init_cgrp_cset_link.cgrp = cgroup_dummy_top;
- list_add(&init_cgrp_cset_link.cset_link, &cgroup_dummy_top->cset_links);
- list_add(&init_cgrp_cset_link.cgrp_link, &init_css_set.cgrp_links);
-
- /* at bootup time, we don't worry about modular subsystems */
- for_each_builtin_subsys(ss, i) {
- BUG_ON(!ss->name);
- BUG_ON(strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN);
- BUG_ON(!ss->css_alloc);
- BUG_ON(!ss->css_free);
- if (ss->subsys_id != i) {
- printk(KERN_ERR "cgroup: Subsys %s id == %d\n",
- ss->name, ss->subsys_id);
- BUG();
- }
+ for_each_subsys(ss, i) {
+ WARN(!ss->css_alloc || !ss->css_free || ss->name || ss->id,
+ "invalid cgroup_subsys %d:%s css_alloc=%p css_free=%p name:id=%d:%s\n",
+ i, cgroup_subsys_name[i], ss->css_alloc, ss->css_free,
+ ss->id, ss->name);
+ WARN(strlen(cgroup_subsys_name[i]) > MAX_CGROUP_TYPE_NAMELEN,
+ "cgroup_subsys_name %s too long\n", cgroup_subsys_name[i]);
+
+ ss->id = i;
+ ss->name = cgroup_subsys_name[i];
if (ss->early_init)
cgroup_init_subsys(ss);
{
struct cgroup_subsys *ss;
unsigned long key;
- int i, err;
-
- err = bdi_init(&cgroup_backing_dev_info);
- if (err)
- return err;
+ int ssid, err;
- for_each_builtin_subsys(ss, i) {
- if (!ss->early_init)
- cgroup_init_subsys(ss);
- }
+ BUG_ON(cgroup_init_cftypes(NULL, cgroup_base_files));
- /* allocate id for the dummy hierarchy */
+ mutex_lock(&cgroup_tree_mutex);
mutex_lock(&cgroup_mutex);
- mutex_lock(&cgroup_root_mutex);
/* Add init_css_set to the hash table */
key = css_set_hash(init_css_set.subsys);
hash_add(css_set_table, &init_css_set.hlist, key);
- BUG_ON(cgroup_init_root_id(&cgroup_dummy_root, 0, 1));
-
- err = idr_alloc(&cgroup_dummy_root.cgroup_idr, cgroup_dummy_top,
- 0, 1, GFP_KERNEL);
- BUG_ON(err < 0);
+ BUG_ON(cgroup_setup_root(&cgrp_dfl_root, 0));
- mutex_unlock(&cgroup_root_mutex);
mutex_unlock(&cgroup_mutex);
+ mutex_unlock(&cgroup_tree_mutex);
- cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj);
- if (!cgroup_kobj) {
- err = -ENOMEM;
- goto out;
+ for_each_subsys(ss, ssid) {
+ if (!ss->early_init)
+ cgroup_init_subsys(ss);
+
+ /*
+ * cftype registration needs kmalloc and can't be done
+ * during early_init. Register base cftypes separately.
+ */
+ if (ss->base_cftypes)
+ WARN_ON(cgroup_add_cftypes(ss, ss->base_cftypes));
}
+ cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj);
+ if (!cgroup_kobj)
+ return -ENOMEM;
+
err = register_filesystem(&cgroup_fs_type);
if (err < 0) {
kobject_put(cgroup_kobj);
- goto out;
+ return err;
}
proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations);
-
- out:
- if (err)
- bdi_destroy(&cgroup_backing_dev_info);
-
- return err;
+ return 0;
}
static int __init cgroup_wq_init(void)
* proc_cgroup_show()
* - Print task's cgroup paths into seq_file, one line for each hierarchy
* - Used for /proc/<pid>/cgroup.
