*/
static int need_forkexit_callback __read_mostly;
+static struct cftype cgroup_base_files[];
+
static void cgroup_offline_fn(struct work_struct *work);
static int cgroup_destroy_locked(struct cgroup *cgrp);
static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys,
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;
}
/**
- * 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);
- }
}
/*
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;
/* 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;
}
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;
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, NULL, 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, NULL, 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);
EXPORT_SYMBOL_GPL(cgroup_path);
/**
- * task_cgroup_path_from_hierarchy - cgroup path of a task on a hierarchy
+ * task_cgroup_path - cgroup path of a task in the first cgroup hierarchy
* @task: target task
- * @hierarchy_id: the hierarchy to look up @task's cgroup from
* @buf: the buffer to write the path into
* @buflen: the length of the buffer
*
- * Determine @task's cgroup on the hierarchy specified by @hierarchy_id and
- * copy its path into @buf. This function grabs cgroup_mutex and shouldn't
- * be used inside locks used by cgroup controller callbacks.
+ * Determine @task's cgroup on the first (the one with the lowest non-zero
+ * hierarchy_id) cgroup hierarchy and copy its path into @buf. This
+ * function grabs cgroup_mutex and shouldn't be used inside locks used by
+ * cgroup controller callbacks.
+ *
+ * Returns 0 on success, fails with -%ENAMETOOLONG if @buflen is too short.
*/
-int task_cgroup_path_from_hierarchy(struct task_struct *task, int hierarchy_id,
- char *buf, size_t buflen)
+int task_cgroup_path(struct task_struct *task, char *buf, size_t buflen)
{
struct cgroupfs_root *root;
- struct cgroup *cgrp = NULL;
- int ret = -ENOENT;
+ struct cgroup *cgrp;
+ int hierarchy_id = 1, ret = 0;
+
+ if (buflen < 2)
+ return -ENAMETOOLONG;
mutex_lock(&cgroup_mutex);
- root = idr_find(&cgroup_hierarchy_idr, hierarchy_id);
+ root = idr_get_next(&cgroup_hierarchy_idr, &hierarchy_id);
+
if (root) {
cgrp = task_cgroup_from_root(task, root);
ret = cgroup_path(cgrp, buf, buflen);
+ } else {
+ /* if no hierarchy exists, everyone is in "/" */
+ memcpy(buf, "/", 2);
}
mutex_unlock(&cgroup_mutex);
-
return ret;
}
-EXPORT_SYMBOL_GPL(task_cgroup_path_from_hierarchy);
+EXPORT_SYMBOL_GPL(task_cgroup_path);
/*
* Control Group taskset
return error;
}
+/**
+ * cgroup_addrm_files - add or remove files to a cgroup directory
+ * @cgrp: the target cgroup
+ * @subsys: the subsystem of files to be added
+ * @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.
+ * All @cfts should belong to @subsys. 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 cgroup_subsys *subsys,
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, subsys, 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)
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 cgroup_subsys *ss,
+ struct cftype *cfts, bool is_add)
__releases(&cgroup_mutex)
{
LIST_HEAD(pending);
struct dentry *prev = NULL;
struct inode *inode;
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;
}
/*
inode = root->dentry->d_inode;
mutex_lock(&inode->i_mutex);
mutex_lock(&cgroup_mutex);
- cgroup_addrm_files(root, ss, cfts, is_add);
+ ret = cgroup_addrm_files(root, ss, cfts, is_add);
mutex_unlock(&cgroup_mutex);
mutex_unlock(&inode->i_mutex);
+ if (ret)
+ goto out_deact;
+
/* add/rm files for all cgroups created before */
rcu_read_lock();
cgroup_for_each_descendant_pre(cgrp, root) {
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, ss, cfts, is_add);
mutex_unlock(&cgroup_mutex);
mutex_unlock(&inode->i_mutex);
rcu_read_lock();
+ if (ret)
+ break;
}
rcu_read_unlock();
dput(prev);
+out_deact:
deactivate_super(sb);
+ return ret;
}
/**
int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
{
struct cftype_set *set;
+ int ret;
set = kzalloc(sizeof(*set), GFP_KERNEL);
if (!set)
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(ss, cfts, true);
+ if (ret)
+ cgroup_rm_cftypes(ss, cfts);
+ return ret;
}
EXPORT_SYMBOL_GPL(cgroup_add_cftypes);
};
/**
- * 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, ss, set->cfts, true);
+ if (ret < 0)
+ goto err;
+ }
}
/* This cgroup is ready now */
}
return 0;
+err:
+ cgroup_clear_dir(cgrp, subsys_mask);
+ return ret;
}
static void css_dput_fn(struct work_struct *work)
}
}
- err = cgroup_populate_dir(cgrp, true, root->subsys_mask);
+ err = cgroup_addrm_files(cgrp, NULL, cgroup_base_files, true);
+ if (err)
+ goto err_destroy;
+
+ err = cgroup_populate_dir(cgrp, root->subsys_mask);
if (err)
goto err_destroy;
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.
+ * Clear and remove @cgrp directory. The removal puts the base ref
+ * but we aren't quite done with @cgrp yet, so hold onto it.
*/
+ cgroup_clear_dir(cgrp, cgrp->root->subsys_mask);
+ cgroup_addrm_files(cgrp, NULL, cgroup_base_files, false);
dget(d);
cgroup_d_remove_dir(d);
/*
* 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);
projects / karo-tx-linux.git / blobdiff