#include <linux/kmod.h>
#include <linux/delayacct.h>
#include <linux/cgroupstats.h>
+#include <linux/hash.h>
+#include <linux/namei.h>
#include <asm/atomic.h>
/* Tracks how many cgroups are currently defined in hierarchy.*/
int number_of_cgroups;
- /* A list running through the mounted hierarchies */
+ /* 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. No locking
- * between setting and use - so if userspace updates this
- * while child cgroups exist, you could miss a
- * notification. We ensure that it's always a valid
- * NUL-terminated string */
+ /* The path to use for release notifications. */
char release_agent_path[PATH_MAX];
};
-
/*
* The "rootnode" hierarchy is the "dummy hierarchy", reserved for the
* subsystems that are otherwise unattached - it never has more than a
*/
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);
* extra work in the fork/exit path if none of the subsystems need to
* be called.
*/
-static int need_forkexit_callback;
-
-/* bits in struct cgroup flags field */
-enum {
- /* Control Group is dead */
- CGRP_REMOVED,
- /* Control Group has previously had a child cgroup or a task,
- * but no longer (only if CGRP_NOTIFY_ON_RELEASE is set) */
- CGRP_RELEASABLE,
- /* Control Group requires release notifications to userspace */
- CGRP_NOTIFY_ON_RELEASE,
-};
+static int need_forkexit_callback __read_mostly;
/* convenient tests for these bits */
inline int cgroup_is_removed(const struct cgroup *cgrp)
#define for_each_subsys(_root, _ss) \
list_for_each_entry(_ss, &_root->subsys_list, sibling)
-/* for_each_root() allows you to iterate across the active hierarchies */
-#define for_each_root(_root) \
+/* 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
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 */
+#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];
+}
+
/* 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;
+static int use_task_css_set_links __read_mostly;
/* When we create or destroy a css_set, the operation simply
* takes/releases a reference count on all the cgroups referenced
*/
static void unlink_css_set(struct css_set *cg)
{
- write_lock(&css_set_lock);
- list_del(&cg->list);
+ struct cg_cgroup_link *link;
+ struct cg_cgroup_link *saved_link;
+
+ hlist_del(&cg->hlist);
css_set_count--;
- while (!list_empty(&cg->cg_links)) {
- struct cg_cgroup_link *link;
- link = list_entry(cg->cg_links.next,
- struct cg_cgroup_link, cg_link_list);
+
+ list_for_each_entry_safe(link, saved_link, &cg->cg_links,
+ cg_link_list) {
list_del(&link->cg_link_list);
list_del(&link->cgrp_link_list);
kfree(link);
}
- write_unlock(&css_set_lock);
}
-static void __release_css_set(struct kref *k, int taskexit)
+static void __put_css_set(struct css_set *cg, int taskexit)
{
int i;
- struct css_set *cg = container_of(k, struct css_set, ref);
-
+ /*
+ * 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;
+ }
unlink_css_set(cg);
+ write_unlock(&css_set_lock);
rcu_read_lock();
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
- struct cgroup *cgrp = cg->subsys[i]->cgroup;
+ struct cgroup *cgrp = rcu_dereference(cg->subsys[i]->cgroup);
if (atomic_dec_and_test(&cgrp->count) &&
notify_on_release(cgrp)) {
if (taskexit)
kfree(cg);
}
-static void release_css_set(struct kref *k)
-{
- __release_css_set(k, 0);
-}
-
-static void release_css_set_taskexit(struct kref *k)
-{
- __release_css_set(k, 1);
-}
-
/*
* refcounted get/put for css_set objects
*/
static inline void get_css_set(struct css_set *cg)
{
- kref_get(&cg->ref);
+ atomic_inc(&cg->refcount);
}
static inline void put_css_set(struct css_set *cg)
{
- kref_put(&cg->ref, release_css_set);
+ __put_css_set(cg, 0);
}
static inline void put_css_set_taskexit(struct css_set *cg)
{
- kref_put(&cg->ref, release_css_set_taskexit);
+ __put_css_set(cg, 1);
}
/*
* find_existing_css_set() is a helper for
* find_css_set(), and checks to see whether an existing
- * css_set is suitable. This currently walks a linked-list for
- * simplicity; a later patch will use a hash table for better
- * performance
+ * css_set is suitable.