- * - No need to task_lock(tsk) on this tsk->cgroup reference, as it
- * doesn't really matter if tsk->cgroup changes after we read it,
- * and we take cgroup_mutex, keeping cgroup_attach_task() from changing it
- * anyway. No need to check that tsk->cgroup != NULL, thanks to
- * the_top_cgroup_hack in cgroup_exit(), which sets an exiting tasks
- * cgroup to top_cgroup.
*/
/* TODO: Use a proper seq_file iterator */
{
struct pid *pid;
struct task_struct *tsk;
- char *buf;
+ char *buf, *path;
int retval;
- struct cgroupfs_root *root;
+ struct cgroup_root *root;
retval = -ENOMEM;
- buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
+ buf = kmalloc(PATH_MAX, GFP_KERNEL);
if (!buf)
goto out;
retval = 0;
mutex_lock(&cgroup_mutex);
+ down_read(&css_set_rwsem);
- for_each_active_root(root) {
+ for_each_root(root) {
struct cgroup_subsys *ss;
struct cgroup *cgrp;
int ssid, count = 0;
+ if (root == &cgrp_dfl_root && !cgrp_dfl_root_visible)
+ continue;
+
seq_printf(m, "%d:", root->hierarchy_id);
for_each_subsys(ss, ssid)
- if (root->subsys_mask & (1 << ssid))
+ if (root->cgrp.subsys_mask & (1 << ssid))
seq_printf(m, "%s%s", count++ ? "," : "", ss->name);
if (strlen(root->name))
seq_printf(m, "%sname=%s", count ? "," : "",
root->name);
seq_putc(m, ':');
cgrp = task_cgroup_from_root(tsk, root);
- retval = cgroup_path(cgrp, buf, PAGE_SIZE);
- if (retval < 0)
+ path = cgroup_path(cgrp, buf, PATH_MAX);
+ if (!path) {
+ retval = -ENAMETOOLONG;
goto out_unlock;
- seq_puts(m, buf);
+ }
+ seq_puts(m, path);
seq_putc(m, '\n');
}
out_unlock:
+ up_read(&css_set_rwsem);
mutex_unlock(&cgroup_mutex);
put_task_struct(tsk);
out_free:
for_each_subsys(ss, i)
seq_printf(m, "%s\t%d\t%d\t%d\n",
ss->name, ss->root->hierarchy_id,
- ss->root->number_of_cgroups, !ss->disabled);
+ atomic_read(&ss->root->nr_cgrps), !ss->disabled);
mutex_unlock(&cgroup_mutex);
return 0;
};
/**
- * cgroup_fork - attach newly forked task to its parents cgroup.
+ * cgroup_fork - initialize cgroup related fields during copy_process()
* @child: pointer to task_struct of forking parent process.
*
- * Description: A task inherits its parent's cgroup at fork().
- *
- * A pointer to the shared css_set was automatically copied in
- * fork.c by dup_task_struct(). However, we ignore that copy, since
- * it was not made under the protection of RCU or cgroup_mutex, so
- * might no longer be a valid cgroup pointer. cgroup_attach_task() might
- * have already changed current->cgroups, allowing the previously
- * referenced cgroup group to be removed and freed.
- *
- * At the point that cgroup_fork() is called, 'current' is the parent
- * task, and the passed argument 'child' points to the child task.
+ * A task is associated with the init_css_set until cgroup_post_fork()
+ * attaches it to the parent's css_set. Empty cg_list indicates that
+ * @child isn't holding reference to its css_set.
*/
void cgroup_fork(struct task_struct *child)
{
- task_lock(current);
- get_css_set(task_css_set(current));
- child->cgroups = current->cgroups;
- task_unlock(current);
+ RCU_INIT_POINTER(child->cgroups, &init_css_set);
INIT_LIST_HEAD(&child->cg_list);
}
int i;
/*
- * use_task_css_set_links is set to 1 before we walk the tasklist
- * under the tasklist_lock and we read it here after we added the child
- * to the tasklist under the tasklist_lock as well. If the child wasn't
- * yet in the tasklist when we walked through it from
- * cgroup_enable_task_cg_lists(), then use_task_css_set_links value
- * should be visible now due to the paired locking and barriers implied
- * by LOCK/UNLOCK: it is written before the tasklist_lock unlock
- * in cgroup_enable_task_cg_lists() and read here after the tasklist_lock
- * lock on fork.
+ * This may race against cgroup_enable_task_cg_links(). As that
+ * function sets use_task_css_set_links before grabbing
+ * tasklist_lock and we just went through tasklist_lock to add
+ * @child, it's guaranteed that either we see the set
+ * use_task_css_set_links or cgroup_enable_task_cg_lists() sees
+ * @child during its iteration.
+ *
+ * If we won the race, @child is associated with %current's
+ * css_set. Grabbing css_set_rwsem guarantees both that the
+ * association is stable, and, on completion of the parent's
+ * migration, @child is visible in the source of migration or
+ * already in the destination cgroup. This guarantee is necessary
+ * when implementing operations which need to migrate all tasks of
+ * a cgroup to another.
+ *
+ * Note that if we lose to cgroup_enable_task_cg_links(), @child
+ * will remain in init_css_set. This is safe because all tasks are
+ * in the init_css_set before cg_links is enabled and there's no
+ * operation which transfers all tasks out of init_css_set.
*/
if (use_task_css_set_links) {
- write_lock(&css_set_lock);
- task_lock(child);
- if (list_empty(&child->cg_list))
- list_add(&child->cg_list, &task_css_set(child)->tasks);
- task_unlock(child);
- write_unlock(&css_set_lock);
+ struct css_set *cset;
+
+ down_write(&css_set_rwsem);
+ cset = task_css_set(current);
+ if (list_empty(&child->cg_list)) {
+ rcu_assign_pointer(child->cgroups, cset);
+ list_add(&child->cg_list, &cset->tasks);
+ get_css_set(cset);
+ }
+ up_write(&css_set_rwsem);
}
/*
* and addition to css_set.
*/
if (need_forkexit_callback) {
- /*
- * fork/exit callbacks are supported only for builtin
- * subsystems, and the builtin section of the subsys
- * array is immutable, so we don't need to lock the
- * subsys array here. On the other hand, modular section
- * of the array can be freed at module unload, so we
- * can't touch that.
- */
- for_each_builtin_subsys(ss, i)
+ for_each_subsys(ss, i)
if (ss->fork)
ss->fork(child);
}
/**
* cgroup_exit - detach cgroup from exiting task
* @tsk: pointer to task_struct of exiting process
- * @run_callback: run exit callbacks?
*
* Description: Detach cgroup from @tsk and release it.
*
* use notify_on_release cgroups where very high task exit scaling
* is required on large systems.
*
- * the_top_cgroup_hack:
- *
- * Set the exiting tasks cgroup to the root cgroup (top_cgroup).
- *
- * We call cgroup_exit() while the task is still competent to
- * handle notify_on_release(), then leave the task attached to the
- * root cgroup in each hierarchy for the remainder of its exit.
- *
- * To do this properly, we would increment the reference count on
- * top_cgroup, and near the very end of the kernel/exit.c do_exit()
- * code we would add a second cgroup function call, to drop that
- * reference. This would just create an unnecessary hot spot on
- * the top_cgroup reference count, to no avail.
- *
- * Normally, holding a reference to a cgroup without bumping its
- * count is unsafe. The cgroup could go away, or someone could
- * attach us to a different cgroup, decrementing the count on
- * the first cgroup that we never incremented. But in this case,
- * top_cgroup isn't going away, and either task has PF_EXITING set,
- * which wards off any cgroup_attach_task() attempts, or task is a failed
- * fork, never visible to cgroup_attach_task.
+ * We set the exiting tasks cgroup to the root cgroup (top_cgroup). We
+ * call cgroup_exit() while the task is still competent to handle
+ * notify_on_release(), then leave the task attached to the root cgroup in
+ * each hierarchy for the remainder of its exit. No need to bother with
+ * init_css_set refcnting. init_css_set never goes away and we can't race
+ * with migration path - PF_EXITING is visible to migration path.
