/*
- * kernel/cgroup.c
- *
* Generic process-grouping system.
*
* Based originally on the cpuset system, extracted by Paul Menage
#include <linux/mutex.h>
#include <linux/mount.h>
#include <linux/pagemap.h>
+#include <linux/proc_fs.h>
#include <linux/rcupdate.h>
#include <linux/sched.h>
+#include <linux/backing-dev.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/magic.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/sort.h>
+#include <linux/kmod.h>
+#include <linux/delayacct.h>
+#include <linux/cgroupstats.h>
+
#include <asm/atomic.h>
+static DEFINE_MUTEX(cgroup_mutex);
+
/* Generate an array of cgroup subsystem pointers */
#define SUBSYS(_x) &_x ## _subsys,
/* 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 */
+ char release_agent_path[PATH_MAX];
};
/* The list of hierarchy roots */
static LIST_HEAD(roots);
+static int root_count;
/* dummytop is a shorthand for the dummy hierarchy's top cgroup */
#define dummytop (&rootnode.top_cgroup)
/* This flag indicates whether tasks in the fork and exit paths should
- * take callback_mutex and check for fork/exit handlers to call. This
- * avoids us having to do extra work in the fork/exit path if none of the
- * subsystems need to be called.
+ * check for fork/exit handlers to call. This avoids us having to do
+ * extra work in the fork/exit path if none of the subsystems need to
+ * be called.
*/
static int need_forkexit_callback;
/* bits in struct cgroup flags field */
enum {
- CONT_REMOVED,
+ /* 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,
};
/* convenient tests for these bits */
-inline int cgroup_is_removed(const struct cgroup *cont)
+inline int cgroup_is_removed(const struct cgroup *cgrp)
{
- return test_bit(CONT_REMOVED, &cont->flags);
+ return test_bit(CGRP_REMOVED, &cgrp->flags);
}
/* bits in struct cgroupfs_root flags field */
ROOT_NOPREFIX, /* mounted subsystems have no named prefix */
};
+static int cgroup_is_releasable(const struct cgroup *cgrp)
+{
+ const int bits =
+ (1 << CGRP_RELEASABLE) |
+ (1 << CGRP_NOTIFY_ON_RELEASE);
+ return (cgrp->flags & bits) == bits;
+}
+
+static int notify_on_release(const struct cgroup *cgrp)
+{
+ return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
+}
+
/*
* for_each_subsys() allows you to iterate on each subsystem attached to
* an active hierarchy
#define for_each_root(_root) \
list_for_each_entry(_root, &roots, root_list)
+/* the list of cgroups eligible for automatic release. Protected by
+ * release_list_lock */
+static LIST_HEAD(release_list);
+static DEFINE_SPINLOCK(release_list_lock);
+static void cgroup_release_agent(struct work_struct *work);
+static DECLARE_WORK(release_agent_work, cgroup_release_agent);
+static void check_for_release(struct cgroup *cgrp);
+
+/* Link structure for associating css_set objects with cgroups */
+struct cg_cgroup_link {
+ /*
+ * List running through cg_cgroup_links associated with a
+ * cgroup, anchored on cgroup->css_sets
+ */
+ struct list_head cgrp_link_list;
+ /*
+ * List running through cg_cgroup_links pointing at a
+ * single css_set object, anchored on css_set->cg_links
+ */
+ struct list_head cg_link_list;
+ struct css_set *cg;
+};
+
+/* The default css_set - used by init and its children prior to any
+ * hierarchies being mounted. It contains a pointer to the root state
+ * for each subsystem. Also used to anchor the list of css_sets. Not
+ * reference-counted, to improve performance when child cgroups
+ * haven't been created.
+ */
+
+static struct css_set init_css_set;
+static struct cg_cgroup_link init_css_set_link;
+
+/* 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;
+
+/* 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;
+
+/* When we create or destroy a css_set, the operation simply
+ * takes/releases a reference count on all the cgroups referenced
+ * by subsystems in this css_set. This can end up multiple-counting
+ * some cgroups, but that's OK - the ref-count is just a
+ * busy/not-busy indicator; ensuring that we only count each cgroup
+ * once would require taking a global lock to ensure that no
+ * subsystems moved between hierarchies while we were doing so.