*
* oldcg: the cgroup group that we're using before the cgroup
* transition
{
int i;
struct cgroupfs_root *root = cgrp->root;
- struct list_head *l = &init_css_set.list;
+ 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 */
}
}
- /* Look through existing cgroup groups to find one to reuse */
- do {
- struct css_set *cg =
- list_entry(l, struct css_set, list);
-
+ hhead = css_set_hash(template);
+ hlist_for_each_entry(cg, node, hhead, hlist) {
if (!memcmp(template, cg->subsys, sizeof(cg->subsys))) {
/* All subsystems matched */
return cg;
}
- /* Try the next cgroup group */
- l = l->next;
- } while (l != &init_css_set.list);
+ }
/* 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
for (i = 0; i < count; i++) {
link = kmalloc(sizeof(*link), GFP_KERNEL);
if (!link) {
- while (!list_empty(tmp)) {
- link = list_entry(tmp->next,
- struct cg_cgroup_link,
- cgrp_link_list);
- list_del(&link->cgrp_link_list);
- kfree(link);
- }
+ free_cg_links(tmp);
return -ENOMEM;
}
list_add(&link->cgrp_link_list, tmp);
return 0;
}
-static void free_cg_links(struct list_head *tmp)
+/**
+ * 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)
{
- while (!list_empty(tmp)) {
- struct cg_cgroup_link *link;
- link = list_entry(tmp->next,
- struct cg_cgroup_link,
- cgrp_link_list);
- list_del(&link->cgrp_link_list);
- kfree(link);
- }
+ 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;
+ list_move(&link->cgrp_link_list, &cgrp->css_sets);
+ list_add(&link->cg_link_list, &cg->cg_links);
}
/*
int i;
struct list_head tmp_cg_links;
- struct cg_cgroup_link *link;
+
+ struct hlist_head *hhead;
/* First see if we already have a cgroup group that matches
* the desired set */
- write_lock(&css_set_lock);
+ read_lock(&css_set_lock);
res = find_existing_css_set(oldcg, cgrp, template);
if (res)
get_css_set(res);
- write_unlock(&css_set_lock);
+ read_unlock(&css_set_lock);
if (res)
return res;
return NULL;
}
- kref_init(&res->ref);
+ 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() */
* only do it for the first subsystem in each
* hierarchy
*/
- if (ss->root->subsys_list.next == &ss->sibling) {
- BUG_ON(list_empty(&tmp_cg_links));
- link = list_entry(tmp_cg_links.next,
- struct cg_cgroup_link,
- cgrp_link_list);
- list_del(&link->cgrp_link_list);
- list_add(&link->cgrp_link_list, &cgrp->css_sets);
- link->cg = res;
- list_add(&link->cg_link_list, &res->cg_links);
- }
- }
- if (list_empty(&rootnode.subsys_list)) {
- link = list_entry(tmp_cg_links.next,
- struct cg_cgroup_link,
- cgrp_link_list);
- list_del(&link->cgrp_link_list);
- list_add(&link->cgrp_link_list, &dummytop->css_sets);
- link->cg = res;
- list_add(&link->cg_link_list, &res->cg_links);
+ if (ss->root->subsys_list.next == &ss->sibling)
+ link_css_set(&tmp_cg_links, res, cgrp);
}
+ if (list_empty(&rootnode.subsys_list))
+ link_css_set(&tmp_cg_links, res, dummytop);
BUG_ON(!list_empty(&tmp_cg_links));
- /* Link this cgroup group into the list */
- list_add(&res->list, &init_css_set.list);
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;
* knows that the cgroup won't be removed, as cgroup_rmdir()
* needs that mutex.
*
- * The cgroup_common_file_write handler for operations that modify
- * the cgroup hierarchy holds cgroup_mutex across the entire operation,
- * single threading all such cgroup modifications across the system.
- *
* 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(),
static struct file_operations proc_cgroupstats_operations;
static struct backing_dev_info cgroup_backing_dev_info = {
- .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
+ .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_blocks = 0;
+ 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;
}
* Call subsys's pre_destroy handler.
* This is called before css refcnt check.
*/
-static void cgroup_call_pre_destroy(struct cgroup *cgrp)
+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 && cgrp->subsys[ss->subsys_id])
- ss->pre_destroy(ss, cgrp);
- return;
+ 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)
/*
* Release the subsystem state objects.
*/
- for_each_subsys(cgrp->root, ss) {
- if (cgrp->subsys[ss->subsys_id])
- ss->destroy(ss, cgrp);
- }
+ 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 */
+ /*
+ * Drop the active superblock reference that we took when we
+ * created the cgroup
+ */
deactivate_super(cgrp->root->sb);
- kfree(cgrp);
+ call_rcu(&cgrp->rcu_head, free_cgroup_rcu);
}
iput(inode);
}
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 modified under cgroup's inode->i_mutex;
+ */
+DECLARE_WAIT_QUEUE_HEAD(cgroup_rmdir_waitq);
+
+static void cgroup_wakeup_rmdir_waiters(const struct cgroup *cgrp)
+{
+ if (unlikely(test_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags)))
+ wake_up_all(&cgroup_rmdir_waitq);
+}
+
static int rebind_subsystems(struct cgroupfs_root *root,
unsigned long final_bits)
{
* any child cgroups exist. This is theoretically supportable
* but involves complex error handling, so it's being left until
* later */
- if (!list_empty(&cgrp->children))
+ if (root->number_of_cgroups > 1)
return -EBUSY;
/* Process each subsystem */
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_add(&ss->sibling, &root->subsys_list);
- rcu_assign_pointer(ss->root, root);
+ 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;
- rcu_assign_pointer(subsys[i]->root, &rootnode);
- list_del(&ss->sibling);
+ 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]);
}
ret = rebind_subsystems(root, opts.subsys_bits);
+ if (ret)
+ goto out_unlock;
/* (re)populate subsystem files */
- if (!ret)
- cgroup_populate_dir(cgrp);