*/
- void cgroup_exit(struct task_struct *tsk, int run_callbacks)
+ void cgroup_exit(struct task_struct *tsk)
{
struct cgroup_subsys *ss;
struct css_set *cset;
+ bool put_cset = false;
int i;
/*
- * Unlink from the css_set task list if necessary.
- * Optimistically check cg_list before taking
- * css_set_lock
+ * Unlink from @tsk from its css_set. As migration path can't race
+ * with us, we can check cg_list without grabbing css_set_rwsem.
*/
if (!list_empty(&tsk->cg_list)) {
- write_lock(&css_set_lock);
- if (!list_empty(&tsk->cg_list))
- list_del_init(&tsk->cg_list);
- write_unlock(&css_set_lock);
+ down_write(&css_set_rwsem);
+ list_del_init(&tsk->cg_list);
+ up_write(&css_set_rwsem);
+ put_cset = true;
}
/* Reassign the task to the init_css_set. */
- task_lock(tsk);
cset = task_css_set(tsk);
RCU_INIT_POINTER(tsk->cgroups, &init_css_set);
- if (run_callbacks && need_forkexit_callback) {
- /*
- * fork/exit callbacks are supported only for builtin
- * subsystems, see cgroup_post_fork() for details.
- */
- for_each_builtin_subsys(ss, i) {
+ if (need_forkexit_callback) {
+ /* see cgroup_post_fork() for details */
+ for_each_subsys(ss, i) {
if (ss->exit) {
struct cgroup_subsys_state *old_css = cset->subsys[i];
struct cgroup_subsys_state *css = task_css(tsk, i);
}
}
}
- task_unlock(tsk);
- put_css_set_taskexit(cset);
+ if (put_cset)
+ put_css_set(cset, true);
}
static void check_for_release(struct cgroup *cgrp)
while (!list_empty(&release_list)) {
char *argv[3], *envp[3];
int i;
- char *pathbuf = NULL, *agentbuf = NULL;
+ char *pathbuf = NULL, *agentbuf = NULL, *path;
struct cgroup *cgrp = list_entry(release_list.next,
struct cgroup,
release_list);
list_del_init(&cgrp->release_list);
raw_spin_unlock(&release_list_lock);
- pathbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
+ pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
if (!pathbuf)
goto continue_free;
- if (cgroup_path(cgrp, pathbuf, PAGE_SIZE) < 0)
+ path = cgroup_path(cgrp, pathbuf, PATH_MAX);
+ if (!path)
goto continue_free;
agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL);
if (!agentbuf)
i = 0;
argv[i++] = agentbuf;
- argv[i++] = pathbuf;
+ argv[i++] = path;
argv[i] = NULL;
i = 0;
if (!*token)
continue;
- /*
- * cgroup_disable, being at boot time, can't know about
- * module subsystems, so we don't worry about them.
- */
- for_each_builtin_subsys(ss, i) {
+ for_each_subsys(ss, i) {
if (!strcmp(token, ss->name)) {
ss->disabled = 1;
printk(KERN_INFO "Disabling %s control group"
__setup("cgroup_disable=", cgroup_disable);
/**
- * css_from_dir - get corresponding css from the dentry of a cgroup dir
+ * css_tryget_from_dir - get corresponding css from the dentry of a cgroup dir
* @dentry: directory dentry of interest
* @ss: subsystem of interest
*
- * Must be called under cgroup_mutex or RCU read lock. The caller is
- * responsible for pinning the returned css if it needs to be accessed
- * outside the critical section.
+ * If @dentry is a directory for a cgroup which has @ss enabled on it, try
+ * to get the corresponding css and return it. If such css doesn't exist
+ * or can't be pinned, an ERR_PTR value is returned.
