4197 lines
108 KiB
C
4197 lines
108 KiB
C
/*
|
|
* Generic process-grouping system.
|
|
*
|
|
* Based originally on the cpuset system, extracted by Paul Menage
|
|
* Copyright (C) 2006 Google, Inc
|
|
*
|
|
* Copyright notices from the original cpuset code:
|
|
* --------------------------------------------------
|
|
* Copyright (C) 2003 BULL SA.
|
|
* Copyright (C) 2004-2006 Silicon Graphics, Inc.
|
|
*
|
|
* Portions derived from Patrick Mochel's sysfs code.
|
|
* sysfs is Copyright (c) 2001-3 Patrick Mochel
|
|
*
|
|
* 2003-10-10 Written by Simon Derr.
|
|
* 2003-10-22 Updates by Stephen Hemminger.
|
|
* 2004 May-July Rework by Paul Jackson.
|
|
* ---------------------------------------------------
|
|
*
|
|
* This file is subject to the terms and conditions of the GNU General Public
|
|
* License. See the file COPYING in the main directory of the Linux
|
|
* distribution for more details.
|
|
*/
|
|
|
|
#include <linux/cgroup.h>
|
|
#include <linux/ctype.h>
|
|
#include <linux/errno.h>
|
|
#include <linux/fs.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/list.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/mutex.h>
|
|
#include <linux/mount.h>
|
|
#include <linux/pagemap.h>
|
|
#include <linux/proc_fs.h>
|
|
#include <linux/rcupdate.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/backing-dev.h>
|
|
#include <linux/seq_file.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/magic.h>
|
|
#include <linux/spinlock.h>
|
|
#include <linux/string.h>
|
|
#include <linux/sort.h>
|
|
#include <linux/kmod.h>
|
|
#include <linux/delayacct.h>
|
|
#include <linux/cgroupstats.h>
|
|
#include <linux/hash.h>
|
|
#include <linux/namei.h>
|
|
#include <linux/smp_lock.h>
|
|
#include <linux/pid_namespace.h>
|
|
#include <linux/idr.h>
|
|
#include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */
|
|
|
|
#include <asm/atomic.h>
|
|
|
|
static DEFINE_MUTEX(cgroup_mutex);
|
|
|
|
/* Generate an array of cgroup subsystem pointers */
|
|
#define SUBSYS(_x) &_x ## _subsys,
|
|
|
|
static struct cgroup_subsys *subsys[] = {
|
|
#include <linux/cgroup_subsys.h>
|
|
};
|
|
|
|
#define MAX_CGROUP_ROOT_NAMELEN 64
|
|
|
|
/*
|
|
* A cgroupfs_root represents the root of a cgroup hierarchy,
|
|
* and may be associated with a superblock to form an active
|
|
* hierarchy
|
|
*/
|
|
struct cgroupfs_root {
|
|
struct super_block *sb;
|
|
|
|
/*
|
|
* The bitmask of subsystems intended to be attached to this
|
|
* hierarchy
|
|
*/
|
|
unsigned long subsys_bits;
|
|
|
|
/* Unique id for this hierarchy. */
|
|
int hierarchy_id;
|
|
|
|
/* The bitmask of subsystems currently attached to this hierarchy */
|
|
unsigned long actual_subsys_bits;
|
|
|
|
/* A list running through the attached subsystems */
|
|
struct list_head subsys_list;
|
|
|
|
/* The root cgroup for this hierarchy */
|
|
struct cgroup top_cgroup;
|
|
|
|
/* Tracks how many cgroups are currently defined in hierarchy.*/
|
|
int number_of_cgroups;
|
|
|
|
/* A list running through the active hierarchies */
|
|
struct list_head root_list;
|
|
|
|
/* Hierarchy-specific flags */
|
|
unsigned long flags;
|
|
|
|
/* The path to use for release notifications. */
|
|
char release_agent_path[PATH_MAX];
|
|
|
|
/* The name for this hierarchy - may be empty */
|
|
char name[MAX_CGROUP_ROOT_NAMELEN];
|
|
};
|
|
|
|
/*
|
|
* The "rootnode" hierarchy is the "dummy hierarchy", reserved for the
|
|
* subsystems that are otherwise unattached - it never has more than a
|
|
* single cgroup, and all tasks are part of that cgroup.
|
|
*/
|
|
static struct cgroupfs_root rootnode;
|
|
|
|
/*
|
|
* CSS ID -- ID per subsys's Cgroup Subsys State(CSS). used only when
|
|
* cgroup_subsys->use_id != 0.
|
|
*/
|
|
#define CSS_ID_MAX (65535)
|
|
struct css_id {
|
|
/*
|
|
* The css to which this ID points. This pointer is set to valid value
|
|
* after cgroup is populated. If cgroup is removed, this will be NULL.
|
|
* This pointer is expected to be RCU-safe because destroy()
|
|
* is called after synchronize_rcu(). But for safe use, css_is_removed()
|
|
* css_tryget() should be used for avoiding race.
|
|
*/
|
|
struct cgroup_subsys_state *css;
|
|
/*
|
|
* ID of this css.
|
|
*/
|
|
unsigned short id;
|
|
/*
|
|
* Depth in hierarchy which this ID belongs to.
|
|
*/
|
|
unsigned short depth;
|
|
/*
|
|
* ID is freed by RCU. (and lookup routine is RCU safe.)
|
|
*/
|
|
struct rcu_head rcu_head;
|
|
/*
|
|
* Hierarchy of CSS ID belongs to.
|
|
*/
|
|
unsigned short stack[0]; /* Array of Length (depth+1) */
|
|
};
|
|
|
|
|
|
/* The list of hierarchy roots */
|
|
|
|
static LIST_HEAD(roots);
|
|
static int root_count;
|
|
|
|
static DEFINE_IDA(hierarchy_ida);
|
|
static int next_hierarchy_id;
|
|
static DEFINE_SPINLOCK(hierarchy_id_lock);
|
|
|
|
/* dummytop is a shorthand for the dummy hierarchy's top cgroup */
|
|
#define dummytop (&rootnode.top_cgroup)
|
|
|
|
/* This flag indicates whether tasks in the fork and exit paths should
|
|
* check for fork/exit handlers to call. This avoids us having to do
|
|
* extra work in the fork/exit path if none of the subsystems need to
|
|
* be called.
|
|
*/
|
|
static int need_forkexit_callback __read_mostly;
|
|
|
|
/* convenient tests for these bits */
|
|
inline int cgroup_is_removed(const struct cgroup *cgrp)
|
|
{
|
|
return test_bit(CGRP_REMOVED, &cgrp->flags);
|
|
}
|
|
|
|
/* bits in struct cgroupfs_root flags field */
|
|
enum {
|
|
ROOT_NOPREFIX, /* mounted subsystems have no named prefix */
|
|
};
|
|
|
|
static int cgroup_is_releasable(const struct cgroup *cgrp)
|
|
{
|
|
const int bits =
|
|
(1 << CGRP_RELEASABLE) |
|
|
(1 << CGRP_NOTIFY_ON_RELEASE);
|
|
return (cgrp->flags & bits) == bits;
|
|
}
|
|
|
|
static int notify_on_release(const struct cgroup *cgrp)
|
|
{
|
|
return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
|
|
}
|
|
|
|
/*
|
|
* for_each_subsys() allows you to iterate on each subsystem attached to
|
|
* an active hierarchy
|
|
*/
|
|
#define for_each_subsys(_root, _ss) \
|
|
list_for_each_entry(_ss, &_root->subsys_list, sibling)
|
|
|
|
/* for_each_active_root() allows you to iterate across the active hierarchies */
|
|
#define for_each_active_root(_root) \
|
|
list_for_each_entry(_root, &roots, root_list)
|
|
|
|
/* the list of cgroups eligible for automatic release. Protected by
|
|
* release_list_lock */
|
|
static LIST_HEAD(release_list);
|
|
static DEFINE_SPINLOCK(release_list_lock);
|
|
static void cgroup_release_agent(struct work_struct *work);
|
|
static DECLARE_WORK(release_agent_work, cgroup_release_agent);
|
|
static void check_for_release(struct cgroup *cgrp);
|
|
|
|
/* Link structure for associating css_set objects with cgroups */
|
|
struct cg_cgroup_link {
|
|
/*
|
|
* List running through cg_cgroup_links associated with a
|
|
* cgroup, anchored on cgroup->css_sets
|
|
*/
|
|
struct list_head cgrp_link_list;
|
|
struct cgroup *cgrp;
|
|
/*
|
|
* List running through cg_cgroup_links pointing at a
|
|
* single css_set object, anchored on css_set->cg_links
|
|
*/
|
|
struct list_head cg_link_list;
|
|
struct css_set *cg;
|
|
};
|
|
|
|
/* The default css_set - used by init and its children prior to any
|
|
* hierarchies being mounted. It contains a pointer to the root state
|
|
* for each subsystem. Also used to anchor the list of css_sets. Not
|
|
* reference-counted, to improve performance when child cgroups
|
|
* haven't been created.
|
|
*/
|
|
|
|
static struct css_set init_css_set;
|
|
static struct cg_cgroup_link init_css_set_link;
|
|
|
|
static int cgroup_subsys_init_idr(struct cgroup_subsys *ss);
|
|
|
|
/* 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() */
|
|
static DEFINE_RWLOCK(css_set_lock);
|
|
static int css_set_count;
|
|
|
|
/*
|
|
* hash table for cgroup groups. This improves the performance to find
|
|
* an existing css_set. This hash doesn't (currently) take into
|
|
* account cgroups in empty hierarchies.
|
|
*/
|
|
#define CSS_SET_HASH_BITS 7
|
|
#define CSS_SET_TABLE_SIZE (1 << CSS_SET_HASH_BITS)
|
|
static struct hlist_head css_set_table[CSS_SET_TABLE_SIZE];
|
|
|
|
static struct hlist_head *css_set_hash(struct cgroup_subsys_state *css[])
|
|
{
|
|
int i;
|
|
int index;
|
|
unsigned long tmp = 0UL;
|
|
|
|
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++)
|
|
tmp += (unsigned long)css[i];
|
|
tmp = (tmp >> 16) ^ tmp;
|
|
|
|
index = hash_long(tmp, CSS_SET_HASH_BITS);
|
|
|
|
return &css_set_table[index];
|
|
}
|
|
|
|
static void free_css_set_rcu(struct rcu_head *obj)
|
|
{
|
|
struct css_set *cg = container_of(obj, struct css_set, rcu_head);
|
|
kfree(cg);
|
|
}
|
|
|
|
/* 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 */
|
|
static int use_task_css_set_links __read_mostly;
|
|
|
|
static void __put_css_set(struct css_set *cg, int taskexit)
|
|
{
|
|
struct cg_cgroup_link *link;
|
|
struct cg_cgroup_link *saved_link;
|
|
/*
|
|
* Ensure that the refcount doesn't hit zero while any readers
|
|
* can see it. Similar to atomic_dec_and_lock(), but for an
|
|
* rwlock
|
|
*/
|
|
if (atomic_add_unless(&cg->refcount, -1, 1))
|
|
return;
|
|
write_lock(&css_set_lock);
|
|
if (!atomic_dec_and_test(&cg->refcount)) {
|
|
write_unlock(&css_set_lock);
|
|
return;
|
|
}
|
|
|
|
/* This css_set is dead. unlink it and release cgroup refcounts */
|
|
hlist_del(&cg->hlist);
|
|
css_set_count--;
|
|
|
|
list_for_each_entry_safe(link, saved_link, &cg->cg_links,
|
|
cg_link_list) {
|
|
struct cgroup *cgrp = link->cgrp;
|
|
list_del(&link->cg_link_list);
|
|
list_del(&link->cgrp_link_list);
|
|
if (atomic_dec_and_test(&cgrp->count) &&
|
|
notify_on_release(cgrp)) {
|
|
if (taskexit)
|
|
set_bit(CGRP_RELEASABLE, &cgrp->flags);
|
|
check_for_release(cgrp);
|
|
}
|
|
|
|
kfree(link);
|
|
}
|
|
|
|
write_unlock(&css_set_lock);
|
|
call_rcu(&cg->rcu_head, free_css_set_rcu);
|
|
}
|
|
|
|
/*
|
|
* refcounted get/put for css_set objects
|
|
*/
|
|
static inline void get_css_set(struct css_set *cg)
|
|
{
|
|
atomic_inc(&cg->refcount);
|
|
}
|
|
|
|
static inline void put_css_set(struct css_set *cg)
|
|
{
|
|
__put_css_set(cg, 0);
|
|
}
|
|
|
|
static inline void put_css_set_taskexit(struct css_set *cg)
|
|
{
|
|
__put_css_set(cg, 1);
|
|
}
|
|
|
|
/*
|
|
* compare_css_sets - helper function for find_existing_css_set().
|
|
* @cg: candidate css_set being tested
|
|
* @old_cg: existing css_set for a task
|
|
* @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
|
|
* which "new_cgrp" belongs to, for which it should match "new_cgrp".
|
|
*/
|
|
static bool compare_css_sets(struct css_set *cg,
|
|
struct css_set *old_cg,
|
|
struct cgroup *new_cgrp,
|
|
struct cgroup_subsys_state *template[])
|
|
{
|
|
struct list_head *l1, *l2;
|
|
|
|
if (memcmp(template, cg->subsys, sizeof(cg->subsys))) {
|
|
/* Not all subsystems matched */
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* Compare cgroup pointers in order to distinguish between
|
|
* different cgroups in heirarchies with no subsystems. We
|
|
* could get by with just this check alone (and skip the
|
|
* memcmp above) but on most setups the memcmp check will
|
|
* avoid the need for this more expensive check on almost all
|
|
* candidates.
|
|
*/
|
|
|
|
l1 = &cg->cg_links;
|
|
l2 = &old_cg->cg_links;
|
|
while (1) {
|
|
struct cg_cgroup_link *cgl1, *cgl2;
|
|
struct cgroup *cg1, *cg2;
|
|
|
|
l1 = l1->next;
|
|
l2 = l2->next;
|
|
/* See if we reached the end - both lists are equal length. */
|
|
if (l1 == &cg->cg_links) {
|
|
BUG_ON(l2 != &old_cg->cg_links);
|
|
break;
|
|
} else {
|
|
BUG_ON(l2 == &old_cg->cg_links);
|
|
}
|
|
/* Locate the cgroups associated with these links. */
|
|
cgl1 = list_entry(l1, struct cg_cgroup_link, cg_link_list);
|
|
cgl2 = list_entry(l2, struct cg_cgroup_link, cg_link_list);
|
|
cg1 = cgl1->cgrp;
|
|
cg2 = cgl2->cgrp;
|
|
/* Hierarchies should be linked in the same order. */
|
|
BUG_ON(cg1->root != cg2->root);
|
|
|
|
/*
|
|
* If this hierarchy is the hierarchy of the cgroup
|
|
* that's changing, then we need to check that this
|
|
* css_set points to the new cgroup; if it's any other
|
|
* hierarchy, then this css_set should point to the
|
|
* same cgroup as the old css_set.
|
|
*/
|
|
if (cg1->root == new_cgrp->root) {
|
|
if (cg1 != new_cgrp)
|
|
return false;
|
|
} else {
|
|
if (cg1 != cg2)
|
|
return false;
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* find_existing_css_set() is a helper for
|
|
* find_css_set(), and checks to see whether an existing
|
|
* css_set is suitable.
