*/
#ifdef CONFIG_PROVE_RCU
DEFINE_MUTEX(cgroup_mutex);
-EXPORT_SYMBOL_GPL(cgroup_mutex); /* only for task_subsys_state_check() */
+EXPORT_SYMBOL_GPL(cgroup_mutex); /* only for lockdep */
#else
static DEFINE_MUTEX(cgroup_mutex);
#endif
struct list_head node;
struct dentry *dentry;
struct cftype *type;
+ struct cgroup_subsys_state *css;
/* file xattrs */
struct simple_xattrs xattrs;
*/
struct cgroup_event {
/*
- * Cgroup which the event belongs to.
+ * css which the event belongs to.
*/
- struct cgroup *cgrp;
+ struct cgroup_subsys_state *css;
/*
* Control file which the event associated.
*/
*/
static int need_forkexit_callback __read_mostly;
-static void cgroup_offline_fn(struct work_struct *work);
+static struct cftype cgroup_base_files[];
+
+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 cgroup_subsys *subsys,
- struct cftype cfts[], bool is_add);
+static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[],
+ bool is_add);
+
+/**
+ * cgroup_css - obtain a cgroup's css for the specified subsystem
+ * @cgrp: the cgroup of interest
+ * @ss: the subsystem of interest (%NULL returns the dummy_css)
+ *
+ * Return @cgrp's css (cgroup_subsys_state) associated with @ss. This
+ * function must be called either under cgroup_mutex or rcu_read_lock() and
+ * the caller is responsible for pinning the returned css if it wants to
+ * keep accessing it outside the said locks. This function may return
+ * %NULL if @cgrp doesn't have @subsys_id enabled.
+ */
+static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp,
+ struct cgroup_subsys *ss)
+{
+ if (ss)
+ return rcu_dereference_check(cgrp->subsys[ss->subsys_id],
+ lockdep_is_held(&cgroup_mutex));
+ else
+ return &cgrp->dummy_css;
+}
/* convenient tests for these bits */
static inline bool cgroup_is_dead(const struct cgroup *cgrp)
static int cgroup_init_idr(struct cgroup_subsys *ss,
struct cgroup_subsys_state *css);
-/* 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 cgroup_iter_start() */
+/*
+ * 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;
return key;
}
-/* We don't maintain the lists running through each css_set to its
- * task until after the first call to cgroup_iter_start(). This
- * reduces the fork()/exit() overhead for people who have cgroups
- * compiled into their kernel but not actually in use */
+/*
+ * 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)
* @new_cgrp: cgroup that's being entered by the task
* @template: desired set of css pointers in css_set (pre-calculated)
*
- * Returns true if "cg" matches "old_cg" except for the hierarchy
+ * Returns true if "cset" matches "old_cset" except for the hierarchy
* which "new_cgrp" belongs to, for which it should match "new_cgrp".
*/
static bool compare_css_sets(struct css_set *cset,
/* Subsystem is in this hierarchy. So we want
* the subsystem state from the new
* cgroup */
- template[i] = cgrp->subsys[i];
+ template[i] = cgroup_css(cgrp, ss);
} else {
/* Subsystem is not in this hierarchy, so we
* don't want to change the subsystem state */
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, bool base_files,
- unsigned long subsys_mask);
+static int cgroup_populate_dir(struct cgroup *cgrp, unsigned long subsys_mask);
static const struct inode_operations cgroup_dir_inode_operations;
static const struct file_operations proc_cgroupstats_operations;
.capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
};
-static int alloc_css_id(struct cgroup_subsys *ss,
- struct cgroup *parent, struct cgroup *child);
+static int alloc_css_id(struct cgroup_subsys_state *child_css);
static struct inode *cgroup_new_inode(umode_t mode, struct super_block *sb)
{
static void cgroup_free_fn(struct work_struct *work)
{
struct cgroup *cgrp = container_of(work, struct cgroup, destroy_work);
- struct cgroup_subsys *ss;
mutex_lock(&cgroup_mutex);
- /*
- * Release the subsystem state objects.
- */
- for_each_root_subsys(cgrp->root, ss)
- ss->css_free(cgrp);
-
cgrp->root->number_of_cgroups--;
mutex_unlock(&cgroup_mutex);
*/
dput(cgrp->parent->dentry);
- ida_simple_remove(&cgrp->root->cgroup_ida, cgrp->id);
-
/*
* Drop the active superblock reference that we took when we
* created the cgroup. This will free cgrp->root, if we are
}
/**
- * cgroup_clear_directory - selective removal of base and subsystem files
- * @dir: directory containing the files
- * @base_files: true if the base files should be removed
+ * cgroup_clear_dir - remove subsys files in a cgroup directory
+ * @cgrp: target cgroup
* @subsys_mask: mask of the subsystem ids whose files should be removed
*/
-static void cgroup_clear_directory(struct dentry *dir, bool base_files,
- unsigned long subsys_mask)
+static void cgroup_clear_dir(struct cgroup *cgrp, unsigned long subsys_mask)
{
- struct cgroup *cgrp = __d_cgrp(dir);
struct cgroup_subsys *ss;
+ int i;
- for_each_root_subsys(cgrp->root, ss) {
+ for_each_subsys(ss, i) {
struct cftype_set *set;
- if (!test_bit(ss->subsys_id, &subsys_mask))
+
+ if (!test_bit(i, &subsys_mask))
continue;
list_for_each_entry(set, &ss->cftsets, node)
- cgroup_addrm_files(cgrp, NULL, set->cfts, false);
- }
- if (base_files) {
- while (!list_empty(&cgrp->files))
- cgroup_rm_file(cgrp, NULL);
+ cgroup_addrm_files(cgrp, set->cfts, false);
}
}
static void cgroup_d_remove_dir(struct dentry *dentry)
{
struct dentry *parent;
- struct cgroupfs_root *root = dentry->d_sb->s_fs_info;
-
- cgroup_clear_directory(dentry, true, root->subsys_mask);
parent = dentry->d_parent;
spin_lock(&parent->d_lock);
{
struct cgroup *cgrp = &root->top_cgroup;
struct cgroup_subsys *ss;
- int i;
+ unsigned long pinned = 0;
+ int i, ret;
BUG_ON(!mutex_is_locked(&cgroup_mutex));
BUG_ON(!mutex_is_locked(&cgroup_root_mutex));
/* Check that any added subsystems are currently free */
for_each_subsys(ss, i) {
- unsigned long bit = 1UL << i;
-
- if (!(bit & added_mask))
+ if (!(added_mask & (1 << i)))
continue;
+ /* is the subsystem mounted elsewhere? */
if (ss->root != &cgroup_dummy_root) {
- /* Subsystem isn't free */
- return -EBUSY;
+ ret = -EBUSY;
+ goto out_put;
+ }
+
+ /* pin the module */
+ if (!try_module_get(ss->module)) {
+ ret = -ENOENT;
+ goto out_put;
}
+ pinned |= 1 << i;
}
- /* Currently we don't handle adding/removing subsystems when
- * any child cgroups exist. This is theoretically supportable
- * but involves complex error handling, so it's being left until
- * later */
- if (root->number_of_cgroups > 1)
- 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(cgrp, added_mask);
+ if (ret)
+ goto out_put;
+
+ /*
+ * Nothing can fail from this point on. Remove files for the
+ * removed subsystems and rebind each subsystem.
+ */
+ cgroup_clear_dir(cgrp, removed_mask);
- /* Process each subsystem */
for_each_subsys(ss, i) {
unsigned long bit = 1UL << i;
if (bit & added_mask) {
/* We're binding this subsystem to this hierarchy */
- BUG_ON(cgrp->subsys[i]);
- BUG_ON(!cgroup_dummy_top->subsys[i]);
- BUG_ON(cgroup_dummy_top->subsys[i]->cgroup != cgroup_dummy_top);
+ 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);
+
+ rcu_assign_pointer(cgrp->subsys[i],
+ cgroup_css(cgroup_dummy_top, ss));
+ cgroup_css(cgrp, ss)->cgroup = cgrp;
- cgrp->subsys[i] = cgroup_dummy_top->subsys[i];
- cgrp->subsys[i]->cgroup = cgrp;
list_move(&ss->sibling, &root->subsys_list);
ss->root = root;
if (ss->bind)
- ss->bind(cgrp);
+ ss->bind(cgroup_css(cgrp, ss));
/* 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(cgrp->subsys[i] != cgroup_dummy_top->subsys[i]);
- BUG_ON(cgrp->subsys[i]->cgroup != cgrp);
+ BUG_ON(cgroup_css(cgrp, ss) != cgroup_css(cgroup_dummy_top, ss));
+ BUG_ON(cgroup_css(cgrp, ss)->cgroup != cgrp);
if (ss->bind)
- ss->bind(cgroup_dummy_top);
- cgroup_dummy_top->subsys[i]->cgroup = cgroup_dummy_top;
- cgrp->subsys[i] = NULL;
+ ss->bind(cgroup_css(cgroup_dummy_top, ss));
+
+ cgroup_css(cgroup_dummy_top, ss)->cgroup = cgroup_dummy_top;
+ RCU_INIT_POINTER(cgrp->subsys[i], NULL);
+
cgroup_subsys[i]->root = &cgroup_dummy_root;
list_move(&ss->sibling, &cgroup_dummy_root.subsys_list);
/* subsystem is now free - drop reference on module */
module_put(ss->module);
root->subsys_mask &= ~bit;
- } else if (bit & root->subsys_mask) {
- /* Subsystem state should already exist */
- BUG_ON(!cgrp->subsys[i]);
- /*
- * a refcount was taken, but we already had one, so
- * drop the extra reference.
- */
- module_put(ss->module);
-#ifdef CONFIG_MODULE_UNLOAD
- BUG_ON(ss->module && !module_refcount(ss->module));
-#endif
- } else {
- /* Subsystem state shouldn't exist */
- BUG_ON(cgrp->subsys[i]);
}
}
root->flags |= CGRP_ROOT_SUBSYS_BOUND;
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)
char *token, *o = data;
bool all_ss = false, one_ss = false;
unsigned long mask = (unsigned long)-1;
- bool module_pin_failed = false;
struct cgroup_subsys *ss;
int i;
if (!opts->subsys_mask && !opts->name)
return -EINVAL;
- /*
- * Grab references on all the modules we'll need, so the subsystems
- * don't dance around before rebind_subsystems attaches them. This may
- * take duplicate reference counts on a subsystem that's already used,
- * but rebind_subsystems handles this case.
- */
- for_each_subsys(ss, i) {
- if (!(opts->subsys_mask & (1UL << i)))
- continue;
- if (!try_module_get(cgroup_subsys[i]->module)) {
- module_pin_failed = true;
- break;
- }
- }
- if (module_pin_failed) {
- /*
- * oops, one of the modules was going away. this means that we
- * raced with a module_delete call, and to the user this is
- * essentially a "subsystem doesn't exist" case.
