/* 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 */
* be called.
*/
static int need_forkexit_callback __read_mostly;
-static int need_mm_owner_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
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)
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;
+ list_move(&link->cgrp_link_list, &cgrp->css_sets);
+ list_add(&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
int i;
struct list_head tmp_cg_links;
- struct cg_cgroup_link *link;
struct hlist_head *hhead;
* 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));
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;
}
{
struct cgroup_subsys *ss;
for_each_subsys(cgrp->root, ss)
- if (ss->pre_destroy && cgrp->subsys[ss->subsys_id])
+ if (ss->pre_destroy)
ss->pre_destroy(ss, cgrp);
return;
}
+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 */
/*
* 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);
}
* 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]);
.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)
root = NULL;
} else {
/* New superblock */
- struct cgroup *cgrp = &root->top_cgroup;
+ struct cgroup *root_cgrp = &root->top_cgroup;
struct inode *inode;
int i;
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
struct hlist_node *node;
struct css_set *cg;
- hlist_for_each_entry(cg, node, hhead, hlist) {
- struct cg_cgroup_link *link;
-
- 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);
- }
+ 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);
+ free_cg_links:
+ free_cg_links(&tmp_cg_links);
drop_new_super:
up_write(&sb->s_umount);
deactivate_super(sb);
- free_cg_links(&tmp_cg_links);
return ret;
}
}
write_unlock(&css_set_lock);
- if (!list_empty(&root->root_list)) {
- list_del(&root->root_list);
- root_count--;
- }
+ list_del(&root->root_list);
+ root_count--;
+
mutex_unlock(&cgroup_mutex);
kfree(root);
* @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;
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_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);
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);
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)
err = generic_file_open(inode, file);
if (err)
return err;
-
cft = __d_cft(file->f_dentry);
- if (!cft)
- return -ENODEV;
+
if (cft->read_map || cft->read_seq_string) {
struct cgroup_seqfile_state *state =
kzalloc(sizeof(*state), GFP_USER);
if (!error) {
dentry->d_fsdata = cgrp;
inc_nlink(parent->d_inode);
- cgrp->dentry = dentry;
+ rcu_assign_pointer(cgrp->dentry, dentry);
dget(dentry);
}
dput(dentry);
{
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;
+
+ 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;
- for (i = 0; i < npids; i++)
- cnt += snprintf(buf + cnt, max(sz - cnt, 0), "%d\n", a[i]);
- return cnt;
+ 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;
}
{
.name = "tasks",
.open = cgroup_tasks_open,
- .read = cgroup_tasks_read,
.write_u64 = cgroup_tasks_write,
.release = cgroup_tasks_release,
.private = FILE_TASKLIST,
struct cgroup *cgrp)
{
css->cgroup = cgrp;
- atomic_set(&css->refcnt, 0);
+ atomic_set(&css->refcnt, 1);
css->flags = 0;
if (cgrp == dummytop)
set_bit(CSS_ROOT, &css->flags);
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_nested(&ss->hierarchy_mutex, i);
+ }
+}
+
+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
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;
init_cgroup_css(css, ss, cgrp);
}
+ 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);
{
/* 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;
+ do {
+ /* 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
+ */
+ } while (atomic_cmpxchg(&css->refcnt, refcnt, 0) != refcnt);
+ }
+ 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;
/* the vfs holds both inode->i_mutex already */
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
*/
cgroup_call_pre_destroy(cgrp);
- if (cgroup_has_css_refs(cgrp)) {
+ mutex_lock(&cgroup_mutex);
+ parent = cgrp->parent;
+
+ if (atomic_read(&cgrp->count)
+ || !list_empty(&cgrp->children)
+ || !cgroup_clear_css_refs(cgrp)) {
mutex_unlock(&cgroup_mutex);
return -EBUSY;
}
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);
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 */
init_css_set.subsys[ss->subsys_id] = dummytop->subsys[ss->subsys_id];
need_forkexit_callback |= ss->fork || ss->exit;
- need_mm_owner_callback |= !!ss->mm_owner_changed;
/* 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);
ss->active = 1;
}
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;
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);
}
}
-#ifdef CONFIG_MM_OWNER
-/**
- * cgroup_mm_owner_callbacks - run callbacks when the mm->owner changes
- * @p: the new owner
- *
- * Called on every change to mm->owner. mm_init_owner() does not
- * invoke this routine, since it assigns the mm->owner the first time
- * and does not change it.
- *
- * The callbacks are invoked with mmap_sem held in read mode.
- */
-void cgroup_mm_owner_callbacks(struct task_struct *old, struct task_struct *new)
-{
- struct cgroup *oldcgrp, *newcgrp = NULL;
-
- if (need_mm_owner_callback) {
- int i;
- for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
- struct cgroup_subsys *ss = subsys[i];
- oldcgrp = task_cgroup(old, ss->subsys_id);
- if (new)
- newcgrp = task_cgroup(new, ss->subsys_id);
- if (oldcgrp == newcgrp)
- continue;
- if (ss->mm_owner_changed)
- ss->mm_owner_changed(ss, oldcgrp, newcgrp, new);
- }
- }
-}
-#endif /* CONFIG_MM_OWNER */
-
/**
* cgroup_post_fork - called on a new task after adding it to the task list
* @child: the task in question
{
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);
}
}
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;
}
+ task_lock(tsk);
cg = tsk->cgroups;
parent = task_cgroup(tsk, subsys->subsys_id);
/* Pin the hierarchy */
- atomic_inc(&parent->root->sb->s_active);
+ if (!atomic_inc_not_zero(&parent->root->sb->s_active)) {
+ /* We race with the final deactivate_super() */
+ mutex_unlock(&cgroup_mutex);
+ return 0;
+ }
/* Keep the cgroup alive */
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. */
{
struct cgroup *cgrp = css->cgroup;
rcu_read_lock();
- if (atomic_dec_and_test(&css->refcnt) && notify_on_release(cgrp)) {
+ if ((atomic_dec_return(&css->refcnt) == 1) &&
+ notify_on_release(cgrp)) {
set_bit(CGRP_RELEASABLE, &cgrp->flags);
check_for_release(cgrp);
}
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff