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authorLinus Torvalds <torvalds@linux-foundation.org>2013-02-20 09:16:21 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2013-02-20 09:16:21 -0800
commit502b24c23b44fbaa01cc2cbd86d8035845b7811f (patch)
tree3096deeb99f6acc2d72ee33f145008ec5e2c68b3 /kernel/cgroup.c
parentece8e0b2f9c980e5511fe8db2d68c6f1859b9d83 (diff)
parentf169007b2773f285e098cb84c74aac0154d65ff7 (diff)
downloadvexpress-lsk-502b24c23b44fbaa01cc2cbd86d8035845b7811f.tar.gz
Merge branch 'for-3.9' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup changes from Tejun Heo: "Nothing too drastic. - Removal of synchronize_rcu() from userland visible paths. - Various fixes and cleanups from Li. - cgroup_rightmost_descendant() added which will be used by cpuset changes (it will be a separate pull request)." * 'for-3.9' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: fail if monitored file and event_control are in different cgroup cgroup: fix cgroup_rmdir() vs close(eventfd) race cpuset: fix cpuset_print_task_mems_allowed() vs rename() race cgroup: fix exit() vs rmdir() race cgroup: remove bogus comments in cgroup_diput() cgroup: remove synchronize_rcu() from cgroup_diput() cgroup: remove duplicate RCU free on struct cgroup sched: remove redundant NULL cgroup check in task_group_path() sched: split out css_online/css_offline from tg creation/destruction cgroup: initialize cgrp->dentry before css_alloc() cgroup: remove a NULL check in cgroup_exit() cgroup: fix bogus kernel warnings when cgroup_create() failed cgroup: remove synchronize_rcu() from rebind_subsystems() cgroup: remove synchronize_rcu() from cgroup_attach_{task|proc}() cgroup: use new hashtable implementation cgroups: fix cgroup_event_listener error handling cgroups: move cgroup_event_listener.c to tools/cgroup cgroup: implement cgroup_rightmost_descendant() cgroup: remove unused dummy cgroup_fork_callbacks()
Diffstat (limited to 'kernel/cgroup.c')
-rw-r--r--kernel/cgroup.c288
1 files changed, 168 insertions, 120 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 4855892798f..b5c64327e71 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -52,7 +52,7 @@
#include <linux/module.h>
#include <linux/delayacct.h>
#include <linux/cgroupstats.h>
-#include <linux/hash.h>
+#include <linux/hashtable.h>
#include <linux/namei.h>
#include <linux/pid_namespace.h>
#include <linux/idr.h>
@@ -376,22 +376,18 @@ static int css_set_count;
* 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 DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS);
-static struct hlist_head *css_set_hash(struct cgroup_subsys_state *css[])
+static unsigned long css_set_hash(struct cgroup_subsys_state *css[])
{
int i;
- int index;
- unsigned long tmp = 0UL;
+ unsigned long key = 0UL;
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++)
- tmp += (unsigned long)css[i];
- tmp = (tmp >> 16) ^ tmp;
+ key += (unsigned long)css[i];
+ key = (key >> 16) ^ key;
- index = hash_long(tmp, CSS_SET_HASH_BITS);
-
- return &css_set_table[index];
+ return key;
}
/* We don't maintain the lists running through each css_set to its
@@ -418,7 +414,7 @@ static void __put_css_set(struct css_set *cg, int taskexit)
}
/* This css_set is dead. unlink it and release cgroup refcounts */
- hlist_del(&cg->hlist);
+ hash_del(&cg->hlist);
css_set_count--;
list_for_each_entry_safe(link, saved_link, &cg->cg_links,
@@ -426,12 +422,20 @@ static void __put_css_set(struct css_set *cg, int taskexit)
struct cgroup *cgrp = link->cgrp;
list_del(&link->cg_link_list);
list_del(&link->cgrp_link_list);
+
+ /*
+ * We may not be holding cgroup_mutex, and if cgrp->count is
+ * dropped to 0 the cgroup can be destroyed at any time, hence
+ * rcu_read_lock is used to keep it alive.
+ */
+ rcu_read_lock();
if (atomic_dec_and_test(&cgrp->count) &&
notify_on_release(cgrp)) {
if (taskexit)
set_bit(CGRP_RELEASABLE, &cgrp->flags);
check_for_release(cgrp);
}
+ rcu_read_unlock();
kfree(link);
}
@@ -550,9 +554,9 @@ static struct css_set *find_existing_css_set(
{
int i;
struct cgroupfs_root *root = cgrp->root;
- struct hlist_head *hhead;
struct hlist_node *node;
struct css_set *cg;
+ unsigned long key;
/*
* Build the set of subsystem state objects that we want to see in the
@@ -572,8 +576,8 @@ static struct css_set *find_existing_css_set(
}
}
- hhead = css_set_hash(template);
- hlist_for_each_entry(cg, node, hhead, hlist) {
+ key = css_set_hash(template);
+ hash_for_each_possible(css_set_table, cg, node, hlist, key) {
if (!compare_css_sets(cg, oldcg, cgrp, template))
continue;
@@ -657,8 +661,8 @@ static struct css_set *find_css_set(
struct list_head tmp_cg_links;
- struct hlist_head *hhead;
struct cg_cgroup_link *link;
+ unsigned long key;
/* First see if we already have a cgroup group that matches
* the desired set */
@@ -704,8 +708,8 @@ static struct css_set *find_css_set(
css_set_count++;
/* Add this cgroup group to the hash table */
- hhead = css_set_hash(res->subsys);
- hlist_add_head(&res->hlist, hhead);
+ key = css_set_hash(res->subsys);
+ hash_add(css_set_table, &res->hlist, key);
write_unlock(&css_set_lock);
@@ -856,47 +860,54 @@ static struct inode *cgroup_new_inode(umode_t mode, struct super_block *sb)
return inode;
}
-static void cgroup_diput(struct dentry *dentry, struct inode *inode)
+static void cgroup_free_fn(struct work_struct *work)
{
- /* 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();
+ struct cgroup *cgrp = container_of(work, struct cgroup, free_work);
+ struct cgroup_subsys *ss;
- mutex_lock(&cgroup_mutex);
- /*
- * Release the subsystem state objects.
- */
- for_each_subsys(cgrp->root, ss)
- ss->css_free(cgrp);
+ mutex_lock(&cgroup_mutex);
+ /*
+ * Release the subsystem state objects.
+ */
+ for_each_subsys(cgrp->root, ss)
+ ss->css_free(cgrp);
- cgrp->root->number_of_cgroups--;
- mutex_unlock(&cgroup_mutex);
+ 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);
+ /*
+ * 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));
+ /*
+ * if we're getting rid of the cgroup, refcount should ensure
+ * that there are no pidlists left.
+ */
+ BUG_ON(!list_empty(&cgrp->pidlists));
- simple_xattrs_free(&cgrp->xattrs);
+ simple_xattrs_free(&cgrp->xattrs);
- ida_simple_remove(&cgrp->root->cgroup_ida, cgrp->id);
- kfree_rcu(cgrp, rcu_head);
+ ida_simple_remove(&cgrp->root->cgroup_ida, cgrp->id);
+ kfree(cgrp);
+}
+
+static void cgroup_free_rcu(struct rcu_head *head)
+{
+ struct cgroup *cgrp = container_of(head, struct cgroup, rcu_head);
+
+ schedule_work(&cgrp->free_work);
+}
+
+static void cgroup_diput(struct dentry *dentry, struct inode *inode)
+{
+ /* is dentry a directory ? if so, kfree() associated cgroup */
+ if (S_ISDIR(inode->i_mode)) {
+ struct cgroup *cgrp = dentry->d_fsdata;
+
+ BUG_ON(!(cgroup_is_removed(cgrp)));
+ call_rcu(&cgrp->rcu_head, cgroup_free_rcu);
} else {
struct cfent *cfe = __d_cfe(dentry);
struct cgroup *cgrp = dentry->d_parent->d_fsdata;
@@ -925,13 +936,17 @@ static void remove_dir(struct dentry *d)
dput(parent);
}
-static int cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
+static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
{
struct cfent *cfe;
lockdep_assert_held(&cgrp->dentry->d_inode->i_mutex);
lockdep_assert_held(&cgroup_mutex);
+ /*
+ * If we're doing cleanup due to failure of cgroup_create(),
+ * the corresponding @cfe may not exist.