- */
- for (i--; i >= 0; i--) {
- /* drop refcounts only on the ones we took */
- unsigned long bit = 1UL << i;
-
- if (!(bit & opts->subsys_mask))
- continue;
- module_put(cgroup_subsys[i]->module);
- }
- return -ENOENT;
- }
-
return 0;
}
-static void drop_parsed_module_refcounts(unsigned long subsys_mask)
-{
- struct cgroup_subsys *ss;
- int i;
-
- mutex_lock(&cgroup_mutex);
- for_each_subsys(ss, i)
- if (subsys_mask & (1UL << i))
- module_put(cgroup_subsys[i]->module);
- mutex_unlock(&cgroup_mutex);
-}
-
static int cgroup_remount(struct super_block *sb, int *flags, char *data)
{
int ret = 0;
goto out_unlock;
}
- /*
- * Clear out the files of subsystems that should be removed, do
- * this before rebind_subsystems, since rebind_subsystems may
- * change this hierarchy's subsys_list.
- */
- cgroup_clear_directory(cgrp->dentry, false, removed_mask);
-
- ret = rebind_subsystems(root, added_mask, removed_mask);
- if (ret) {
- /* rebind_subsystems failed, re-populate the removed files */
- cgroup_populate_dir(cgrp, false, removed_mask);
+ /* remounting is not allowed for populated hierarchies */
+ if (root->number_of_cgroups > 1) {
+ ret = -EBUSY;
goto out_unlock;
}
- /* re-populate subsystem files */
- cgroup_populate_dir(cgrp, false, added_mask);
+ ret = rebind_subsystems(root, added_mask, removed_mask);
+ if (ret)
+ goto out_unlock;
if (opts.release_agent)
strcpy(root->release_agent_path, opts.release_agent);
mutex_unlock(&cgroup_root_mutex);
mutex_unlock(&cgroup_mutex);
mutex_unlock(&cgrp->dentry->d_inode->i_mutex);
- if (ret)
- drop_parsed_module_refcounts(opts.subsys_mask);
return ret;
}
INIT_LIST_HEAD(&cgrp->release_list);
INIT_LIST_HEAD(&cgrp->pidlists);
mutex_init(&cgrp->pidlist_mutex);
+ cgrp->dummy_css.cgroup = cgrp;
INIT_LIST_HEAD(&cgrp->event_list);
spin_lock_init(&cgrp->event_list_lock);
simple_xattrs_init(&cgrp->xattrs);
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)
*/
root->subsys_mask = opts->subsys_mask;
root->flags = opts->flags;
- ida_init(&root->cgroup_ida);
if (opts->release_agent)
strcpy(root->release_agent_path, opts->release_agent);
if (opts->name)
/* hierarhcy ID shoulid already have been released */
WARN_ON_ONCE(root->hierarchy_id);
- ida_destroy(&root->cgroup_ida);
+ idr_destroy(&root->cgroup_idr);
kfree(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;
/* First find the desired set of subsystems */
mutex_lock(&cgroup_mutex);
new_root = cgroup_root_from_opts(&opts);
if (IS_ERR(new_root)) {
ret = PTR_ERR(new_root);
- goto drop_modules;
+ goto out_err;
}
opts.new_root = new_root;
if (IS_ERR(sb)) {
ret = PTR_ERR(sb);
cgroup_free_root(opts.new_root);
- goto drop_modules;
+ goto out_err;
}
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 list_head tmp_links;
struct cgroup *root_cgrp = &root->top_cgroup;
struct cgroupfs_root *existing_root;
- const struct cred *cred;
int i;
struct css_set *cset;
mutex_lock(&cgroup_mutex);
mutex_lock(&cgroup_root_mutex);
+ root_cgrp->id = idr_alloc(&root->cgroup_idr, root_cgrp,
+ 0, 1, GFP_KERNEL);
+ if (root_cgrp->id < 0)
+ goto unlock_drop;
+
/* Check for name clashes with existing mounts */
ret = -EBUSY;
if (strlen(root->name))
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;
+
ret = rebind_subsystems(root, root->subsys_mask, 0);
- if (ret == -EBUSY) {
- free_cgrp_cset_links(&tmp_links);
- goto unlock_drop;
- }
+ if (ret)
+ goto rm_base_files;
+
+ revert_creds(cred);
+
/*
* There must be no failure case after here, since rebinding
* takes care of subsystems' refcounts, which are explicitly
* dropped in the failure exit path.
*/
- /* EBUSY should be the only error here */
- BUG_ON(ret);
-
list_add(&root->root_list, &cgroup_roots);
cgroup_root_count++;
- sb->s_root->d_fsdata = root_cgrp;
- root->top_cgroup.dentry = sb->s_root;
-
/* Link the top cgroup in this hierarchy into all
* the css_set objects */
write_lock(&css_set_lock);
BUG_ON(!list_empty(&root_cgrp->children));
BUG_ON(root->number_of_cgroups != 1);
- cred = override_creds(&init_cred);
- cgroup_populate_dir(root_cgrp, true, root->subsys_mask);
- revert_creds(cred);
mutex_unlock(&cgroup_root_mutex);
mutex_unlock(&cgroup_mutex);
mutex_unlock(&inode->i_mutex);
pr_warning("cgroup: new mount options do not match the existing superblock, will be ignored\n");
}
}
-
- /* no subsys rebinding, so refcounts don't change */
- drop_parsed_module_refcounts(opts.subsys_mask);
}
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(&inode->i_mutex);
drop_new_super:
deactivate_locked_super(sb);
- drop_modules:
- drop_parsed_module_refcounts(opts.subsys_mask);
out_err:
kfree(opts.release_agent);
kfree(opts.name);
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);
mutex_unlock(&cgroup_root_mutex);
mutex_unlock(&cgroup_mutex);
+ mutex_unlock(&cgrp->dentry->d_inode->i_mutex);
simple_xattrs_free(&cgrp->xattrs);
struct task_and_cgroup {
struct task_struct *task;
struct cgroup *cgrp;
- struct css_set *cg;
+ struct css_set *cset;
};
struct cgroup_taskset {
EXPORT_SYMBOL_GPL(cgroup_taskset_next);
/**
- * cgroup_taskset_cur_cgroup - return the matching cgroup for the current 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 cgroup for the current (last returned) task of @tset. This
- * function must be preceded by either cgroup_taskset_first() or
- * cgroup_taskset_next().
+ * 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 *cgroup_taskset_cur_cgroup(struct cgroup_taskset *tset)
+struct cgroup_subsys_state *cgroup_taskset_cur_css(struct cgroup_taskset *tset,
+ int subsys_id)
{
- return tset->cur_cgrp;
+ return cgroup_css(tset->cur_cgrp, cgroup_subsys[subsys_id]);
}
-EXPORT_SYMBOL_GPL(cgroup_taskset_cur_cgroup);
+EXPORT_SYMBOL_GPL(cgroup_taskset_cur_css);
/**
* cgroup_taskset_size - return the number of tasks in taskset
* step 1: check that we can legitimately attach to the cgroup.
*/
for_each_root_subsys(root, ss) {
+ struct cgroup_subsys_state *css = cgroup_css(cgrp, ss);
+
if (ss->can_attach) {
- retval = ss->can_attach(cgrp, &tset);
+ retval = ss->can_attach(css, &tset);
if (retval) {
failed_ss = ss;
goto out_cancel_attach;
tc = flex_array_get(group, i);
old_cset = task_css_set(tc->task);
- tc->cg = find_css_set(old_cset, cgrp);
- if (!tc->cg) {
+ tc->cset = find_css_set(old_cset, cgrp);
+ if (!tc->cset) {
retval = -ENOMEM;
goto out_put_css_set_refs;
}
*/
for (i = 0; i < group_size; i++) {
tc = flex_array_get(group, i);
- cgroup_task_migrate(tc->cgrp, tc->task, tc->cg);
+ cgroup_task_migrate(tc->cgrp, tc->task, tc->cset);
}
/* nothing is sensitive to fork() after this point. */
* step 4: do subsystem attach callbacks.
*/
for_each_root_subsys(root, ss) {
+ struct cgroup_subsys_state *css = cgroup_css(cgrp, ss);
+
if (ss->attach)
- ss->attach(cgrp, &tset);
+ ss->attach(css, &tset);
}
/*
if (retval) {
for (i = 0; i < group_size; i++) {
tc = flex_array_get(group, i);
- if (!tc->cg)
+ if (!tc->cset)
break;
- put_css_set(tc->cg);
+ put_css_set(tc->cset);
}
}
out_cancel_attach:
if (retval) {
for_each_root_subsys(root, ss) {
+ struct cgroup_subsys_state *css = cgroup_css(cgrp, ss);
+
if (ss == failed_ss)
break;
if (ss->cancel_attach)
- ss->cancel_attach(cgrp, &tset);
+ ss->cancel_attach(css, &tset);
}
}
out_free_group_list:
mutex_lock(&cgroup_mutex);
for_each_active_root(root) {
- struct cgroup *from_cg = task_cgroup_from_root(from, root);
+ struct cgroup *from_cgrp = task_cgroup_from_root(from, root);
- retval = cgroup_attach_task(from_cg, tsk, false);
+ retval = cgroup_attach_task(from_cgrp, tsk, false);
if (retval)
break;
}
}
EXPORT_SYMBOL_GPL(cgroup_attach_task_all);
-static int cgroup_tasks_write(struct cgroup *cgrp, struct cftype *cft, u64 pid)
+static int cgroup_tasks_write(struct cgroup_subsys_state *css,
+ struct cftype *cft, u64 pid)
{
- return attach_task_by_pid(cgrp, pid, false);
+ return attach_task_by_pid(css->cgroup, pid, false);
}
-static int cgroup_procs_write(struct cgroup *cgrp, struct cftype *cft, u64 tgid)
+static int cgroup_procs_write(struct cgroup_subsys_state *css,
+ struct cftype *cft, u64 tgid)
{
- return attach_task_by_pid(cgrp, tgid, true);
+ return attach_task_by_pid(css->cgroup, tgid, true);
}
-static int cgroup_release_agent_write(struct cgroup *cgrp, struct cftype *cft,
- const char *buffer)
+static int cgroup_release_agent_write(struct cgroup_subsys_state *css,
+ struct cftype *cft, const char *buffer)
{
- BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX);
+ BUILD_BUG_ON(sizeof(css->cgroup->root->release_agent_path) < PATH_MAX);
if (strlen(buffer) >= PATH_MAX)
return -EINVAL;
- if (!cgroup_lock_live_group(cgrp))
+ if (!cgroup_lock_live_group(css->cgroup))
return -ENODEV;
mutex_lock(&cgroup_root_mutex);
- strcpy(cgrp->root->release_agent_path, buffer);
+ strcpy(css->cgroup->root->release_agent_path, buffer);
mutex_unlock(&cgroup_root_mutex);
mutex_unlock(&cgroup_mutex);
return 0;
}
-static int cgroup_release_agent_show(struct cgroup *cgrp, struct cftype *cft,
- struct seq_file *seq)
+static int cgroup_release_agent_show(struct cgroup_subsys_state *css,
+ struct cftype *cft, struct seq_file *seq)
{
+ struct cgroup *cgrp = css->cgroup;
+
if (!cgroup_lock_live_group(cgrp))
return -ENODEV;
seq_puts(seq, cgrp->root->release_agent_path);
return 0;
}
-static int cgroup_sane_behavior_show(struct cgroup *cgrp, struct cftype *cft,