+ *
+ * Possible TODO: decide at boot time based on the number of
+ * registered subsystems and the number of CPUs or NUMA nodes whether
+ * it's better for performance to ref-count every subsystem, or to
+ * take a global lock and only add one ref count to each hierarchy.
+ */
+
+/*
+ * unlink a css_set from the list and free it
+ */
+static void unlink_css_set(struct css_set *cg)
+{
+ write_lock(&css_set_lock);
+ list_del(&cg->list);
+ 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_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)
+{
+ int i;
+ struct css_set *cg = container_of(k, struct css_set, ref);
+
+ unlink_css_set(cg);
+
+ rcu_read_lock();
+ for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
+ struct cgroup *cgrp = cg->subsys[i]->cgroup;
+ 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(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);
+}
+
+static inline void put_css_set(struct css_set *cg)
+{
+ kref_put(&cg->ref, release_css_set);
+}
+
+static inline void put_css_set_taskexit(struct css_set *cg)
+{
+ kref_put(&cg->ref, release_css_set_taskexit);
+}
+
+/*
+ * 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
+ *
+ * oldcg: the cgroup group that we're using before the cgroup
+ * transition
+ *
+ * cgrp: the cgroup that we're moving into
+ *
+ * template: location in which to build the desired set of subsystem
+ * state objects for the new cgroup group
+ */
+static struct css_set *find_existing_css_set(
+ struct css_set *oldcg,
+ struct cgroup *cgrp,
+ struct cgroup_subsys_state *template[])
+{
+ int i;
+ struct cgroupfs_root *root = cgrp->root;
+ struct list_head *l = &init_css_set.list;
+
+ /* Built the set of subsystem state objects that we want to
+ * see in the new css_set */
+ for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
+ if (root->subsys_bits & (1ull << i)) {
+ /* Subsystem is in this hierarchy. So we want
+ * the subsystem state from the new
+ * cgroup */
+ template[i] = cgrp->subsys[i];
+ } else {
+ /* Subsystem is not in this hierarchy, so we
+ * don't want to change the subsystem state */
+ template[i] = oldcg->subsys[i];
+ }
+ }
+
+ /* Look through existing cgroup groups to find one to reuse */
+ do {
+ struct css_set *cg =
+ list_entry(l, struct css_set, list);
+
+ 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;
+}
+
+/*
+ * allocate_cg_links() allocates "count" cg_cgroup_link structures
+ * and chains them on tmp through their cgrp_link_list fields. Returns 0 on
+ * success or a negative error
+ */
+static int allocate_cg_links(int count, struct list_head *tmp)
+{
+ struct cg_cgroup_link *link;
+ int i;
+ INIT_LIST_HEAD(tmp);
+ for (i = 0; i < count; i++) {
+ link = kmalloc(sizeof(*link), GFP_KERNEL);
+ if (!link) {
+ while (!list_empty(tmp)) {
+ link = list_entry(tmp->next,
+ struct cg_cgroup_link,
+ cgrp_link_list);
+ list_del(&link->cgrp_link_list);
+ kfree(link);
+ }
+ return -ENOMEM;
+ }
+ list_add(&link->cgrp_link_list, tmp);
+ }
+ return 0;
+}
+
+static void free_cg_links(struct list_head *tmp)
+{
+ 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);
+ }
+}
+
+/*
+ * find_css_set() takes an existing cgroup group and a
+ * cgroup object, and returns a css_set object that's
+ * equivalent to the old group, but with the given cgroup
+ * substituted into the appropriate hierarchy. Must be called with
+ * cgroup_mutex held
+ */
+static struct css_set *find_css_set(
+ struct css_set *oldcg, struct cgroup *cgrp)
+{
+ struct css_set *res;
+ struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT];
+ int i;
+
+ struct list_head tmp_cg_links;
+ struct cg_cgroup_link *link;
+
+ /* First see if we already have a cgroup group that matches
+ * the desired set */
+ write_lock(&css_set_lock);
+ res = find_existing_css_set(oldcg, cgrp, template);
+ if (res)
+ get_css_set(res);
+ write_unlock(&css_set_lock);
+
+ if (res)
+ return res;
+
+ res = kmalloc(sizeof(*res), GFP_KERNEL);
+ if (!res)
+ return NULL;
+
+ /* Allocate all the cg_cgroup_link objects that we'll need */
+ if (allocate_cg_links(root_count, &tmp_cg_links) < 0) {
+ kfree(res);
+ return NULL;
+ }
+
+ kref_init(&res->ref);
+ INIT_LIST_HEAD(&res->cg_links);
+ INIT_LIST_HEAD(&res->tasks);
+
+ /* Copy the set of subsystem state objects generated in
+ * find_existing_css_set() */
+ memcpy(res->subsys, template, sizeof(res->subsys));
+
+ write_lock(&css_set_lock);
+ /* Add reference counts and links from the new css_set. */
+ for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
+ struct cgroup *cgrp = res->subsys[i]->cgroup;
+ struct cgroup_subsys *ss = subsys[i];
+ atomic_inc(&cgrp->count);
+ /*
+ * We want to add a link once per cgroup, so we
+ * 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);
+ }
+
+ 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++;
+ INIT_LIST_HEAD(&res->tasks);
+ write_unlock(&css_set_lock);
+
+ return res;
+}
+
/*
* There is one global cgroup mutex. We also require taking
* task_lock() when dereferencing a task's cgroup subsys pointers.