|
|
*
|
|
* oldcg: the cgroup group that we're using before the cgroup
|
|
* transition
|
|
*
|
|
* cgrp: the cgroup that we're moving into
|
|
*
|
|
* template: location in which to build the desired set of subsystem
|
|
* state objects for the new cgroup group
|
|
*/
|
|
static struct css_set *find_existing_css_set(
|
|
struct css_set *oldcg,
|
|
struct cgroup *cgrp,
|
|
struct cgroup_subsys_state *template[])
|
|
{
|
|
int i;
|
|
struct cgroupfs_root *root = cgrp->root;
|
|
struct hlist_head *hhead;
|
|
struct hlist_node *node;
|
|
struct css_set *cg;
|
|
|
|
/* Built the set of subsystem state objects that we want to
|
|
* see in the new css_set */
|
|
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
|
|
if (root->subsys_bits & (1UL << i)) {
|
|
/* Subsystem is in this hierarchy. So we want
|
|
* the subsystem state from the new
|
|
* cgroup */
|
|
template[i] = cgrp->subsys[i];
|
|
} else {
|
|
/* Subsystem is not in this hierarchy, so we
|
|
* don't want to change the subsystem state */
|
|
template[i] = oldcg->subsys[i];
|
|
}
|
|
}
|
|
|
|
hhead = css_set_hash(template);
|
|
hlist_for_each_entry(cg, node, hhead, hlist) {
|
|
if (!compare_css_sets(cg, oldcg, cgrp, template))
|
|
continue;
|
|
|
|
/* This css_set matches what we need */
|
|
return cg;
|
|
}
|
|
|
|
/* No existing cgroup group matched */
|
|
return NULL;
|
|
}
|
|
|
|
static void free_cg_links(struct list_head *tmp)
|
|
{
|
|
struct cg_cgroup_link *link;
|
|
struct cg_cgroup_link *saved_link;
|
|
|
|
list_for_each_entry_safe(link, saved_link, tmp, cgrp_link_list) {
|
|
list_del(&link->cgrp_link_list);
|
|
kfree(link);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* allocate_cg_links() allocates "count" cg_cgroup_link structures
|
|
* and chains them on tmp through their cgrp_link_list fields. Returns 0 on
|
|
* success or a negative error
|
|
*/
|
|
static int allocate_cg_links(int count, struct list_head *tmp)
|
|
{
|
|
struct cg_cgroup_link *link;
|
|
int i;
|
|
INIT_LIST_HEAD(tmp);
|
|
for (i = 0; i < count; i++) {
|
|
link = kmalloc(sizeof(*link), GFP_KERNEL);
|
|
if (!link) {
|
|
free_cg_links(tmp);
|
|
return -ENOMEM;
|
|
}
|
|
list_add(&link->cgrp_link_list, tmp);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* link_css_set - a helper function to link a css_set to a cgroup
|
|
* @tmp_cg_links: cg_cgroup_link objects allocated by allocate_cg_links()
|
|
* @cg: the css_set to be linked
|
|
* @cgrp: the destination cgroup
|
|
*/
|
|
static void link_css_set(struct list_head *tmp_cg_links,
|
|
struct css_set *cg, struct cgroup *cgrp)
|
|
{
|
|
struct cg_cgroup_link *link;
|
|
|
|
BUG_ON(list_empty(tmp_cg_links));
|
|
link = list_first_entry(tmp_cg_links, struct cg_cgroup_link,
|
|
cgrp_link_list);
|
|
link->cg = cg;
|
|
link->cgrp = cgrp;
|
|
atomic_inc(&cgrp->count);
|
|
list_move(&link->cgrp_link_list, &cgrp->css_sets);
|
|
/*
|
|
* Always add links to the tail of the list so that the list
|
|
* is sorted by order of hierarchy creation
|
|
*/
|
|
list_add_tail(&link->cg_link_list, &cg->cg_links);
|
|
}
|
|
|
|
/*
|
|
* find_css_set() takes an existing cgroup group and a
|
|
* cgroup object, and returns a css_set object that's
|
|
* equivalent to the old group, but with the given cgroup
|
|
* substituted into the appropriate hierarchy. Must be called with
|
|
* cgroup_mutex held
|
|
*/
|
|
static struct css_set *find_css_set(
|
|
struct css_set *oldcg, struct cgroup *cgrp)
|
|
{
|
|
struct css_set *res;
|
|
struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT];
|
|
|
|
struct list_head tmp_cg_links;
|
|
|
|
struct hlist_head *hhead;
|
|
struct cg_cgroup_link *link;
|
|
|
|
/* First see if we already have a cgroup group that matches
|
|
* the desired set */
|
|
read_lock(&css_set_lock);
|
|
res = find_existing_css_set(oldcg, cgrp, template);
|
|
if (res)
|
|
get_css_set(res);
|
|
read_unlock(&css_set_lock);
|
|
|
|
if (res)
|
|
return res;
|
|
|
|
res = kmalloc(sizeof(*res), GFP_KERNEL);
|
|
if (!res)
|
|
return NULL;
|
|
|
|
/* Allocate all the cg_cgroup_link objects that we'll need */
|
|
if (allocate_cg_links(root_count, &tmp_cg_links) < 0) {
|
|
kfree(res);
|
|
return NULL;
|
|
}
|
|
|
|
atomic_set(&res->refcount, 1);
|
|
INIT_LIST_HEAD(&res->cg_links);
|
|
INIT_LIST_HEAD(&res->tasks);
|
|
INIT_HLIST_NODE(&res->hlist);
|
|
|
|
/* Copy the set of subsystem state objects generated in
|
|
* find_existing_css_set() */
|
|
memcpy(res->subsys, template, sizeof(res->subsys));
|
|
|
|
write_lock(&css_set_lock);
|
|
/* Add reference counts and links from the new css_set. */
|
|
list_for_each_entry(link, &oldcg->cg_links, cg_link_list) {
|
|
struct cgroup *c = link->cgrp;
|
|
if (c->root == cgrp->root)
|
|
c = cgrp;
|
|
link_css_set(&tmp_cg_links, res, c);
|
|
}
|
|
|
|
BUG_ON(!list_empty(&tmp_cg_links));
|
|
|
|
css_set_count++;
|
|
|
|
/* Add this cgroup group to the hash table */
|
|
hhead = css_set_hash(res->subsys);
|
|
hlist_add_head(&res->hlist, hhead);
|
|
|
|
write_unlock(&css_set_lock);
|
|
|
|
return res;
|
|
}
|
|
|
|
/*
|
|
* Return the cgroup for "task" from the given hierarchy. Must be
|
|
* called with cgroup_mutex held.
|
|
*/
|
|
static struct cgroup *task_cgroup_from_root(struct task_struct *task,
|
|
struct cgroupfs_root *root)
|
|
{
|
|
struct css_set *css;
|
|
struct cgroup *res = NULL;
|
|
|
|
BUG_ON(!mutex_is_locked(&cgroup_mutex));
|
|
read_lock(&css_set_lock);
|
|
/*
|
|
* No need to lock the task - since we hold cgroup_mutex the
|
|
* task can't change groups, so the only thing that can happen
|
|
* is that it exits and its css is set back to init_css_set.
|
|
*/
|
|
css = task->cgroups;
|
|
if (css == &init_css_set) {
|
|
res = &root->top_cgroup;
|
|
} else {
|
|
struct cg_cgroup_link *link;
|
|
list_for_each_entry(link, &css->cg_links, cg_link_list) {
|
|
struct cgroup *c = link->cgrp;
|
|
if (c->root == root) {
|
|
res = c;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
read_unlock(&css_set_lock);
|
|
BUG_ON(!res);
|
|
return res;
|
|
}
|
|
|
|
/*
|
|
* There is one global cgroup mutex. We also require taking
|
|
* task_lock() when dereferencing a task's cgroup subsys pointers.
|
|
* See "The task_lock() exception", at the end of this comment.
|
|
*
|
|
* A task must hold cgroup_mutex to modify cgroups.
|
|
*
|
|
* Any task can increment and decrement the count field without lock.
|
|
* So in general, code holding cgroup_mutex can't rely on the count
|
|
* field not changing. However, if the count goes to zero, then only
|
|
* cgroup_attach_task() can increment it again. Because a count of zero
|
|
* means that no tasks are currently attached, therefore there is no
|
|
* way a task attached to that cgroup can fork (the other way to
|
|
* increment the count). So code holding cgroup_mutex can safely
|
|
* assume that if the count is zero, it will stay zero. Similarly, if
|
|
* a task holds cgroup_mutex on a cgroup with zero count, it
|
|
* knows that the cgroup won't be removed, as cgroup_rmdir()
|
|
* needs that mutex.
|
|
*
|
|
* The fork and exit callbacks cgroup_fork() and cgroup_exit(), don't
|
|
* (usually) take cgroup_mutex. These are the two most performance
|
|
* critical pieces of code here. The exception occurs on cgroup_exit(),
|
|
* when a task in a notify_on_release cgroup exits. Then cgroup_mutex
|
|
* is taken, and if the cgroup count is zero, a usermode call made
|
|
* to the release agent with the name of the cgroup (path relative to
|
|
* the root of cgroup file system) as the argument.
|
|
*
|
|
* A cgroup can only be deleted if both its 'count' of using tasks
|
|
* is zero, and its list of 'children' cgroups is empty. Since all
|
|
* tasks in the system use _some_ cgroup, and since there is always at
|
|
* least one task in the system (init, pid == 1), therefore, top_cgroup
|
|
* always has either children cgroups and/or using tasks. So we don't
|
|
* need a special hack to ensure that top_cgroup cannot be deleted.
|
|
*
|
|
* The task_lock() exception
|
|
*
|
|
* The need for this exception arises from the action of
|
|
* cgroup_attach_task(), which overwrites one tasks cgroup pointer with
|
|
* another. It does so using cgroup_mutex, however there are
|
|
* several performance critical places that need to reference
|
|
* task->cgroup without the expense of grabbing a system global
|
|
* mutex. Therefore except as noted below, when dereferencing or, as
|
|
* in cgroup_attach_task(), modifying a task'ss cgroup pointer we use
|
|
* task_lock(), which acts on a spinlock (task->alloc_lock) already in
|
|
* the task_struct routinely used for such matters.
|
|
*
|
|
* P.S. One more locking exception. RCU is used to guard the
|
|
* update of a tasks cgroup pointer by cgroup_attach_task()
|
|
*/
|
|
|
|
/**
|
|
* cgroup_lock - lock out any changes to cgroup structures
|
|
*
|
|
*/
|
|
void cgroup_lock(void)
|
|
{
|
|
mutex_lock(&cgroup_mutex);
|
|
}
|
|
|
|
/**
|
|
* cgroup_unlock - release lock on cgroup changes
|
|
*
|
|
* Undo the lock taken in a previous cgroup_lock() call.
|
|
*/
|
|
void cgroup_unlock(void)
|
|
{
|
|
mutex_unlock(&cgroup_mutex);
|
|
}
|
|
|
|
/*
|
|
* A couple of forward declarations required, due to cyclic reference loop:
|
|
* cgroup_mkdir -> cgroup_create -> cgroup_populate_dir ->
|
|
* cgroup_add_file -> cgroup_create_file -> cgroup_dir_inode_operations
|
|
* -> cgroup_mkdir.
|
|
*/
|
|
|
|
static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, int mode);
|
|
static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry);
|
|
static int cgroup_populate_dir(struct cgroup *cgrp);
|
|
static const struct inode_operations cgroup_dir_inode_operations;
|
|
static const struct file_operations proc_cgroupstats_operations;
|
|
|
|
static struct backing_dev_info cgroup_backing_dev_info = {
|
|
.name = "cgroup",
|
|
.capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
|
|
};
|
|
|
|
static int alloc_css_id(struct cgroup_subsys *ss,
|
|
struct cgroup *parent, struct cgroup *child);
|
|
|
|
static struct inode *cgroup_new_inode(mode_t mode, struct super_block *sb)
|
|
{
|
|
struct inode *inode = new_inode(sb);
|
|
|
|
if (inode) {
|
|
inode->i_mode = mode;
|
|
inode->i_uid = current_fsuid();
|
|
inode->i_gid = current_fsgid();
|
|
inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
|
|
inode->i_mapping->backing_dev_info = &cgroup_backing_dev_info;
|
|
}
|
|
return inode;
|
|
}
|
|
|
|
/*
|
|
* Call subsys's pre_destroy handler.
|
|
* This is called before css refcnt check.
|
|
*/
|
|
static int cgroup_call_pre_destroy(struct cgroup *cgrp)
|
|
{
|
|
struct cgroup_subsys *ss;
|
|
int ret = 0;
|
|
|
|
for_each_subsys(cgrp->root, ss)
|
|
if (ss->pre_destroy) {
|
|
ret = ss->pre_destroy(ss, cgrp);
|
|
if (ret)
|
|
break;
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
static void free_cgroup_rcu(struct rcu_head *obj)
|
|
{
|
|
struct cgroup *cgrp = container_of(obj, struct cgroup, rcu_head);
|
|
|
|
kfree(cgrp);
|
|
}
|
|
|
|
static void cgroup_diput(struct dentry *dentry, struct inode *inode)
|
|
{
|
|
/* is dentry a directory ? if so, kfree() associated cgroup */
|
|
if (S_ISDIR(inode->i_mode)) {
|
|
struct cgroup *cgrp = dentry->d_fsdata;
|
|
struct cgroup_subsys *ss;
|
|
BUG_ON(!(cgroup_is_removed(cgrp)));
|
|
/* It's possible for external users to be holding css
|
|
* reference counts on a cgroup; css_put() needs to
|
|
* be able to access the cgroup after decrementing
|
|
* the reference count in order to know if it needs to
|
|
* queue the cgroup to be handled by the release
|
|
* agent */
|
|
synchronize_rcu();
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
/*
|
|
* Release the subsystem state objects.
|
|
*/
|
|
for_each_subsys(cgrp->root, ss)
|
|
ss->destroy(ss, cgrp);
|
|
|
|
cgrp->root->number_of_cgroups--;
|
|
mutex_unlock(&cgroup_mutex);
|
|
|
|
/*
|
|
* Drop the active superblock reference that we took when we
|
|
* created the cgroup
|
|
*/
|
|
deactivate_super(cgrp->root->sb);
|
|
|
|
/*
|
|
* if we're getting rid of the cgroup, refcount should ensure
|
|
* that there are no pidlists left.
|
|
*/
|
|
BUG_ON(!list_empty(&cgrp->pidlists));
|
|
|
|
call_rcu(&cgrp->rcu_head, free_cgroup_rcu);
|
|
}
|
|
iput(inode);
|
|
}
|
|
|
|
static void remove_dir(struct dentry *d)
|
|
{
|
|
struct dentry *parent = dget(d->d_parent);
|
|
|
|
d_delete(d);
|
|
simple_rmdir(parent->d_inode, d);
|
|
dput(parent);
|
|
}
|
|
|
|
static void cgroup_clear_directory(struct dentry *dentry)
|
|
{
|
|
struct list_head *node;
|
|
|
|
BUG_ON(!mutex_is_locked(&dentry->d_inode->i_mutex));
|
|
spin_lock(&dcache_lock);
|
|
node = dentry->d_subdirs.next;
|
|
while (node != &dentry->d_subdirs) {
|
|
struct dentry *d = list_entry(node, struct dentry, d_u.d_child);
|
|
list_del_init(node);
|
|
if (d->d_inode) {
|
|
/* This should never be called on a cgroup
|
|
* directory with child cgroups */
|
|
BUG_ON(d->d_inode->i_mode & S_IFDIR);
|
|
d = dget_locked(d);
|
|
spin_unlock(&dcache_lock);
|
|
d_delete(d);
|
|
simple_unlink(dentry->d_inode, d);
|
|
dput(d);
|
|
spin_lock(&dcache_lock);
|
|
}
|
|
node = dentry->d_subdirs.next;
|
|
}
|
|
spin_unlock(&dcache_lock);
|
|
}
|
|
|
|
/*
|
|
* NOTE : the dentry must have been dget()'ed
|
|
*/
|
|
static void cgroup_d_remove_dir(struct dentry *dentry)
|
|
{
|
|
cgroup_clear_directory(dentry);
|
|
|
|
spin_lock(&dcache_lock);
|
|
list_del_init(&dentry->d_u.d_child);
|
|
spin_unlock(&dcache_lock);
|
|
remove_dir(dentry);
|
|
}
|
|
|
|
/*
|
|
* A queue for waiters to do rmdir() cgroup. A tasks will sleep when
|
|
* cgroup->count == 0 && list_empty(&cgroup->children) && subsys has some
|
|
* reference to css->refcnt. In general, this refcnt is expected to goes down
|
|
* to zero, soon.
|
|
*
|
|
* CGRP_WAIT_ON_RMDIR flag is set under cgroup's inode->i_mutex;
|
|
*/
|
|
DECLARE_WAIT_QUEUE_HEAD(cgroup_rmdir_waitq);
|
|
|
|
static void cgroup_wakeup_rmdir_waiter(struct cgroup *cgrp)
|
|
{
|
|
if (unlikely(test_and_clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags)))
|
|
wake_up_all(&cgroup_rmdir_waitq);
|
|
}
|
|
|
|
void cgroup_exclude_rmdir(struct cgroup_subsys_state *css)
|
|
{
|
|
css_get(css);
|
|
}
|
|
|
|
void cgroup_release_and_wakeup_rmdir(struct cgroup_subsys_state *css)
|
|
{
|
|
cgroup_wakeup_rmdir_waiter(css->cgroup);
|
|
css_put(css);
|
|
}
|
|
|
|
|
|
static int rebind_subsystems(struct cgroupfs_root *root,
|
|
unsigned long final_bits)
|
|
{
|
|
unsigned long added_bits, removed_bits;
|
|
struct cgroup *cgrp = &root->top_cgroup;
|
|
int i;
|
|
|
|
removed_bits = root->actual_subsys_bits & ~final_bits;
|
|
added_bits = final_bits & ~root->actual_subsys_bits;
|
|
/* Check that any added subsystems are currently free */
|
|
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
|
|
unsigned long bit = 1UL << i;
|
|
struct cgroup_subsys *ss = subsys[i];
|
|
if (!(bit & added_bits))
|
|
continue;
|
|
if (ss->root != &rootnode) {
|
|
/* Subsystem isn't free */
|
|
return -EBUSY;
|
|
}
|
|
}
|
|
|
|
/* 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;
|
|
|
|
/* Process each subsystem */
|
|
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
|
|
struct cgroup_subsys *ss = subsys[i];
|
|
unsigned long bit = 1UL << i;
|
|
if (bit & added_bits) {
|
|
/* We're binding this subsystem to this hierarchy */
|
|
BUG_ON(cgrp->subsys[i]);
|
|
BUG_ON(!dummytop->subsys[i]);
|
|
BUG_ON(dummytop->subsys[i]->cgroup != dummytop);
|
|
mutex_lock(&ss->hierarchy_mutex);
|
|
cgrp->subsys[i] = dummytop->subsys[i];
|
|
cgrp->subsys[i]->cgroup = cgrp;
|
|
list_move(&ss->sibling, &root->subsys_list);
|
|
ss->root = root;
|
|
if (ss->bind)
|
|
ss->bind(ss, cgrp);
|
|
mutex_unlock(&ss->hierarchy_mutex);
|
|
} else if (bit & removed_bits) {
|
|
/* We're removing this subsystem */
|
|
BUG_ON(cgrp->subsys[i] != dummytop->subsys[i]);
|
|
BUG_ON(cgrp->subsys[i]->cgroup != cgrp);
|
|
mutex_lock(&ss->hierarchy_mutex);
|
|
if (ss->bind)
|
|
ss->bind(ss, dummytop);
|
|
dummytop->subsys[i]->cgroup = dummytop;
|
|
cgrp->subsys[i] = NULL;
|
|
subsys[i]->root = &rootnode;
|
|
list_move(&ss->sibling, &rootnode.subsys_list);
|
|
mutex_unlock(&ss->hierarchy_mutex);
|
|
} else if (bit & final_bits) {
|
|
/* Subsystem state should already exist */
|
|
BUG_ON(!cgrp->subsys[i]);
|
|
} else {
|
|
/* Subsystem state shouldn't exist */
|
|
BUG_ON(cgrp->subsys[i]);
|
|
}
|
|
}
|
|
root->subsys_bits = root->actual_subsys_bits = final_bits;
|
|
synchronize_rcu();
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int cgroup_show_options(struct seq_file *seq, struct vfsmount *vfs)
|
|
{
|
|
struct cgroupfs_root *root = vfs->mnt_sb->s_fs_info;
|
|
struct cgroup_subsys *ss;
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
for_each_subsys(root, ss)
|
|
seq_printf(seq, ",%s", ss->name);
|
|
if (test_bit(ROOT_NOPREFIX, &root->flags))
|
|
seq_puts(seq, ",noprefix");
|
|
if (strlen(root->release_agent_path))
|
|
seq_printf(seq, ",release_agent=%s", root->release_agent_path);
|
|
if (strlen(root->name))
|
|
seq_printf(seq, ",name=%s", root->name);
|
|
mutex_unlock(&cgroup_mutex);
|
|
return 0;
|
|
}
|
|
|
|
struct cgroup_sb_opts {
|
|
unsigned long subsys_bits;
|
|
unsigned long flags;
|
|
char *release_agent;
|
|
char *name;
|
|
/* User explicitly requested empty subsystem */
|
|
bool none;
|
|
|
|
struct cgroupfs_root *new_root;
|
|
|
|
};
|
|
|
|
/* Convert a hierarchy specifier into a bitmask of subsystems and
|
|
* flags. */
|
|
static int parse_cgroupfs_options(char *data,
|
|
struct cgroup_sb_opts *opts)
|
|
{
|
|
char *token, *o = data ?: "all";
|
|
unsigned long mask = (unsigned long)-1;
|
|
|
|
#ifdef CONFIG_CPUSETS
|
|
mask = ~(1UL << cpuset_subsys_id);
|
|
#endif
|
|
|
|
memset(opts, 0, sizeof(*opts));
|
|
|
|
while ((token = strsep(&o, ",")) != NULL) {
|
|
if (!*token)
|
|
return -EINVAL;
|
|
if (!strcmp(token, "all")) {
|
|
/* Add all non-disabled subsystems */
|
|
int i;
|
|
opts->subsys_bits = 0;
|
|
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
|
|
struct cgroup_subsys *ss = subsys[i];
|
|
if (!ss->disabled)
|
|
opts->subsys_bits |= 1ul << i;
|
|
}
|
|
} else if (!strcmp(token, "none")) {
|
|
/* Explicitly have no subsystems */
|
|
opts->none = true;
|
|
} else if (!strcmp(token, "noprefix")) {
|
|
set_bit(ROOT_NOPREFIX, &opts->flags);
|
|
} else if (!strncmp(token, "release_agent=", 14)) {
|
|
/* Specifying two release agents is forbidden */
|
|
if (opts->release_agent)
|
|
return -EINVAL;
|
|
opts->release_agent =
|
|
kstrndup(token + 14, PATH_MAX, GFP_KERNEL);
|
|
if (!opts->release_agent)
|
|
return -ENOMEM;
|
|
} else if (!strncmp(token, "name=", 5)) {
|
|
int i;
|
|
const char *name = token + 5;
|
|
/* Can't specify an empty name */
|
|
if (!strlen(name))
|
|
return -EINVAL;
|
|
/* Must match [\w.-]+ */
|
|
for (i = 0; i < strlen(name); i++) {
|
|
char c = name[i];
|
|
if (isalnum(c))
|
|
continue;
|
|
if ((c == '.') || (c == '-') || (c == '_'))
|
|
continue;
|
|
return -EINVAL;
|
|
}
|
|
/* Specifying two names is forbidden */
|
|
if (opts->name)
|
|
return -EINVAL;
|
|
opts->name = kstrndup(name,
|
|
MAX_CGROUP_ROOT_NAMELEN,
|
|
GFP_KERNEL);
|
|
if (!opts->name)
|
|
return -ENOMEM;
|
|
} else {
|
|
struct cgroup_subsys *ss;
|
|
int i;
|
|
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
|
|
ss = subsys[i];
|
|
if (!strcmp(token, ss->name)) {
|
|
if (!ss->disabled)
|
|
set_bit(i, &opts->subsys_bits);
|
|
break;
|
|
}
|
|
}
|
|
if (i == CGROUP_SUBSYS_COUNT)
|
|
return -ENOENT;
|
|
}
|
|
}
|
|
|
|
/* Consistency checks */
|
|
|
|
/*
|
|
* Option noprefix was introduced just for backward compatibility
|
|
* with the old cpuset, so we allow noprefix only if mounting just
|
|
* the cpuset subsystem.