- struct seq_file *seq)
+static int cgroup_sane_behavior_show(struct cgroup_subsys_state *css,
+ struct cftype *cft, struct seq_file *seq)
{
- seq_printf(seq, "%d\n", cgroup_sane_behavior(cgrp));
+ seq_printf(seq, "%d\n", cgroup_sane_behavior(css->cgroup));
return 0;
}
/* A buffer size big enough for numbers or short strings */
#define CGROUP_LOCAL_BUFFER_SIZE 64
-static ssize_t cgroup_write_X64(struct cgroup *cgrp, struct cftype *cft,
- struct file *file,
- const char __user *userbuf,
- size_t nbytes, loff_t *unused_ppos)
+static ssize_t cgroup_write_X64(struct cgroup_subsys_state *css,
+ struct cftype *cft, struct file *file,
+ const char __user *userbuf, size_t nbytes,
+ loff_t *unused_ppos)
{
char buffer[CGROUP_LOCAL_BUFFER_SIZE];
int retval = 0;
u64 val = simple_strtoull(strstrip(buffer), &end, 0);
if (*end)
return -EINVAL;
- retval = cft->write_u64(cgrp, cft, val);
+ retval = cft->write_u64(css, cft, val);
} else {
s64 val = simple_strtoll(strstrip(buffer), &end, 0);
if (*end)
return -EINVAL;
- retval = cft->write_s64(cgrp, cft, val);
+ retval = cft->write_s64(css, cft, val);
}
if (!retval)
retval = nbytes;
return retval;
}
-static ssize_t cgroup_write_string(struct cgroup *cgrp, struct cftype *cft,
- struct file *file,
- const char __user *userbuf,
- size_t nbytes, loff_t *unused_ppos)
+static ssize_t cgroup_write_string(struct cgroup_subsys_state *css,
+ struct cftype *cft, struct file *file,
+ const char __user *userbuf, size_t nbytes,
+ loff_t *unused_ppos)
{
char local_buffer[CGROUP_LOCAL_BUFFER_SIZE];
int retval = 0;
}
buffer[nbytes] = 0; /* nul-terminate */
- retval = cft->write_string(cgrp, cft, strstrip(buffer));
+ retval = cft->write_string(css, cft, strstrip(buffer));
if (!retval)
retval = nbytes;
out:
}
static ssize_t cgroup_file_write(struct file *file, const char __user *buf,
- size_t nbytes, loff_t *ppos)
+ size_t nbytes, loff_t *ppos)
{
+ struct cfent *cfe = __d_cfe(file->f_dentry);
struct cftype *cft = __d_cft(file->f_dentry);
- struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);
+ struct cgroup_subsys_state *css = cfe->css;
- if (cgroup_is_dead(cgrp))
- return -ENODEV;
if (cft->write)
- return cft->write(cgrp, cft, file, buf, nbytes, ppos);
+ return cft->write(css, cft, file, buf, nbytes, ppos);
if (cft->write_u64 || cft->write_s64)
- return cgroup_write_X64(cgrp, cft, file, buf, nbytes, ppos);
+ return cgroup_write_X64(css, cft, file, buf, nbytes, ppos);
if (cft->write_string)
- return cgroup_write_string(cgrp, cft, file, buf, nbytes, ppos);
+ return cgroup_write_string(css, cft, file, buf, nbytes, ppos);
if (cft->trigger) {
- int ret = cft->trigger(cgrp, (unsigned int)cft->private);
+ int ret = cft->trigger(css, (unsigned int)cft->private);
return ret ? ret : nbytes;
}
return -EINVAL;
}
-static ssize_t cgroup_read_u64(struct cgroup *cgrp, struct cftype *cft,
- struct file *file,
- char __user *buf, size_t nbytes,
- loff_t *ppos)
+static ssize_t cgroup_read_u64(struct cgroup_subsys_state *css,
+ struct cftype *cft, struct file *file,
+ char __user *buf, size_t nbytes, loff_t *ppos)
{
char tmp[CGROUP_LOCAL_BUFFER_SIZE];
- u64 val = cft->read_u64(cgrp, cft);
+ u64 val = cft->read_u64(css, cft);
int len = sprintf(tmp, "%llu\n", (unsigned long long) val);
return simple_read_from_buffer(buf, nbytes, ppos, tmp, len);
}
-static ssize_t cgroup_read_s64(struct cgroup *cgrp, struct cftype *cft,
- struct file *file,
- char __user *buf, size_t nbytes,
- loff_t *ppos)
+static ssize_t cgroup_read_s64(struct cgroup_subsys_state *css,
+ struct cftype *cft, struct file *file,
+ char __user *buf, size_t nbytes, loff_t *ppos)
{
char tmp[CGROUP_LOCAL_BUFFER_SIZE];
- s64 val = cft->read_s64(cgrp, cft);
+ s64 val = cft->read_s64(css, cft);
int len = sprintf(tmp, "%lld\n", (long long) val);
return simple_read_from_buffer(buf, nbytes, ppos, tmp, len);
}
static ssize_t cgroup_file_read(struct file *file, char __user *buf,
- size_t nbytes, loff_t *ppos)
+ size_t nbytes, loff_t *ppos)
{
+ struct cfent *cfe = __d_cfe(file->f_dentry);
struct cftype *cft = __d_cft(file->f_dentry);
- struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);
-
- if (cgroup_is_dead(cgrp))
- return -ENODEV;
+ struct cgroup_subsys_state *css = cfe->css;
if (cft->read)
- return cft->read(cgrp, cft, file, buf, nbytes, ppos);
+ return cft->read(css, cft, file, buf, nbytes, ppos);
if (cft->read_u64)
- return cgroup_read_u64(cgrp, cft, file, buf, nbytes, ppos);
+ return cgroup_read_u64(css, cft, file, buf, nbytes, ppos);
if (cft->read_s64)
- return cgroup_read_s64(cgrp, cft, file, buf, nbytes, ppos);
+ return cgroup_read_s64(css, cft, file, buf, nbytes, ppos);
return -EINVAL;
}
* supports string->u64 maps, but can be extended in future.
*/
-struct cgroup_seqfile_state {
- struct cftype *cft;
- struct cgroup *cgroup;
-};
-
static int cgroup_map_add(struct cgroup_map_cb *cb, const char *key, u64 value)
{
struct seq_file *sf = cb->state;
static int cgroup_seqfile_show(struct seq_file *m, void *arg)
{
- struct cgroup_seqfile_state *state = m->private;
- struct cftype *cft = state->cft;
+ struct cfent *cfe = m->private;
+ struct cftype *cft = cfe->type;
+ struct cgroup_subsys_state *css = cfe->css;
+
if (cft->read_map) {
struct cgroup_map_cb cb = {
.fill = cgroup_map_add,
.state = m,
};
- return cft->read_map(state->cgroup, cft, &cb);
+ return cft->read_map(css, cft, &cb);
}
- return cft->read_seq_string(state->cgroup, cft, m);
-}
-
-static int cgroup_seqfile_release(struct inode *inode, struct file *file)
-{
- struct seq_file *seq = file->private_data;
- kfree(seq->private);
- return single_release(inode, file);
+ return cft->read_seq_string(css, cft, m);
}
static const struct file_operations cgroup_seqfile_operations = {
.read = seq_read,
.write = cgroup_file_write,
.llseek = seq_lseek,
- .release = cgroup_seqfile_release,
+ .release = single_release,
};
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;
int err;
- struct cftype *cft;
err = generic_file_open(inode, file);
if (err)
return err;
- cft = __d_cft(file->f_dentry);
- if (cft->read_map || cft->read_seq_string) {
- struct cgroup_seqfile_state *state;
+ /*
+ * 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();
- state = kzalloc(sizeof(*state), GFP_USER);
- if (!state)
- return -ENOMEM;
+ 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;
- state->cft = cft;
- state->cgroup = __d_cgrp(file->f_dentry->d_parent);
+ if (cft->read_map || cft->read_seq_string) {
file->f_op = &cgroup_seqfile_operations;
- err = single_open(file, cgroup_seqfile_show, state);
- if (err < 0)
- kfree(state);
- } else if (cft->open)
+ err = single_open(file, cgroup_seqfile_show, cfe);
+ } else if (cft->open) {
err = cft->open(inode, file);
- else
- err = 0;
+ }
+ if (css->ss && err)
+ css_put(css);
return err;
}
static int cgroup_file_release(struct inode *inode, struct file *file)
{
+ struct cfent *cfe = __d_cfe(file->f_dentry);
struct cftype *cft = __d_cft(file->f_dentry);
+ struct cgroup_subsys_state *css = cfe->css;
+ int ret = 0;
+
if (cft->release)
- return cft->release(inode, file);
- return 0;
+ ret = cft->release(inode, file);
+ if (css->ss)
+ css_put(css);
+ return ret;
}
/*
return mode;
}
-static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys,
- struct cftype *cft)
+static int cgroup_add_file(struct cgroup *cgrp, struct cftype *cft)
{
struct dentry *dir = cgrp->dentry;
struct cgroup *parent = __d_cgrp(dir);
umode_t mode;
char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 };
- if (subsys && !(cgrp->root->flags & CGRP_ROOT_NOPREFIX)) {
- strcpy(name, subsys->name);
+ 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);
return error;
}
-static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys,
- struct cftype cfts[], bool is_add)
+/**
+ * cgroup_addrm_files - add or remove files to a cgroup directory
+ * @cgrp: the target cgroup
+ * @cfts: array of cftypes to be added
+ * @is_add: whether to add or remove
+ *
+ * Depending on @is_add, add or remove files defined by @cfts on @cgrp.
+ * For removals, this function never fails. If addition fails, this
+ * function doesn't remove files already added. The caller is responsible
+ * for cleaning up.
+ */
+static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[],
+ bool is_add)
{
struct cftype *cft;
- int err, ret = 0;
+ int ret;
+
+ lockdep_assert_held(&cgrp->dentry->d_inode->i_mutex);
+ lockdep_assert_held(&cgroup_mutex);
for (cft = cfts; cft->name[0] != '\0'; cft++) {
/* does cft->flags tell us to skip this file on @cgrp? */
continue;
if (is_add) {
- err = cgroup_add_file(cgrp, subsys, cft);
- if (err)
+ ret = cgroup_add_file(cgrp, cft);
+ if (ret) {
pr_warn("cgroup_addrm_files: failed to add %s, err=%d\n",
- cft->name, err);
- ret = err;
+ cft->name, ret);
+ return ret;
+ }
} else {
cgroup_rm_file(cgrp, cft);
}
}
- return ret;
+ return 0;
}
static void cgroup_cfts_prepare(void)
/*
* Thanks to the entanglement with vfs inode locking, we can't walk
* the existing cgroups under cgroup_mutex and create files.
- * Instead, we use cgroup_for_each_descendant_pre() and drop RCU
- * read lock before calling cgroup_addrm_files().
+ * Instead, we use css_for_each_descendant_pre() and drop RCU read
+ * lock before calling cgroup_addrm_files().
*/
mutex_lock(&cgroup_mutex);
}
-static void cgroup_cfts_commit(struct cgroup_subsys *ss,
- struct cftype *cfts, bool is_add)
+static int cgroup_cfts_commit(struct cftype *cfts, bool is_add)
__releases(&cgroup_mutex)
{
LIST_HEAD(pending);
- struct cgroup *cgrp, *root = &ss->root->top_cgroup;
+ 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_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;
+ return 0;
}
/*
mutex_unlock(&cgroup_mutex);
- /* @root always needs to be updated */
- inode = root->dentry->d_inode;
- mutex_lock(&inode->i_mutex);
- mutex_lock(&cgroup_mutex);
- cgroup_addrm_files(root, ss, cfts, is_add);
- mutex_unlock(&cgroup_mutex);
- mutex_unlock(&inode->i_mutex);
-
/* add/rm files for all cgroups created before */
rcu_read_lock();
- cgroup_for_each_descendant_pre(cgrp, root) {
+ css_for_each_descendant_pre(css, cgroup_css(root, ss)) {
+ struct cgroup *cgrp = css->cgroup;
+
if (cgroup_is_dead(cgrp))
continue;
mutex_lock(&inode->i_mutex);
mutex_lock(&cgroup_mutex);
if (cgrp->serial_nr < update_before && !cgroup_is_dead(cgrp))
- cgroup_addrm_files(cgrp, ss, cfts, is_add);
+ ret = cgroup_addrm_files(cgrp, cfts, is_add);
mutex_unlock(&cgroup_mutex);
mutex_unlock(&inode->i_mutex);
rcu_read_lock();
+ if (ret)
+ break;
}
rcu_read_unlock();
dput(prev);
deactivate_super(sb);
+ return ret;
}
/**
int cgroup_add_cftypes(struct cgroup_subsys *ss, 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++)
+ cft->ss = ss;
+
cgroup_cfts_prepare();
set->cfts = cfts;
list_add_tail(&set->node, &ss->cftsets);
- cgroup_cfts_commit(ss, cfts, true);
-
- return 0;
+ ret = cgroup_cfts_commit(cfts, true);
+ if (ret)
+ cgroup_rm_cftypes(cfts);
+ return ret;
}
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.
+ * Unregister @cfts. Files described by @cfts are removed from all
+ * existing cgroups and all future cgroups won't have them either. This
+ * function can be called anytime whether @cfts' subsys is attached or not.
*
* Returns 0 on successful unregistration, -ENOENT if @cfts is not
- * registered with @ss.
+ * registered.
*/
-int cgroup_rm_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
+int cgroup_rm_cftypes(struct cftype *cfts)
{
struct cftype_set *set;
+ if (!cfts || !cfts[0].ss)
+ return -ENOENT;
+
cgroup_cfts_prepare();
- list_for_each_entry(set, &ss->cftsets, node) {
+ list_for_each_entry(set, &cfts[0].ss->cftsets, node) {
if (set->cfts == cfts) {
list_del(&set->node);
kfree(set);
- cgroup_cfts_commit(ss, cfts, false);
+ cgroup_cfts_commit(cfts, false);
return 0;
}
}
- cgroup_cfts_commit(ss, NULL, false);
+ cgroup_cfts_commit(NULL, false);
return -ENOENT;
}
}
/*
- * Advance a list_head iterator. The iterator should be positioned at
- * the start of a css_set
- */
-static void cgroup_advance_iter(struct cgroup *cgrp, struct cgroup_iter *it)
-{
- struct list_head *l = it->cset_link;
- struct cgrp_cset_link *link;
- struct css_set *cset;
-
- /* Advance to the next non-empty css_set */
- do {
- l = l->next;
- if (l == &cgrp->cset_links) {
- it->cset_link = NULL;
- return;
- }
- link = list_entry(l, struct cgrp_cset_link, cset_link);
- cset = link->cset;
- } while (list_empty(&cset->tasks));
- it->cset_link = l;
- it->task = cset->tasks.next;
-}
-
-/*
- * 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 cgroup_iter_start().
+ * 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)
{
}
/**
- * cgroup_next_sibling - find the next sibling of a given cgroup
- * @pos: the current cgroup
+ * css_next_child - find the next child of a given css
+ * @pos_css: the current position (%NULL to initiate traversal)
+ * @parent_css: css whose children to walk
*
- * This function returns the next sibling of @pos and should be called
- * under RCU read lock. The only requirement is that @pos is accessible.
- * The next sibling is guaranteed to be returned regardless of @pos's
- * state.
+ * This function returns the next child of @parent_css and should be called
+ * under RCU read lock. The only requirement is that @parent_css and
+ * @pos_css are accessible. The next sibling is guaranteed to be returned
+ * regardless of their states.
*/
-struct cgroup *cgroup_next_sibling(struct cgroup *pos)
+struct cgroup_subsys_state *
+css_next_child(struct cgroup_subsys_state *pos_css,
+ struct cgroup_subsys_state *parent_css)
{
+ struct cgroup *pos = pos_css ? pos_css->cgroup : NULL;
+ struct cgroup *cgrp = parent_css->cgroup;
struct cgroup *next;
WARN_ON_ONCE(!rcu_read_lock_held());
* safe to dereference from this RCU critical section. If
* ->sibling.next is inaccessible, cgroup_is_dead() is guaranteed
* to be visible as %true here.
+ *
+ * If @pos is dead, its next pointer can't be dereferenced;
+ * however, as each cgroup is given a monotonically increasing
+ * unique serial number and always appended to the sibling list,
+ * the next one can be found by walking the parent's children until
+ * we see a cgroup with higher serial number than @pos's. While
+ * this path can be slower, it's taken only when either the current
+ * cgroup is removed or iteration and removal race.
*/
- if (likely(!cgroup_is_dead(pos))) {
+ if (!pos) {
+ next = list_entry_rcu(cgrp->children.next, struct cgroup, sibling);
+ } else if (likely(!cgroup_is_dead(pos))) {
next = list_entry_rcu(pos->sibling.next, struct cgroup, sibling);
- if (&next->sibling != &pos->parent->children)
- return next;
- return NULL;
+ } else {
+ list_for_each_entry_rcu(next, &cgrp->children, sibling)
+ if (next->serial_nr > pos->serial_nr)
+ break;
}
- /*
- * Can't dereference the next pointer. Each cgroup is given a
- * monotonically increasing unique serial number and always
- * appended to the sibling list, so the next one can be found by
- * walking the parent's children until we see a cgroup with higher
- * serial number than @pos's.
- *
- * While this path can be slow, it's taken only when either the
- * current cgroup is removed or iteration and removal race.
- */
- list_for_each_entry_rcu(next, &pos->parent->children, sibling)
- if (next->serial_nr > pos->serial_nr)
- return next;
- return NULL;
+ if (&next->sibling == &cgrp->children)
+ return NULL;
+
+ return cgroup_css(next, parent_css->ss);
}
-EXPORT_SYMBOL_GPL(cgroup_next_sibling);
+EXPORT_SYMBOL_GPL(css_next_child);
/**
- * cgroup_next_descendant_pre - find the next descendant for pre-order walk
+ * css_next_descendant_pre - find the next descendant for pre-order walk
* @pos: the current position (%NULL to initiate traversal)
- * @cgroup: cgroup whose descendants to walk
+ * @root: css whose descendants to walk
*
- * To be used by cgroup_for_each_descendant_pre(). Find the next
- * descendant to visit for pre-order traversal of @cgroup's descendants.
+ * To be used by css_for_each_descendant_pre(). Find the next descendant
+ * to visit for pre-order traversal of @root's descendants. @root is
+ * included in the iteration and the first node to be visited.
*
* While this function requires RCU read locking, it doesn't require the
* whole traversal to be contained in a single RCU critical section. This
* function will return the correct next descendant as long as both @pos
- * and @cgroup are accessible and @pos is a descendant of @cgroup.
+ * and @root are accessible and @pos is a descendant of @root.
*/
-struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos,
- struct cgroup *cgroup)
+struct cgroup_subsys_state *
+css_next_descendant_pre(struct cgroup_subsys_state *pos,
+ struct cgroup_subsys_state *root)
{
- struct cgroup *next;
+ struct cgroup_subsys_state *next;
WARN_ON_ONCE(!rcu_read_lock_held());
- /* if first iteration, pretend we just visited @cgroup */
+ /* if first iteration, visit @root */
if (!pos)
- pos = cgroup;
+ return root;
/* visit the first child if exists */
- next = list_first_or_null_rcu(&pos->children, struct cgroup, sibling);
+ next = css_next_child(NULL, pos);
if (next)
return next;
/* no child, visit my or the closest ancestor's next sibling */
- while (pos != cgroup) {
- next = cgroup_next_sibling(pos);
+ while (pos != root) {
+ next = css_next_child(pos, css_parent(pos));
if (next)
return next;
- pos = pos->parent;
+ pos = css_parent(pos);
}
return NULL;
}
-EXPORT_SYMBOL_GPL(cgroup_next_descendant_pre);
+EXPORT_SYMBOL_GPL(css_next_descendant_pre);
/**
- * cgroup_rightmost_descendant - return the rightmost descendant of a cgroup
- * @pos: cgroup of interest
+ * css_rightmost_descendant - return the rightmost descendant of a css
+ * @pos: css of interest
*
- * Return the rightmost descendant of @pos. If there's no descendant,
- * @pos is returned. This can be used during pre-order traversal to skip
+ * Return the rightmost descendant of @pos. If there's no descendant, @pos
+ * is returned. This can be used during pre-order traversal to skip
* subtree of @pos.
*
* While this function requires RCU read locking, it doesn't require the
* function will return the correct rightmost descendant as long as @pos is
* accessible.
*/
-struct cgroup *cgroup_rightmost_descendant(struct cgroup *pos)
+struct cgroup_subsys_state *
+css_rightmost_descendant(struct cgroup_subsys_state *pos)
{
- struct cgroup *last, *tmp;
+ struct cgroup_subsys_state *last, *tmp;
WARN_ON_ONCE(!rcu_read_lock_held());
last = pos;
/* ->prev isn't RCU safe, walk ->next till the end */
pos = NULL;
- list_for_each_entry_rcu(tmp, &last->children, sibling)
+ css_for_each_child(tmp, last)
pos = tmp;
} while (pos);
return last;
}
-EXPORT_SYMBOL_GPL(cgroup_rightmost_descendant);
+EXPORT_SYMBOL_GPL(css_rightmost_descendant);
-static struct cgroup *cgroup_leftmost_descendant(struct cgroup *pos)
+static struct cgroup_subsys_state *
+css_leftmost_descendant(struct cgroup_subsys_state *pos)
{
- struct cgroup *last;
+ struct cgroup_subsys_state *last;
do {
last = pos;
- pos = list_first_or_null_rcu(&pos->children, struct cgroup,
- sibling);
+ pos = css_next_child(NULL, pos);
} while (pos);
return last;
}
/**
- * cgroup_next_descendant_post - find the next descendant for post-order walk
+ * css_next_descendant_post - find the next descendant for post-order walk
* @pos: the current position (%NULL to initiate traversal)
- * @cgroup: cgroup whose descendants to walk
+ * @root: css whose descendants to walk
*
- * To be used by cgroup_for_each_descendant_post(). Find the next
- * descendant to visit for post-order traversal of @cgroup's descendants.
+ * To be used by css_for_each_descendant_post(). Find the next descendant
+ * to visit for post-order traversal of @root's descendants. @root is
+ * included in the iteration and the last node to be visited.
*
* While this function requires RCU read locking, it doesn't require the
* whole traversal to be contained in a single RCU critical section. This
* function will return the correct next descendant as long as both @pos
* and @cgroup are accessible and @pos is a descendant of @cgroup.
*/
-struct cgroup *cgroup_next_descendant_post(struct cgroup *pos,
- struct cgroup *cgroup)
+struct cgroup_subsys_state *
+css_next_descendant_post(struct cgroup_subsys_state *pos,
+ struct cgroup_subsys_state *root)
{
- struct cgroup *next;
+ struct cgroup_subsys_state *next;
WARN_ON_ONCE(!rcu_read_lock_held());
- /* if first iteration, visit the leftmost descendant */
- if (!pos) {
- next = cgroup_leftmost_descendant(cgroup);
- return next != cgroup ? next : NULL;
- }
+ /* if first iteration, visit leftmost descendant which may be @root */
+ if (!pos)
+ return css_leftmost_descendant(root);
+
+ /* if we visited @root, we're done */
+ if (pos == root)
+ return NULL;
/* if there's an unvisited sibling, visit its leftmost descendant */
- next = cgroup_next_sibling(pos);
+ next = css_next_child(pos, css_parent(pos));
if (next)
- return cgroup_leftmost_descendant(next);
+ return css_leftmost_descendant(next);
/* no sibling left, visit parent */
- next = pos->parent;
- return next != cgroup ? next : NULL;
+ return css_parent(pos);
}
-EXPORT_SYMBOL_GPL(cgroup_next_descendant_post);
+EXPORT_SYMBOL_GPL(css_next_descendant_post);
-void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it)
+/**
+ * css_advance_task_iter - advance a task itererator to the next css_set
+ * @it: the iterator to advance
+ *
+ * Advance @it to the next css_set to walk.
+ */
+static void css_advance_task_iter(struct css_task_iter *it)
+{
+ struct list_head *l = it->cset_link;
+ struct cgrp_cset_link *link;
+ struct css_set *cset;
+
+ /* Advance to the next non-empty css_set */
+ do {
+ l = l->next;
+ if (l == &it->origin_css->cgroup->cset_links) {
+ it->cset_link = NULL;
+ return;
+ }
+ link = list_entry(l, struct cgrp_cset_link, cset_link);
+ cset = link->cset;
+ } while (list_empty(&cset->tasks));
+ it->cset_link = l;
+ it->task = cset->tasks.next;
+}
+
+/**
+ * css_task_iter_start - initiate task iteration
+ * @css: the css to walk tasks of
+ * @it: the task iterator to use
+ *
+ * Initiate iteration through the tasks of @css. The caller can call
+ * css_task_iter_next() to walk through the tasks until the function
+ * returns NULL. On completion of iteration, css_task_iter_end() must be
+ * called.
+ *
+ * Note that this function acquires a lock which is released when the
+ * iteration finishes. The caller can't sleep while iteration is in
+ * progress.
+ */
+void css_task_iter_start(struct cgroup_subsys_state *css,
+ struct css_task_iter *it)
__acquires(css_set_lock)
{
/*
- * The first time anyone tries to iterate across a cgroup,
- * we need to enable the list linking each css_set to its
- * tasks, and fix up all existing tasks.
+ * 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();
read_lock(&css_set_lock);
- it->cset_link = &cgrp->cset_links;
- cgroup_advance_iter(cgrp, it);
+
+ it->origin_css = css;
+ it->cset_link = &css->cgroup->cset_links;
+
+ css_advance_task_iter(it);
}
-struct task_struct *cgroup_iter_next(struct cgroup *cgrp,
- struct cgroup_iter *it)
+/**
+ * css_task_iter_next - return the next task for the iterator
+ * @it: the task iterator being iterated
+ *
+ * The "next" function for task iteration. @it should have been
+ * initialized via css_task_iter_start(). Returns NULL when the iteration
+ * reaches the end.
+ */
+struct task_struct *css_task_iter_next(struct css_task_iter *it)
{
struct task_struct *res;
struct list_head *l = it->task;
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 cg_cgroup_link */
- cgroup_advance_iter(cgrp, it);
+ /*
+ * We reached the end of this task list - move on to the
+ * next cgrp_cset_link.
+ */
+ css_advance_task_iter(it);
} else {
it->task = l;
}
return res;
}
-void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it)
+/**
+ * css_task_iter_end - finish task iteration
+ * @it: the task iterator to finish
+ *
+ * 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);
}
/**
- * cgroup_scan_tasks - iterate though all the tasks in a cgroup
- * @scan: struct cgroup_scanner containing arguments for the scan
+ * 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.
*
- * Arguments include pointers to callback functions test_task() and
- * process_task().
- * Iterate through all the tasks in a cgroup, calling test_task() for each,
- * and if it returns true, call process_task() for it also.
- * The test_task pointer may be NULL, meaning always true (select all tasks).
- * Effectively duplicates cgroup_iter_{start,next,end}()
- * but does not lock css_set_lock for the call to process_task().
- * The struct cgroup_scanner may be embedded in any structure of the caller's
- * creation.
- * It is guaranteed that process_task() will act on every task that
- * is a member of the cgroup for the duration of this call. This
- * function may or may not call process_task() for tasks that exit
- * or move to a different cgroup during the call, or are forked or
- * move into the cgroup during the call.
+ * 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_task() may be called with locks held, and may in some
- * situations be called multiple times for the same task, so it should
- * be cheap.
- * If the heap pointer in the struct cgroup_scanner 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).
+ * 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.
+ *
+ * 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).
*/
-int cgroup_scan_tasks(struct cgroup_scanner *scan)
+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 retval, i;
- struct cgroup_iter it;
+ 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 ptr_heap *heap;
struct timespec latest_time = { 0, 0 };
- if (scan->heap) {
+ if (heap) {
/* The caller supplied our heap and pre-allocated its memory */
- heap = scan->heap;
heap->gt = &started_after;
} else {
/* We need to allocate our own heap memory */
again:
/*
- * Scan tasks in the cgroup, using the scanner's "test_task" callback
- * to determine which are of interest, and using the scanner's
- * "process_task" callback to process any of them that 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
+ * 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;
- cgroup_iter_start(scan->cg, &it);
- while ((p = cgroup_iter_next(scan->cg, &it))) {
+ 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 (scan->test_task && !scan->test_task(p, scan))
+ if (test && !test(p, data))
continue;
/*
* Only process tasks that started after the last task
* the heap and wasn't inserted
*/
}
- cgroup_iter_end(scan->cg, &it);
+ css_task_iter_end(&it);
if (heap->size) {
for (i = 0; i < heap->size; i++) {
latest_task = q;
}
/* Process the task per the caller's callback */
- scan->process_task(q, scan);
+ process(q, data);
put_task_struct(q);
}
/*
return 0;
}
-static void cgroup_transfer_one_task(struct task_struct *task,
- struct cgroup_scanner *scan)
+static void cgroup_transfer_one_task(struct task_struct *task, void *data)
{
- struct cgroup *new_cgroup = scan->data;
+ struct cgroup *new_cgroup = data;
mutex_lock(&cgroup_mutex);
cgroup_attach_task(new_cgroup, task, false);
*/
int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
{
- struct cgroup_scanner scan;
-
- scan.cg = from;
- scan.test_task = NULL; /* select all tasks in cgroup */
- scan.process_task = cgroup_transfer_one_task;
- scan.heap = NULL;
- scan.data = to;
-
- return cgroup_scan_tasks(&scan);
+ return css_scan_tasks(&from->dummy_css, NULL, cgroup_transfer_one_task,
+ to, NULL);
}
/*
/* pointer to the cgroup we belong to, for list removal purposes */
struct cgroup *owner;
/* protects the other fields */
- struct rw_semaphore mutex;
+ struct rw_semaphore rwsem;
};
/*
struct pid_namespace *ns = task_active_pid_ns(current);
/*
- * We can't drop the pidlist_mutex before taking the l->mutex in case
+ * We can't drop the pidlist_mutex before taking the l->rwsem in case
* the last ref-holder is trying to remove l from the list at the same
* time. Holding the pidlist_mutex precludes somebody taking whichever
* list we find out from under us - compare release_pid_array().
list_for_each_entry(l, &cgrp->pidlists, links) {
if (l->key.type == type && l->key.ns == ns) {
/* make sure l doesn't vanish out from under us */
- down_write(&l->mutex);
+ down_write(&l->rwsem);
mutex_unlock(&cgrp->pidlist_mutex);
return l;
}
mutex_unlock(&cgrp->pidlist_mutex);
return l;
}
- init_rwsem(&l->mutex);
- down_write(&l->mutex);
+ init_rwsem(&l->rwsem);
+ down_write(&l->rwsem);
l->key.type = type;
l->key.ns = get_pid_ns(ns);
l->owner = cgrp;
pid_t *array;
int length;
int pid, n = 0; /* used for populating the array */
- struct cgroup_iter it;
+ struct css_task_iter it;
struct task_struct *tsk;
struct cgroup_pidlist *l;
if (!array)
return -ENOMEM;
/* now, populate the array */
- cgroup_iter_start(cgrp, &it);
- while ((tsk = cgroup_iter_next(cgrp, &it))) {
+ css_task_iter_start(&cgrp->dummy_css, &it);
+ while ((tsk = css_task_iter_next(&it))) {
if (unlikely(n == length))
break;
/* get tgid or pid for procs or tasks file respectively */
if (pid > 0) /* make sure to only use valid results */
array[n++] = pid;
}
- cgroup_iter_end(cgrp, &it);
+ css_task_iter_end(&it);
length = n;
/* now sort & (if procs) strip out duplicates */
sort(array, length, sizeof(pid_t), cmppid, NULL);
l->list = array;
l->length = length;
l->use_count++;
- up_write(&l->mutex);
+ up_write(&l->rwsem);
*lp = l;
return 0;
}
{
int ret = -EINVAL;
struct cgroup *cgrp;
- struct cgroup_iter it;
+ struct css_task_iter it;
struct task_struct *tsk;
/*
ret = 0;
cgrp = dentry->d_fsdata;
- cgroup_iter_start(cgrp, &it);
- while ((tsk = cgroup_iter_next(cgrp, &it))) {
+ css_task_iter_start(&cgrp->dummy_css, &it);
+ while ((tsk = css_task_iter_next(&it))) {
switch (tsk->state) {
case TASK_RUNNING:
stats->nr_running++;
break;
}
}
- cgroup_iter_end(cgrp, &it);
+ css_task_iter_end(&it);
err:
return ret;
int index = 0, pid = *pos;
int *iter;
- down_read(&l->mutex);
+ down_read(&l->rwsem);
if (pid) {
int end = l->length;
static void cgroup_pidlist_stop(struct seq_file *s, void *v)
{
struct cgroup_pidlist *l = s->private;
- up_read(&l->mutex);
+ up_read(&l->rwsem);
}
static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos)
* pidlist_mutex, we have to take pidlist_mutex first.