*/
- struct cgroup_subsys_state *css_from_dir(struct dentry *dentry,
- struct cgroup_subsys *ss)
+ struct cgroup_subsys_state *css_tryget_from_dir(struct dentry *dentry,
+ struct cgroup_subsys *ss)
{
+ struct kernfs_node *kn = kernfs_node_from_dentry(dentry);
+ struct cgroup_subsys_state *css = NULL;
struct cgroup *cgrp;
- cgroup_assert_mutex_or_rcu_locked();
-
/* is @dentry a cgroup dir? */
- if (!dentry->d_inode ||
- dentry->d_inode->i_op != &cgroup_dir_inode_operations)
+ if (dentry->d_sb->s_type != &cgroup_fs_type || !kn ||
+ kernfs_type(kn) != KERNFS_DIR)
return ERR_PTR(-EBADF);
- cgrp = __d_cgrp(dentry);
- return cgroup_css(cgrp, ss) ?: ERR_PTR(-ENOENT);
+ rcu_read_lock();
+
+ /*
+ * This path doesn't originate from kernfs and @kn could already
+ * have been or be removed at any point. @kn->priv is RCU
+ * protected for this access. See destroy_locked() for details.
+ */
+ cgrp = rcu_dereference(kn->priv);
+ if (cgrp)
+ css = cgroup_css(cgrp, ss);
+
+ if (!css || !css_tryget(css))
+ css = ERR_PTR(-ENOENT);
+
+ rcu_read_unlock();
+ return css;
}
/**
{
struct cgroup *cgrp;
- cgroup_assert_mutex_or_rcu_locked();
+ cgroup_assert_mutexes_or_rcu_locked();
cgrp = idr_find(&ss->root->cgroup_idr, id);
if (cgrp)
{
struct cgrp_cset_link *link;
struct css_set *cset;
+ char *name_buf;
+
+ name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL);
+ if (!name_buf)
+ return -ENOMEM;
- read_lock(&css_set_lock);
+ down_read(&css_set_rwsem);
rcu_read_lock();
cset = rcu_dereference(current->cgroups);
list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
struct cgroup *c = link->cgrp;
- const char *name;
- if (c->dentry)
- name = c->dentry->d_name.name;
- else
- name = "?";
+ cgroup_name(c, name_buf, NAME_MAX + 1);
seq_printf(seq, "Root %d group %s\n",
- c->root->hierarchy_id, name);
+ c->root->hierarchy_id, name_buf);
}
rcu_read_unlock();
- read_unlock(&css_set_lock);
+ up_read(&css_set_rwsem);
+ kfree(name_buf);
return 0;
}
struct cgroup_subsys_state *css = seq_css(seq);
struct cgrp_cset_link *link;
- read_lock(&css_set_lock);
+ down_read(&css_set_rwsem);
list_for_each_entry(link, &css->cgroup->cset_links, cset_link) {
struct css_set *cset = link->cset;
struct task_struct *task;
int count = 0;
+
seq_printf(seq, "css_set %p\n", cset);
+
list_for_each_entry(task, &cset->tasks, cg_list) {
- if (count++ > MAX_TASKS_SHOWN_PER_CSS) {
- seq_puts(seq, " ...\n");
- break;
- } else {
- seq_printf(seq, " task %d\n",
- task_pid_vnr(task));
- }
+ if (count++ > MAX_TASKS_SHOWN_PER_CSS)
+ goto overflow;
+ seq_printf(seq, " task %d\n", task_pid_vnr(task));
+ }
+
+ list_for_each_entry(task, &cset->mg_tasks, cg_list) {
+ if (count++ > MAX_TASKS_SHOWN_PER_CSS)
+ goto overflow;
+ seq_printf(seq, " task %d\n", task_pid_vnr(task));
}
+ continue;
+ overflow:
+ seq_puts(seq, " ...\n");
}
- read_unlock(&css_set_lock);
+ up_read(&css_set_rwsem);
return 0;
}
{ } /* terminate */
};
- struct cgroup_subsys debug_subsys = {
- .name = "debug",
+ struct cgroup_subsys debug_cgrp_subsys = {
.css_alloc = debug_css_alloc,
.css_free = debug_css_free,
- .subsys_id = debug_subsys_id,
.base_cftypes = debug_files,
};
#endif /* CONFIG_CGROUP_DEBUG */
projects / cascardo / linux.git / commitdiff