|
|
*/
|
|
if (test_bit(ROOT_NOPREFIX, &opts->flags) &&
|
|
(opts->subsys_bits & mask))
|
|
return -EINVAL;
|
|
|
|
|
|
/* Can't specify "none" and some subsystems */
|
|
if (opts->subsys_bits && opts->none)
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* We either have to specify by name or by subsystems. (So all
|
|
* empty hierarchies must have a name).
|
|
*/
|
|
if (!opts->subsys_bits && !opts->name)
|
|
return -EINVAL;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int cgroup_remount(struct super_block *sb, int *flags, char *data)
|
|
{
|
|
int ret = 0;
|
|
struct cgroupfs_root *root = sb->s_fs_info;
|
|
struct cgroup *cgrp = &root->top_cgroup;
|
|
struct cgroup_sb_opts opts;
|
|
|
|
lock_kernel();
|
|
mutex_lock(&cgrp->dentry->d_inode->i_mutex);
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
/* See what subsystems are wanted */
|
|
ret = parse_cgroupfs_options(data, &opts);
|
|
if (ret)
|
|
goto out_unlock;
|
|
|
|
/* Don't allow flags to change at remount */
|
|
if (opts.flags != root->flags) {
|
|
ret = -EINVAL;
|
|
goto out_unlock;
|
|
}
|
|
|
|
/* Don't allow name to change at remount */
|
|
if (opts.name && strcmp(opts.name, root->name)) {
|
|
ret = -EINVAL;
|
|
goto out_unlock;
|
|
}
|
|
|
|
ret = rebind_subsystems(root, opts.subsys_bits);
|
|
if (ret)
|
|
goto out_unlock;
|
|
|
|
/* (re)populate subsystem files */
|
|
cgroup_populate_dir(cgrp);
|
|
|
|
if (opts.release_agent)
|
|
strcpy(root->release_agent_path, opts.release_agent);
|
|
out_unlock:
|
|
kfree(opts.release_agent);
|
|
kfree(opts.name);
|
|
mutex_unlock(&cgroup_mutex);
|
|
mutex_unlock(&cgrp->dentry->d_inode->i_mutex);
|
|
unlock_kernel();
|
|
return ret;
|
|
}
|
|
|
|
static const struct super_operations cgroup_ops = {
|
|
.statfs = simple_statfs,
|
|
.drop_inode = generic_delete_inode,
|
|
.show_options = cgroup_show_options,
|
|
.remount_fs = cgroup_remount,
|
|
};
|
|
|
|
static void init_cgroup_housekeeping(struct cgroup *cgrp)
|
|
{
|
|
INIT_LIST_HEAD(&cgrp->sibling);
|
|
INIT_LIST_HEAD(&cgrp->children);
|
|
INIT_LIST_HEAD(&cgrp->css_sets);
|
|
INIT_LIST_HEAD(&cgrp->release_list);
|
|
INIT_LIST_HEAD(&cgrp->pidlists);
|
|
mutex_init(&cgrp->pidlist_mutex);
|
|
}
|
|
|
|
static void init_cgroup_root(struct cgroupfs_root *root)
|
|
{
|
|
struct cgroup *cgrp = &root->top_cgroup;
|
|
INIT_LIST_HEAD(&root->subsys_list);
|
|
INIT_LIST_HEAD(&root->root_list);
|
|
root->number_of_cgroups = 1;
|
|
cgrp->root = root;
|
|
cgrp->top_cgroup = cgrp;
|
|
init_cgroup_housekeeping(cgrp);
|
|
}
|
|
|
|
static bool init_root_id(struct cgroupfs_root *root)
|
|
{
|
|
int ret = 0;
|
|
|
|
do {
|
|
if (!ida_pre_get(&hierarchy_ida, GFP_KERNEL))
|
|
return false;
|
|
spin_lock(&hierarchy_id_lock);
|
|
/* Try to allocate the next unused ID */
|
|
ret = ida_get_new_above(&hierarchy_ida, next_hierarchy_id,
|
|
&root->hierarchy_id);
|
|
if (ret == -ENOSPC)
|
|
/* Try again starting from 0 */
|
|
ret = ida_get_new(&hierarchy_ida, &root->hierarchy_id);
|
|
if (!ret) {
|
|
next_hierarchy_id = root->hierarchy_id + 1;
|
|
} else if (ret != -EAGAIN) {
|
|
/* Can only get here if the 31-bit IDR is full ... */
|
|
BUG_ON(ret);
|
|
}
|
|
spin_unlock(&hierarchy_id_lock);
|
|
} while (ret);
|
|
return true;
|
|
}
|
|
|
|
static int cgroup_test_super(struct super_block *sb, void *data)
|
|
{
|
|
struct cgroup_sb_opts *opts = data;
|
|
struct cgroupfs_root *root = sb->s_fs_info;
|
|
|
|
/* If we asked for a name then it must match */
|
|
if (opts->name && strcmp(opts->name, root->name))
|
|
return 0;
|
|
|
|
/*
|
|
* If we asked for subsystems (or explicitly for no
|
|
* subsystems) then they must match
|
|
*/
|
|
if ((opts->subsys_bits || opts->none)
|
|
&& (opts->subsys_bits != root->subsys_bits))
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts)
|
|
{
|
|
struct cgroupfs_root *root;
|
|
|
|
if (!opts->subsys_bits && !opts->none)
|
|
return NULL;
|
|
|
|
root = kzalloc(sizeof(*root), GFP_KERNEL);
|
|
if (!root)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
if (!init_root_id(root)) {
|
|
kfree(root);
|
|
return ERR_PTR(-ENOMEM);
|
|
}
|
|
init_cgroup_root(root);
|
|
|
|
root->subsys_bits = opts->subsys_bits;
|
|
root->flags = opts->flags;
|
|
if (opts->release_agent)
|
|
strcpy(root->release_agent_path, opts->release_agent);
|
|
if (opts->name)
|
|
strcpy(root->name, opts->name);
|
|
return root;
|
|
}
|
|
|
|
static void cgroup_drop_root(struct cgroupfs_root *root)
|
|
{
|
|
if (!root)
|
|
return;
|
|
|
|
BUG_ON(!root->hierarchy_id);
|
|
spin_lock(&hierarchy_id_lock);
|
|
ida_remove(&hierarchy_ida, root->hierarchy_id);
|
|
spin_unlock(&hierarchy_id_lock);
|
|
kfree(root);
|
|
}
|
|
|
|
static int cgroup_set_super(struct super_block *sb, void *data)
|
|
{
|
|
int ret;
|
|
struct cgroup_sb_opts *opts = data;
|
|
|
|
/* If we don't have a new root, we can't set up a new sb */
|
|
if (!opts->new_root)
|
|
return -EINVAL;
|
|
|
|
BUG_ON(!opts->subsys_bits && !opts->none);
|
|
|
|
ret = set_anon_super(sb, NULL);
|
|
if (ret)
|
|
return ret;
|
|
|
|
sb->s_fs_info = opts->new_root;
|
|
opts->new_root->sb = sb;
|
|
|
|
sb->s_blocksize = PAGE_CACHE_SIZE;
|
|
sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
|
|
sb->s_magic = CGROUP_SUPER_MAGIC;
|
|
sb->s_op = &cgroup_ops;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int cgroup_get_rootdir(struct super_block *sb)
|
|
{
|
|
struct inode *inode =
|
|
cgroup_new_inode(S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR, sb);
|
|
struct dentry *dentry;
|
|
|
|
if (!inode)
|
|
return -ENOMEM;
|
|
|
|
inode->i_fop = &simple_dir_operations;
|
|
inode->i_op = &cgroup_dir_inode_operations;
|
|
/* directories start off with i_nlink == 2 (for "." entry) */
|
|
inc_nlink(inode);
|
|
dentry = d_alloc_root(inode);
|
|
if (!dentry) {
|
|
iput(inode);
|
|
return -ENOMEM;
|
|
}
|
|
sb->s_root = dentry;
|
|
return 0;
|
|
}
|
|
|
|
static int cgroup_get_sb(struct file_system_type *fs_type,
|
|
int flags, const char *unused_dev_name,
|
|
void *data, struct vfsmount *mnt)
|
|
{
|
|
struct cgroup_sb_opts opts;
|
|
struct cgroupfs_root *root;
|
|
int ret = 0;
|
|
struct super_block *sb;
|
|
struct cgroupfs_root *new_root;
|
|
|
|
/* First find the desired set of subsystems */
|
|
ret = parse_cgroupfs_options(data, &opts);
|
|
if (ret)
|
|
goto out_err;
|
|
|
|
/*
|
|
* Allocate a new cgroup root. We may not need it if we're
|
|
* reusing an existing hierarchy.
|
|
*/
|
|
new_root = cgroup_root_from_opts(&opts);
|
|
if (IS_ERR(new_root)) {
|
|
ret = PTR_ERR(new_root);
|
|
goto out_err;
|
|
}
|
|
opts.new_root = new_root;
|
|
|
|
/* Locate an existing or new sb for this hierarchy */
|
|
sb = sget(fs_type, cgroup_test_super, cgroup_set_super, &opts);
|
|
if (IS_ERR(sb)) {
|
|
ret = PTR_ERR(sb);
|
|
cgroup_drop_root(opts.new_root);
|
|
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_cg_links;
|
|
struct cgroup *root_cgrp = &root->top_cgroup;
|
|
struct inode *inode;
|
|
struct cgroupfs_root *existing_root;
|
|
int i;
|
|
|
|
BUG_ON(sb->s_root != NULL);
|
|
|
|
ret = cgroup_get_rootdir(sb);
|
|
if (ret)
|
|
goto drop_new_super;
|
|
inode = sb->s_root->d_inode;
|
|
|
|
mutex_lock(&inode->i_mutex);
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
if (strlen(root->name)) {
|
|
/* Check for name clashes with existing mounts */
|
|
for_each_active_root(existing_root) {
|
|
if (!strcmp(existing_root->name, root->name)) {
|
|
ret = -EBUSY;
|
|
mutex_unlock(&cgroup_mutex);
|
|
mutex_unlock(&inode->i_mutex);
|
|
goto drop_new_super;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* We're accessing css_set_count without locking
|
|
* css_set_lock here, but that's OK - it can only be
|
|
* increased by someone holding cgroup_lock, and
|
|
* that's us. The worst that can happen is that we
|
|
* have some link structures left over
|
|
*/
|
|
ret = allocate_cg_links(css_set_count, &tmp_cg_links);
|
|
if (ret) {
|
|
mutex_unlock(&cgroup_mutex);
|
|
mutex_unlock(&inode->i_mutex);
|
|
goto drop_new_super;
|
|
}
|
|
|
|
ret = rebind_subsystems(root, root->subsys_bits);
|
|
if (ret == -EBUSY) {
|
|
mutex_unlock(&cgroup_mutex);
|
|
mutex_unlock(&inode->i_mutex);
|
|
free_cg_links(&tmp_cg_links);
|
|
goto drop_new_super;
|
|
}
|
|
|
|
/* EBUSY should be the only error here */
|
|
BUG_ON(ret);
|
|
|
|
list_add(&root->root_list, &roots);
|
|
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);
|
|
for (i = 0; i < CSS_SET_TABLE_SIZE; i++) {
|
|
struct hlist_head *hhead = &css_set_table[i];
|
|
struct hlist_node *node;
|
|
struct css_set *cg;
|
|
|
|
hlist_for_each_entry(cg, node, hhead, hlist)
|
|
link_css_set(&tmp_cg_links, cg, root_cgrp);
|
|
}
|
|
write_unlock(&css_set_lock);
|
|
|
|
free_cg_links(&tmp_cg_links);
|
|
|
|
BUG_ON(!list_empty(&root_cgrp->sibling));
|
|
BUG_ON(!list_empty(&root_cgrp->children));
|
|
BUG_ON(root->number_of_cgroups != 1);
|
|
|
|
cgroup_populate_dir(root_cgrp);
|
|
mutex_unlock(&cgroup_mutex);
|
|
mutex_unlock(&inode->i_mutex);
|
|
} else {
|
|
/*
|
|
* We re-used an existing hierarchy - the new root (if
|
|
* any) is not needed
|
|
*/
|
|
cgroup_drop_root(opts.new_root);
|
|
}
|
|
|
|
simple_set_mnt(mnt, sb);
|
|
kfree(opts.release_agent);
|
|
kfree(opts.name);
|
|
return 0;
|
|
|
|
drop_new_super:
|
|
deactivate_locked_super(sb);
|
|
out_err:
|
|
kfree(opts.release_agent);
|
|
kfree(opts.name);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static void cgroup_kill_sb(struct super_block *sb) {
|
|
struct cgroupfs_root *root = sb->s_fs_info;
|
|
struct cgroup *cgrp = &root->top_cgroup;
|
|
int ret;
|
|
struct cg_cgroup_link *link;
|
|
struct cg_cgroup_link *saved_link;
|
|
|
|
BUG_ON(!root);
|
|
|
|
BUG_ON(root->number_of_cgroups != 1);
|
|
BUG_ON(!list_empty(&cgrp->children));
|
|
BUG_ON(!list_empty(&cgrp->sibling));
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
/* Rebind all subsystems back to the default hierarchy */
|
|
ret = rebind_subsystems(root, 0);
|
|
/* Shouldn't be able to fail ... */
|
|
BUG_ON(ret);
|
|
|
|
/*
|
|
* Release all the links from css_sets to this hierarchy's
|
|
* root cgroup
|
|
*/
|
|
write_lock(&css_set_lock);
|
|
|
|
list_for_each_entry_safe(link, saved_link, &cgrp->css_sets,
|
|
cgrp_link_list) {
|
|
list_del(&link->cg_link_list);
|
|
list_del(&link->cgrp_link_list);
|
|
kfree(link);
|
|
}
|
|
write_unlock(&css_set_lock);
|
|
|
|
if (!list_empty(&root->root_list)) {
|
|
list_del(&root->root_list);
|
|
root_count--;
|
|
}
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
|
|
kill_litter_super(sb);
|
|
cgroup_drop_root(root);
|
|
}
|
|
|
|
static struct file_system_type cgroup_fs_type = {
|
|
.name = "cgroup",
|
|
.get_sb = cgroup_get_sb,
|
|
.kill_sb = cgroup_kill_sb,
|
|
};
|
|
|
|
static inline struct cgroup *__d_cgrp(struct dentry *dentry)
|
|
{
|
|
return dentry->d_fsdata;
|
|
}
|
|
|
|
static inline struct cftype *__d_cft(struct dentry *dentry)
|
|
{
|
|
return dentry->d_fsdata;
|
|
}
|
|
|
|
/**
|
|
* cgroup_path - generate the path of a cgroup
|
|
* @cgrp: the cgroup in question
|
|
* @buf: the buffer to write the path into
|
|
* @buflen: the length of the buffer
|
|
*
|
|
* Called with cgroup_mutex held or else with an RCU-protected cgroup
|
|
* reference. Writes path of cgroup into buf. Returns 0 on success,
|
|
* -errno on error.