*/
mutex_lock(&l->owner->pidlist_mutex);
- down_write(&l->mutex);
+ down_write(&l->rwsem);
BUG_ON(!l->use_count);
if (!--l->use_count) {
/* we're the last user if refcount is 0; remove and free */
mutex_unlock(&l->owner->pidlist_mutex);
pidlist_free(l->list);
put_pid_ns(l->key.ns);
- up_write(&l->mutex);
+ up_write(&l->rwsem);
kfree(l);
return;
}
mutex_unlock(&l->owner->pidlist_mutex);
- up_write(&l->mutex);
+ up_write(&l->rwsem);
}
static int cgroup_pidlist_release(struct inode *inode, struct file *file)
return cgroup_pidlist_open(file, CGROUP_FILE_PROCS);
}
-static u64 cgroup_read_notify_on_release(struct cgroup *cgrp,
- struct cftype *cft)
+static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css,
+ struct cftype *cft)
{
- return notify_on_release(cgrp);
+ return notify_on_release(css->cgroup);
}
-static int cgroup_write_notify_on_release(struct cgroup *cgrp,
- struct cftype *cft,
- u64 val)
+static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css,
+ struct cftype *cft, u64 val)
{
- clear_bit(CGRP_RELEASABLE, &cgrp->flags);
+ clear_bit(CGRP_RELEASABLE, &css->cgroup->flags);
if (val)
- set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
+ set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
else
- clear_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
+ clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
return 0;
}
{
struct cgroup_event *event = container_of(work, struct cgroup_event,
remove);
- struct cgroup *cgrp = event->cgrp;
+ struct cgroup_subsys_state *css = event->css;
remove_wait_queue(event->wqh, &event->wait);
- event->cft->unregister_event(cgrp, event->cft, event->eventfd);
+ event->cft->unregister_event(css, event->cft, event->eventfd);
/* Notify userspace the event is going away. */
eventfd_signal(event->eventfd, 1);
eventfd_ctx_put(event->eventfd);
kfree(event);
- cgroup_dput(cgrp);
+ css_put(css);
}
/*
{
struct cgroup_event *event = container_of(wait,
struct cgroup_event, wait);
- struct cgroup *cgrp = event->cgrp;
+ struct cgroup *cgrp = event->css->cgroup;
unsigned long flags = (unsigned long)key;
if (flags & POLLHUP) {
* Input must be in format '<event_fd> <control_fd> <args>'.
* Interpretation of args is defined by control file implementation.
*/
-static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft,
- const char *buffer)
+static int cgroup_write_event_control(struct cgroup_subsys_state *dummy_css,
+ struct cftype *cft, const char *buffer)
{
- struct cgroup_event *event = NULL;
- struct cgroup *cgrp_cfile;
+ struct cgroup *cgrp = dummy_css->cgroup;
+ struct cgroup_event *event;
+ struct cgroup_subsys_state *cfile_css;
unsigned int efd, cfd;
- struct file *efile = NULL;
- struct file *cfile = NULL;
+ struct file *efile;
+ struct file *cfile;
char *endp;
int ret;
event = kzalloc(sizeof(*event), GFP_KERNEL);
if (!event)
return -ENOMEM;
- event->cgrp = cgrp;
+
INIT_LIST_HEAD(&event->list);
init_poll_funcptr(&event->pt, cgroup_event_ptable_queue_proc);
init_waitqueue_func_entry(&event->wait, cgroup_event_wake);
efile = eventfd_fget(efd);
if (IS_ERR(efile)) {
ret = PTR_ERR(efile);
- goto fail;
+ goto out_kfree;
}
event->eventfd = eventfd_ctx_fileget(efile);
if (IS_ERR(event->eventfd)) {
ret = PTR_ERR(event->eventfd);
- goto fail;
+ goto out_put_efile;
}
cfile = fget(cfd);
if (!cfile) {
ret = -EBADF;
- goto fail;
+ goto out_put_eventfd;
}
/* the process need read permission on control file */
/* AV: shouldn't we check that it's been opened for read instead? */
ret = inode_permission(file_inode(cfile), MAY_READ);
if (ret < 0)
- goto fail;
+ goto out_put_cfile;
event->cft = __file_cft(cfile);
if (IS_ERR(event->cft)) {
ret = PTR_ERR(event->cft);
- goto fail;
+ goto out_put_cfile;
+ }
+
+ if (!event->cft->ss) {
+ ret = -EBADF;
+ goto out_put_cfile;
}
/*
- * The file to be monitored must be in the same cgroup as
- * cgroup.event_control is.
+ * Determine the css of @cfile, verify it belongs to the same
+ * cgroup as cgroup.event_control, and associate @event with it.
+ * Remaining events are automatically removed on cgroup destruction
+ * but the removal is asynchronous, so take an extra ref.
*/
- cgrp_cfile = __d_cgrp(cfile->f_dentry->d_parent);
- if (cgrp_cfile != cgrp) {
- ret = -EINVAL;
- goto fail;
- }
+ rcu_read_lock();
+
+ ret = -EINVAL;
+ event->css = cgroup_css(cgrp, event->cft->ss);
+ cfile_css = css_from_dir(cfile->f_dentry->d_parent, event->cft->ss);
+ if (event->css && event->css == cfile_css && css_tryget(event->css))
+ ret = 0;
+
+ rcu_read_unlock();
+ if (ret)
+ goto out_put_cfile;
if (!event->cft->register_event || !event->cft->unregister_event) {
ret = -EINVAL;
- goto fail;
+ goto out_put_css;
}
- ret = event->cft->register_event(cgrp, event->cft,
+ ret = event->cft->register_event(event->css, event->cft,
event->eventfd, buffer);
if (ret)
- goto fail;
+ goto out_put_css;
efile->f_op->poll(efile, &event->pt);
- /*
- * Events should be removed after rmdir of cgroup directory, but before
- * destroying subsystem state objects. Let's take reference to cgroup
- * directory dentry to do that.
- */
- dget(cgrp->dentry);
-
spin_lock(&cgrp->event_list_lock);
list_add(&event->list, &cgrp->event_list);
spin_unlock(&cgrp->event_list_lock);
return 0;
-fail:
- if (cfile)
- fput(cfile);
-
- if (event && event->eventfd && !IS_ERR(event->eventfd))
- eventfd_ctx_put(event->eventfd);
-
- if (!IS_ERR_OR_NULL(efile))
- fput(efile);
-
+out_put_css:
+ css_put(event->css);
+out_put_cfile:
+ fput(cfile);
+out_put_eventfd:
+ eventfd_ctx_put(event->eventfd);
+out_put_efile:
+ fput(efile);
+out_kfree:
kfree(event);
return ret;
}
-static u64 cgroup_clone_children_read(struct cgroup *cgrp,
- struct cftype *cft)
+static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css,
+ struct cftype *cft)
{
- return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags);
+ return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
}
-static int cgroup_clone_children_write(struct cgroup *cgrp,
- struct cftype *cft,
- u64 val)
+static int cgroup_clone_children_write(struct cgroup_subsys_state *css,
+ struct cftype *cft, u64 val)
{
if (val)
- set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags);
+ set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
else
- clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags);
+ clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
return 0;
}
};
/**
- * cgroup_populate_dir - selectively creation of files in a directory
+ * cgroup_populate_dir - create subsys files in a cgroup directory
* @cgrp: target cgroup
- * @base_files: true if the base files should be added
* @subsys_mask: mask of the subsystem ids whose files should be added
+ *
+ * On failure, no file is added.
*/
-static int cgroup_populate_dir(struct cgroup *cgrp, bool base_files,
- unsigned long subsys_mask)
+static int cgroup_populate_dir(struct cgroup *cgrp, unsigned long subsys_mask)
{
- int err;
struct cgroup_subsys *ss;
-
- if (base_files) {
- err = cgroup_addrm_files(cgrp, NULL, cgroup_base_files, true);
- if (err < 0)
- return err;
- }
+ int i, ret = 0;
/* process cftsets of each subsystem */
- for_each_root_subsys(cgrp->root, ss) {
+ for_each_subsys(ss, i) {
struct cftype_set *set;
- if (!test_bit(ss->subsys_id, &subsys_mask))
+
+ if (!test_bit(i, &subsys_mask))
continue;
- list_for_each_entry(set, &ss->cftsets, node)
- cgroup_addrm_files(cgrp, ss, set->cfts, true);
+ list_for_each_entry(set, &ss->cftsets, node) {
+ ret = cgroup_addrm_files(cgrp, set->cfts, true);
+ if (ret < 0)
+ goto err;
+ }
}
/* This cgroup is ready now */
for_each_root_subsys(cgrp->root, ss) {
- struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];
+ struct cgroup_subsys_state *css = cgroup_css(cgrp, ss);
struct css_id *id = rcu_dereference_protected(css->id, true);
/*
}
return 0;
+err:
+ cgroup_clear_dir(cgrp, subsys_mask);
+ return ret;
+}
+
+/*
+ * css destruction is four-stage process.
+ *
+ * 1. Destruction starts. Killing of the percpu_ref is initiated.
+ * Implemented in kill_css().
+ *
+ * 2. When the percpu_ref is confirmed to be visible as killed on all CPUs
+ * and thus css_tryget() is guaranteed to fail, the css can be offlined
+ * by invoking offline_css(). After offlining, the base ref is put.
+ * Implemented in css_killed_work_fn().
+ *
+ * 3. When the percpu_ref reaches zero, the only possible remaining
+ * accessors are inside RCU read sections. css_release() schedules the
+ * RCU callback.
+ *
+ * 4. After the grace period, the css can be freed. Implemented in
+ * css_free_work_fn().
+ *
+ * It is actually hairier because both step 2 and 4 require process context
+ * and thus involve punting to css->destroy_work adding two additional
+ * steps to the already complex sequence.
+ */
+static void css_free_work_fn(struct work_struct *work)
+{
+ struct cgroup_subsys_state *css =
+ container_of(work, struct cgroup_subsys_state, destroy_work);
+ struct cgroup *cgrp = css->cgroup;
+
+ if (css->parent)
+ css_put(css->parent);
+
+ css->ss->css_free(css);
+ cgroup_dput(cgrp);
}
-static void css_dput_fn(struct work_struct *work)
+static void css_free_rcu_fn(struct rcu_head *rcu_head)
{
struct cgroup_subsys_state *css =
- container_of(work, struct cgroup_subsys_state, dput_work);
+ container_of(rcu_head, struct cgroup_subsys_state, rcu_head);
- cgroup_dput(css->cgroup);
+ /*
+ * 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);
+ schedule_work(&css->destroy_work);
}
static void css_release(struct percpu_ref *ref)
struct cgroup_subsys_state *css =
container_of(ref, struct cgroup_subsys_state, refcnt);
- schedule_work(&css->dput_work);
+ call_rcu(&css->rcu_head, css_free_rcu_fn);
}
-static void init_cgroup_css(struct cgroup_subsys_state *css,
- struct cgroup_subsys *ss,
- struct cgroup *cgrp)
+static void init_css(struct cgroup_subsys_state *css, struct cgroup_subsys *ss,
+ struct cgroup *cgrp)
{
css->cgroup = cgrp;
+ css->ss = ss;
css->flags = 0;
css->id = NULL;
- if (cgrp == cgroup_dummy_top)
+
+ if (cgrp->parent)
+ css->parent = cgroup_css(cgrp->parent, ss);
+ else
css->flags |= CSS_ROOT;
- BUG_ON(cgrp->subsys[ss->subsys_id]);
- cgrp->subsys[ss->subsys_id] = css;
- /*
- * 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);
+ BUG_ON(cgroup_css(cgrp, ss));
}
-/* invoke ->post_create() on a new CSS and mark it online if successful */
-static int online_css(struct cgroup_subsys *ss, struct cgroup *cgrp)
+/* invoke ->css_online() on a new CSS and mark it online if successful */
+static int online_css(struct cgroup_subsys_state *css)
{
+ struct cgroup_subsys *ss = css->ss;
int ret = 0;
lockdep_assert_held(&cgroup_mutex);
if (ss->css_online)
- ret = ss->css_online(cgrp);
- if (!ret)
- cgrp->subsys[ss->subsys_id]->flags |= CSS_ONLINE;
+ ret = ss->css_online(css);
+ if (!ret) {
+ css->flags |= CSS_ONLINE;
+ css->cgroup->nr_css++;
+ rcu_assign_pointer(css->cgroup->subsys[ss->subsys_id], css);
+ }
return ret;
}
-/* if the CSS is online, invoke ->pre_destory() on it and mark it offline */
-static void offline_css(struct cgroup_subsys *ss, struct cgroup *cgrp)
- __releases(&cgroup_mutex) __acquires(&cgroup_mutex)
+/* if the CSS is online, invoke ->css_offline() on it and mark it offline */
+static void offline_css(struct cgroup_subsys_state *css)
{
- struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];
+ struct cgroup_subsys *ss = css->ss;
lockdep_assert_held(&cgroup_mutex);
return;
if (ss->css_offline)
- ss->css_offline(cgrp);
+ ss->css_offline(css);
- cgrp->subsys[ss->subsys_id]->flags &= ~CSS_ONLINE;
+ css->flags &= ~CSS_ONLINE;
+ css->cgroup->nr_css--;
+ RCU_INIT_POINTER(css->cgroup->subsys[ss->subsys_id], css);
}
/*
static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
umode_t mode)
{
+ struct cgroup_subsys_state *css_ar[CGROUP_SUBSYS_COUNT] = { };
struct cgroup *cgrp;
struct cgroup_name *name;
struct cgroupfs_root *root = parent->root;
goto err_free_cgrp;
rcu_assign_pointer(cgrp->name, name);
- cgrp->id = ida_simple_get(&root->cgroup_ida, 1, 0, GFP_KERNEL);
+ /*
+ * Temporarily set the pointer to NULL, so idr_find() won't return
+ * a half-baked cgroup.
+ */
+ cgrp->id = idr_alloc(&root->cgroup_idr, NULL, 1, 0, GFP_KERNEL);
if (cgrp->id < 0)
goto err_free_name;
cgrp->dentry = dentry;
cgrp->parent = parent;
+ cgrp->dummy_css.parent = &parent->dummy_css;
cgrp->root = parent->root;
if (notify_on_release(parent))
for_each_root_subsys(root, ss) {
struct cgroup_subsys_state *css;
- css = ss->css_alloc(cgrp);
+ css = ss->css_alloc(cgroup_css(parent, ss));
if (IS_ERR(css)) {
err = PTR_ERR(css);
goto err_free_all;
}
+ css_ar[ss->subsys_id] = css;
err = percpu_ref_init(&css->refcnt, css_release);
- if (err) {
- ss->css_free(cgrp);
+ if (err)
goto err_free_all;
- }
- init_cgroup_css(css, ss, cgrp);
+ init_css(css, ss, cgrp);
if (ss->use_id) {
- err = alloc_css_id(ss, parent, cgrp);
+ err = alloc_css_id(css);
if (err)
goto err_free_all;
}
list_add_tail_rcu(&cgrp->sibling, &cgrp->parent->children);
root->number_of_cgroups++;
- /* each css holds a ref to the cgroup's dentry */
- for_each_root_subsys(root, ss)
+ /* each css holds a ref to the cgroup's dentry and the parent css */
+ for_each_root_subsys(root, ss) {
+ struct cgroup_subsys_state *css = css_ar[ss->subsys_id];
+
dget(dentry);
+ css_get(css->parent);
+ }
/* hold a ref to the parent's dentry */
dget(parent->dentry);
/* creation succeeded, notify subsystems */
for_each_root_subsys(root, ss) {
- err = online_css(ss, cgrp);
+ struct cgroup_subsys_state *css = css_ar[ss->subsys_id];
+
+ err = online_css(css);
if (err)
goto err_destroy;
}
}
- err = cgroup_populate_dir(cgrp, true, root->subsys_mask);
+ idr_replace(&root->cgroup_idr, cgrp, cgrp->id);
+
+ err = cgroup_addrm_files(cgrp, cgroup_base_files, true);
+ if (err)
+ goto err_destroy;
+
+ err = cgroup_populate_dir(cgrp, root->subsys_mask);
if (err)
goto err_destroy;
err_free_all:
for_each_root_subsys(root, ss) {
- struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];
+ struct cgroup_subsys_state *css = css_ar[ss->subsys_id];
if (css) {
percpu_ref_cancel_init(&css->refcnt);
- ss->css_free(cgrp);
+ ss->css_free(css);
}
}
mutex_unlock(&cgroup_mutex);
/* Release the reference count that we took on the superblock */
deactivate_super(sb);
err_free_id:
- ida_simple_remove(&root->cgroup_ida, cgrp->id);
+ idr_remove(&root->cgroup_idr, cgrp->id);
err_free_name:
kfree(rcu_dereference_raw(cgrp->name));
err_free_cgrp:
return cgroup_create(c_parent, dentry, mode | S_IFDIR);
}
-static void cgroup_css_killed(struct cgroup *cgrp)
+/*
+ * This is called when the refcnt of a css is confirmed to be killed.
+ * css_tryget() is now guaranteed to fail.
+ */
+static void css_killed_work_fn(struct work_struct *work)
{
- if (!atomic_dec_and_test(&cgrp->css_kill_cnt))
- return;
+ struct cgroup_subsys_state *css =
+ container_of(work, struct cgroup_subsys_state, destroy_work);
+ struct cgroup *cgrp = css->cgroup;
- /* percpu ref's of all css's are killed, kick off the next step */
- INIT_WORK(&cgrp->destroy_work, cgroup_offline_fn);
- schedule_work(&cgrp->destroy_work);
+ mutex_lock(&cgroup_mutex);
+
+ /*
+ * css_tryget() is guaranteed to fail now. Tell subsystems to
+ * initate destruction.
+ */
+ offline_css(css);
+
+ /*
+ * If @cgrp is marked dead, it's waiting for refs of all css's to
+ * be disabled before proceeding to the second phase of cgroup
+ * destruction. If we are the last one, kick it off.
+ */
+ if (!cgrp->nr_css && cgroup_is_dead(cgrp))
+ cgroup_destroy_css_killed(cgrp);
+
+ mutex_unlock(&cgroup_mutex);
+
+ /*
+ * Put the css refs from kill_css(). Each css holds an extra
+ * reference to the cgroup's dentry and cgroup removal proceeds
+ * regardless of css refs. 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.
+ */
+ css_put(css);
}
-static void css_ref_killed_fn(struct percpu_ref *ref)
+/* css kill confirmation processing requires process context, bounce */
+static void css_killed_ref_fn(struct percpu_ref *ref)
{
struct cgroup_subsys_state *css =
container_of(ref, struct cgroup_subsys_state, refcnt);
- cgroup_css_killed(css->cgroup);
+ INIT_WORK(&css->destroy_work, css_killed_work_fn);
+ schedule_work(&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)
+{
+ cgroup_clear_dir(css->cgroup, 1 << css->ss->subsys_id);
+
+ /*
+ * Killing would put the base ref, but we need to keep it alive
+ * until after ->css_offline().
+ */
+ css_get(css);
+
+ /*
+ * cgroup core guarantees that, by the time ->css_offline() is
+ * invoked, no new css reference will be given out via
+ * css_tryget(). We can't simply call percpu_ref_kill() and
+ * proceed to offlining css's because percpu_ref_kill() doesn't
+ * guarantee that the ref is seen as killed on all CPUs on return.
+ *
+ * Use percpu_ref_kill_and_confirm() to get notifications as each
+ * css is confirmed to be seen as killed on all CPUs.
+ */
+ percpu_ref_kill_and_confirm(&css->refcnt, css_killed_ref_fn);
}
/**
return -EBUSY;
/*
- * Block new css_tryget() by killing css refcnts. cgroup core
- * guarantees that, by the time ->css_offline() is invoked, no new
- * css reference will be given out via css_tryget(). We can't
- * simply call percpu_ref_kill() and proceed to offlining css's
- * because percpu_ref_kill() doesn't guarantee that the ref is seen
- * as killed on all CPUs on return.
- *
- * Use percpu_ref_kill_and_confirm() to get notifications as each
- * css is confirmed to be seen as killed on all CPUs. The
- * notification callback keeps track of the number of css's to be
- * killed and schedules cgroup_offline_fn() to perform the rest of
- * destruction once the percpu refs of all css's are confirmed to
- * be killed.
+ * 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.
*/
- atomic_set(&cgrp->css_kill_cnt, 1);
- for_each_root_subsys(cgrp->root, ss) {
- struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];
-
- /*
- * Killing would put the base ref, but we need to keep it
- * alive until after ->css_offline.
- */
- percpu_ref_get(&css->refcnt);
-
- atomic_inc(&cgrp->css_kill_cnt);
- percpu_ref_kill_and_confirm(&css->refcnt, css_ref_killed_fn);
- }
- cgroup_css_killed(cgrp);
+ for_each_root_subsys(cgrp->root, ss)
+ kill_css(cgroup_css(cgrp, ss));
/*
* Mark @cgrp dead. This prevents further task migration and child
* creation by disabling cgroup_lock_live_group(). Note that
- * CGRP_DEAD assertion is depended upon by cgroup_next_sibling() to
+ * CGRP_DEAD assertion is depended upon by css_next_child() to
* resume iteration after dropping RCU read lock. See
- * cgroup_next_sibling() for details.
+ * css_next_child() for details.
*/
set_bit(CGRP_DEAD, &cgrp->flags);
raw_spin_unlock(&release_list_lock);
/*
- * Remove @cgrp directory. The removal puts the base ref but we
- * aren't quite done with @cgrp yet, so hold onto it.
+ * If @cgrp has css's attached, the second stage of cgroup
+ * destruction is kicked off from css_killed_work_fn() after the
+ * refs of all attached css's are killed. If @cgrp doesn't have
+ * any css, we kick it off here.
*/
+ if (!cgrp->nr_css)
+ cgroup_destroy_css_killed(cgrp);
+
+ /*
+ * 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.