+ cgroup_populate_dir(cgrp);
if (opts.release_agent)
strcpy(root->release_agent_path, opts.release_agent);
out_unlock:
- if (opts.release_agent)
- kfree(opts.release_agent);
+ kfree(opts.release_agent);
mutex_unlock(&cgroup_mutex);
mutex_unlock(&cgrp->dentry->d_inode->i_mutex);
return ret;
.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_rwsem(&cgrp->pids_mutex);
+}
static void init_cgroup_root(struct cgroupfs_root *root)
{
struct cgroup *cgrp = &root->top_cgroup;
root->number_of_cgroups = 1;
cgrp->root = root;
cgrp->top_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_cgroup_housekeeping(cgrp);
}
static int cgroup_test_super(struct super_block *sb, void *data)
int ret = 0;
struct super_block *sb;
struct cgroupfs_root *root;
- struct list_head tmp_cg_links, *l;
- INIT_LIST_HEAD(&tmp_cg_links);
+ struct list_head tmp_cg_links;
/* First find the desired set of subsystems */
ret = parse_cgroupfs_options(data, &opts);
if (ret) {
- if (opts.release_agent)
- kfree(opts.release_agent);
+ kfree(opts.release_agent);
return ret;
}
root = kzalloc(sizeof(*root), GFP_KERNEL);
if (!root) {
- if (opts.release_agent)
- kfree(opts.release_agent);
+ kfree(opts.release_agent);
return -ENOMEM;
}
root = NULL;
} else {
/* New superblock */
- struct cgroup *cgrp = &root->top_cgroup;
+ struct cgroup *root_cgrp = &root->top_cgroup;
struct inode *inode;
+ int i;
BUG_ON(sb->s_root != NULL);
if (ret == -EBUSY) {
mutex_unlock(&cgroup_mutex);
mutex_unlock(&inode->i_mutex);
- goto drop_new_super;
+ goto free_cg_links;
}
/* EBUSY should be the only error here */
list_add(&root->root_list, &roots);
root_count++;
- sb->s_root->d_fsdata = &root->top_cgroup;
+ 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);
- l = &init_css_set.list;
- do {
+ 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;
- struct cg_cgroup_link *link;
- cg = list_entry(l, struct css_set, list);
- BUG_ON(list_empty(&tmp_cg_links));
- link = list_entry(tmp_cg_links.next,
- struct cg_cgroup_link,
- cgrp_link_list);
- list_del(&link->cgrp_link_list);
- link->cg = cg;
- list_add(&link->cgrp_link_list,
- &root->top_cgroup.css_sets);
- list_add(&link->cg_link_list, &cg->cg_links);
- l = l->next;
- } while (l != &init_css_set.list);
+
+ 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(&cgrp->sibling));
- BUG_ON(!list_empty(&cgrp->children));
+ BUG_ON(!list_empty(&root_cgrp->sibling));
+ BUG_ON(!list_empty(&root_cgrp->children));
BUG_ON(root->number_of_cgroups != 1);
- cgroup_populate_dir(cgrp);
+ cgroup_populate_dir(root_cgrp);
mutex_unlock(&inode->i_mutex);
mutex_unlock(&cgroup_mutex);
}
- return simple_set_mnt(mnt, sb);
+ simple_set_mnt(mnt, sb);
+ return 0;
- drop_new_super:
- up_write(&sb->s_umount);
- deactivate_super(sb);
+ free_cg_links:
free_cg_links(&tmp_cg_links);
+ drop_new_super:
+ deactivate_locked_super(sb);
return ret;
}
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);
* root cgroup
*/
write_lock(&css_set_lock);
- while (!list_empty(&cgrp->css_sets)) {
- struct cg_cgroup_link *link;
- link = list_entry(cgrp->css_sets.next,
- struct cg_cgroup_link, cgrp_link_list);
+
+ 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);
list_del(&root->root_list);
root_count--;
}
+
mutex_unlock(&cgroup_mutex);
- kfree(root);
kill_litter_super(sb);
+ kfree(root);
}
static struct file_system_type cgroup_fs_type = {
* @buf: the buffer to write the path into
* @buflen: the length of the buffer
*
- * Called with cgroup_mutex held. Writes path of cgroup into buf.
- * Returns 0 on success, -errno on error.
+ * 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 (cgrp == dummytop) {
+ if (!dentry || cgrp == dummytop) {
/*
* Inactive subsystems have no dentry for their root
* cgroup
*--start = '\0';
for (;;) {
- int len = cgrp->dentry->d_name.len;
+ 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)
int retval = 0;
struct cgroup_subsys *ss;
struct cgroup *oldcgrp;
- struct css_set *cg = tsk->cgroups;
+ struct css_set *cg;
struct css_set *newcg;
struct cgroupfs_root *root = cgrp->root;
int subsys_id;
}
}
+ 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;
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_waiters(cgrp);
return 0;
}
/*
- * Attach task with pid 'pid' to cgroup 'cgrp'. Call with
- * cgroup_mutex, may take task_lock of task
+ * 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, char *pidbuf)
+static int attach_task_by_pid(struct cgroup *cgrp, u64 pid)
{
- pid_t pid;
struct task_struct *tsk;
+ const struct cred *cred = current_cred(), *tcred;
int ret;
- if (sscanf(pidbuf, "%d", &pid) != 1)
- return -EIO;
-
if (pid) {
rcu_read_lock();
tsk = find_task_by_vpid(pid);
rcu_read_unlock();
return -ESRCH;
}
- get_task_struct(tsk);
- rcu_read_unlock();
- if ((current->euid) && (current->euid != tsk->uid)
- && (current->euid != tsk->suid)) {
- put_task_struct(tsk);
+ 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);
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;
+}
+
/* The various types of files and directories in a cgroup file system */
enum cgroup_filetype {
FILE_ROOT,
FILE_DIR,
FILE_TASKLIST,
FILE_NOTIFY_ON_RELEASE,
- FILE_RELEASABLE,
FILE_RELEASE_AGENT,
};
-static ssize_t cgroup_write_uint(struct cgroup *cgrp, struct cftype *cft,
- struct file *file,
- const char __user *userbuf,
- size_t nbytes, loff_t *unused_ppos)
+/**
+ * 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[64];
+ char buffer[CGROUP_LOCAL_BUFFER_SIZE];
int retval = 0;
- u64 val;
char *end;
if (!nbytes)
return -EFAULT;
buffer[nbytes] = 0; /* nul-terminate */
-
- /* strip newline if necessary */