|
|
*/
|
|
int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen)
|
|
{
|
|
char *start;
|
|
struct dentry *dentry = rcu_dereference(cgrp->dentry);
|
|
|
|
if (!dentry || cgrp == dummytop) {
|
|
/*
|
|
* Inactive subsystems have no dentry for their root
|
|
* cgroup
|
|
*/
|
|
strcpy(buf, "/");
|
|
return 0;
|
|
}
|
|
|
|
start = buf + buflen;
|
|
|
|
*--start = '\0';
|
|
for (;;) {
|
|
int len = dentry->d_name.len;
|
|
if ((start -= len) < buf)
|
|
return -ENAMETOOLONG;
|
|
memcpy(start, cgrp->dentry->d_name.name, len);
|
|
cgrp = cgrp->parent;
|
|
if (!cgrp)
|
|
break;
|
|
dentry = rcu_dereference(cgrp->dentry);
|
|
if (!cgrp->parent)
|
|
continue;
|
|
if (--start < buf)
|
|
return -ENAMETOOLONG;
|
|
*start = '/';
|
|
}
|
|
memmove(buf, start, buf + buflen - start);
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* cgroup_attach_task - attach task 'tsk' to cgroup 'cgrp'
|
|
* @cgrp: the cgroup the task is attaching to
|
|
* @tsk: the task to be attached
|
|
*
|
|
* Call holding cgroup_mutex. May take task_lock of
|
|
* the task 'tsk' during call.
|
|
*/
|
|
int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
|
|
{
|
|
int retval = 0;
|
|
struct cgroup_subsys *ss;
|
|
struct cgroup *oldcgrp;
|
|
struct css_set *cg;
|
|
struct css_set *newcg;
|
|
struct cgroupfs_root *root = cgrp->root;
|
|
|
|
/* Nothing to do if the task is already in that cgroup */
|
|
oldcgrp = task_cgroup_from_root(tsk, root);
|
|
if (cgrp == oldcgrp)
|
|
return 0;
|
|
|
|
for_each_subsys(root, ss) {
|
|
if (ss->can_attach) {
|
|
retval = ss->can_attach(ss, cgrp, tsk, false);
|
|
if (retval)
|
|
return retval;
|
|
}
|
|
}
|
|
|
|
task_lock(tsk);
|
|
cg = tsk->cgroups;
|
|
get_css_set(cg);
|
|
task_unlock(tsk);
|
|
/*
|
|
* Locate or allocate a new css_set for this task,
|
|
* based on its final set of cgroups
|
|
*/
|
|
newcg = find_css_set(cg, cgrp);
|
|
put_css_set(cg);
|
|
if (!newcg)
|
|
return -ENOMEM;
|
|
|
|
task_lock(tsk);
|
|
if (tsk->flags & PF_EXITING) {
|
|
task_unlock(tsk);
|
|
put_css_set(newcg);
|
|
return -ESRCH;
|
|
}
|
|
rcu_assign_pointer(tsk->cgroups, newcg);
|
|
task_unlock(tsk);
|
|
|
|
/* Update the css_set linked lists if we're using them */
|
|
write_lock(&css_set_lock);
|
|
if (!list_empty(&tsk->cg_list)) {
|
|
list_del(&tsk->cg_list);
|
|
list_add(&tsk->cg_list, &newcg->tasks);
|
|
}
|
|
write_unlock(&css_set_lock);
|
|
|
|
for_each_subsys(root, ss) {
|
|
if (ss->attach)
|
|
ss->attach(ss, cgrp, oldcgrp, tsk, false);
|
|
}
|
|
set_bit(CGRP_RELEASABLE, &oldcgrp->flags);
|
|
synchronize_rcu();
|
|
put_css_set(cg);
|
|
|
|
/*
|
|
* wake up rmdir() waiter. the rmdir should fail since the cgroup
|
|
* is no longer empty.
|
|
*/
|
|
cgroup_wakeup_rmdir_waiter(cgrp);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Attach task with pid 'pid' to cgroup 'cgrp'. Call with cgroup_mutex
|
|
* held. May take task_lock of task
|
|
*/
|
|
static int attach_task_by_pid(struct cgroup *cgrp, u64 pid)
|
|
{
|
|
struct task_struct *tsk;
|
|
const struct cred *cred = current_cred(), *tcred;
|
|
int ret;
|
|
|
|
if (pid) {
|
|
rcu_read_lock();
|
|
tsk = find_task_by_vpid(pid);
|
|
if (!tsk || tsk->flags & PF_EXITING) {
|
|
rcu_read_unlock();
|
|
return -ESRCH;
|
|
}
|
|
|
|
tcred = __task_cred(tsk);
|
|
if (cred->euid &&
|
|
cred->euid != tcred->uid &&
|
|
cred->euid != tcred->suid) {
|
|
rcu_read_unlock();
|
|
return -EACCES;
|
|
}
|
|
get_task_struct(tsk);
|
|
rcu_read_unlock();
|
|
} else {
|
|
tsk = current;
|
|
get_task_struct(tsk);
|
|
}
|
|
|
|
ret = cgroup_attach_task(cgrp, tsk);
|
|
put_task_struct(tsk);
|
|
return ret;
|
|
}
|
|
|
|
static int cgroup_tasks_write(struct cgroup *cgrp, struct cftype *cft, u64 pid)
|
|
{
|
|
int ret;
|
|
if (!cgroup_lock_live_group(cgrp))
|
|
return -ENODEV;
|
|
ret = attach_task_by_pid(cgrp, pid);
|
|
cgroup_unlock();
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive.
|
|
* @cgrp: the cgroup to be checked for liveness
|
|
*
|
|
* On success, returns true; the lock should be later released with
|
|
* cgroup_unlock(). On failure returns false with no lock held.
|
|
*/
|
|
bool cgroup_lock_live_group(struct cgroup *cgrp)
|
|
{
|
|
mutex_lock(&cgroup_mutex);
|
|
if (cgroup_is_removed(cgrp)) {
|
|
mutex_unlock(&cgroup_mutex);
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
static int cgroup_release_agent_write(struct cgroup *cgrp, struct cftype *cft,
|
|
const char *buffer)
|
|
{
|
|
BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX);
|
|
if (!cgroup_lock_live_group(cgrp))
|
|
return -ENODEV;
|
|
strcpy(cgrp->root->release_agent_path, buffer);
|
|
cgroup_unlock();
|
|
return 0;
|
|
}
|
|
|
|
static int cgroup_release_agent_show(struct cgroup *cgrp, struct cftype *cft,
|
|
struct seq_file *seq)
|
|
{
|
|
if (!cgroup_lock_live_group(cgrp))
|
|
return -ENODEV;
|
|
seq_puts(seq, cgrp->root->release_agent_path);
|
|
seq_putc(seq, '\n');
|
|
cgroup_unlock();
|
|
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)
|
|
{
|
|
char buffer[CGROUP_LOCAL_BUFFER_SIZE];
|
|
int retval = 0;
|
|
char *end;
|
|
|
|
if (!nbytes)
|
|
return -EINVAL;
|
|
if (nbytes >= sizeof(buffer))
|
|
return -E2BIG;
|
|
if (copy_from_user(buffer, userbuf, nbytes))
|
|
return -EFAULT;
|
|
|
|
buffer[nbytes] = 0; /* nul-terminate */
|
|
if (cft->write_u64) {
|
|
u64 val = simple_strtoull(strstrip(buffer), &end, 0);
|
|
if (*end)
|
|
return -EINVAL;
|
|
retval = cft->write_u64(cgrp, cft, val);
|
|
} else {
|
|
s64 val = simple_strtoll(strstrip(buffer), &end, 0);
|
|
if (*end)
|
|
return -EINVAL;
|
|
retval = cft->write_s64(cgrp, 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)
|
|
{
|
|
char local_buffer[CGROUP_LOCAL_BUFFER_SIZE];
|
|
int retval = 0;
|
|
size_t max_bytes = cft->max_write_len;
|
|
char *buffer = local_buffer;
|
|
|
|
if (!max_bytes)
|
|
max_bytes = sizeof(local_buffer) - 1;
|
|
if (nbytes >= max_bytes)
|
|
return -E2BIG;
|
|
/* Allocate a dynamic buffer if we need one */
|
|
if (nbytes >= sizeof(local_buffer)) {
|
|
buffer = kmalloc(nbytes + 1, GFP_KERNEL);
|
|
if (buffer == NULL)
|
|
return -ENOMEM;
|
|
}
|
|
if (nbytes && copy_from_user(buffer, userbuf, nbytes)) {
|
|
retval = -EFAULT;
|
|
goto out;
|
|
}
|
|
|
|
buffer[nbytes] = 0; /* nul-terminate */
|
|
retval = cft->write_string(cgrp, cft, strstrip(buffer));
|
|
if (!retval)
|
|
retval = nbytes;
|
|
out:
|
|
if (buffer != local_buffer)
|
|
kfree(buffer);
|
|
return retval;
|
|
}
|
|
|
|
static ssize_t cgroup_file_write(struct file *file, const char __user *buf,
|
|
size_t nbytes, loff_t *ppos)
|
|
{
|
|
struct cftype *cft = __d_cft(file->f_dentry);
|
|
struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);
|
|
|
|
if (cgroup_is_removed(cgrp))
|
|
return -ENODEV;
|
|
if (cft->write)
|
|
return cft->write(cgrp, cft, file, buf, nbytes, ppos);
|
|
if (cft->write_u64 || cft->write_s64)
|
|
return cgroup_write_X64(cgrp, cft, file, buf, nbytes, ppos);
|
|
if (cft->write_string)
|
|
return cgroup_write_string(cgrp, cft, file, buf, nbytes, ppos);
|
|
if (cft->trigger) {
|
|
int ret = cft->trigger(cgrp, (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)
|
|
{
|
|
char tmp[CGROUP_LOCAL_BUFFER_SIZE];
|
|
u64 val = cft->read_u64(cgrp, 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)
|
|
{
|
|
char tmp[CGROUP_LOCAL_BUFFER_SIZE];
|
|
s64 val = cft->read_s64(cgrp, 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)
|
|
{
|
|
struct cftype *cft = __d_cft(file->f_dentry);
|
|
struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);
|
|
|
|
if (cgroup_is_removed(cgrp))
|
|
return -ENODEV;
|
|
|
|
if (cft->read)
|
|
return cft->read(cgrp, cft, file, buf, nbytes, ppos);
|
|
if (cft->read_u64)
|
|
return cgroup_read_u64(cgrp, cft, file, buf, nbytes, ppos);
|
|
if (cft->read_s64)
|
|
return cgroup_read_s64(cgrp, cft, file, buf, nbytes, ppos);
|
|
return -EINVAL;
|
|
}
|
|
|
|
/*
|
|
* seqfile ops/methods for returning structured data. Currently just
|
|
* 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;
|
|
return seq_printf(sf, "%s %llu\n", key, (unsigned long long)value);
|
|
}
|
|
|
|
static int cgroup_seqfile_show(struct seq_file *m, void *arg)
|
|
{
|
|
struct cgroup_seqfile_state *state = m->private;
|
|
struct cftype *cft = state->cft;
|
|
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_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);
|
|
}
|
|
|
|
static const struct file_operations cgroup_seqfile_operations = {
|
|
.read = seq_read,
|
|
.write = cgroup_file_write,
|
|
.llseek = seq_lseek,
|
|
.release = cgroup_seqfile_release,
|
|
};
|
|
|
|
static int cgroup_file_open(struct inode *inode, struct file *file)
|
|
{
|
|
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 =
|
|
kzalloc(sizeof(*state), GFP_USER);
|
|
if (!state)
|
|
return -ENOMEM;
|
|
state->cft = cft;
|
|
state->cgroup = __d_cgrp(file->f_dentry->d_parent);
|
|
file->f_op = &cgroup_seqfile_operations;
|
|
err = single_open(file, cgroup_seqfile_show, state);
|
|
if (err < 0)
|
|
kfree(state);
|
|
} else if (cft->open)
|
|
err = cft->open(inode, file);
|
|
else
|
|
err = 0;
|
|
|
|
return err;
|
|
}
|
|
|
|
static int cgroup_file_release(struct inode *inode, struct file *file)
|
|
{
|
|
struct cftype *cft = __d_cft(file->f_dentry);
|
|
if (cft->release)
|
|
return cft->release(inode, file);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* cgroup_rename - Only allow simple rename of directories in place.
|
|
*/
|
|
static int cgroup_rename(struct inode *old_dir, struct dentry *old_dentry,
|
|
struct inode *new_dir, struct dentry *new_dentry)
|
|
{
|
|
if (!S_ISDIR(old_dentry->d_inode->i_mode))
|
|
return -ENOTDIR;
|
|
if (new_dentry->d_inode)
|
|
return -EEXIST;
|
|
if (old_dir != new_dir)
|
|
return -EIO;
|
|
return simple_rename(old_dir, old_dentry, new_dir, new_dentry);
|
|
}
|
|
|
|
static const struct file_operations cgroup_file_operations = {
|
|
.read = cgroup_file_read,
|
|
.write = cgroup_file_write,
|
|
.llseek = generic_file_llseek,
|
|
.open = cgroup_file_open,
|
|
.release = cgroup_file_release,
|
|
};
|
|
|
|
static const struct inode_operations cgroup_dir_inode_operations = {
|
|
.lookup = simple_lookup,
|
|
.mkdir = cgroup_mkdir,
|
|
.rmdir = cgroup_rmdir,
|
|
.rename = cgroup_rename,
|
|
};
|
|
|
|
static int cgroup_create_file(struct dentry *dentry, mode_t mode,
|
|
struct super_block *sb)
|
|
{
|
|
static const struct dentry_operations cgroup_dops = {
|
|
.d_iput = cgroup_diput,
|
|
};
|
|
|
|
struct inode *inode;
|
|
|
|
if (!dentry)
|
|
return -ENOENT;
|
|
if (dentry->d_inode)
|
|
return -EEXIST;
|
|
|
|
inode = cgroup_new_inode(mode, sb);
|
|
if (!inode)
|
|
return -ENOMEM;
|
|
|
|
if (S_ISDIR(mode)) {
|
|
inode->i_op = &cgroup_dir_inode_operations;
|
|
inode->i_fop = &simple_dir_operations;
|
|
|
|
/* start off with i_nlink == 2 (for "." entry) */
|
|
inc_nlink(inode);
|
|
|
|
/* start with the directory inode held, so that we can
|
|
* populate it without racing with another mkdir */
|
|
mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD);
|
|
} else if (S_ISREG(mode)) {
|
|
inode->i_size = 0;
|
|
inode->i_fop = &cgroup_file_operations;
|
|
}
|
|
dentry->d_op = &cgroup_dops;
|
|
d_instantiate(dentry, inode);
|
|
dget(dentry); /* Extra count - pin the dentry in core */
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* cgroup_create_dir - create a directory for an object.
|
|
* @cgrp: the cgroup we create the directory for. It must have a valid
|
|
* ->parent field. And we are going to fill its ->dentry field.
|
|
* @dentry: dentry of the new cgroup
|
|
* @mode: mode to set on new directory.
|
|
*/
|
|
static int cgroup_create_dir(struct cgroup *cgrp, struct dentry *dentry,
|
|
mode_t mode)
|
|
{
|
|
struct dentry *parent;
|
|
int error = 0;
|
|
|
|
parent = cgrp->parent->dentry;
|
|
error = cgroup_create_file(dentry, S_IFDIR | mode, cgrp->root->sb);
|
|
if (!error) {
|
|
dentry->d_fsdata = cgrp;
|
|
inc_nlink(parent->d_inode);
|
|
rcu_assign_pointer(cgrp->dentry, dentry);
|
|
dget(dentry);
|
|
}
|
|
dput(dentry);
|
|
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* cgroup_file_mode - deduce file mode of a control file
|
|
* @cft: the control file in question
|
|
*
|
|
* returns cft->mode if ->mode is not 0
|
|
* returns S_IRUGO|S_IWUSR if it has both a read and a write handler
|
|
* returns S_IRUGO if it has only a read handler
|
|
* returns S_IWUSR if it has only a write hander
|
|
*/
|
|
static mode_t cgroup_file_mode(const struct cftype *cft)
|
|
{
|
|
mode_t mode = 0;
|
|
|
|
if (cft->mode)
|
|
return cft->mode;
|
|
|
|
if (cft->read || cft->read_u64 || cft->read_s64 ||
|
|
cft->read_map || cft->read_seq_string)
|
|
mode |= S_IRUGO;
|
|
|
|
if (cft->write || cft->write_u64 || cft->write_s64 ||
|
|
cft->write_string || cft->trigger)
|
|
mode |= S_IWUSR;
|
|
|
|
return mode;
|
|
}
|
|
|
|
int cgroup_add_file(struct cgroup *cgrp,
|
|
struct cgroup_subsys *subsys,
|
|
const struct cftype *cft)
|
|
{
|
|
struct dentry *dir = cgrp->dentry;
|
|
struct dentry *dentry;
|
|
int error;
|
|
mode_t mode;
|
|
|
|
char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 };
|
|
if (subsys && !test_bit(ROOT_NOPREFIX, &cgrp->root->flags)) {
|
|
strcpy(name, subsys->name);
|
|
strcat(name, ".");
|
|
}
|
|
strcat(name, cft->name);
|
|
BUG_ON(!mutex_is_locked(&dir->d_inode->i_mutex));
|
|
dentry = lookup_one_len(name, dir, strlen(name));
|
|
if (!IS_ERR(dentry)) {
|
|
mode = cgroup_file_mode(cft);
|
|
error = cgroup_create_file(dentry, mode | S_IFREG,
|
|
cgrp->root->sb);
|
|
if (!error)
|
|
dentry->d_fsdata = (void *)cft;
|
|
dput(dentry);
|
|
} else
|
|
error = PTR_ERR(dentry);
|
|
return error;
|
|
}
|
|
|
|
int cgroup_add_files(struct cgroup *cgrp,
|
|
struct cgroup_subsys *subsys,
|
|
const struct cftype cft[],
|
|
int count)
|
|
{
|
|
int i, err;
|
|
for (i = 0; i < count; i++) {
|
|
err = cgroup_add_file(cgrp, subsys, &cft[i]);
|
|
if (err)
|
|
return err;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* cgroup_task_count - count the number of tasks in a cgroup.
|
|
* @cgrp: the cgroup in question
|
|
*
|
|
* Return the number of tasks in the cgroup.
|
|
*/
|
|
int cgroup_task_count(const struct cgroup *cgrp)
|
|
{
|
|
int count = 0;
|
|
struct cg_cgroup_link *link;
|
|
|
|
read_lock(&css_set_lock);
|
|
list_for_each_entry(link, &cgrp->css_sets, cgrp_link_list) {
|
|
count += atomic_read(&link->cg->refcount);
|
|
}
|
|
read_unlock(&css_set_lock);
|
|
return count;
|
|
}
|
|
|
|
/*
|
|
* 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->cg_link;
|
|
struct cg_cgroup_link *link;
|
|
struct css_set *cg;
|
|
|
|
/* Advance to the next non-empty css_set */
|
|
do {
|
|
l = l->next;
|
|
if (l == &cgrp->css_sets) {
|
|
it->cg_link = NULL;
|
|
return;
|
|
}
|
|
link = list_entry(l, struct cg_cgroup_link, cgrp_link_list);
|
|
cg = link->cg;
|
|
} while (list_empty(&cg->tasks));
|
|
it->cg_link = l;
|
|
it->task = cg->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().
|
|
*
|
|
* The tasklist_lock is not held here, as do_each_thread() and
|
|
* while_each_thread() are protected by RCU.
|
|
*/
|
|
static void cgroup_enable_task_cg_lists(void)
|
|
{
|
|
struct task_struct *p, *g;
|
|
write_lock(&css_set_lock);
|
|
use_task_css_set_links = 1;
|
|
do_each_thread(g, p) {
|
|
task_lock(p);
|
|
/*
|
|
* We should check if the process is exiting, otherwise
|
|
* it will race with cgroup_exit() in that the list
|
|
* entry won't be deleted though the process has exited.
|
|
*/
|
|
if (!(p->flags & PF_EXITING) && list_empty(&p->cg_list))
|
|
list_add(&p->cg_list, &p->cgroups->tasks);
|
|
task_unlock(p);
|
|
} while_each_thread(g, p);
|
|
write_unlock(&css_set_lock);
|
|
}
|
|
|
|
void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it)
|
|
{
|
|
/*
|
|
* 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.
|
|
*/
|
|
if (!use_task_css_set_links)
|
|
cgroup_enable_task_cg_lists();
|
|
|
|
read_lock(&css_set_lock);
|
|
it->cg_link = &cgrp->css_sets;
|
|
cgroup_advance_iter(cgrp, it);
|
|
}
|
|
|
|
struct task_struct *cgroup_iter_next(struct cgroup *cgrp,
|
|
struct cgroup_iter *it)
|
|
{
|
|
struct task_struct *res;
|
|
struct list_head *l = it->task;
|
|
struct cg_cgroup_link *link;
|
|
|
|
/* If the iterator cg is NULL, we have no tasks */
|
|
if (!it->cg_link)
|
|
return NULL;
|
|
res = list_entry(l, struct task_struct, cg_list);
|
|
/* Advance iterator to find next entry */
|
|
l = l->next;
|
|
link = list_entry(it->cg_link, struct cg_cgroup_link, cgrp_link_list);
|
|
if (l == &link->cg->tasks) {
|
|
/* We reached the end of this task list - move on to
|
|
* the next cg_cgroup_link */
|
|
cgroup_advance_iter(cgrp, it);
|
|
} else {
|
|
it->task = l;
|
|
}
|
|
return res;
|
|
}
|
|
|
|
void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it)
|
|
{
|
|
read_unlock(&css_set_lock);
|
|
}
|
|
|
|
static inline int started_after_time(struct task_struct *t1,
|
|
struct timespec *time,
|
|
struct task_struct *t2)
|
|
{
|
|
int start_diff = timespec_compare(&t1->start_time, time);
|
|
if (start_diff > 0) {
|
|
return 1;
|
|
} else if (start_diff < 0) {
|
|
return 0;
|
|
} else {
|
|
/*
|
|
* Arbitrarily, if two processes started at the same
|
|
* time, we'll say that the lower pointer value
|
|
* started first. Note that t2 may have exited by now
|
|
* so this may not be a valid pointer any longer, but
|
|
* that's fine - it still serves to distinguish
|
|
* between two tasks started (effectively) simultaneously.
|
|
*/
|
|
return t1 > t2;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* This function is a callback from heap_insert() and is used to order
|
|
* the heap.
|
|
* In this case we order the heap in descending task start time.
|
|
*/
|
|
static inline int started_after(void *p1, void *p2)
|
|
{
|
|
struct task_struct *t1 = p1;
|
|
struct task_struct *t2 = p2;
|
|
return started_after_time(t1, &t2->start_time, t2);
|
|
}
|
|
|
|
/**
|
|
* cgroup_scan_tasks - iterate though all the tasks in a cgroup
|
|
* @scan: struct cgroup_scanner containing arguments for the scan
|
|
*
|
|
* 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.
|
|
*
|
|
* 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).
|
|
*/
|
|
int cgroup_scan_tasks(struct cgroup_scanner *scan)
|
|
{
|
|
int retval, i;
|
|
struct cgroup_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) {
|
|
/* 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 */
|
|
heap = &tmp_heap;
|
|
retval = heap_init(heap, PAGE_SIZE, GFP_KERNEL, &started_after);
|
|
if (retval)
|
|
/* cannot allocate the heap */
|
|
return retval;
|
|
}
|
|
|
|
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
|
|
* 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))) {
|
|
/*
|
|
* Only affect tasks that qualify per the caller's callback,
|
|
* if he provided one
|
|
*/
|
|
if (scan->test_task && !scan->test_task(p, scan))
|
|
continue;
|
|
/*
|
|
* Only process tasks that started after the last task
|
|
* we processed
|
|
*/
|
|
if (!started_after_time(p, &latest_time, latest_task))
|
|
continue;
|
|
dropped = heap_insert(heap, p);
|
|
if (dropped == NULL) {
|
|
/*
|
|
* The new task was inserted; the heap wasn't
|
|
* previously full
|
|
*/
|
|
get_task_struct(p);
|
|
} else if (dropped != p) {
|
|
/*
|
|
* The new task was inserted, and pushed out a
|
|
* different task
|
|
*/
|
|
get_task_struct(p);
|
|
put_task_struct(dropped);
|
|
}
|
|
/*
|
|
* Else the new task was newer than anything already in
|
|
* the heap and wasn't inserted
|
|
*/
|
|
}
|
|
cgroup_iter_end(scan->cg, &it);
|
|
|
|
if (heap->size) {
|
|
for (i = 0; i < heap->size; i++) {
|
|
struct task_struct *q = heap->ptrs[i];
|
|
if (i == 0) {
|
|
latest_time = q->start_time;
|
|
latest_task = q;
|
|
}
|
|
/* Process the task per the caller's callback */
|
|
scan->process_task(q, scan);
|
|
put_task_struct(q);
|
|
}
|
|
/*
|
|
* If we had to process any tasks at all, scan again
|
|
* in case some of them were in the middle of forking
|
|
* children that didn't get processed.
|
|
* Not the most efficient way to do it, but it avoids
|
|
* having to take callback_mutex in the fork path
|
|
*/
|
|
goto again;
|
|
}
|
|
if (heap == &tmp_heap)
|
|
heap_free(&tmp_heap);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Stuff for reading the 'tasks'/'procs' files.
|
|
*
|
|
* Reading this file can return large amounts of data if a cgroup has
|
|
* *lots* of attached tasks. So it may need several calls to read(),
|
|
* but we cannot guarantee that the information we produce is correct
|
|
* unless we produce it entirely atomically.
|
|
*
|
|
*/
|
|
|
|
/*
|
|
* The following two functions "fix" the issue where there are more pids
|
|
* than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
|
|
* TODO: replace with a kernel-wide solution to this problem
|
|
*/
|
|
#define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2))
|
|
static void *pidlist_allocate(int count)
|
|
{
|
|
if (PIDLIST_TOO_LARGE(count))
|
|
return vmalloc(count * sizeof(pid_t));
|
|
else
|
|
return kmalloc(count * sizeof(pid_t), GFP_KERNEL);
|
|
}
|
|
static void pidlist_free(void *p)
|
|
{
|
|
if (is_vmalloc_addr(p))
|
|
vfree(p);
|
|
else
|
|
kfree(p);
|
|
}
|
|
static void *pidlist_resize(void *p, int newcount)
|
|
{
|
|
void *newlist;
|
|
/* note: if new alloc fails, old p will still be valid either way */
|
|
if (is_vmalloc_addr(p)) {
|
|
newlist = vmalloc(newcount * sizeof(pid_t));
|
|
if (!newlist)
|
|
return NULL;
|
|
memcpy(newlist, p, newcount * sizeof(pid_t));
|
|
vfree(p);
|
|
} else {
|
|
newlist = krealloc(p, newcount * sizeof(pid_t), GFP_KERNEL);
|
|
}
|
|
return newlist;
|
|
}
|
|
|
|
/*
|
|
* pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
|
|
* If the new stripped list is sufficiently smaller and there's enough memory
|
|
* to allocate a new buffer, will let go of the unneeded memory. Returns the
|
|
* number of unique elements.
|
|
*/
|
|
/* is the size difference enough that we should re-allocate the array? */
|
|
#define PIDLIST_REALLOC_DIFFERENCE(old, new) ((old) - PAGE_SIZE >= (new))
|
|
static int pidlist_uniq(pid_t **p, int length)
|
|
{
|
|
int src, dest = 1;
|
|
pid_t *list = *p;
|
|
pid_t *newlist;
|
|
|
|
/*
|
|
* we presume the 0th element is unique, so i starts at 1. trivial
|
|
* edge cases first; no work needs to be done for either
|
|
*/
|
|
if (length == 0 || length == 1)
|
|
return length;
|
|
/* src and dest walk down the list; dest counts unique elements */
|
|
for (src = 1; src < length; src++) {
|
|
/* find next unique element */
|
|
while (list[src] == list[src-1]) {
|
|
src++;
|
|
if (src == length)
|
|
goto after;
|
|
}
|
|
/* dest always points to where the next unique element goes */
|
|
list[dest] = list[src];
|
|
dest++;
|
|
}
|
|
after:
|
|
/*
|
|
* if the length difference is large enough, we want to allocate a
|
|
* smaller buffer to save memory. if this fails due to out of memory,
|
|
* we'll just stay with what we've got.
|
|
*/
|
|
if (PIDLIST_REALLOC_DIFFERENCE(length, dest)) {
|
|
newlist = pidlist_resize(list, dest);
|
|
if (newlist)
|
|
*p = newlist;
|
|
}
|
|
return dest;
|
|
}
|
|
|
|
static int cmppid(const void *a, const void *b)
|
|
{
|
|
return *(pid_t *)a - *(pid_t *)b;
|
|
}
|
|
|
|
/*
|
|
* find the appropriate pidlist for our purpose (given procs vs tasks)
|
|
* returns with the lock on that pidlist already held, and takes care
|
|
* of the use count, or returns NULL with no locks held if we're out of
|
|
* memory.
|
|
*/
|
|
static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp,
|
|
enum cgroup_filetype type)
|
|
{
|
|
struct cgroup_pidlist *l;
|
|
/* don't need task_nsproxy() if we're looking at ourself */
|
|
struct pid_namespace *ns = get_pid_ns(current->nsproxy->pid_ns);
|
|
/*
|
|
* We can't drop the pidlist_mutex before taking the l->mutex 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().
|
|
*/
|
|
mutex_lock(&cgrp->pidlist_mutex);
|
|
list_for_each_entry(l, &cgrp->pidlists, links) {
|
|
if (l->key.type == type && l->key.ns == ns) {
|
|
/* found a matching list - drop the extra refcount */
|
|
put_pid_ns(ns);
|
|
/* make sure l doesn't vanish out from under us */
|
|
down_write(&l->mutex);
|
|
mutex_unlock(&cgrp->pidlist_mutex);
|
|
return l;
|
|
}
|
|
}
|
|
/* entry not found; create a new one */
|
|
l = kmalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL);
|
|
if (!l) {
|
|
mutex_unlock(&cgrp->pidlist_mutex);
|
|
put_pid_ns(ns);
|
|
return l;
|
|
}
|
|
init_rwsem(&l->mutex);
|
|
down_write(&l->mutex);
|
|
l->key.type = type;
|
|
l->key.ns = ns;
|
|
l->use_count = 0; /* don't increment here */
|
|
l->list = NULL;
|
|
l->owner = cgrp;
|
|
list_add(&l->links, &cgrp->pidlists);
|
|
mutex_unlock(&cgrp->pidlist_mutex);
|
|
return l;
|
|
}
|
|
|
|
/*
|
|
* Load a cgroup's pidarray with either procs' tgids or tasks' pids
|
|
*/
|
|
static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
|
|
struct cgroup_pidlist **lp)
|
|
{
|
|
pid_t *array;
|
|
int length;
|
|
int pid, n = 0; /* used for populating the array */
|
|
struct cgroup_iter it;
|
|
struct task_struct *tsk;
|
|
struct cgroup_pidlist *l;
|
|
|
|
/*
|
|
* If cgroup gets more users after we read count, we won't have
|
|
* enough space - tough. This race is indistinguishable to the
|
|
* caller from the case that the additional cgroup users didn't
|
|
* show up until sometime later on.
|
|
*/
|
|
length = cgroup_task_count(cgrp);
|
|
array = pidlist_allocate(length);
|
|
if (!array)
|
|
return -ENOMEM;
|
|
/* now, populate the array */
|
|
cgroup_iter_start(cgrp, &it);
|
|
while ((tsk = cgroup_iter_next(cgrp, &it))) {
|
|
if (unlikely(n == length))
|
|
break;
|
|
/* get tgid or pid for procs or tasks file respectively */
|
|
if (type == CGROUP_FILE_PROCS)
|
|
pid = task_tgid_vnr(tsk);
|
|
else
|
|
pid = task_pid_vnr(tsk);
|
|
if (pid > 0) /* make sure to only use valid results */
|
|
array[n++] = pid;
|
|
}
|
|
cgroup_iter_end(cgrp, &it);
|
|
length = n;
|
|
/* now sort & (if procs) strip out duplicates */
|
|
sort(array, length, sizeof(pid_t), cmppid, NULL);
|
|
if (type == CGROUP_FILE_PROCS)
|
|
length = pidlist_uniq(&array, length);
|
|
l = cgroup_pidlist_find(cgrp, type);
|
|
if (!l) {
|
|
pidlist_free(array);
|
|
return -ENOMEM;
|
|
}
|
|
/* store array, freeing old if necessary - lock already held */
|
|
pidlist_free(l->list);
|
|
l->list = array;
|
|
l->length = length;
|
|
l->use_count++;
|
|
up_write(&l->mutex);
|
|
*lp = l;
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* cgroupstats_build - build and fill cgroupstats
|
|
* @stats: cgroupstats to fill information into
|
|
* @dentry: A dentry entry belonging to the cgroup for which stats have
|
|
* been requested.
|
|
*
|
|
* Build and fill cgroupstats so that taskstats can export it to user
|
|
* space.
|
|
*/
|
|
int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
|
|
{
|
|
int ret = -EINVAL;
|
|
struct cgroup *cgrp;
|
|
struct cgroup_iter it;
|
|
struct task_struct *tsk;
|
|
|
|
/*
|
|
* Validate dentry by checking the superblock operations,
|
|
* and make sure it's a directory.
|
|
*/
|
|
if (dentry->d_sb->s_op != &cgroup_ops ||
|
|
!S_ISDIR(dentry->d_inode->i_mode))
|
|
goto err;
|
|
|
|
ret = 0;
|
|
cgrp = dentry->d_fsdata;
|
|
|
|
cgroup_iter_start(cgrp, &it);
|
|
while ((tsk = cgroup_iter_next(cgrp, &it))) {
|
|
switch (tsk->state) {
|
|
case TASK_RUNNING:
|
|
stats->nr_running++;
|
|
break;
|
|
case TASK_INTERRUPTIBLE:
|
|
stats->nr_sleeping++;
|
|
break;
|
|
case TASK_UNINTERRUPTIBLE:
|
|
stats->nr_uninterruptible++;
|
|
break;
|
|
case TASK_STOPPED:
|
|
stats->nr_stopped++;
|
|
break;
|
|
default:
|
|
if (delayacct_is_task_waiting_on_io(tsk))
|
|
stats->nr_io_wait++;
|
|
break;
|
|
}
|
|
}
|
|
cgroup_iter_end(cgrp, &it);
|
|
|
|
err:
|
|
return ret;
|
|
}
|
|
|
|
|
|
/*
|
|
* seq_file methods for the tasks/procs files. The seq_file position is the
|
|
* next pid to display; the seq_file iterator is a pointer to the pid
|
|
* in the cgroup->l->list array.
|
|
*/
|
|
|
|
static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos)
|
|
{
|
|
/*
|
|
* Initially we receive a position value that corresponds to
|
|
* one more than the last pid shown (or 0 on the first call or
|
|
* after a seek to the start). Use a binary-search to find the
|
|
* next pid to display, if any
|
|
*/
|
|
struct cgroup_pidlist *l = s->private;
|
|
int index = 0, pid = *pos;
|
|
int *iter;
|
|
|
|
down_read(&l->mutex);
|
|
if (pid) {
|
|
int end = l->length;
|
|
|
|
while (index < end) {
|
|
int mid = (index + end) / 2;
|
|
if (l->list[mid] == pid) {
|
|
index = mid;
|
|
break;
|
|
} else if (l->list[mid] <= pid)
|
|
index = mid + 1;
|
|
else
|
|
end = mid;
|
|
}
|
|
}
|
|
/* If we're off the end of the array, we're done */
|
|
if (index >= l->length)
|
|
return NULL;
|
|
/* Update the abstract position to be the actual pid that we found */
|
|
iter = l->list + index;
|
|
*pos = *iter;
|
|
return iter;
|
|
}
|
|
|
|
static void cgroup_pidlist_stop(struct seq_file *s, void *v)
|
|
{
|
|
struct cgroup_pidlist *l = s->private;
|
|
up_read(&l->mutex);
|
|
}
|
|
|
|
static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos)
|
|
{
|
|
struct cgroup_pidlist *l = s->private;
|
|
pid_t *p = v;
|
|
pid_t *end = l->list + l->length;
|
|
/*
|
|
* Advance to the next pid in the array. If this goes off the
|
|
* end, we're done
|
|
*/
|
|
p++;
|
|
if (p >= end) {
|
|
return NULL;
|
|
} else {
|
|
*pos = *p;
|
|
return p;
|
|
}
|
|
}
|
|
|
|
static int cgroup_pidlist_show(struct seq_file *s, void *v)
|
|
{
|
|
return seq_printf(s, "%d\n", *(int *)v);
|
|
}
|
|
|
|
/*
|
|
* seq_operations functions for iterating on pidlists through seq_file -
|
|
* independent of whether it's tasks or procs
|
|
*/
|
|
static const struct seq_operations cgroup_pidlist_seq_operations = {
|
|
.start = cgroup_pidlist_start,
|
|
.stop = cgroup_pidlist_stop,
|
|
.next = cgroup_pidlist_next,
|
|
.show = cgroup_pidlist_show,
|
|
};
|
|
|
|
static void cgroup_release_pid_array(struct cgroup_pidlist *l)
|
|
{
|
|
/*
|
|
* the case where we're the last user of this particular pidlist will
|
|
* have us remove it from the cgroup's list, which entails taking the
|
|
* mutex. since in pidlist_find the pidlist->lock depends on cgroup->
|
|
* pidlist_mutex, we have to take pidlist_mutex first.
