#include <linux/eventfd.h>
#include <linux/poll.h>
#include <linux/flex_array.h> /* used in cgroup_attach_proc */
+#include <linux/kthread.h>
#include <linux/atomic.h>
+/* css deactivation bias, makes css->refcnt negative to deny new trygets */
+#define CSS_DEACT_BIAS INT_MIN
+
/*
* cgroup_mutex is the master lock. Any modification to cgroup or its
* hierarchy must be performed while holding it.
/* A list running through the active hierarchies */
struct list_head root_list;
+ /* All cgroups on this root, cgroup_mutex protected */
+ struct list_head allcg_list;
+
/* Hierarchy-specific flags */
unsigned long flags;
*/
static struct cgroupfs_root rootnode;
+/*
+ * cgroupfs file entry, pointed to from leaf dentry->d_fsdata.
+ */
+struct cfent {
+ struct list_head node;
+ struct dentry *dentry;
+ struct cftype *type;
+};
+
/*
* CSS ID -- ID per subsys's Cgroup Subsys State(CSS). used only when
* cgroup_subsys->use_id != 0.
EXPORT_SYMBOL_GPL(cgroup_lock_is_held);
+/* the current nr of refs, always >= 0 whether @css is deactivated or not */
+static int css_refcnt(struct cgroup_subsys_state *css)
+{
+ int v = atomic_read(&css->refcnt);
+
+ return v >= 0 ? v : v - CSS_DEACT_BIAS;
+}
+
/* convenient tests for these bits */
inline int cgroup_is_removed(const struct cgroup *cgrp)
{
#define for_each_active_root(_root) \
list_for_each_entry(_root, &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;
+}
+
/* the list of cgroups eligible for automatic release. Protected by
* release_list_lock */
static LIST_HEAD(release_list);
struct cgroup_subsys *ss;
int ret = 0;
- for_each_subsys(cgrp->root, ss)
- if (ss->pre_destroy) {
- ret = ss->pre_destroy(cgrp);
- if (ret)
- break;
+ for_each_subsys(cgrp->root, ss) {
+ if (!ss->pre_destroy)
+ continue;
+
+ ret = ss->pre_destroy(cgrp);
+ if (ret) {
+ /* ->pre_destroy() failure is being deprecated */
+ WARN_ON_ONCE(!ss->__DEPRECATED_clear_css_refs);
+ break;
}
+ }
return ret;
}
mutex_unlock(&cgroup_mutex);
/*
- * Drop the active superblock reference that we took when we
- * created the cgroup
+ * We want to drop the active superblock reference from the
+ * cgroup creation after all the dentry refs are gone -
+ * kill_sb gets mighty unhappy otherwise. Mark
+ * dentry->d_fsdata with cgroup_diput() to tell
+ * cgroup_d_release() to call deactivate_super().
*/
- deactivate_super(cgrp->root->sb);
+ dentry->d_fsdata = cgroup_diput;
/*
* if we're getting rid of the cgroup, refcount should ensure
BUG_ON(!list_empty(&cgrp->pidlists));
kfree_rcu(cgrp, rcu_head);
+ } 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);
+ kfree(cfe);
}
iput(inode);
}
return 1;
}
+static void cgroup_d_release(struct dentry *dentry)
+{
+ /* did cgroup_diput() tell me to deactivate super? */
+ if (dentry->d_fsdata == cgroup_diput)
+ deactivate_super(dentry->d_sb);
+}
+
static void remove_dir(struct dentry *d)
{
struct dentry *parent = dget(d->d_parent);
dput(parent);
}
-static void cgroup_clear_directory(struct dentry *dentry)
-{
- struct list_head *node;
-
- BUG_ON(!mutex_is_locked(&dentry->d_inode->i_mutex));
- spin_lock(&dentry->d_lock);
- node = dentry->d_subdirs.next;
- while (node != &dentry->d_subdirs) {
- struct dentry *d = list_entry(node, struct dentry, d_u.d_child);
-
- spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED);