- if (nbytes && (buffer[nbytes-1] == '\n'))
- buffer[nbytes-1] = 0;
- val = simple_strtoull(buffer, &end, 0);
- if (*end)
- return -EINVAL;
-
- /* Pass to subsystem */
- retval = cft->write_uint(cgrp, cft, val);
+ strstrip(buffer);
+ if (cft->write_u64) {
+ u64 val = simple_strtoull(buffer, &end, 0);
+ if (*end)
+ return -EINVAL;
+ retval = cft->write_u64(cgrp, cft, val);
+ } else {
+ s64 val = simple_strtoll(buffer, &end, 0);
+ if (*end)
+ return -EINVAL;
+ retval = cft->write_s64(cgrp, cft, val);
+ }
if (!retval)
retval = nbytes;
return retval;
}
-static ssize_t cgroup_common_file_write(struct cgroup *cgrp,
- struct cftype *cft,
- struct file *file,
- const char __user *userbuf,
- size_t nbytes, loff_t *unused_ppos)
+static ssize_t cgroup_write_string(struct cgroup *cgrp, struct cftype *cft,
+ struct file *file,
+ const char __user *userbuf,
+ size_t nbytes, loff_t *unused_ppos)
{
- enum cgroup_filetype type = cft->private;
- char *buffer;
+ char local_buffer[CGROUP_LOCAL_BUFFER_SIZE];
int retval = 0;
+ size_t max_bytes = cft->max_write_len;
+ char *buffer = local_buffer;
- if (nbytes >= PATH_MAX)
+ if (!max_bytes)
+ max_bytes = sizeof(local_buffer) - 1;
+ if (nbytes >= max_bytes)
return -E2BIG;
-
- /* +1 for nul-terminator */
- buffer = kmalloc(nbytes + 1, GFP_KERNEL);
- if (buffer == NULL)
- return -ENOMEM;
-
- if (copy_from_user(buffer, userbuf, nbytes)) {
+ /* 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 out1;
+ goto out;
}
- buffer[nbytes] = 0; /* nul-terminate */
- strstrip(buffer); /* strip -just- trailing whitespace */
- mutex_lock(&cgroup_mutex);
-
- /*
- * This was already checked for in cgroup_file_write(), but
- * check again now we're holding cgroup_mutex.
- */
- if (cgroup_is_removed(cgrp)) {
- retval = -ENODEV;
- goto out2;
- }
-
- switch (type) {
- case FILE_TASKLIST:
- retval = attach_task_by_pid(cgrp, buffer);
- break;
- case FILE_NOTIFY_ON_RELEASE:
- clear_bit(CGRP_RELEASABLE, &cgrp->flags);
- if (simple_strtoul(buffer, NULL, 10) != 0)
- set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
- else
- clear_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
- break;
- case FILE_RELEASE_AGENT:
- BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX);
- strcpy(cgrp->root->release_agent_path, buffer);
- break;
- default:
- retval = -EINVAL;
- goto out2;
- }
-
- if (retval == 0)
+ buffer[nbytes] = 0; /* nul-terminate */
+ strstrip(buffer);
+ retval = cft->write_string(cgrp, cft, buffer);
+ if (!retval)
retval = nbytes;
-out2:
- mutex_unlock(&cgroup_mutex);
-out1:
- kfree(buffer);
+out:
+ if (buffer != local_buffer)
+ kfree(buffer);
return retval;
}
struct cftype *cft = __d_cft(file->f_dentry);
struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);
- if (!cft || cgroup_is_removed(cgrp))
+ if (cgroup_is_removed(cgrp))
return -ENODEV;
if (cft->write)
return cft->write(cgrp, cft, file, buf, nbytes, ppos);
- if (cft->write_uint)
- return cgroup_write_uint(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_uint(struct cgroup *cgrp, struct cftype *cft,
- struct file *file,
- char __user *buf, size_t nbytes,
- loff_t *ppos)
+static ssize_t cgroup_read_u64(struct cgroup *cgrp, struct cftype *cft,
+ struct file *file,
+ char __user *buf, size_t nbytes,
+ loff_t *ppos)
{
- char tmp[64];
- u64 val = cft->read_uint(cgrp, cft);
+ 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_common_file_read(struct cgroup *cgrp,
- struct cftype *cft,
- struct file *file,
- char __user *buf,
- size_t nbytes, loff_t *ppos)
+static ssize_t cgroup_read_s64(struct cgroup *cgrp, struct cftype *cft,
+ struct file *file,
+ char __user *buf, size_t nbytes,
+ loff_t *ppos)
{
- enum cgroup_filetype type = cft->private;
- char *page;
- ssize_t retval = 0;
- char *s;
-
- if (!(page = (char *)__get_free_page(GFP_KERNEL)))
- return -ENOMEM;
-
- s = page;
-
- switch (type) {
- case FILE_RELEASE_AGENT:
- {
- struct cgroupfs_root *root;
- size_t n;
- mutex_lock(&cgroup_mutex);
- root = cgrp->root;
- n = strnlen(root->release_agent_path,
- sizeof(root->release_agent_path));
- n = min(n, (size_t) PAGE_SIZE);
- strncpy(s, root->release_agent_path, n);
- mutex_unlock(&cgroup_mutex);
- s += n;
- break;
- }
- default:
- retval = -EINVAL;
- goto out;
- }
- *s++ = '\n';
+ char tmp[CGROUP_LOCAL_BUFFER_SIZE];
+ s64 val = cft->read_s64(cgrp, cft);
+ int len = sprintf(tmp, "%lld\n", (long long) val);
- retval = simple_read_from_buffer(buf, nbytes, ppos, page, s - page);
-out:
- free_page((unsigned long)page);
- return retval;
+ return simple_read_from_buffer(buf, nbytes, ppos, tmp, len);
}
static ssize_t cgroup_file_read(struct file *file, char __user *buf,
struct cftype *cft = __d_cft(file->f_dentry);
struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);
- if (!cft || cgroup_is_removed(cgrp))
+ if (cgroup_is_removed(cgrp))
return -ENODEV;
if (cft->read)
return cft->read(cgrp, cft, file, buf, nbytes, ppos);
- if (cft->read_uint)
- return cgroup_read_uint(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 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;
err = generic_file_open(inode, file);
if (err)
return err;
-
cft = __d_cft(file->f_dentry);
- if (!cft)
- return -ENODEV;
- if (cft->open)
+
+ 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;
.rename = cgroup_rename,
};
-static int cgroup_create_file(struct dentry *dentry, int mode,
+static int cgroup_create_file(struct dentry *dentry, mode_t mode,
struct super_block *sb)
{
- static struct dentry_operations cgroup_dops = {
+ static const struct dentry_operations cgroup_dops = {
.d_iput = cgroup_diput,
};
* @mode: mode to set on new directory.