+ */
list_for_each_entry(cfe, &cgrp->files, node) {
struct dentry *d = cfe->dentry;
@@ -944,9 +959,8 @@ static int cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
list_del_init(&cfe->node);
dput(d);
- return 0;
+ break;
}
- return -ENOENT;
}
/**
@@ -1083,7 +1097,6 @@ static int rebind_subsystems(struct cgroupfs_root *root,
}
}
root->subsys_mask = root->actual_subsys_mask = final_subsys_mask;
- synchronize_rcu();
return 0;
}
@@ -1393,6 +1406,7 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp)
INIT_LIST_HEAD(&cgrp->allcg_node);
INIT_LIST_HEAD(&cgrp->release_list);
INIT_LIST_HEAD(&cgrp->pidlists);
+ INIT_WORK(&cgrp->free_work, cgroup_free_fn);
mutex_init(&cgrp->pidlist_mutex);
INIT_LIST_HEAD(&cgrp->event_list);
spin_lock_init(&cgrp->event_list_lock);
@@ -1597,6 +1611,8 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
struct cgroupfs_root *existing_root;
const struct cred *cred;
int i;
+ struct hlist_node *node;
+ struct css_set *cg;
BUG_ON(sb->s_root != NULL);
@@ -1650,14 +1666,8 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
/* 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);
- }
+ hash_for_each(css_set_table, i, node, cg, hlist)
+ link_css_set(&tmp_cg_links, cg, root_cgrp);
write_unlock(&css_set_lock);
free_cg_links(&tmp_cg_links);
@@ -1773,7 +1783,7 @@ int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen)
rcu_lockdep_assert(rcu_read_lock_held() || cgroup_lock_is_held(),
"cgroup_path() called without proper locking");
- if (!dentry || cgrp == dummytop) {
+ if (cgrp == dummytop) {
/*
* Inactive subsystems have no dentry for their root
* cgroup
@@ -1982,7 +1992,6 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
ss->attach(cgrp, &tset);
}
- synchronize_rcu();
out:
if (retval) {
for_each_subsys(root, ss) {
@@ -2151,7 +2160,6 @@ static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
/*
* step 5: success! and cleanup
*/
- synchronize_rcu();
retval = 0;
out_put_css_set_refs:
if (retval) {
@@ -2769,14 +2777,14 @@ static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys,
if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgrp->parent)
continue;
- if (is_add)
+ if (is_add) {
err = cgroup_add_file(cgrp, subsys, cft);
- else
- err = cgroup_rm_file(cgrp, cft);
- if (err) {
- pr_warning("cgroup_addrm_files: failed to %s %s, err=%d\n",
- is_add ? "add" : "remove", cft->name, err);
+ if (err)
+ pr_warn("cgroup_addrm_files: failed to add %s, err=%d\n",
+ cft->name, err);
ret = err;
+ } else {
+ cgroup_rm_file(cgrp, cft);
}
}
return ret;
@@ -3017,6 +3025,32 @@ struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos,
}
EXPORT_SYMBOL_GPL(cgroup_next_descendant_pre);
+/**
+ * cgroup_rightmost_descendant - return the rightmost descendant of a cgroup
+ * @pos: cgroup of interest
+ *
+ * Return the rightmost descendant of @pos. If there's no descendant,
+ * @pos is returned. This can be used during pre-order traversal to skip
+ * subtree of @pos.