- list_del_init(node);
- if (d->d_inode) {
- /* This should never be called on a cgroup
- * directory with child cgroups */
- BUG_ON(d->d_inode->i_mode & S_IFDIR);
- dget_dlock(d);
- spin_unlock(&d->d_lock);
- spin_unlock(&dentry->d_lock);
- d_delete(d);
- simple_unlink(dentry->d_inode, d);
- dput(d);
- spin_lock(&dentry->d_lock);
- } else
- spin_unlock(&d->d_lock);
- node = dentry->d_subdirs.next;
+static int cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
+{
+ struct cfent *cfe;
+
+ lockdep_assert_held(&cgrp->dentry->d_inode->i_mutex);
+ lockdep_assert_held(&cgroup_mutex);
+
+ list_for_each_entry(cfe, &cgrp->files, node) {
+ struct dentry *d = cfe->dentry;
+
+ if (cft && cfe->type != cft)
+ continue;
+
+ dget(d);
+ d_delete(d);
+ simple_unlink(d->d_inode, d);
+ list_del_init(&cfe->node);
+ dput(d);
+
+ return 0;
}
- spin_unlock(&dentry->d_lock);
+ return -ENOENT;
+}
+
+static void cgroup_clear_directory(struct dentry *dir)
+{
+ struct cgroup *cgrp = __d_cgrp(dir);
+
+ while (!list_empty(&cgrp->files))
+ cgroup_rm_file(cgrp, NULL);
}
/*
if (ret)
goto out_unlock;
+ /* See feature-removal-schedule.txt */
+ if (opts.subsys_bits != root->actual_subsys_bits || opts.release_agent)
+ pr_warning("cgroup: option changes via remount are deprecated (pid=%d comm=%s)\n",
+ task_tgid_nr(current), current->comm);
+
/* Don't allow flags or name to change at remount */
if (opts.flags != root->flags ||
(opts.name && strcmp(opts.name, root->name))) {
goto out_unlock;
}
- /* (re)populate subsystem files */
+ /* clear out any existing files and repopulate subsystem files */
+ cgroup_clear_directory(cgrp->dentry);
cgroup_populate_dir(cgrp);
if (opts.release_agent)
{
INIT_LIST_HEAD(&cgrp->sibling);
INIT_LIST_HEAD(&cgrp->children);
+ INIT_LIST_HEAD(&cgrp->files);
INIT_LIST_HEAD(&cgrp->css_sets);
INIT_LIST_HEAD(&cgrp->release_list);
INIT_LIST_HEAD(&cgrp->pidlists);
static void init_cgroup_root(struct cgroupfs_root *root)
{
struct cgroup *cgrp = &root->top_cgroup;
+
INIT_LIST_HEAD(&root->subsys_list);
INIT_LIST_HEAD(&root->root_list);
+ INIT_LIST_HEAD(&root->allcg_list);
root->number_of_cgroups = 1;
cgrp->root = root;
cgrp->top_cgroup = cgrp;
+ list_add_tail(&cgrp->allcg_node, &root->allcg_list);
init_cgroup_housekeeping(cgrp);
}
static const struct dentry_operations cgroup_dops = {
.d_iput = cgroup_diput,
.d_delete = cgroup_delete,
+ .d_release = cgroup_d_release,
};
struct inode *inode =
static struct kobject *cgroup_kobj;
-static inline struct cgroup *__d_cgrp(struct dentry *dentry)
-{
- return dentry->d_fsdata;
-}
-
-static inline struct cftype *__d_cft(struct dentry *dentry)
-{
- return dentry->d_fsdata;
-}
-
/**
* cgroup_path - generate the path of a cgroup
* @cgrp: the cgroup in question
* only need to check permissions on one of them.
*/
tcred = __task_cred(tsk);
- if (cred->euid &&
- cred->euid != tcred->uid &&
- cred->euid != tcred->suid) {
+ if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) &&
+ !uid_eq(cred->euid, tcred->uid) &&
+ !uid_eq(cred->euid, tcred->suid)) {
rcu_read_unlock();
ret = -EACCES;
goto out_unlock_cgroup;
if (threadgroup)
tsk = tsk->group_leader;
+
+ /*
+ * Workqueue threads may acquire PF_THREAD_BOUND and become
+ * trapped in a cpuset, or RT worker may be born in a cgroup
+ * with no rt_runtime allocated. Just say no.
+ */
+ if (tsk == kthreadd_task || (tsk->flags & PF_THREAD_BOUND)) {
+ ret = -EINVAL;
+ rcu_read_unlock();
+ goto out_unlock_cgroup;
+ }
+
get_task_struct(tsk);
rcu_read_unlock();
return mode;
}
-int cgroup_add_file(struct cgroup *cgrp,
- struct cgroup_subsys *subsys,
- const struct cftype *cft)
+static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys,
+ const 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 };
+
+ /* does @cft->flags tell us to skip creation on @cgrp? */
+ if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgrp->parent)
+ return 0;
+ if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgrp->parent)
+ return 0;
+
if (subsys && !test_bit(ROOT_NOPREFIX, &cgrp->root->flags)) {
strcpy(name, subsys->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;
+
dentry = lookup_one_len(name, dir, strlen(name));
- if (!IS_ERR(dentry)) {
- mode = cgroup_file_mode(cft);
- error = cgroup_create_file(dentry, mode | S_IFREG,
- cgrp->root->sb);
- if (!error)
- dentry->d_fsdata = (void *)cft;
- dput(dentry);
- } else
+ if (IS_ERR(dentry)) {
error = PTR_ERR(dentry);
+ goto out;
+ }
+
+ mode = cgroup_file_mode(cft);
+ error = cgroup_create_file(dentry, mode | S_IFREG, cgrp->root->sb);
+ if (!error) {
+ cfe->type = (void *)cft;
+ cfe->dentry = dentry;
+ dentry->d_fsdata = cfe;
+ list_add_tail(&cfe->node, &parent->files);
+ cfe = NULL;
+ }
+ dput(dentry);
+out:
+ kfree(cfe);
return error;
}
-EXPORT_SYMBOL_GPL(cgroup_add_file);
-int cgroup_add_files(struct cgroup *cgrp,
- struct cgroup_subsys *subsys,
- const struct cftype cft[],
- int count)
+static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys,
+ const struct cftype cfts[], bool is_add)
{
- int i, err;
- for (i = 0; i < count; i++) {
- err = cgroup_add_file(cgrp, subsys, &cft[i]);
- if (err)
- return err;
+ const struct cftype *cft;
+ int err, ret = 0;
+
+ for (cft = cfts; cft->name[0] != '\0'; cft++) {
+ if (is_add)
+ err = cgroup_add_file(cgrp, subsys, cft);
+ else
+ err = cgroup_rm_file(cgrp, cft);
+ if (err) {
+ pr_warning("cgroup_addrm_files: failed to %s %s, err=%d\n",
+ is_add ? "add" : "remove", cft->name, err);
+ ret = err;
+ }
}
+ return ret;
+}
+
+static DEFINE_MUTEX(cgroup_cft_mutex);
+
+static void cgroup_cfts_prepare(void)
+ __acquires(&cgroup_cft_mutex) __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 increment reference on all cgroups and build list of
+ * them using @cgrp->cft_q_node. Grab cgroup_cft_mutex to ensure
+ * exclusive access to the field.
+ */
+ mutex_lock(&cgroup_cft_mutex);
+ mutex_lock(&cgroup_mutex);
+}
+
+static void cgroup_cfts_commit(struct cgroup_subsys *ss,
+ const struct cftype *cfts, bool is_add)
+ __releases(&cgroup_mutex) __releases(&cgroup_cft_mutex)
+{
+ LIST_HEAD(pending);
+ struct cgroup *cgrp, *n;
+
+ /* %NULL @cfts indicates abort and don't bother if @ss isn't attached */
+ if (cfts && ss->root != &rootnode) {
+ list_for_each_entry(cgrp, &ss->root->allcg_list, allcg_node) {
+ dget(cgrp->dentry);
+ list_add_tail(&cgrp->cft_q_node, &pending);
+ }
+ }
+
+ mutex_unlock(&cgroup_mutex);
+
+ /*
+ * All new cgroups will see @cfts update on @ss->cftsets. Add/rm
+ * files for all cgroups which were created before.