*/
static int cgroup_create_dir(struct cgroup *cgrp, struct dentry *dentry,
- int mode)
+ mode_t mode)
{
struct dentry *parent;
int error = 0;
if (!error) {
dentry->d_fsdata = cgrp;
inc_nlink(parent->d_inode);
- cgrp->dentry = dentry;
+ 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)) {
BUG_ON(!mutex_is_locked(&dir->d_inode->i_mutex));
dentry = lookup_one_len(name, dir, strlen(name));
if (!IS_ERR(dentry)) {
- error = cgroup_create_file(dentry, 0644 | S_IFREG,
+ mode = cgroup_file_mode(cft);
+ error = cgroup_create_file(dentry, mode | S_IFREG,
cgrp->root->sb);
if (!error)
dentry->d_fsdata = (void *)cft;
int cgroup_task_count(const struct cgroup *cgrp)
{
int count = 0;
- struct list_head *l;
+ struct cg_cgroup_link *link;
read_lock(&css_set_lock);
- l = cgrp->css_sets.next;
- while (l != &cgrp->css_sets) {
- struct cg_cgroup_link *link =
- list_entry(l, struct cg_cgroup_link, cgrp_link_list);
- count += atomic_read(&link->cg->ref.refcount);
- l = l->next;
+ list_for_each_entry(link, &cgrp->css_sets, cgrp_link_list) {
+ count += atomic_read(&link->cg->refcount);
}
read_unlock(&css_set_lock);
return count;
{
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)
res = list_entry(l, struct task_struct, cg_list);
/* Advance iterator to find next entry */
l = l->next;
- if (l == &res->cgroups->tasks) {
+ 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);
* but we cannot guarantee that the information we produce is correct
* unless we produce it entirely atomically.
*
- * Upon tasks file open(), a struct ctr_struct is allocated, that
- * will have a pointer to an array (also allocated here). The struct
- * ctr_struct * is stored in file->private_data. Its resources will
- * be freed by release() when the file is closed. The array is used
- * to sprintf the PIDs and then used by read().
*/
-struct ctr_struct {
- char *buf;
- int bufsz;
-};
/*
* Load into 'pidarray' up to 'npids' of the tasks using cgroup
*/
static int pid_array_load(pid_t *pidarray, int npids, struct cgroup *cgrp)
{
- int n = 0;
+ int n = 0, pid;
struct cgroup_iter it;
struct task_struct *tsk;
cgroup_iter_start(cgrp, &it);
while ((tsk = cgroup_iter_next(cgrp, &it))) {
if (unlikely(n == npids))
break;
- pidarray[n++] = task_pid_vnr(tsk);
+ pid = task_pid_vnr(tsk);
+ if (pid > 0)
+ pidarray[n++] = pid;
}
cgroup_iter_end(cgrp, &it);
return n;
struct cgroup *cgrp;
struct cgroup_iter it;
struct task_struct *tsk;
+
/*
- * Validate dentry by checking the superblock operations
+ * Validate dentry by checking the superblock operations,
+ * and make sure it's a directory.
*/
- if (dentry->d_sb->s_op != &cgroup_ops)
+ if (dentry->d_sb->s_op != &cgroup_ops ||
+ !S_ISDIR(dentry->d_inode->i_mode))
goto err;
ret = 0;
cgrp = dentry->d_fsdata;
- rcu_read_lock();
cgroup_iter_start(cgrp, &it);
while ((tsk = cgroup_iter_next(cgrp, &it))) {
}
cgroup_iter_end(cgrp, &it);
- rcu_read_unlock();
err:
return ret;
}
return *(pid_t *)a - *(pid_t *)b;
}
+
/*
- * Convert array 'a' of 'npids' pid_t's to a string of newline separated
- * decimal pids in 'buf'. Don't write more than 'sz' chars, but return
- * count 'cnt' of how many chars would be written if buf were large enough.
+ * seq_file methods for the "tasks" file. The seq_file position is the
+ * next pid to display; the seq_file iterator is a pointer to the pid
+ * in the cgroup->tasks_pids array.
*/
-static int pid_array_to_buf(char *buf, int sz, pid_t *a, int npids)
+
+static void *cgroup_tasks_start(struct seq_file *s, loff_t *pos)
{
- int cnt = 0;
- int i;
+ /*
+ * 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 *cgrp = s->private;
+ int index = 0, pid = *pos;
+ int *iter;
- for (i = 0; i < npids; i++)
- cnt += snprintf(buf + cnt, max(sz - cnt, 0), "%d\n", a[i]);
- return cnt;
+ down_read(&cgrp->pids_mutex);
+ if (pid) {
+ int end = cgrp->pids_length;
+
+ while (index < end) {
+ int mid = (index + end) / 2;
+ if (cgrp->tasks_pids[mid] == pid) {
+ index = mid;
+ break;
+ } else if (cgrp->tasks_pids[mid] <= pid)
+ index = mid + 1;
+ else
+ end = mid;
+ }
+ }
+ /* If we're off the end of the array, we're done */
+ if (index >= cgrp->pids_length)
+ return NULL;
+ /* Update the abstract position to be the actual pid that we found */
+ iter = cgrp->tasks_pids + index;
+ *pos = *iter;
+ return iter;
}
+static void cgroup_tasks_stop(struct seq_file *s, void *v)
+{
+ struct cgroup *cgrp = s->private;
+ up_read(&cgrp->pids_mutex);
+}
+
+static void *cgroup_tasks_next(struct seq_file *s, void *v, loff_t *pos)
+{
+ struct cgroup *cgrp = s->private;
+ int *p = v;
+ int *end = cgrp->tasks_pids + cgrp->pids_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_tasks_show(struct seq_file *s, void *v)
+{
+ return seq_printf(s, "%d\n", *(int *)v);
+}
+
+static struct seq_operations cgroup_tasks_seq_operations = {
+ .start = cgroup_tasks_start,
+ .stop = cgroup_tasks_stop,
+ .next = cgroup_tasks_next,
+ .show = cgroup_tasks_show,
+};
+
+static void release_cgroup_pid_array(struct cgroup *cgrp)
+{
+ down_write(&cgrp->pids_mutex);
+ BUG_ON(!cgrp->pids_use_count);
+ if (!--cgrp->pids_use_count) {
+ kfree(cgrp->tasks_pids);
+ cgrp->tasks_pids = NULL;
+ cgrp->pids_length = 0;
+ }
+ up_write(&cgrp->pids_mutex);
+}
+
+static int cgroup_tasks_release(struct inode *inode, struct file *file)
+{
+ struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);
+
+ if (!(file->f_mode & FMODE_READ))
+ return 0;
+
+ release_cgroup_pid_array(cgrp);
+ return seq_release(inode, file);
+}
+
+static struct file_operations cgroup_tasks_operations = {
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .write = cgroup_file_write,
+ .release = cgroup_tasks_release,
+};
+
/*
- * Handle an open on 'tasks' file. Prepare a buffer listing the
+ * Handle an open on 'tasks' file. Prepare an array containing the
* process id's of tasks currently attached to the cgroup being opened.
- *
- * Does not require any specific cgroup mutexes, and does not take any.
*/
+
static int cgroup_tasks_open(struct inode *unused, struct file *file)
{
struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);
- struct ctr_struct *ctr;
pid_t *pidarray;
int npids;
- char c;
+ int retval;
+ /* Nothing to do for write-only files */
if (!(file->f_mode & FMODE_READ))
return 0;
- ctr = kmalloc(sizeof(*ctr), GFP_KERNEL);
- if (!ctr)
- goto err0;
-
/*
* If cgroup gets more users after we read count, we won't have
* enough space - tough. This race is indistinguishable to the
* show up until sometime later on.
*/
npids = cgroup_task_count(cgrp);
- if (npids) {
- pidarray = kmalloc(npids * sizeof(pid_t), GFP_KERNEL);
- if (!pidarray)
- goto err1;
-
- npids = pid_array_load(pidarray, npids, cgrp);
- sort(pidarray, npids, sizeof(pid_t), cmppid, NULL);
-
- /* Call pid_array_to_buf() twice, first just to get bufsz */
- ctr->bufsz = pid_array_to_buf(&c, sizeof(c), pidarray, npids) + 1;
- ctr->buf = kmalloc(ctr->bufsz, GFP_KERNEL);
- if (!ctr->buf)
- goto err2;
- ctr->bufsz = pid_array_to_buf(ctr->buf, ctr->bufsz, pidarray, npids);
-
- kfree(pidarray);
- } else {
- ctr->buf = NULL;
- ctr->bufsz = 0;
- }
- file->private_data = ctr;
- return 0;
-
-err2:
- kfree(pidarray);
-err1:
- kfree(ctr);
-err0:
- return -ENOMEM;
-}
-
-static ssize_t cgroup_tasks_read(struct cgroup *cgrp,
- struct cftype *cft,
- struct file *file, char __user *buf,
- size_t nbytes, loff_t *ppos)
-{
- struct ctr_struct *ctr = file->private_data;
+ pidarray = kmalloc(npids * sizeof(pid_t), GFP_KERNEL);
+ if (!pidarray)
+ return -ENOMEM;
+ npids = pid_array_load(pidarray, npids, cgrp);
+ sort(pidarray, npids, sizeof(pid_t), cmppid, NULL);
- return simple_read_from_buffer(buf, nbytes, ppos, ctr->buf, ctr->bufsz);
-}
+ /*
+ * Store the array in the cgroup, freeing the old
+ * array if necessary
+ */
+ down_write(&cgrp->pids_mutex);
+ kfree(cgrp->tasks_pids);
+ cgrp->tasks_pids = pidarray;
+ cgrp->pids_length = npids;
+ cgrp->pids_use_count++;
+ up_write(&cgrp->pids_mutex);
-static int cgroup_tasks_release(struct inode *unused_inode,
- struct file *file)
-{
- struct ctr_struct *ctr;
+ file->f_op = &cgroup_tasks_operations;
- if (file->f_mode & FMODE_READ) {
- ctr = file->private_data;
- kfree(ctr->buf);
- kfree(ctr);
+ retval = seq_open(file, &cgroup_tasks_seq_operations);
+ if (retval) {
+ release_cgroup_pid_array(cgrp);
+ return retval;
}
+ ((struct seq_file *)file->private_data)->private = cgrp;
return 0;
}
return notify_on_release(cgrp);
}
-static u64 cgroup_read_releasable(struct cgroup *cgrp, struct cftype *cft)
+static int cgroup_write_notify_on_release(struct cgroup *cgrp,
+ struct cftype *cft,
+ u64 val)
{
- return test_bit(CGRP_RELEASABLE, &cgrp->flags);
+ 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;
}
/*
{
.name = "tasks",
.open = cgroup_tasks_open,
- .read = cgroup_tasks_read,
- .write = cgroup_common_file_write,
+ .write_u64 = cgroup_tasks_write,
.release = cgroup_tasks_release,
.private = FILE_TASKLIST,
+ .mode = S_IRUGO | S_IWUSR,
},
{
.name = "notify_on_release",
- .read_uint = cgroup_read_notify_on_release,
- .write = cgroup_common_file_write,
+ .read_u64 = cgroup_read_notify_on_release,
+ .write_u64 = cgroup_write_notify_on_release,
.private = FILE_NOTIFY_ON_RELEASE,
},
-
- {
- .name = "releasable",
- .read_uint = cgroup_read_releasable,
- .private = FILE_RELEASABLE,
- }
};
static struct cftype cft_release_agent = {
.name = "release_agent",
- .read = cgroup_common_file_read,
- .write = cgroup_common_file_write,
+ .read_seq_string = cgroup_release_agent_show,
+ .write_string = cgroup_release_agent_write,
+ .max_write_len = PATH_MAX,
.private = FILE_RELEASE_AGENT,
};
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;
}
struct cgroup *cgrp)
{
css->cgroup = cgrp;
- atomic_set(&css->refcnt, 0);
+ 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
* Must be called with the mutex on the parent inode held
*/
static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
- int mode)
+ mode_t mode)
{
struct cgroup *cgrp;
struct cgroupfs_root *root = parent->root;
mutex_lock(&cgroup_mutex);
- INIT_LIST_HEAD(&cgrp->sibling);
- INIT_LIST_HEAD(&cgrp->children);
- INIT_LIST_HEAD(&cgrp->css_sets);
- INIT_LIST_HEAD(&cgrp->release_list);
+ init_cgroup_housekeeping(cgrp);
cgrp->parent = parent;
cgrp->root = parent->root;
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);
err_remove:
+ cgroup_lock_hierarchy(root);
list_del(&cgrp->sibling);
+ cgroup_unlock_hierarchy(root);
root->number_of_cgroups--;
err_destroy:
return cgroup_create(c_parent, dentry, mode | S_IFDIR);
}
-static inline int cgroup_has_css_refs(struct cgroup *cgrp)
+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 0, then there should
+ * 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
* 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))
+ 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;
- struct super_block *sb;
- struct cgroupfs_root *root;
+ 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);
mutex_unlock(&cgroup_mutex);
return -EBUSY;
}
-
- parent = cgrp->parent;
- root = cgrp->root;
- sb = root->sb;
+ mutex_unlock(&cgroup_mutex);
/*
* Call pre_destroy handlers of subsys. Notify subsystems
* that rmdir() request comes.
*/
- cgroup_call_pre_destroy(cgrp);
+ ret = cgroup_call_pre_destroy(cgrp);
+ if (ret)
+ return ret;
- if (cgroup_has_css_refs(cgrp)) {
+ mutex_lock(&cgroup_mutex);
+ parent = cgrp->parent;
+ if (atomic_read(&cgrp->count) || !list_empty(&cgrp->children)) {
mutex_unlock(&cgroup_mutex);
return -EBUSY;
}
+ /*
+ * css_put/get is provided for subsys to grab refcnt to css. In typical
+ * case, subsystem has no reference after pre_destroy(). But, under
+ * hierarchy management, some *temporal* refcnt can be hold.
+ * To avoid returning -EBUSY to a user, waitqueue is used. If subsys
+ * is really busy, it should return -EBUSY at pre_destroy(). wake_up
+ * is called when css_put() is called and refcnt goes down to 0.