|
|
*/
|
|
mutex_lock(&l->owner->pidlist_mutex);
|
|
down_write(&l->mutex);
|
|
BUG_ON(!l->use_count);
|
|
if (!--l->use_count) {
|
|
/* we're the last user if refcount is 0; remove and free */
|
|
list_del(&l->links);
|
|
mutex_unlock(&l->owner->pidlist_mutex);
|
|
pidlist_free(l->list);
|
|
put_pid_ns(l->key.ns);
|
|
up_write(&l->mutex);
|
|
kfree(l);
|
|
return;
|
|
}
|
|
mutex_unlock(&l->owner->pidlist_mutex);
|
|
up_write(&l->mutex);
|
|
}
|
|
|
|
static int cgroup_pidlist_release(struct inode *inode, struct file *file)
|
|
{
|
|
struct cgroup_pidlist *l;
|
|
if (!(file->f_mode & FMODE_READ))
|
|
return 0;
|
|
/*
|
|
* the seq_file will only be initialized if the file was opened for
|
|
* reading; hence we check if it's not null only in that case.
|
|
*/
|
|
l = ((struct seq_file *)file->private_data)->private;
|
|
cgroup_release_pid_array(l);
|
|
return seq_release(inode, file);
|
|
}
|
|
|
|
static const struct file_operations cgroup_pidlist_operations = {
|
|
.read = seq_read,
|
|
.llseek = seq_lseek,
|
|
.write = cgroup_file_write,
|
|
.release = cgroup_pidlist_release,
|
|
};
|
|
|
|
/*
|
|
* The following functions handle opens on a file that displays a pidlist
|
|
* (tasks or procs). Prepare an array of the process/thread IDs of whoever's
|
|
* in the cgroup.
|
|
*/
|
|
/* helper function for the two below it */
|
|
static int cgroup_pidlist_open(struct file *file, enum cgroup_filetype type)
|
|
{
|
|
struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);
|
|
struct cgroup_pidlist *l;
|
|
int retval;
|
|
|
|
/* Nothing to do for write-only files */
|
|
if (!(file->f_mode & FMODE_READ))
|
|
return 0;
|
|
|
|
/* have the array populated */
|
|
retval = pidlist_array_load(cgrp, type, &l);
|
|
if (retval)
|
|
return retval;
|
|
/* configure file information */
|
|
file->f_op = &cgroup_pidlist_operations;
|
|
|
|
retval = seq_open(file, &cgroup_pidlist_seq_operations);
|
|
if (retval) {
|
|
cgroup_release_pid_array(l);
|
|
return retval;
|
|
}
|
|
((struct seq_file *)file->private_data)->private = l;
|
|
return 0;
|
|
}
|
|
static int cgroup_tasks_open(struct inode *unused, struct file *file)
|
|
{
|
|
return cgroup_pidlist_open(file, CGROUP_FILE_TASKS);
|
|
}
|
|
static int cgroup_procs_open(struct inode *unused, struct file *file)
|
|
{
|
|
return cgroup_pidlist_open(file, CGROUP_FILE_PROCS);
|
|
}
|
|
|
|
static u64 cgroup_read_notify_on_release(struct cgroup *cgrp,
|
|
struct cftype *cft)
|
|
{
|
|
return notify_on_release(cgrp);
|
|
}
|
|
|
|
static int cgroup_write_notify_on_release(struct cgroup *cgrp,
|
|
struct cftype *cft,
|
|
u64 val)
|
|
{
|
|
clear_bit(CGRP_RELEASABLE, &cgrp->flags);
|
|
if (val)
|
|
set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
|
|
else
|
|
clear_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* for the common functions, 'private' gives the type of file
|
|
*/
|
|
/* for hysterical raisins, we can't put this on the older files */
|
|
#define CGROUP_FILE_GENERIC_PREFIX "cgroup."
|
|
static struct cftype files[] = {
|
|
{
|
|
.name = "tasks",
|
|
.open = cgroup_tasks_open,
|
|
.write_u64 = cgroup_tasks_write,
|
|
.release = cgroup_pidlist_release,
|
|
.mode = S_IRUGO | S_IWUSR,
|
|
},
|
|
{
|
|
.name = CGROUP_FILE_GENERIC_PREFIX "procs",
|
|
.open = cgroup_procs_open,
|
|
/* .write_u64 = cgroup_procs_write, TODO */
|
|
.release = cgroup_pidlist_release,
|
|
.mode = S_IRUGO,
|
|
},
|
|
{
|
|
.name = "notify_on_release",
|
|
.read_u64 = cgroup_read_notify_on_release,
|
|
.write_u64 = cgroup_write_notify_on_release,
|
|
},
|
|
};
|
|
|
|
static struct cftype cft_release_agent = {
|
|
.name = "release_agent",
|
|
.read_seq_string = cgroup_release_agent_show,
|
|
.write_string = cgroup_release_agent_write,
|
|
.max_write_len = PATH_MAX,
|
|
};
|
|
|
|
static int cgroup_populate_dir(struct cgroup *cgrp)
|
|
{
|
|
int err;
|
|
struct cgroup_subsys *ss;
|
|
|
|
/* First clear out any existing files */
|
|
cgroup_clear_directory(cgrp->dentry);
|
|
|
|
err = cgroup_add_files(cgrp, NULL, files, ARRAY_SIZE(files));
|
|
if (err < 0)
|
|
return err;
|
|
|
|
if (cgrp == cgrp->top_cgroup) {
|
|
if ((err = cgroup_add_file(cgrp, NULL, &cft_release_agent)) < 0)
|
|
return err;
|
|
}
|
|
|
|
for_each_subsys(cgrp->root, ss) {
|
|
if (ss->populate && (err = ss->populate(ss, cgrp)) < 0)
|
|
return err;
|
|
}
|
|
/* This cgroup is ready now */
|
|
for_each_subsys(cgrp->root, ss) {
|
|
struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];
|
|
/*
|
|
* Update id->css pointer and make this css visible from
|
|
* CSS ID functions. This pointer will be dereferened
|
|
* from RCU-read-side without locks.
|
|
*/
|
|
if (css->id)
|
|
rcu_assign_pointer(css->id->css, css);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void init_cgroup_css(struct cgroup_subsys_state *css,
|
|
struct cgroup_subsys *ss,
|
|
struct cgroup *cgrp)
|
|
{
|
|
css->cgroup = cgrp;
|
|
atomic_set(&css->refcnt, 1);
|
|
css->flags = 0;
|
|
css->id = NULL;
|
|
if (cgrp == dummytop)
|
|
set_bit(CSS_ROOT, &css->flags);
|
|
BUG_ON(cgrp->subsys[ss->subsys_id]);
|
|
cgrp->subsys[ss->subsys_id] = css;
|
|
}
|
|
|
|
static void cgroup_lock_hierarchy(struct cgroupfs_root *root)
|
|
{
|
|
/* We need to take each hierarchy_mutex in a consistent order */
|
|
int i;
|
|
|
|
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
|
|
struct cgroup_subsys *ss = subsys[i];
|
|
if (ss->root == root)
|
|
mutex_lock(&ss->hierarchy_mutex);
|
|
}
|
|
}
|
|
|
|
static void cgroup_unlock_hierarchy(struct cgroupfs_root *root)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
|
|
struct cgroup_subsys *ss = subsys[i];
|
|
if (ss->root == root)
|
|
mutex_unlock(&ss->hierarchy_mutex);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* cgroup_create - create a cgroup
|
|
* @parent: cgroup that will be parent of the new cgroup
|
|
* @dentry: dentry of the new cgroup
|
|
* @mode: mode to set on new inode
|
|
*
|
|
* Must be called with the mutex on the parent inode held
|
|
*/
|
|
static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
|
|
mode_t mode)
|
|
{
|
|
struct cgroup *cgrp;
|
|
struct cgroupfs_root *root = parent->root;
|
|
int err = 0;
|
|
struct cgroup_subsys *ss;
|
|
struct super_block *sb = root->sb;
|
|
|
|
cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL);
|
|
if (!cgrp)
|
|
return -ENOMEM;
|
|
|
|
/* Grab a reference on the superblock so the hierarchy doesn't
|
|
* get deleted on unmount if there are child cgroups. This
|
|
* can be done outside cgroup_mutex, since the sb can't
|
|
* disappear while someone has an open control file on the
|
|
* fs */
|
|
atomic_inc(&sb->s_active);
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
init_cgroup_housekeeping(cgrp);
|
|
|
|
cgrp->parent = parent;
|
|
cgrp->root = parent->root;
|
|
cgrp->top_cgroup = parent->top_cgroup;
|
|
|
|
if (notify_on_release(parent))
|
|
set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
|
|
|
|
for_each_subsys(root, ss) {
|
|
struct cgroup_subsys_state *css = ss->create(ss, cgrp);
|
|
if (IS_ERR(css)) {
|
|
err = PTR_ERR(css);
|
|
goto err_destroy;
|
|
}
|
|
init_cgroup_css(css, ss, cgrp);
|
|
if (ss->use_id)
|
|
if (alloc_css_id(ss, parent, cgrp))
|
|
goto err_destroy;
|
|
/* At error, ->destroy() callback has to free assigned ID. */
|
|
}
|
|
|
|
cgroup_lock_hierarchy(root);
|
|
list_add(&cgrp->sibling, &cgrp->parent->children);
|
|
cgroup_unlock_hierarchy(root);
|
|
root->number_of_cgroups++;
|
|
|
|
err = cgroup_create_dir(cgrp, dentry, mode);
|
|
if (err < 0)
|
|
goto err_remove;
|
|
|
|
/* The cgroup directory was pre-locked for us */
|
|
BUG_ON(!mutex_is_locked(&cgrp->dentry->d_inode->i_mutex));
|
|
|
|
err = cgroup_populate_dir(cgrp);
|
|
/* If err < 0, we have a half-filled directory - oh well ;) */
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
mutex_unlock(&cgrp->dentry->d_inode->i_mutex);
|
|
|
|
return 0;
|
|
|
|
err_remove:
|
|
|
|
cgroup_lock_hierarchy(root);
|
|
list_del(&cgrp->sibling);
|
|
cgroup_unlock_hierarchy(root);
|
|
root->number_of_cgroups--;
|
|
|
|
err_destroy:
|
|
|
|
for_each_subsys(root, ss) {
|
|
if (cgrp->subsys[ss->subsys_id])
|
|
ss->destroy(ss, cgrp);
|
|
}
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
|
|
/* Release the reference count that we took on the superblock */
|
|
deactivate_super(sb);
|
|
|
|
kfree(cgrp);
|
|
return err;
|
|
}
|
|
|
|
static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, int mode)
|
|
{
|
|
struct cgroup *c_parent = dentry->d_parent->d_fsdata;
|
|
|
|
/* the vfs holds inode->i_mutex already */
|
|
return cgroup_create(c_parent, dentry, mode | S_IFDIR);
|
|
}
|
|
|
|
static int cgroup_has_css_refs(struct cgroup *cgrp)
|
|
{
|
|
/* Check the reference count on each subsystem. Since we
|
|
* already established that there are no tasks in the
|
|
* cgroup, if the css refcount is also 1, then there should
|
|
* be no outstanding references, so the subsystem is safe to
|
|
* destroy. We scan across all subsystems rather than using
|
|
* the per-hierarchy linked list of mounted subsystems since
|
|
* we can be called via check_for_release() with no
|
|
* synchronization other than RCU, and the subsystem linked
|
|
* list isn't RCU-safe */
|
|
int i;
|
|
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
|
|
struct cgroup_subsys *ss = subsys[i];
|
|
struct cgroup_subsys_state *css;
|
|
/* Skip subsystems not in this hierarchy */
|
|
if (ss->root != cgrp->root)
|
|
continue;
|
|
css = cgrp->subsys[ss->subsys_id];
|
|
/* When called from check_for_release() it's possible
|
|
* that by this point the cgroup has been removed
|
|
* and the css deleted. But a false-positive doesn't
|
|
* matter, since it can only happen if the cgroup
|
|
* has been deleted and hence no longer needs the
|
|
* release agent to be called anyway. */
|
|
if (css && (atomic_read(&css->refcnt) > 1))
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Atomically mark all (or else none) of the cgroup's CSS objects as
|
|
* CSS_REMOVED. Return true on success, or false if the cgroup has
|
|
* busy subsystems. Call with cgroup_mutex held
|
|
*/
|
|
|
|
static int cgroup_clear_css_refs(struct cgroup *cgrp)
|
|
{
|
|
struct cgroup_subsys *ss;
|
|
unsigned long flags;
|
|
bool failed = false;
|
|
local_irq_save(flags);
|
|
for_each_subsys(cgrp->root, ss) {
|
|
struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];
|
|
int refcnt;
|
|
while (1) {
|
|
/* We can only remove a CSS with a refcnt==1 */
|
|
refcnt = atomic_read(&css->refcnt);
|
|
if (refcnt > 1) {
|
|
failed = true;
|
|
goto done;
|
|
}
|
|
BUG_ON(!refcnt);
|
|
/*
|
|
* Drop the refcnt to 0 while we check other
|
|
* subsystems. This will cause any racing
|
|
* css_tryget() to spin until we set the
|
|
* CSS_REMOVED bits or abort
|
|
*/
|
|
if (atomic_cmpxchg(&css->refcnt, refcnt, 0) == refcnt)
|
|
break;
|
|
cpu_relax();
|
|
}
|
|
}
|
|
done:
|
|
for_each_subsys(cgrp->root, ss) {
|
|
struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];
|
|
if (failed) {
|
|
/*
|
|
* Restore old refcnt if we previously managed
|
|
* to clear it from 1 to 0
|
|
*/
|
|
if (!atomic_read(&css->refcnt))
|
|
atomic_set(&css->refcnt, 1);
|
|
} else {
|
|
/* Commit the fact that the CSS is removed */
|
|
set_bit(CSS_REMOVED, &css->flags);
|
|
}
|
|
}
|
|
local_irq_restore(flags);
|
|
return !failed;
|
|
}
|
|
|
|
static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry)
|
|
{
|
|
struct cgroup *cgrp = dentry->d_fsdata;
|
|
struct dentry *d;
|
|
struct cgroup *parent;
|
|
DEFINE_WAIT(wait);
|
|
int ret;
|
|
|
|
/* the vfs holds both inode->i_mutex already */
|
|
again:
|
|
mutex_lock(&cgroup_mutex);
|
|
if (atomic_read(&cgrp->count) != 0) {
|
|
mutex_unlock(&cgroup_mutex);
|
|
return -EBUSY;
|
|
}
|
|
if (!list_empty(&cgrp->children)) {
|
|
mutex_unlock(&cgroup_mutex);
|
|
return -EBUSY;
|
|
}
|
|
mutex_unlock(&cgroup_mutex);
|
|
|
|
/*
|
|
* In general, subsystem has no css->refcnt after pre_destroy(). But
|
|
* in racy cases, subsystem may have to get css->refcnt after
|
|
* pre_destroy() and it makes rmdir return with -EBUSY. This sometimes
|
|
* make rmdir return -EBUSY too often. To avoid that, we use waitqueue
|
|
* for cgroup's rmdir. CGRP_WAIT_ON_RMDIR is for synchronizing rmdir
|
|
* and subsystem's reference count handling. Please see css_get/put
|
|
* and css_tryget() and cgroup_wakeup_rmdir_waiter() implementation.
|
|
*/
|
|
set_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags);
|
|
|
|
/*
|
|
* Call pre_destroy handlers of subsys. Notify subsystems
|
|
* that rmdir() request comes.
|
|
*/
|
|
ret = cgroup_call_pre_destroy(cgrp);
|
|
if (ret) {
|
|
clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags);
|
|
return ret;
|
|
}
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
parent = cgrp->parent;
|
|
if (atomic_read(&cgrp->count) || !list_empty(&cgrp->children)) {
|
|
clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags);
|
|
mutex_unlock(&cgroup_mutex);
|
|
return -EBUSY;
|
|
}
|
|
prepare_to_wait(&cgroup_rmdir_waitq, &wait, TASK_INTERRUPTIBLE);
|
|
if (!cgroup_clear_css_refs(cgrp)) {
|
|
mutex_unlock(&cgroup_mutex);
|
|
/*
|
|
* Because someone may call cgroup_wakeup_rmdir_waiter() before
|
|
* prepare_to_wait(), we need to check this flag.
|
|
*/
|
|
if (test_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags))
|
|
schedule();
|
|
finish_wait(&cgroup_rmdir_waitq, &wait);
|
|
clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags);
|
|
if (signal_pending(current))
|
|
return -EINTR;
|
|
goto again;
|
|
}
|
|
/* NO css_tryget() can success after here. */
|
|
finish_wait(&cgroup_rmdir_waitq, &wait);
|
|
clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags);
|
|
|
|
spin_lock(&release_list_lock);
|
|
set_bit(CGRP_REMOVED, &cgrp->flags);
|
|
if (!list_empty(&cgrp->release_list))
|
|
list_del(&cgrp->release_list);
|
|
spin_unlock(&release_list_lock);
|
|
|
|
cgroup_lock_hierarchy(cgrp->root);
|
|
/* delete this cgroup from parent->children */
|
|
list_del(&cgrp->sibling);
|
|
cgroup_unlock_hierarchy(cgrp->root);
|
|
|
|
spin_lock(&cgrp->dentry->d_lock);
|
|
d = dget(cgrp->dentry);
|
|
spin_unlock(&d->d_lock);
|
|
|
|
cgroup_d_remove_dir(d);
|
|
dput(d);
|
|
|
|
set_bit(CGRP_RELEASABLE, &parent->flags);
|
|
check_for_release(parent);
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
return 0;
|
|
}
|
|
|
|
static void __init cgroup_init_subsys(struct cgroup_subsys *ss)
|
|
{
|
|
struct cgroup_subsys_state *css;
|
|
|
|
printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name);
|
|
|
|
/* Create the top cgroup state for this subsystem */
|
|
list_add(&ss->sibling, &rootnode.subsys_list);
|
|
ss->root = &rootnode;
|
|
css = ss->create(ss, dummytop);
|
|
/* We don't handle early failures gracefully */
|
|
BUG_ON(IS_ERR(css));
|
|
init_cgroup_css(css, ss, dummytop);
|
|
|
|
/* Update the init_css_set to contain a subsys
|
|
* pointer to this state - since the subsystem is
|
|
* newly registered, all tasks and hence the
|
|
* init_css_set is in the subsystem's top cgroup. */
|
|
init_css_set.subsys[ss->subsys_id] = dummytop->subsys[ss->subsys_id];
|
|
|
|
need_forkexit_callback |= ss->fork || ss->exit;
|
|
|
|
/* At system boot, before all subsystems have been
|
|
* registered, no tasks have been forked, so we don't
|
|
* need to invoke fork callbacks here. */
|
|
BUG_ON(!list_empty(&init_task.tasks));
|
|
|
|
mutex_init(&ss->hierarchy_mutex);
|
|
lockdep_set_class(&ss->hierarchy_mutex, &ss->subsys_key);
|
|
ss->active = 1;
|
|
}
|
|
|
|
/**
|
|
* cgroup_init_early - cgroup initialization at system boot
|
|
*
|
|
* Initialize cgroups at system boot, and initialize any
|
|
* subsystems that request early init.
|
|
*/
|
|
int __init cgroup_init_early(void)
|
|
{
|
|
int i;
|
|
atomic_set(&init_css_set.refcount, 1);
|
|
INIT_LIST_HEAD(&init_css_set.cg_links);
|
|
INIT_LIST_HEAD(&init_css_set.tasks);
|
|
INIT_HLIST_NODE(&init_css_set.hlist);
|
|
css_set_count = 1;
|
|
init_cgroup_root(&rootnode);
|
|
root_count = 1;
|
|
init_task.cgroups = &init_css_set;
|
|
|
|
init_css_set_link.cg = &init_css_set;
|
|
init_css_set_link.cgrp = dummytop;
|
|
list_add(&init_css_set_link.cgrp_link_list,
|
|
&rootnode.top_cgroup.css_sets);
|
|
list_add(&init_css_set_link.cg_link_list,
|
|
&init_css_set.cg_links);
|
|
|
|
for (i = 0; i < CSS_SET_TABLE_SIZE; i++)
|
|
INIT_HLIST_HEAD(&css_set_table[i]);
|
|
|
|
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
|
|
struct cgroup_subsys *ss = subsys[i];
|
|
|
|
BUG_ON(!ss->name);
|
|
BUG_ON(strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN);
|
|
BUG_ON(!ss->create);
|
|
BUG_ON(!ss->destroy);
|
|
if (ss->subsys_id != i) {
|
|
printk(KERN_ERR "cgroup: Subsys %s id == %d\n",
|
|
ss->name, ss->subsys_id);
|
|
BUG();
|
|
}
|
|
|
|
if (ss->early_init)
|
|
cgroup_init_subsys(ss);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* cgroup_init - cgroup initialization
|
|
*
|
|
* Register cgroup filesystem and /proc file, and initialize
|
|
* any subsystems that didn't request early init.
|
|
*/
|
|
int __init cgroup_init(void)
|
|
{
|
|
int err;
|
|
int i;
|
|
struct hlist_head *hhead;
|
|
|
|
err = bdi_init(&cgroup_backing_dev_info);
|
|
if (err)
|
|
return err;
|
|
|
|
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
|
|
struct cgroup_subsys *ss = subsys[i];
|
|
if (!ss->early_init)
|
|
cgroup_init_subsys(ss);
|
|
if (ss->use_id)
|
|
cgroup_subsys_init_idr(ss);
|
|
}
|
|
|
|
/* Add init_css_set to the hash table */
|
|
hhead = css_set_hash(init_css_set.subsys);
|
|
hlist_add_head(&init_css_set.hlist, hhead);
|
|
BUG_ON(!init_root_id(&rootnode));
|
|
err = register_filesystem(&cgroup_fs_type);
|
|
if (err < 0)
|
|
goto out;
|
|
|
|
proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations);
|
|
|
|
out:
|
|
if (err)
|
|
bdi_destroy(&cgroup_backing_dev_info);
|
|
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* proc_cgroup_show()
|
|
* - Print task's cgroup paths into seq_file, one line for each hierarchy
|
|
* - Used for /proc/<pid>/cgroup.
|
|
* - No need to task_lock(tsk) on this tsk->cgroup reference, as it
|
|
* doesn't really matter if tsk->cgroup changes after we read it,
|
|
* and we take cgroup_mutex, keeping cgroup_attach_task() from changing it
|
|
* anyway. No need to check that tsk->cgroup != NULL, thanks to
|
|
* the_top_cgroup_hack in cgroup_exit(), which sets an exiting tasks
|
|
* cgroup to top_cgroup.
|
|
*/
|
|
|
|
/* TODO: Use a proper seq_file iterator */
|
|
static int proc_cgroup_show(struct seq_file *m, void *v)
|
|
{
|
|
struct pid *pid;
|
|
struct task_struct *tsk;
|
|
char *buf;
|
|
int retval;
|
|
struct cgroupfs_root *root;
|
|
|
|
retval = -ENOMEM;
|
|
buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
|
|
if (!buf)
|
|
goto out;
|
|
|
|
retval = -ESRCH;
|
|
pid = m->private;
|
|
tsk = get_pid_task(pid, PIDTYPE_PID);
|
|
if (!tsk)
|
|
goto out_free;
|
|
|
|
retval = 0;
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
for_each_active_root(root) {
|
|
struct cgroup_subsys *ss;
|
|
struct cgroup *cgrp;
|
|
int count = 0;
|
|
|
|
seq_printf(m, "%d:", root->hierarchy_id);
|
|
for_each_subsys(root, ss)
|
|
seq_printf(m, "%s%s", count++ ? "," : "", ss->name);
|
|
if (strlen(root->name))
|
|
seq_printf(m, "%sname=%s", count ? "," : "",
|
|
root->name);
|
|
seq_putc(m, ':');
|
|
cgrp = task_cgroup_from_root(tsk, root);
|
|
retval = cgroup_path(cgrp, buf, PAGE_SIZE);
|
|
if (retval < 0)
|
|
goto out_unlock;
|
|
seq_puts(m, buf);
|
|
seq_putc(m, '\n');
|
|
}
|
|
|
|
out_unlock:
|
|
mutex_unlock(&cgroup_mutex);
|
|
put_task_struct(tsk);
|
|
out_free:
|
|
kfree(buf);
|
|
out:
|
|
return retval;
|
|
}
|
|
|
|
static int cgroup_open(struct inode *inode, struct file *file)
|
|
{
|
|
struct pid *pid = PROC_I(inode)->pid;
|
|
return single_open(file, proc_cgroup_show, pid);
|
|
}
|
|
|
|
const struct file_operations proc_cgroup_operations = {
|
|
.open = cgroup_open,
|
|
.read = seq_read,
|
|
.llseek = seq_lseek,
|
|
.release = single_release,
|
|
};
|
|
|
|
/* Display information about each subsystem and each hierarchy */
|
|
static int proc_cgroupstats_show(struct seq_file *m, void *v)
|
|
{
|
|
int i;
|
|
|
|
seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
|
|
mutex_lock(&cgroup_mutex);
|
|
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
|
|
struct cgroup_subsys *ss = subsys[i];
|
|
seq_printf(m, "%s\t%d\t%d\t%d\n",
|
|
ss->name, ss->root->hierarchy_id,
|
|
ss->root->number_of_cgroups, !ss->disabled);
|
|
}
|
|
mutex_unlock(&cgroup_mutex);
|
|
return 0;
|
|
}
|
|
|
|
static int cgroupstats_open(struct inode *inode, struct file *file)
|
|
{
|
|
return single_open(file, proc_cgroupstats_show, NULL);
|
|
}
|
|
|
|
static const struct file_operations proc_cgroupstats_operations = {
|
|
.open = cgroupstats_open,
|
|
.read = seq_read,
|
|
.llseek = seq_lseek,
|
|
.release = single_release,
|
|
};
|
|
|
|
/**
|
|
* cgroup_fork - attach newly forked task to its parents cgroup.
|
|
* @child: pointer to task_struct of forking parent process.
|
|
*
|
|
* Description: A task inherits its parent's cgroup at fork().
|
|
*
|
|
* A pointer to the shared css_set was automatically copied in
|
|
* fork.c by dup_task_struct(). However, we ignore that copy, since
|
|
* it was not made under the protection of RCU or cgroup_mutex, so
|
|
* might no longer be a valid cgroup pointer. cgroup_attach_task() might
|
|
* have already changed current->cgroups, allowing the previously
|
|
* referenced cgroup group to be removed and freed.
|
|
*
|
|
* At the point that cgroup_fork() is called, 'current' is the parent
|
|
* task, and the passed argument 'child' points to the child task.
|
|
*/
|
|
void cgroup_fork(struct task_struct *child)
|
|
{
|
|
task_lock(current);
|
|
child->cgroups = current->cgroups;
|
|
get_css_set(child->cgroups);
|
|
task_unlock(current);
|
|
INIT_LIST_HEAD(&child->cg_list);
|
|
}
|
|
|
|
/**
|
|
* cgroup_fork_callbacks - run fork callbacks
|
|
* @child: the new task
|
|
*
|
|
* Called on a new task very soon before adding it to the
|
|
* tasklist. No need to take any locks since no-one can
|
|
* be operating on this task.
|
|
*/
|
|
void cgroup_fork_callbacks(struct task_struct *child)
|
|
{
|
|
if (need_forkexit_callback) {
|
|
int i;
|
|
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
|
|
struct cgroup_subsys *ss = subsys[i];
|
|
if (ss->fork)
|
|
ss->fork(ss, child);
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* cgroup_post_fork - called on a new task after adding it to the task list
|
|
* @child: the task in question
|
|
*
|
|
* Adds the task to the list running through its css_set if necessary.
|
|
* 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 list.
|
|
*/
|
|
void cgroup_post_fork(struct task_struct *child)
|
|
{
|
|
if (use_task_css_set_links) {
|
|
write_lock(&css_set_lock);
|
|
task_lock(child);
|
|
if (list_empty(&child->cg_list))
|
|
list_add(&child->cg_list, &child->cgroups->tasks);
|
|
task_unlock(child);
|
|
write_unlock(&css_set_lock);
|
|
}
|
|
}
|
|
/**
|
|
* cgroup_exit - detach cgroup from exiting task
|
|
* @tsk: pointer to task_struct of exiting process
|
|
* @run_callback: run exit callbacks?
|
|
*
|
|
* Description: Detach cgroup from @tsk and release it.
|
|
*
|
|
* Note that cgroups marked notify_on_release force every task in
|
|
* them to take the global cgroup_mutex mutex when exiting.
|
|
* This could impact scaling on very large systems. Be reluctant to
|
|
* use notify_on_release cgroups where very high task exit scaling
|
|
* is required on large systems.
|
|
*
|
|
* the_top_cgroup_hack:
|
|
*
|
|
* Set the exiting tasks cgroup to the root cgroup (top_cgroup).
|
|
*
|
|
* We call cgroup_exit() while the task is still competent to
|
|
* handle notify_on_release(), then leave the task attached to the
|
|
* root cgroup in each hierarchy for the remainder of its exit.
|
|
*
|
|
* To do this properly, we would increment the reference count on
|
|
* top_cgroup, and near the very end of the kernel/exit.c do_exit()
|
|
* code we would add a second cgroup function call, to drop that
|
|
* reference. This would just create an unnecessary hot spot on
|
|
* the top_cgroup reference count, to no avail.
|
|
*
|
|
* Normally, holding a reference to a cgroup without bumping its
|
|
* count is unsafe. The cgroup could go away, or someone could
|
|
* attach us to a different cgroup, decrementing the count on
|
|
* the first cgroup that we never incremented. But in this case,
|
|
* top_cgroup isn't going away, and either task has PF_EXITING set,
|
|
* which wards off any cgroup_attach_task() attempts, or task is a failed
|
|
* fork, never visible to cgroup_attach_task.
|
|
*/
|
|
void cgroup_exit(struct task_struct *tsk, int run_callbacks)
|
|
{
|
|
int i;
|
|
struct css_set *cg;
|
|
|
|
if (run_callbacks && need_forkexit_callback) {
|
|
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
|
|
struct cgroup_subsys *ss = subsys[i];
|
|
if (ss->exit)
|
|
ss->exit(ss, tsk);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Unlink from the css_set task list if necessary.
|
|
* Optimistically check cg_list before taking
|
|
* css_set_lock
|
|
*/
|
|
if (!list_empty(&tsk->cg_list)) {
|
|
write_lock(&css_set_lock);
|
|
if (!list_empty(&tsk->cg_list))
|
|
list_del(&tsk->cg_list);
|
|
write_unlock(&css_set_lock);
|
|
}
|
|
|
|
/* Reassign the task to the init_css_set. */
|
|
task_lock(tsk);
|
|
cg = tsk->cgroups;
|
|
tsk->cgroups = &init_css_set;
|
|
task_unlock(tsk);
|
|
if (cg)
|
|
put_css_set_taskexit(cg);
|
|
}
|
|
|
|
/**
|
|
* cgroup_clone - clone the cgroup the given subsystem is attached to
|
|
* @tsk: the task to be moved
|
|
* @subsys: the given subsystem
|
|
* @nodename: the name for the new cgroup
|
|
*
|
|
* Duplicate the current cgroup in the hierarchy that the given
|
|
* subsystem is attached to, and move this task into the new
|
|
* child.
|
|
*/
|
|
int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *subsys,
|
|
char *nodename)
|
|
{
|
|
struct dentry *dentry;
|
|
int ret = 0;
|
|
struct cgroup *parent, *child;
|
|
struct inode *inode;
|
|
struct css_set *cg;
|
|
struct cgroupfs_root *root;
|
|
struct cgroup_subsys *ss;
|
|
|
|
/* We shouldn't be called by an unregistered subsystem */
|
|
BUG_ON(!subsys->active);
|
|
|
|
/* First figure out what hierarchy and cgroup we're dealing
|
|
* with, and pin them so we can drop cgroup_mutex */
|
|
mutex_lock(&cgroup_mutex);
|
|
again:
|
|
root = subsys->root;
|
|
if (root == &rootnode) {
|
|
mutex_unlock(&cgroup_mutex);
|
|
return 0;
|
|
}
|
|
|
|
/* Pin the hierarchy */
|
|
if (!atomic_inc_not_zero(&root->sb->s_active)) {
|
|
/* We race with the final deactivate_super() */
|
|
mutex_unlock(&cgroup_mutex);
|
|
return 0;
|
|
}
|
|
|
|
/* Keep the cgroup alive */
|
|
task_lock(tsk);
|
|
parent = task_cgroup(tsk, subsys->subsys_id);
|
|
cg = tsk->cgroups;
|
|
get_css_set(cg);
|
|
task_unlock(tsk);
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
|
|
/* Now do the VFS work to create a cgroup */
|
|
inode = parent->dentry->d_inode;
|
|
|
|
/* Hold the parent directory mutex across this operation to
|
|
* stop anyone else deleting the new cgroup */
|
|
mutex_lock(&inode->i_mutex);
|
|
dentry = lookup_one_len(nodename, parent->dentry, strlen(nodename));
|
|
if (IS_ERR(dentry)) {
|
|
printk(KERN_INFO
|
|
"cgroup: Couldn't allocate dentry for %s: %ld\n", nodename,
|
|
PTR_ERR(dentry));
|
|
ret = PTR_ERR(dentry);
|
|
goto out_release;
|
|
}
|
|
|
|
/* Create the cgroup directory, which also creates the cgroup */
|
|
ret = vfs_mkdir(inode, dentry, 0755);
|
|
child = __d_cgrp(dentry);
|
|
dput(dentry);
|
|
if (ret) {
|
|
printk(KERN_INFO
|
|
"Failed to create cgroup %s: %d\n", nodename,
|
|
ret);
|
|
goto out_release;
|
|
}
|
|
|
|
/* The cgroup now exists. Retake cgroup_mutex and check
|
|
* that we're still in the same state that we thought we
|
|
* were. */
|
|
mutex_lock(&cgroup_mutex);
|
|
if ((root != subsys->root) ||
|
|
(parent != task_cgroup(tsk, subsys->subsys_id))) {
|
|
/* Aargh, we raced ... */
|
|
mutex_unlock(&inode->i_mutex);
|
|
put_css_set(cg);
|
|
|
|
deactivate_super(root->sb);
|
|
/* The cgroup is still accessible in the VFS, but
|
|
* we're not going to try to rmdir() it at this
|
|
* point. */
|
|
printk(KERN_INFO
|
|
"Race in cgroup_clone() - leaking cgroup %s\n",
|
|
nodename);
|
|
goto again;
|
|
}
|
|
|
|
/* do any required auto-setup */
|
|
for_each_subsys(root, ss) {
|
|
if (ss->post_clone)
|
|
ss->post_clone(ss, child);
|
|
}
|
|
|
|
/* All seems fine. Finish by moving the task into the new cgroup */
|
|
ret = cgroup_attach_task(child, tsk);
|
|
mutex_unlock(&cgroup_mutex);
|
|
|
|
out_release:
|
|
mutex_unlock(&inode->i_mutex);
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
put_css_set(cg);
|
|
mutex_unlock(&cgroup_mutex);
|
|
deactivate_super(root->sb);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* cgroup_is_descendant - see if @cgrp is a descendant of @task's cgrp
|
|
* @cgrp: the cgroup in question
|
|
* @task: the task in question
|
|
*
|
|
* See if @cgrp is a descendant of @task's cgroup in the appropriate
|
|
* hierarchy.
|
|
*
|
|
* If we are sending in dummytop, then presumably we are creating
|
|
* the top cgroup in the subsystem.
|
|
*
|
|
* Called only by the ns (nsproxy) cgroup.