+ */
+ list_for_each_entry_safe(cgrp, n, &pending, cft_q_node) {
+ struct inode *inode = cgrp->dentry->d_inode;
+
+ mutex_lock(&inode->i_mutex);
+ mutex_lock(&cgroup_mutex);
+ if (!cgroup_is_removed(cgrp))
+ cgroup_addrm_files(cgrp, ss, cfts, is_add);
+ mutex_unlock(&cgroup_mutex);
+ mutex_unlock(&inode->i_mutex);
+
+ list_del_init(&cgrp->cft_q_node);
+ dput(cgrp->dentry);
+ }
+
+ mutex_unlock(&cgroup_cft_mutex);
+}
+
+/**
+ * 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, const struct cftype *cfts)
+{
+ struct cftype_set *set;
+
+ set = kzalloc(sizeof(*set), GFP_KERNEL);
+ if (!set)
+ return -ENOMEM;
+
+ cgroup_cfts_prepare();
+ set->cfts = cfts;
+ list_add_tail(&set->node, &ss->cftsets);
+ cgroup_cfts_commit(ss, cfts, true);
+
return 0;
}
-EXPORT_SYMBOL_GPL(cgroup_add_files);
+EXPORT_SYMBOL_GPL(cgroup_add_cftypes);
+
+/**
+ * cgroup_rm_cftypes - remove an array of cftypes from a subsystem
+ * @ss: target cgroup subsystem
+ * @cfts: zero-length name terminated array of cftypes
+ *
+ * Unregister @cfts from @ss. Files described by @cfts are removed from
+ * all existing cgroups to which @ss is attached and all future cgroups
+ * won't have them either. This function can be called anytime whether @ss
+ * is attached or not.
+ *
+ * Returns 0 on successful unregistration, -ENOENT if @cfts is not
+ * registered with @ss.
+ */
+int cgroup_rm_cftypes(struct cgroup_subsys *ss, const struct cftype *cfts)
+{
+ struct cftype_set *set;
+
+ cgroup_cfts_prepare();
+
+ list_for_each_entry(set, &ss->cftsets, node) {
+ if (set->cfts == cfts) {
+ list_del_init(&set->node);
+ cgroup_cfts_commit(ss, cfts, false);
+ return 0;
+ }
+ }
+
+ cgroup_cfts_commit(ss, NULL, false);
+ return -ENOENT;
+}
/**
* cgroup_task_count - count the number of tasks in a cgroup.
.read_u64 = cgroup_clone_children_read,
.write_u64 = cgroup_clone_children_write,
},
-};
-
-static struct cftype cft_release_agent = {
- .name = "release_agent",
- .read_seq_string = cgroup_release_agent_show,
- .write_string = cgroup_release_agent_write,
- .max_write_len = PATH_MAX,
+ {
+ .name = "release_agent",
+ .flags = CFTYPE_ONLY_ON_ROOT,
+ .read_seq_string = cgroup_release_agent_show,
+ .write_string = cgroup_release_agent_write,
+ .max_write_len = PATH_MAX,
+ },
+ { } /* terminate */
};
static int cgroup_populate_dir(struct cgroup *cgrp)
int err;
struct cgroup_subsys *ss;
- /* First clear out any existing files */
- cgroup_clear_directory(cgrp->dentry);
-
- err = cgroup_add_files(cgrp, NULL, files, ARRAY_SIZE(files));
+ err = cgroup_addrm_files(cgrp, NULL, files, true);
if (err < 0)
return err;
- if (cgrp == cgrp->top_cgroup) {
- if ((err = cgroup_add_file(cgrp, NULL, &cft_release_agent)) < 0)
- return err;
- }
-
+ /* process cftsets of each subsystem */
for_each_subsys(cgrp->root, ss) {
- if (ss->populate && (err = ss->populate(ss, cgrp)) < 0)
- return err;
+ struct cftype_set *set;
+
+ list_for_each_entry(set, &ss->cftsets, node)
+ cgroup_addrm_files(cgrp, ss, set->cfts, true);
}
+
/* This cgroup is ready now */
for_each_subsys(cgrp->root, ss) {
struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];
return 0;
}
+static void css_dput_fn(struct work_struct *work)
+{
+ struct cgroup_subsys_state *css =
+ container_of(work, struct cgroup_subsys_state, dput_work);
+
+ dput(css->cgroup->dentry);
+}
+
static void init_cgroup_css(struct cgroup_subsys_state *css,
struct cgroup_subsys *ss,
struct cgroup *cgrp)
set_bit(CSS_ROOT, &css->flags);
BUG_ON(cgrp->subsys[ss->subsys_id]);
cgrp->subsys[ss->subsys_id] = css;
+
+ /*
+ * If !clear_css_refs, css holds an extra ref to @cgrp->dentry
+ * which is put on the last css_put(). dput() requires process
+ * context, which css_put() may be called without. @css->dput_work
+ * will be used to invoke dput() asynchronously from css_put().
+ */
+ INIT_WORK(&css->dput_work, css_dput_fn);
+ if (ss->__DEPRECATED_clear_css_refs)
+ set_bit(CSS_CLEAR_CSS_REFS, &css->flags);
}
static void cgroup_lock_hierarchy(struct cgroupfs_root *root)
if (err < 0)
goto err_remove;
+ /* If !clear_css_refs, each css holds a ref to the cgroup's dentry */
+ for_each_subsys(root, ss)
+ if (!ss->__DEPRECATED_clear_css_refs)
+ dget(dentry);
+
/* The cgroup directory was pre-locked for us */
BUG_ON(!mutex_is_locked(&cgrp->dentry->d_inode->i_mutex));
+ list_add_tail(&cgrp->allcg_node, &root->allcg_list);
+
err = cgroup_populate_dir(cgrp);
/* If err < 0, we have a half-filled directory - oh well ;) */
return cgroup_create(c_parent, dentry, mode | S_IFDIR);
}
+/*
+ * Check the reference count on each subsystem. Since we already
+ * established that there are no tasks in the cgroup, if the css refcount
+ * is also 1, then there should be no outstanding references, so the
+ * subsystem is safe to destroy. We scan across all subsystems rather than
+ * using the per-hierarchy linked list of mounted subsystems since we can
+ * be called via check_for_release() with no synchronization other than
+ * RCU, and the subsystem linked list isn't RCU-safe.
+ */
static int cgroup_has_css_refs(struct cgroup *cgrp)
{
- /* Check the reference count on each subsystem. Since we
- * already established that there are no tasks in the
- * cgroup, if the css refcount is also 1, then there should
- * be no outstanding references, so the subsystem is safe to
- * destroy. We scan across all subsystems rather than using
- * the per-hierarchy linked list of mounted subsystems since
- * we can be called via check_for_release() with no
- * synchronization other than RCU, and the subsystem linked
- * list isn't RCU-safe */
int i;
+
/*
* We won't need to lock the subsys array, because the subsystems
* we're concerned about aren't going anywhere since our cgroup root
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
struct cgroup_subsys *ss = subsys[i];
struct cgroup_subsys_state *css;
+
/* Skip subsystems not present or not in this hierarchy */
if (ss == NULL || ss->root != cgrp->root)
continue;
+
css = cgrp->subsys[ss->subsys_id];
- /* When called from check_for_release() it's possible
+ /*
+ * When called from check_for_release() it's possible
* that by this point the cgroup has been removed
* and the css deleted. But a false-positive doesn't
* matter, since it can only happen if the cgroup
* has been deleted and hence no longer needs the
- * release agent to be called anyway. */
- if (css && (atomic_read(&css->refcnt) > 1))
+ * release agent to be called anyway.