+ */
+ set_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags);
+ prepare_to_wait(&cgroup_rmdir_waitq, &wait, TASK_INTERRUPTIBLE);
+
+ if (!cgroup_clear_css_refs(cgrp)) {
+ mutex_unlock(&cgroup_mutex);
+ 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);
- /* delete my sibling from parent->children */
+
+ 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);
- cgrp->dentry = NULL;
spin_unlock(&d->d_lock);
cgroup_d_remove_dir(d);
return 0;
}
-static void cgroup_init_subsys(struct cgroup_subsys *ss)
+static void __init cgroup_init_subsys(struct cgroup_subsys *ss)
{
struct cgroup_subsys_state *css;
- struct list_head *l;
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 all cgroup groups to contain a subsys
+ /* Update the init_css_set to contain a subsys
* pointer to this state - since the subsystem is
- * newly registered, all tasks and hence all cgroup
- * groups are in the subsystem's top cgroup. */
- write_lock(&css_set_lock);
- l = &init_css_set.list;
- do {
- struct css_set *cg =
- list_entry(l, struct css_set, list);
- cg->subsys[ss->subsys_id] = dummytop->subsys[ss->subsys_id];
- l = l->next;
- } while (l != &init_css_set.list);
- write_unlock(&css_set_lock);
-
- /* If this subsystem requested that it be notified with fork
- * events, we should send it one now for every process in the
- * system */
- if (ss->fork) {
- struct task_struct *g, *p;
-
- read_lock(&tasklist_lock);
- do_each_thread(g, p) {
- ss->fork(ss, p);
- } while_each_thread(g, p);
- read_unlock(&tasklist_lock);
- }
+ * 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;
}
int __init cgroup_init_early(void)
{
int i;
- kref_init(&init_css_set.ref);
- kref_get(&init_css_set.ref);
- INIT_LIST_HEAD(&init_css_set.list);
+ 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);
- list_add(&rootnode.root_list, &roots);
root_count = 1;
init_task.cgroups = &init_css_set;
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];
{
int err;
int i;
- struct proc_dir_entry *entry;
+ struct hlist_head *hhead;
err = bdi_init(&cgroup_backing_dev_info);
if (err)
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);
+
err = register_filesystem(&cgroup_fs_type);
if (err < 0)
goto out;
- entry = create_proc_entry("cgroups", 0, NULL);
- if (entry)
- entry->proc_fops = &proc_cgroupstats_operations;
+ proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations);
out:
if (err)
mutex_lock(&cgroup_mutex);
- for_each_root(root) {
+ for_each_active_root(root) {
struct cgroup_subsys *ss;
struct cgroup *cgrp;
int subsys_id;
int count = 0;
- /* Skip this hierarchy if it has no active subsystems */
- if (!root->actual_subsys_bits)
- continue;
seq_printf(m, "%lu:", root->subsys_bits);
for_each_subsys(root, ss)
seq_printf(m, "%s%s", count++ ? "," : "", ss->name);
{
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_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)
+int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *subsys,
+ char *nodename)
{
struct dentry *dentry;
int ret = 0;
- char nodename[MAX_CGROUP_TYPE_NAMELEN];
struct cgroup *parent, *child;
struct inode *inode;
struct css_set *cg;
again:
root = subsys->root;
if (root == &rootnode) {
- printk(KERN_INFO
- "Not cloning cgroup for unused subsystem %s\n",
- subsys->name);
mutex_unlock(&cgroup_mutex);
return 0;
}
- cg = tsk->cgroups;
- parent = task_cgroup(tsk, subsys->subsys_id);
-
- snprintf(nodename, MAX_CGROUP_TYPE_NAMELEN, "node_%d", tsk->pid);
/* Pin the hierarchy */
- atomic_inc(&parent->root->sb->s_active);
+ 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 */
}
/* Create the cgroup directory, which also creates the cgroup */
- ret = vfs_mkdir(inode, dentry, S_IFDIR | 0755);
+ ret = vfs_mkdir(inode, dentry, 0755);
child = __d_cgrp(dentry);
dput(dentry);
if (ret) {
goto out_release;
}
- if (!child) {
- printk(KERN_INFO
- "Couldn't find new cgroup %s\n", nodename);
- ret = -ENOMEM;
- 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_unlock(&inode->i_mutex);
put_css_set(cg);
- deactivate_super(parent->root->sb);
+ 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. */
mutex_lock(&cgroup_mutex);
put_css_set(cg);
mutex_unlock(&cgroup_mutex);
- deactivate_super(parent->root->sb);
+ deactivate_super(root->sb);
return ret;
}
/**
- * cgroup_is_descendant - see if @cgrp is a descendant of current task's cgrp
+ * 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 the current task's cgroup in
- * the appropriate hierarchy.
+ * 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)
+int cgroup_is_descendant(const struct cgroup *cgrp, struct task_struct *task)
{
int ret;
struct cgroup *target;
return 1;
get_first_subsys(cgrp, NULL, &subsys_id);
- target = task_cgroup(current, subsys_id);
+ target = task_cgroup(task, subsys_id);
while (cgrp != target && cgrp!= cgrp->top_cgroup)
cgrp = cgrp->parent;
ret = (cgrp == target);
{
struct cgroup *cgrp = css->cgroup;
rcu_read_lock();
- if (atomic_dec_and_test(&css->refcnt) && notify_on_release(cgrp)) {
- set_bit(CGRP_RELEASABLE, &cgrp->flags);
- check_for_release(cgrp);
+ if (atomic_dec_return(&css->refcnt) == 1) {
+ if (notify_on_release(cgrp)) {
+ set_bit(CGRP_RELEASABLE, &cgrp->flags);
+ check_for_release(cgrp);
+ }
+ cgroup_wakeup_rmdir_waiters(cgrp);
}
rcu_read_unlock();
}
while (!list_empty(&release_list)) {
char *argv[3], *envp[3];
int i;
- char *pathbuf;
+ 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) {
- spin_lock(&release_list_lock);
- continue;
- }
-
- if (cgroup_path(cgrp, pathbuf, PAGE_SIZE) < 0) {
- kfree(pathbuf);
- spin_lock(&release_list_lock);
- continue;
- }
+ 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++] = cgrp->root->release_agent_path;
- argv[i++] = (char *)pathbuf;
+ argv[i++] = agentbuf;
+ argv[i++] = pathbuf;
argv[i] = NULL;
i = 0;
* be a slow process */
mutex_unlock(&cgroup_mutex);
call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
- kfree(pathbuf);
mutex_lock(&cgroup_mutex);
+ continue_free:
+ kfree(pathbuf);
+ kfree(agentbuf);
spin_lock(&release_list_lock);
}
spin_unlock(&release_list_lock);
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;
+}
+
Code Review / linux-2.6.git / blobdiff