|
|
*/
|
|
int cgroup_is_descendant(const struct cgroup *cgrp, struct task_struct *task)
|
|
{
|
|
int ret;
|
|
struct cgroup *target;
|
|
|
|
if (cgrp == dummytop)
|
|
return 1;
|
|
|
|
target = task_cgroup_from_root(task, cgrp->root);
|
|
while (cgrp != target && cgrp!= cgrp->top_cgroup)
|
|
cgrp = cgrp->parent;
|
|
ret = (cgrp == target);
|
|
return ret;
|
|
}
|
|
|
|
static void check_for_release(struct cgroup *cgrp)
|
|
{
|
|
/* All of these checks rely on RCU to keep the cgroup
|
|
* structure alive */
|
|
if (cgroup_is_releasable(cgrp) && !atomic_read(&cgrp->count)
|
|
&& list_empty(&cgrp->children) && !cgroup_has_css_refs(cgrp)) {
|
|
/* Control Group is currently removeable. If it's not
|
|
* already queued for a userspace notification, queue
|
|
* it now */
|
|
int need_schedule_work = 0;
|
|
spin_lock(&release_list_lock);
|
|
if (!cgroup_is_removed(cgrp) &&
|
|
list_empty(&cgrp->release_list)) {
|
|
list_add(&cgrp->release_list, &release_list);
|
|
need_schedule_work = 1;
|
|
}
|
|
spin_unlock(&release_list_lock);
|
|
if (need_schedule_work)
|
|
schedule_work(&release_agent_work);
|
|
}
|
|
}
|
|
|
|
void __css_put(struct cgroup_subsys_state *css)
|
|
{
|
|
struct cgroup *cgrp = css->cgroup;
|
|
int val;
|
|
rcu_read_lock();
|
|
val = atomic_dec_return(&css->refcnt);
|
|
if (val == 1) {
|
|
if (notify_on_release(cgrp)) {
|
|
set_bit(CGRP_RELEASABLE, &cgrp->flags);
|
|
check_for_release(cgrp);
|
|
}
|
|
cgroup_wakeup_rmdir_waiter(cgrp);
|
|
}
|
|
rcu_read_unlock();
|
|
WARN_ON_ONCE(val < 1);
|
|
}
|
|
|
|
/*
|
|
* Notify userspace when a cgroup is released, by running the
|
|
* configured release agent with the name of the cgroup (path
|
|
* relative to the root of cgroup file system) as the argument.
|
|
*
|
|
* Most likely, this user command will try to rmdir this cgroup.
|
|
*
|
|
* This races with the possibility that some other task will be
|
|
* attached to this cgroup before it is removed, or that some other
|
|
* user task will 'mkdir' a child cgroup of this cgroup. That's ok.
|
|
* The presumed 'rmdir' will fail quietly if this cgroup is no longer
|
|
* unused, and this cgroup will be reprieved from its death sentence,
|
|
* to continue to serve a useful existence. Next time it's released,
|
|
* we will get notified again, if it still has 'notify_on_release' set.
|
|
*
|
|
* The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
|
|
* means only wait until the task is successfully execve()'d. The
|
|
* separate release agent task is forked by call_usermodehelper(),
|
|
* then control in this thread returns here, without waiting for the
|
|
* release agent task. We don't bother to wait because the caller of
|
|
* this routine has no use for the exit status of the release agent
|
|
* task, so no sense holding our caller up for that.
|
|
*/
|
|
static void cgroup_release_agent(struct work_struct *work)
|
|
{
|
|
BUG_ON(work != &release_agent_work);
|
|
mutex_lock(&cgroup_mutex);
|
|
spin_lock(&release_list_lock);
|
|
while (!list_empty(&release_list)) {
|
|
char *argv[3], *envp[3];
|
|
int i;
|
|
char *pathbuf = NULL, *agentbuf = NULL;
|
|
struct cgroup *cgrp = list_entry(release_list.next,
|
|
struct cgroup,
|
|
release_list);
|
|
list_del_init(&cgrp->release_list);
|
|
spin_unlock(&release_list_lock);
|
|
pathbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
|
|
if (!pathbuf)
|
|
goto continue_free;
|
|
if (cgroup_path(cgrp, pathbuf, PAGE_SIZE) < 0)
|
|
goto continue_free;
|
|
agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL);
|
|
if (!agentbuf)
|
|
goto continue_free;
|
|
|
|
i = 0;
|
|
argv[i++] = agentbuf;
|
|
argv[i++] = pathbuf;
|
|
argv[i] = NULL;
|
|
|
|
i = 0;
|
|
/* minimal command environment */
|
|
envp[i++] = "HOME=/";
|
|
envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
|
|
envp[i] = NULL;
|
|
|
|
/* Drop the lock while we invoke the usermode helper,
|
|
* since the exec could involve hitting disk and hence
|
|
* be a slow process */
|
|
mutex_unlock(&cgroup_mutex);
|
|
call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
|
|
mutex_lock(&cgroup_mutex);
|
|
continue_free:
|
|
kfree(pathbuf);
|
|
kfree(agentbuf);
|
|
spin_lock(&release_list_lock);
|
|
}
|
|
spin_unlock(&release_list_lock);
|
|
mutex_unlock(&cgroup_mutex);
|
|
}
|
|
|
|
static int __init cgroup_disable(char *str)
|
|
{
|
|
int i;
|
|
char *token;
|
|
|
|
while ((token = strsep(&str, ",")) != NULL) {
|
|
if (!*token)
|
|
continue;
|
|
|
|
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
|
|
struct cgroup_subsys *ss = subsys[i];
|
|
|
|
if (!strcmp(token, ss->name)) {
|
|
ss->disabled = 1;
|
|
printk(KERN_INFO "Disabling %s control group"
|
|
" subsystem\n", ss->name);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
return 1;
|
|
}
|
|
__setup("cgroup_disable=", cgroup_disable);
|
|
|
|
/*
|
|
* Functons for CSS ID.
|
|
*/
|
|
|
|
/*
|
|
*To get ID other than 0, this should be called when !cgroup_is_removed().
|
|
*/
|
|
unsigned short css_id(struct cgroup_subsys_state *css)
|
|
{
|
|
struct css_id *cssid = rcu_dereference(css->id);
|
|
|
|
if (cssid)
|
|
return cssid->id;
|
|
return 0;
|
|
}
|
|
|
|
unsigned short css_depth(struct cgroup_subsys_state *css)
|
|
{
|
|
struct css_id *cssid = rcu_dereference(css->id);
|
|
|
|
if (cssid)
|
|
return cssid->depth;
|
|
return 0;
|
|
}
|
|
|
|
bool css_is_ancestor(struct cgroup_subsys_state *child,
|
|
const struct cgroup_subsys_state *root)
|
|
{
|
|
struct css_id *child_id = rcu_dereference(child->id);
|
|
struct css_id *root_id = rcu_dereference(root->id);
|
|
|
|
if (!child_id || !root_id || (child_id->depth < root_id->depth))
|
|
return false;
|
|
return child_id->stack[root_id->depth] == root_id->id;
|
|
}
|
|
|
|
static void __free_css_id_cb(struct rcu_head *head)
|
|
{
|
|
struct css_id *id;
|
|
|
|
id = container_of(head, struct css_id, rcu_head);
|
|
kfree(id);
|
|
}
|
|
|
|
void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css)
|
|
{
|
|
struct css_id *id = css->id;
|
|
/* When this is called before css_id initialization, id can be NULL */
|
|
if (!id)
|
|
return;
|
|
|
|
BUG_ON(!ss->use_id);
|
|
|
|
rcu_assign_pointer(id->css, NULL);
|
|
rcu_assign_pointer(css->id, NULL);
|
|
spin_lock(&ss->id_lock);
|
|
idr_remove(&ss->idr, id->id);
|
|
spin_unlock(&ss->id_lock);
|
|
call_rcu(&id->rcu_head, __free_css_id_cb);
|
|
}
|
|
|
|
/*
|
|
* This is called by init or create(). Then, calls to this function are
|
|
* always serialized (By cgroup_mutex() at create()).
|
|
*/
|
|
|
|
static struct css_id *get_new_cssid(struct cgroup_subsys *ss, int depth)
|
|
{
|
|
struct css_id *newid;
|
|
int myid, error, size;
|
|
|
|
BUG_ON(!ss->use_id);
|
|
|
|
size = sizeof(*newid) + sizeof(unsigned short) * (depth + 1);
|
|
newid = kzalloc(size, GFP_KERNEL);
|
|
if (!newid)
|
|
return ERR_PTR(-ENOMEM);
|
|
/* get id */
|
|
if (unlikely(!idr_pre_get(&ss->idr, GFP_KERNEL))) {
|
|
error = -ENOMEM;
|
|
goto err_out;
|
|
}
|
|
spin_lock(&ss->id_lock);
|
|
/* Don't use 0. allocates an ID of 1-65535 */
|
|
error = idr_get_new_above(&ss->idr, newid, 1, &myid);
|
|
spin_unlock(&ss->id_lock);
|
|
|
|
/* Returns error when there are no free spaces for new ID.*/
|
|
if (error) {
|
|
error = -ENOSPC;
|
|
goto err_out;
|
|
}
|
|
if (myid > CSS_ID_MAX)
|
|
goto remove_idr;
|
|
|
|
newid->id = myid;
|
|
newid->depth = depth;
|
|
return newid;
|
|
remove_idr:
|
|
error = -ENOSPC;
|
|
spin_lock(&ss->id_lock);
|
|
idr_remove(&ss->idr, myid);
|
|
spin_unlock(&ss->id_lock);
|
|
err_out:
|
|
kfree(newid);
|
|
return ERR_PTR(error);
|
|
|
|
}
|
|
|
|
static int __init cgroup_subsys_init_idr(struct cgroup_subsys *ss)
|
|
{
|
|
struct css_id *newid;
|
|
struct cgroup_subsys_state *rootcss;
|
|
|
|
spin_lock_init(&ss->id_lock);
|
|
idr_init(&ss->idr);
|
|
|
|
rootcss = init_css_set.subsys[ss->subsys_id];
|
|
newid = get_new_cssid(ss, 0);
|
|
if (IS_ERR(newid))
|
|
return PTR_ERR(newid);
|
|
|
|
newid->stack[0] = newid->id;
|
|
newid->css = rootcss;
|
|
rootcss->id = newid;
|
|
return 0;
|
|
}
|
|
|
|
static int alloc_css_id(struct cgroup_subsys *ss, struct cgroup *parent,
|
|
struct cgroup *child)
|
|
{
|
|
int subsys_id, i, depth = 0;
|
|
struct cgroup_subsys_state *parent_css, *child_css;
|
|
struct css_id *child_id, *parent_id = NULL;
|
|
|
|
subsys_id = ss->subsys_id;
|
|
parent_css = parent->subsys[subsys_id];
|
|
child_css = child->subsys[subsys_id];
|
|
depth = css_depth(parent_css) + 1;
|
|
parent_id = parent_css->id;
|
|
|
|
child_id = get_new_cssid(ss, depth);
|
|
if (IS_ERR(child_id))
|
|
return PTR_ERR(child_id);
|
|
|
|
for (i = 0; i < depth; i++)
|
|
child_id->stack[i] = parent_id->stack[i];
|
|
child_id->stack[depth] = child_id->id;
|
|
/*
|
|
* child_id->css pointer will be set after this cgroup is available
|
|
* see cgroup_populate_dir()
|
|
*/
|
|
rcu_assign_pointer(child_css->id, child_id);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* css_lookup - lookup css by id
|
|
* @ss: cgroup subsys to be looked into.
|
|
* @id: the id
|
|
*
|
|
* Returns pointer to cgroup_subsys_state if there is valid one with id.
|
|
* NULL if not. Should be called under rcu_read_lock()
|
|
*/
|
|
struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id)
|
|
{
|
|
struct css_id *cssid = NULL;
|
|
|
|
BUG_ON(!ss->use_id);
|
|
cssid = idr_find(&ss->idr, id);
|
|
|
|
if (unlikely(!cssid))
|
|
return NULL;
|
|
|
|
return rcu_dereference(cssid->css);
|
|
}
|
|
|
|
/**
|
|
* css_get_next - lookup next cgroup under specified hierarchy.
|
|
* @ss: pointer to subsystem
|
|
* @id: current position of iteration.
|
|
* @root: pointer to css. search tree under this.
|
|
* @foundid: position of found object.
|
|
*
|
|
* Search next css under the specified hierarchy of rootid. Calling under
|
|
* rcu_read_lock() is necessary. Returns NULL if it reaches the end.
|
|
*/
|
|
struct cgroup_subsys_state *
|
|
css_get_next(struct cgroup_subsys *ss, int id,
|
|
struct cgroup_subsys_state *root, int *foundid)
|
|
{
|
|
struct cgroup_subsys_state *ret = NULL;
|
|
struct css_id *tmp;
|
|
int tmpid;
|
|
int rootid = css_id(root);
|
|
int depth = css_depth(root);
|
|
|
|
if (!rootid)
|
|
return NULL;
|
|
|
|
BUG_ON(!ss->use_id);
|
|
/* fill start point for scan */
|
|
tmpid = id;
|
|
while (1) {
|
|
/*
|
|
* scan next entry from bitmap(tree), tmpid is updated after
|
|
* idr_get_next().
|
|
*/
|
|
spin_lock(&ss->id_lock);
|
|
tmp = idr_get_next(&ss->idr, &tmpid);
|
|
spin_unlock(&ss->id_lock);
|
|
|
|
if (!tmp)
|
|
break;
|
|
if (tmp->depth >= depth && tmp->stack[depth] == rootid) {
|
|
ret = rcu_dereference(tmp->css);
|
|
if (ret) {
|
|
*foundid = tmpid;
|
|
break;
|
|
}
|
|
}
|
|
/* continue to scan from next id */
|
|
tmpid = tmpid + 1;
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
#ifdef CONFIG_CGROUP_DEBUG
|
|
static struct cgroup_subsys_state *debug_create(struct cgroup_subsys *ss,
|
|
struct cgroup *cont)
|
|
{
|
|
struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
|
|
|
|
if (!css)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
return css;
|
|
}
|
|
|
|
static void debug_destroy(struct cgroup_subsys *ss, struct cgroup *cont)
|
|
{
|
|
kfree(cont->subsys[debug_subsys_id]);
|
|
}
|
|
|
|
static u64 cgroup_refcount_read(struct cgroup *cont, struct cftype *cft)
|
|
{
|
|
return atomic_read(&cont->count);
|
|
}
|
|
|
|
static u64 debug_taskcount_read(struct cgroup *cont, struct cftype *cft)
|
|
{
|
|
return cgroup_task_count(cont);
|
|
}
|
|
|
|
static u64 current_css_set_read(struct cgroup *cont, struct cftype *cft)
|
|
{
|
|
return (u64)(unsigned long)current->cgroups;
|
|
}
|
|
|
|
static u64 current_css_set_refcount_read(struct cgroup *cont,
|
|
struct cftype *cft)
|
|
{
|
|
u64 count;
|
|
|
|
rcu_read_lock();
|
|
count = atomic_read(¤t->cgroups->refcount);
|
|
rcu_read_unlock();
|
|
return count;
|
|
}
|
|
|
|
static int current_css_set_cg_links_read(struct cgroup *cont,
|
|
struct cftype *cft,
|
|
struct seq_file *seq)
|
|
{
|
|
struct cg_cgroup_link *link;
|
|
struct css_set *cg;
|
|
|
|
read_lock(&css_set_lock);
|
|
rcu_read_lock();
|
|
cg = rcu_dereference(current->cgroups);
|
|
list_for_each_entry(link, &cg->cg_links, cg_link_list) {
|
|
struct cgroup *c = link->cgrp;
|
|
const char *name;
|
|
|
|
if (c->dentry)
|
|
name = c->dentry->d_name.name;
|
|
else
|
|
name = "?";
|
|
seq_printf(seq, "Root %d group %s\n",
|
|
c->root->hierarchy_id, name);
|
|
}
|
|
rcu_read_unlock();
|
|
read_unlock(&css_set_lock);
|
|
return 0;
|
|
}
|
|
|
|
#define MAX_TASKS_SHOWN_PER_CSS 25
|
|
static int cgroup_css_links_read(struct cgroup *cont,
|
|
struct cftype *cft,
|
|
struct seq_file *seq)
|
|
{
|
|
struct cg_cgroup_link *link;
|
|
|
|
read_lock(&css_set_lock);
|
|
list_for_each_entry(link, &cont->css_sets, cgrp_link_list) {
|
|
struct css_set *cg = link->cg;
|
|
struct task_struct *task;
|
|
int count = 0;
|
|
seq_printf(seq, "css_set %p\n", cg);
|
|
list_for_each_entry(task, &cg->tasks, cg_list) {
|
|
if (count++ > MAX_TASKS_SHOWN_PER_CSS) {
|
|
seq_puts(seq, " ...\n");
|
|
break;
|
|
} else {
|
|
seq_printf(seq, " task %d\n",
|
|
task_pid_vnr(task));
|
|
}
|
|
}
|
|
}
|
|
read_unlock(&css_set_lock);
|
|
return 0;
|
|
}
|
|
|
|
static u64 releasable_read(struct cgroup *cgrp, struct cftype *cft)
|
|
{
|
|
return test_bit(CGRP_RELEASABLE, &cgrp->flags);
|
|
}
|
|
|
|
static struct cftype debug_files[] = {
|
|
{
|
|
.name = "cgroup_refcount",
|
|
.read_u64 = cgroup_refcount_read,
|
|
},
|
|
{
|
|
.name = "taskcount",
|
|
.read_u64 = debug_taskcount_read,
|
|
},
|
|
|
|
{
|
|
.name = "current_css_set",
|
|
.read_u64 = current_css_set_read,
|
|
},
|
|
|
|
{
|
|
.name = "current_css_set_refcount",
|
|
.read_u64 = current_css_set_refcount_read,
|
|
},
|
|
|
|
{
|
|
.name = "current_css_set_cg_links",
|
|
.read_seq_string = current_css_set_cg_links_read,
|
|
},
|
|
|
|
{
|
|
.name = "cgroup_css_links",
|
|
.read_seq_string = cgroup_css_links_read,
|
|
},
|
|
|
|
{
|
|
.name = "releasable",
|
|
.read_u64 = releasable_read,
|
|
},
|
|
};
|
|
|
|
static int debug_populate(struct cgroup_subsys *ss, struct cgroup *cont)
|
|
{
|
|
return cgroup_add_files(cont, ss, debug_files,
|
|
ARRAY_SIZE(debug_files));
|
|
}
|
|
|
|
struct cgroup_subsys debug_subsys = {
|
|
.name = "debug",
|
|
.create = debug_create,
|
|
.destroy = debug_destroy,
|
|
.populate = debug_populate,
|
|
.subsys_id = debug_subsys_id,
|
|
};
|
|
#endif /* CONFIG_CGROUP_DEBUG */
|