+ */
+ if (css && css_refcnt(css) > 1)
return 1;
}
return 0;
* Atomically mark all (or else none) of the cgroup's CSS objects as
* CSS_REMOVED. Return true on success, or false if the cgroup has
* busy subsystems. Call with cgroup_mutex held
+ *
+ * Depending on whether a subsys has __DEPRECATED_clear_css_refs set or
+ * not, cgroup removal behaves differently.
+ *
+ * If clear is set, css refcnt for the subsystem should be zero before
+ * cgroup removal can be committed. This is implemented by
+ * CGRP_WAIT_ON_RMDIR and retry logic around ->pre_destroy(), which may be
+ * called multiple times until all css refcnts reach zero and is allowed to
+ * veto removal on any invocation. This behavior is deprecated and will be
+ * removed as soon as the existing user (memcg) is updated.
+ *
+ * If clear is not set, each css holds an extra reference to the cgroup's
+ * dentry and cgroup removal proceeds regardless of css refs.
+ * ->pre_destroy() will be called at least once and is not allowed to fail.
+ * On the last put of each css, whenever that may be, the extra dentry ref
+ * is put so that dentry destruction happens only after all css's are
+ * released.
*/
-
static int cgroup_clear_css_refs(struct cgroup *cgrp)
{
struct cgroup_subsys *ss;
unsigned long flags;
bool failed = false;
+
local_irq_save(flags);
+
+ /*
+ * Block new css_tryget() by deactivating refcnt. If all refcnts
+ * for subsystems w/ clear_css_refs set were 1 at the moment of
+ * deactivation, we succeeded.
+ */
for_each_subsys(cgrp->root, ss) {
struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];
- int refcnt;
- while (1) {
- /* We can only remove a CSS with a refcnt==1 */
- refcnt = atomic_read(&css->refcnt);
- if (refcnt > 1) {
- failed = true;
- goto done;
- }
- BUG_ON(!refcnt);
- /*
- * Drop the refcnt to 0 while we check other
- * subsystems. This will cause any racing
- * css_tryget() to spin until we set the
- * CSS_REMOVED bits or abort
- */
- if (atomic_cmpxchg(&css->refcnt, refcnt, 0) == refcnt)
- break;
- cpu_relax();
- }
+
+ WARN_ON(atomic_read(&css->refcnt) < 0);
+ atomic_add(CSS_DEACT_BIAS, &css->refcnt);
+
+ if (ss->__DEPRECATED_clear_css_refs)
+ failed |= css_refcnt(css) != 1;
}
- done:
+
+ /*
+ * If succeeded, set REMOVED and put all the base refs; otherwise,
+ * restore refcnts to positive values. Either way, all in-progress
+ * css_tryget() will be released.
+ */
for_each_subsys(cgrp->root, ss) {
struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];
- if (failed) {
- /*
- * Restore old refcnt if we previously managed
- * to clear it from 1 to 0
- */
- if (!atomic_read(&css->refcnt))
- atomic_set(&css->refcnt, 1);
- } else {
- /* Commit the fact that the CSS is removed */
+
+ if (!failed) {
set_bit(CSS_REMOVED, &css->flags);
+ css_put(css);
+ } else {
+ atomic_sub(CSS_DEACT_BIAS, &css->refcnt);
}
}
+
local_irq_restore(flags);
return !failed;
}
list_del_init(&cgrp->sibling);
cgroup_unlock_hierarchy(cgrp->root);
+ list_del_init(&cgrp->allcg_node);
+
d = dget(cgrp->dentry);
cgroup_d_remove_dir(d);
return 0;
}
+static void __init_or_module cgroup_init_cftsets(struct cgroup_subsys *ss)
+{
+ INIT_LIST_HEAD(&ss->cftsets);
+
+ /*
+ * base_cftset is embedded in subsys itself, no need to worry about
+ * deregistration.
+ */
+ if (ss->base_cftypes) {
+ ss->base_cftset.cfts = ss->base_cftypes;
+ list_add_tail(&ss->base_cftset.node, &ss->cftsets);
+ }
+}
+
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);
+ /* init base cftset */
+ cgroup_init_cftsets(ss);
+
/* Create the top cgroup state for this subsystem */
list_add(&ss->sibling, &rootnode.subsys_list);
ss->root = &rootnode;
return 0;
}
+ /* init base cftset */
+ cgroup_init_cftsets(ss);
+
/*
* need to register a subsys id before anything else - for example,
* init_cgroup_css needs it.