+ */
+struct cgroup *cgroup_rightmost_descendant(struct cgroup *pos)
+{
+ struct cgroup *last, *tmp;
+
+ WARN_ON_ONCE(!rcu_read_lock_held());
+
+ do {
+ last = pos;
+ /* ->prev isn't RCU safe, walk ->next till the end */
+ pos = NULL;
+ list_for_each_entry_rcu(tmp, &last->children, sibling)
+ pos = tmp;
+ } while (pos);
+
+ return last;
+}
+EXPORT_SYMBOL_GPL(cgroup_rightmost_descendant);
+
static struct cgroup *cgroup_leftmost_descendant(struct cgroup *pos)
{
struct cgroup *last;
@@ -3752,8 +3786,13 @@ static void cgroup_event_remove(struct work_struct *work)
remove);
struct cgroup *cgrp = event->cgrp;
+ remove_wait_queue(event->wqh, &event->wait);
+
event->cft->unregister_event(cgrp, event->cft, event->eventfd);
+ /* Notify userspace the event is going away. */
+ eventfd_signal(event->eventfd, 1);
+
eventfd_ctx_put(event->eventfd);
kfree(event);
dput(cgrp->dentry);
@@ -3773,15 +3812,25 @@ static int cgroup_event_wake(wait_queue_t *wait, unsigned mode,
unsigned long flags = (unsigned long)key;
if (flags & POLLHUP) {
- __remove_wait_queue(event->wqh, &event->wait);
- spin_lock(&cgrp->event_list_lock);
- list_del_init(&event->list);
- spin_unlock(&cgrp->event_list_lock);
/*
- * We are in atomic context, but cgroup_event_remove() may
- * sleep, so we have to call it in workqueue.
+ * If the event has been detached at cgroup removal, we
+ * can simply return knowing the other side will cleanup
+ * for us.
+ *
+ * We can't race against event freeing since the other
+ * side will require wqh->lock via remove_wait_queue(),
+ * which we hold.
*/
- schedule_work(&event->remove);
+ spin_lock(&cgrp->event_list_lock);
+ if (!list_empty(&event->list)) {
+ list_del_init(&event->list);
+ /*
+ * We are in atomic context, but cgroup_event_remove()
+ * may sleep, so we have to call it in workqueue.
+ */
+ schedule_work(&event->remove);
+ }
+ spin_unlock(&cgrp->event_list_lock);
}
return 0;
@@ -3807,6 +3856,7 @@ static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft,
const char *buffer)
{
struct cgroup_event *event = NULL;
+ struct cgroup *cgrp_cfile;
unsigned int efd, cfd;
struct file *efile = NULL;
struct file *cfile = NULL;
@@ -3862,6 +3912,16 @@ static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft,
goto fail;
}
+ /*
+ * The file to be monitored must be in the same cgroup as
+ * cgroup.event_control is.
+ */
+ cgrp_cfile = __d_cgrp(cfile->f_dentry->d_parent);
+ if (cgrp_cfile != cgrp) {
+ ret = -EINVAL;
+ goto fail;
+ }
+
if (!event->cft->register_event || !event->cft->unregister_event) {
ret = -EINVAL;
goto fail;
@@ -4135,6 +4195,9 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
init_cgroup_housekeeping(cgrp);
+ dentry->d_fsdata = cgrp;
+ cgrp->dentry = dentry;
+
cgrp->parent = parent;
cgrp->root = parent->root;
cgrp->top_cgroup = parent->top_cgroup;
@@ -4172,8 +4235,6 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
lockdep_assert_held(&dentry->d_inode->i_mutex);
/* allocation complete, commit to creation */
- dentry->d_fsdata = cgrp;
- cgrp->dentry = dentry;
list_add_tail(&cgrp->allcg_node, &root->allcg_list);
list_add_tail_rcu(&cgrp->sibling, &cgrp->parent->children);
root->number_of_cgroups++;
@@ -4340,20 +4401,14 @@ static int cgroup_destroy_locked(struct cgroup *cgrp)
/*
* Unregister events and notify userspace.
* Notify userspace about cgroup removing only after rmdir of cgroup
- * directory to avoid race between userspace and kernelspace. Use
- * a temporary list to avoid a deadlock with cgroup_event_wake(). Since
- * cgroup_event_wake() is called with the wait queue head locked,
- * remove_wait_queue() cannot be called while holding event_list_lock.
+ * directory to avoid race between userspace and kernelspace.
*/
spin_lock(&cgrp->event_list_lock);
- list_splice_init(&cgrp->event_list, &tmp_list);
- spin_unlock(&cgrp->event_list_lock);
- list_for_each_entry_safe(event, tmp, &tmp_list, list) {
+ list_for_each_entry_safe(event, tmp, &cgrp->event_list, list) {
list_del_init(&event->list);
- remove_wait_queue(event->wqh, &event->wait);
- eventfd_signal(event->eventfd, 1);
schedule_work(&event->remove);
}
+ spin_unlock(&cgrp->event_list_lock);
return 0;
}
@@ -4438,6 +4493,9 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
{
struct cgroup_subsys_state *css;
int i, ret;
+ struct hlist_node *node, *tmp;
+ struct css_set *cg;
+ unsigned long key;
/* check name and function validity */
if (ss->name == NULL || strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN ||
@@ -4503,23 +4561,17 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
* this is all done under the css_set_lock.
*/
write_lock(&css_set_lock);
- for (i = 0; i < CSS_SET_TABLE_SIZE; i++) {
- struct css_set *cg;
- struct hlist_node *node, *tmp;
- struct hlist_head *bucket = &css_set_table[i], *new_bucket;
-
- hlist_for_each_entry_safe(cg, node, tmp, bucket, hlist) {
- /* skip entries that we already rehashed */
- if (cg->subsys[ss->subsys_id])
- continue;
- /* remove existing entry */
- hlist_del(&cg->hlist);
- /* set new value */
- cg->subsys[ss->subsys_id] = css;
- /* recompute hash and restore entry */
- new_bucket = css_set_hash(cg->subsys);
- hlist_add_head(&cg->hlist, new_bucket);
- }
+ hash_for_each_safe(css_set_table, i, node, tmp, cg, hlist) {
+ /* skip entries that we already rehashed */
+ if (cg->subsys[ss->subsys_id])
+ continue;
+ /* remove existing entry */
+ hash_del(&cg->hlist);
+ /* set new value */
+ cg->subsys[ss->subsys_id] = css;
+ /* recompute hash and restore entry */
+ key = css_set_hash(cg->subsys);
+ hash_add(css_set_table, node, key);
}
write_unlock(&css_set_lock);
@@ -4551,7 +4603,6 @@ EXPORT_SYMBOL_GPL(cgroup_load_subsys);
void cgroup_unload_subsys(struct cgroup_subsys *ss)
{
struct cg_cgroup_link *link;
- struct hlist_head *hhead;
BUG_ON(ss->module == NULL);
@@ -4585,11 +4636,12 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss)
write_lock(&css_set_lock);
list_for_each_entry(link, &dummytop->css_sets, cgrp_link_list) {
struct css_set *cg = link->cg;
+ unsigned long key;
- hlist_del(&cg->hlist);
+ hash_del(&cg->hlist);
cg->subsys[ss->subsys_id] = NULL;
- hhead = css_set_hash(cg->subsys);
- hlist_add_head(&cg->hlist, hhead);
+ key = css_set_hash(cg->subsys);
+ hash_add(css_set_table, &cg->hlist, key);
}
write_unlock(&css_set_lock);
@@ -4631,9 +4683,6 @@ int __init cgroup_init_early(void)
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];
@@ -4667,7 +4716,7 @@ int __init cgroup_init(void)
{
int err;
int i;
- struct hlist_head *hhead;
+ unsigned long key;
err = bdi_init(&cgroup_backing_dev_info);
if (err)
@@ -4686,8 +4735,8 @@ int __init cgroup_init(void)
}
/* Add init_css_set to the hash table */
- hhead = css_set_hash(init_css_set.subsys);
- hlist_add_head(&init_css_set.hlist, hhead);
+ key = css_set_hash(init_css_set.subsys);
+ hash_add(css_set_table, &init_css_set.hlist, key);
BUG_ON(!init_root_id(&rootnode));
cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj);
@@ -4982,8 +5031,7 @@ void cgroup_exit(struct task_struct *tsk, int run_callbacks)
}
task_unlock(tsk);
- if (cg)
- put_css_set_taskexit(cg);
+ put_css_set_taskexit(cg);
}
/**