+ */
+ cgroup_addrm_files(cgrp, cgroup_base_files, false);
dget(d);
cgroup_d_remove_dir(d);
};
/**
- * cgroup_offline_fn - the second step of cgroup destruction
+ * cgroup_destroy_css_killed - the second step of cgroup destruction
* @work: cgroup->destroy_free_work
*
* This function is invoked from a work item for a cgroup which is being
- * destroyed after the percpu refcnts of all css's are guaranteed to be
- * seen as killed on all CPUs, and performs the rest of destruction. This
- * is the second step of destruction described in the comment above
- * cgroup_destroy_locked().
+ * destroyed after all css's are offlined and performs the rest of
+ * destruction. This is the second step of destruction described in the
+ * comment above cgroup_destroy_locked().
*/
-static void cgroup_offline_fn(struct work_struct *work)
+static void cgroup_destroy_css_killed(struct cgroup *cgrp)
{
- struct cgroup *cgrp = container_of(work, struct cgroup, destroy_work);
struct cgroup *parent = cgrp->parent;
struct dentry *d = cgrp->dentry;
- struct cgroup_subsys *ss;
- mutex_lock(&cgroup_mutex);
+ lockdep_assert_held(&cgroup_mutex);
- /*
- * css_tryget() is guaranteed to fail now. Tell subsystems to
- * initate destruction.
- */
- for_each_root_subsys(cgrp->root, ss)
- offline_css(ss, cgrp);
+ /* delete this cgroup from parent->children */
+ list_del_rcu(&cgrp->sibling);
/*
- * Put the css refs from cgroup_destroy_locked(). Each css holds
- * an extra reference to the cgroup's dentry and cgroup removal
- * proceeds regardless of css refs. 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.
+ * We should remove the cgroup object from idr before its grace
+ * period starts, so we won't be looking up a cgroup while the
+ * cgroup is being freed.
*/
- for_each_root_subsys(cgrp->root, ss)
- css_put(cgrp->subsys[ss->subsys_id]);
-
- /* delete this cgroup from parent->children */
- list_del_rcu(&cgrp->sibling);
+ idr_remove(&cgrp->root->cgroup_idr, cgrp->id);
+ cgrp->id = -1;
dput(d);
set_bit(CGRP_RELEASABLE, &parent->flags);
check_for_release(parent);
-
- mutex_unlock(&cgroup_mutex);
}
static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry)
* deregistration.
*/
if (ss->base_cftypes) {
+ struct cftype *cft;
+
+ for (cft = ss->base_cftypes; cft->name[0] != '\0'; cft++)
+ cft->ss = ss;
+
ss->base_cftset.cfts = ss->base_cftypes;
list_add_tail(&ss->base_cftset.node, &ss->cftsets);
}
/* Create the top cgroup state for this subsystem */
list_add(&ss->sibling, &cgroup_dummy_root.subsys_list);
ss->root = &cgroup_dummy_root;
- css = ss->css_alloc(cgroup_dummy_top);
+ css = ss->css_alloc(cgroup_css(cgroup_dummy_top, ss));
/* We don't handle early failures gracefully */
BUG_ON(IS_ERR(css));
- init_cgroup_css(css, ss, cgroup_dummy_top);
+ init_css(css, ss, cgroup_dummy_top);
/* Update the init_css_set to contain a subsys
* pointer to this state - since the subsystem is
* need to invoke fork callbacks here. */
BUG_ON(!list_empty(&init_task.tasks));
- BUG_ON(online_css(ss, cgroup_dummy_top));
+ BUG_ON(online_css(css));
mutex_unlock(&cgroup_mutex);
* struct, so this can happen first (i.e. before the dummy root
* attachment).
*/
- css = ss->css_alloc(cgroup_dummy_top);
+ 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;
ss->root = &cgroup_dummy_root;
/* our new subsystem will be attached to the dummy hierarchy. */
- init_cgroup_css(css, ss, cgroup_dummy_top);
- /* init_idr must be after init_cgroup_css because it sets css->id. */
+ init_css(css, ss, cgroup_dummy_top);
+ /* init_idr must be after init_css() because it sets css->id. */
if (ss->use_id) {
ret = cgroup_init_idr(ss, css);
if (ret)
}
write_unlock(&css_set_lock);
- ret = online_css(ss, cgroup_dummy_top);
+ ret = online_css(css);
if (ret)
goto err_unload;
/*
* we shouldn't be called if the subsystem is in use, and the use of
- * try_module_get in parse_cgroupfs_options should ensure that it
+ * 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);
- offline_css(ss, cgroup_dummy_top);
+ offline_css(cgroup_css(cgroup_dummy_top, ss));
if (ss->use_id)
idr_destroy(&ss->idr);
* the cgrp->subsys pointer to find their state. note that this
* also takes care of freeing the css_id.
*/
- ss->css_free(cgroup_dummy_top);
- cgroup_dummy_top->subsys[ss->subsys_id] = NULL;
+ ss->css_free(cgroup_css(cgroup_dummy_top, ss));
+ RCU_INIT_POINTER(cgroup_dummy_top->subsys[ss->subsys_id], NULL);
mutex_unlock(&cgroup_mutex);
}
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);
+
mutex_unlock(&cgroup_root_mutex);
mutex_unlock(&cgroup_mutex);
* Adds the task to the list running through its css_set if necessary and
* call the subsystem fork() callbacks. Has to be after the task is
* visible on the task list in case we race with the first call to
- * cgroup_iter_start() - to guarantee that the new task ends up on its
+ * cgroup_task_iter_start() - to guarantee that the new task ends up on its
* list.
*/
void cgroup_post_fork(struct task_struct *child)
*/
for_each_builtin_subsys(ss, i) {
if (ss->exit) {
- struct cgroup *old_cgrp = cset->subsys[i]->cgroup;
- struct cgroup *cgrp = task_cgroup(tsk, i);
+ struct cgroup_subsys_state *old_css = cset->subsys[i];
+ struct cgroup_subsys_state *css = task_css(tsk, i);
- ss->exit(cgrp, old_cgrp, tsk);
+ ss->exit(css, old_css, tsk);
}
}
}
return 0;
}
-static int alloc_css_id(struct cgroup_subsys *ss, struct cgroup *parent,
- struct cgroup *child)
+static int alloc_css_id(struct cgroup_subsys_state *child_css)
{
- int subsys_id, i, depth = 0;
- struct cgroup_subsys_state *parent_css, *child_css;
+ struct cgroup_subsys_state *parent_css = css_parent(child_css);
struct css_id *child_id, *parent_id;
+ int i, depth;
- subsys_id = ss->subsys_id;
- parent_css = parent->subsys[subsys_id];
- child_css = child->subsys[subsys_id];
parent_id = rcu_dereference_protected(parent_css->id, true);
depth = parent_id->depth + 1;
- child_id = get_new_cssid(ss, depth);
+ child_id = get_new_cssid(child_css->ss, depth);
if (IS_ERR(child_id))
return PTR_ERR(child_id);
}
EXPORT_SYMBOL_GPL(css_lookup);
-/*
- * get corresponding css from file open on cgroupfs directory
+/**
+ * css_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 RCU read lock. The caller is responsible for
+ * pinning the returned css if it needs to be accessed outside the RCU
+ * critical section.
*/
-struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id)
+struct cgroup_subsys_state *css_from_dir(struct dentry *dentry,
+ struct cgroup_subsys *ss)
{
struct cgroup *cgrp;
- struct inode *inode;
- struct cgroup_subsys_state *css;
- inode = file_inode(f);
- /* check in cgroup filesystem dir */
- if (inode->i_op != &cgroup_dir_inode_operations)
+ WARN_ON_ONCE(!rcu_read_lock_held());
+
+ /* is @dentry a cgroup dir? */
+ if (!dentry->d_inode ||
+ dentry->d_inode->i_op != &cgroup_dir_inode_operations)
return ERR_PTR(-EBADF);
- if (id < 0 || id >= CGROUP_SUBSYS_COUNT)
- return ERR_PTR(-EINVAL);
+ cgrp = __d_cgrp(dentry);
+ return cgroup_css(cgrp, ss) ?: ERR_PTR(-ENOENT);
+}
- /* get cgroup */
- cgrp = __d_cgrp(f->f_dentry);
- css = cgrp->subsys[id];
- return css ? css : ERR_PTR(-ENOENT);
+/**
+ * css_from_id - lookup css by id
+ * @id: the cgroup id
+ * @ss: cgroup subsys to be looked into
+ *
+ * Returns the css if there's valid one with @id, otherwise returns NULL.
+ * Should be called under rcu_read_lock().
+ */
+struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss)
+{
+ struct cgroup *cgrp;
+
+ rcu_lockdep_assert(rcu_read_lock_held() ||
+ lockdep_is_held(&cgroup_mutex),
+ "css_from_id() needs proper protection");
+
+ cgrp = idr_find(&ss->root->cgroup_idr, id);
+ if (cgrp)
+ return cgroup_css(cgrp, ss);
+ return NULL;
}
#ifdef CONFIG_CGROUP_DEBUG
-static struct cgroup_subsys_state *debug_css_alloc(struct cgroup *cgrp)
+static struct cgroup_subsys_state *
+debug_css_alloc(struct cgroup_subsys_state *parent_css)
{
struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
return css;
}
-static void debug_css_free(struct cgroup *cgrp)
+static void debug_css_free(struct cgroup_subsys_state *css)
{
- kfree(cgrp->subsys[debug_subsys_id]);
+ kfree(css);
}
-static u64 debug_taskcount_read(struct cgroup *cgrp, struct cftype *cft)
+static u64 debug_taskcount_read(struct cgroup_subsys_state *css,
+ struct cftype *cft)
{
- return cgroup_task_count(cgrp);
+ return cgroup_task_count(css->cgroup);
}
-static u64 current_css_set_read(struct cgroup *cgrp, struct cftype *cft)
+static u64 current_css_set_read(struct cgroup_subsys_state *css,
+ struct cftype *cft)
{
return (u64)(unsigned long)current->cgroups;
}
-static u64 current_css_set_refcount_read(struct cgroup *cgrp,
+static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css,
struct cftype *cft)
{
u64 count;
return count;
}
-static int current_css_set_cg_links_read(struct cgroup *cgrp,
+static int current_css_set_cg_links_read(struct cgroup_subsys_state *css,
struct cftype *cft,
struct seq_file *seq)
{
}
#define MAX_TASKS_SHOWN_PER_CSS 25
-static int cgroup_css_links_read(struct cgroup *cgrp,
- struct cftype *cft,
- struct seq_file *seq)
+static int cgroup_css_links_read(struct cgroup_subsys_state *css,
+ struct cftype *cft, struct seq_file *seq)
{
struct cgrp_cset_link *link;
read_lock(&css_set_lock);
- list_for_each_entry(link, &cgrp->cset_links, cset_link) {
+ list_for_each_entry(link, &css->cgroup->cset_links, cset_link) {
struct css_set *cset = link->cset;
struct task_struct *task;
int count = 0;
return 0;
}
-static u64 releasable_read(struct cgroup *cgrp, struct cftype *cft)
+static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft)
{
- return test_bit(CGRP_RELEASABLE, &cgrp->flags);
+ return test_bit(CGRP_RELEASABLE, &css->cgroup->flags);
}
static struct cftype debug_files[] = {
git.openpandora.org / pandora-kernel.git / blobdiff