}
/* Caller must verify that the css is not for root cgroup */
-void __css_put(struct cgroup_subsys_state *css, int count)
+bool __css_tryget(struct cgroup_subsys_state *css)
+{
+ do {
+ int v = css_refcnt(css);
+
+ if (atomic_cmpxchg(&css->refcnt, v, v + 1) == v)
+ return true;
+ cpu_relax();
+ } while (!test_bit(CSS_REMOVED, &css->flags));
+
+ return false;
+}
+EXPORT_SYMBOL_GPL(__css_tryget);
+
+/* Caller must verify that the css is not for root cgroup */
+void __css_put(struct cgroup_subsys_state *css)
{
struct cgroup *cgrp = css->cgroup;
- int val;
+
rcu_read_lock();
- val = atomic_sub_return(count, &css->refcnt);
- if (val == 1) {
+ atomic_dec(&css->refcnt);
+ switch (css_refcnt(css)) {
+ case 1:
if (notify_on_release(cgrp)) {
set_bit(CGRP_RELEASABLE, &cgrp->flags);
check_for_release(cgrp);
}
cgroup_wakeup_rmdir_waiter(cgrp);
+ break;
+ case 0:
+ if (!test_bit(CSS_CLEAR_CSS_REFS, &css->flags))
+ schedule_work(&css->dput_work);
+ break;
}
rcu_read_unlock();
- WARN_ON_ONCE(val < 1);
}
EXPORT_SYMBOL_GPL(__css_put);
* on this or this is under rcu_read_lock(). Once css->id is allocated,
* it's unchanged until freed.
*/
- cssid = rcu_dereference_check(css->id, atomic_read(&css->refcnt));
+ cssid = rcu_dereference_check(css->id, css_refcnt(css));
if (cssid)
return cssid->id;
{
struct css_id *cssid;
- cssid = rcu_dereference_check(css->id, atomic_read(&css->refcnt));
+ cssid = rcu_dereference_check(css->id, css_refcnt(css));
if (cssid)
return cssid->depth;
* @root: the css supporsed to be an ancestor of the child.
*
* Returns true if "root" is an ancestor of "child" in its hierarchy. Because
- * this function reads css->id, this use rcu_dereference() and rcu_read_lock().
+ * this function reads css->id, the caller must hold rcu_read_lock().
* But, considering usual usage, the csses should be valid objects after test.
* Assuming that the caller will do some action to the child if this returns
* returns true, the caller must take "child";s reference count.
{
struct css_id *child_id;
struct css_id *root_id;
- bool ret = true;
- rcu_read_lock();
child_id = rcu_dereference(child->id);
+ if (!child_id)
+ return false;
root_id = rcu_dereference(root->id);
- if (!child_id
- || !root_id
- || (child_id->depth < root_id->depth)
- || (child_id->stack[root_id->depth] != root_id->id))
- ret = false;
- rcu_read_unlock();
- return ret;
+ if (!root_id)
+ return false;
+ if (child_id->depth < root_id->depth)
+ return false;
+ if (child_id->stack[root_id->depth] != root_id->id)
+ return false;
+ return true;
}
void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css)
.name = "releasable",
.read_u64 = releasable_read,
},
-};
-static int debug_populate(struct cgroup_subsys *ss, struct cgroup *cont)
-{
- return cgroup_add_files(cont, ss, debug_files,
- ARRAY_SIZE(debug_files));
-}
+ { } /* terminate */
+};
struct cgroup_subsys debug_subsys = {
.name = "debug",
.create = debug_create,
.destroy = debug_destroy,
- .populate = debug_populate,
.subsys_id = debug_subsys_id,
+ .base_cftypes = debug_files,
};
#endif /* CONFIG_CGROUP_DEBUG */
projects / karo-tx-linux.git / blobdiff