* Any task can increment and decrement the count field without lock.
* So in general, code holding cgroup_mutex can't rely on the count
* field not changing. However, if the count goes to zero, then only
- * attach_task() can increment it again. Because a count of zero
+ * cgroup_attach_task() can increment it again. Because a count of zero
* means that no tasks are currently attached, therefore there is no
* way a task attached to that cgroup can fork (the other way to
* increment the count). So code holding cgroup_mutex can safely
* critical pieces of code here. The exception occurs on cgroup_exit(),
* when a task in a notify_on_release cgroup exits. Then cgroup_mutex
* is taken, and if the cgroup count is zero, a usermode call made
- * to /sbin/cgroup_release_agent with the name of the cgroup (path
- * relative to the root of cgroup file system) as the argument.
+ * to the release agent with the name of the cgroup (path relative to
+ * the root of cgroup file system) as the argument.
*
* A cgroup can only be deleted if both its 'count' of using tasks
* is zero, and its list of 'children' cgroups is empty. Since all
* The task_lock() exception
*
* The need for this exception arises from the action of
- * attach_task(), which overwrites one tasks cgroup pointer with
- * another. It does so using cgroup_mutexe, however there are
+ * cgroup_attach_task(), which overwrites one tasks cgroup pointer with
+ * another. It does so using cgroup_mutex, however there are
* several performance critical places that need to reference
* task->cgroup without the expense of grabbing a system global
* mutex. Therefore except as noted below, when dereferencing or, as
- * in attach_task(), modifying a task'ss cgroup pointer we use
+ * in cgroup_attach_task(), modifying a task'ss cgroup pointer we use
* task_lock(), which acts on a spinlock (task->alloc_lock) already in
* the task_struct routinely used for such matters.
*
* P.S. One more locking exception. RCU is used to guard the
- * update of a tasks cgroup pointer by attach_task()
+ * update of a tasks cgroup pointer by cgroup_attach_task()
*/
-static DEFINE_MUTEX(cgroup_mutex);
-
/**
* cgroup_lock - lock out any changes to cgroup structures
*
*/
-
void cgroup_lock(void)
{
mutex_lock(&cgroup_mutex);
*
* Undo the lock taken in a previous cgroup_lock() call.
*/
-
void cgroup_unlock(void)
{
mutex_unlock(&cgroup_mutex);
static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, int mode);
static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry);
-static int cgroup_populate_dir(struct cgroup *cont);
+static int cgroup_populate_dir(struct cgroup *cgrp);
static struct inode_operations cgroup_dir_inode_operations;
+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,
+};
static struct inode *cgroup_new_inode(mode_t mode, struct super_block *sb)
{
struct inode *inode = new_inode(sb);
- static struct backing_dev_info cgroup_backing_dev_info = {
- .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
- };
if (inode) {
inode->i_mode = mode;
return inode;
}
+/*
+ * Call subsys's pre_destroy handler.
+ * This is called before css refcnt check.
+ */
+static void cgroup_call_pre_destroy(struct cgroup *cgrp)
+{
+ struct cgroup_subsys *ss;
+ for_each_subsys(cgrp->root, ss)
+ if (ss->pre_destroy && cgrp->subsys[ss->subsys_id])
+ ss->pre_destroy(ss, cgrp);
+ return;
+}
+
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 *cont = dentry->d_fsdata;
- BUG_ON(!(cgroup_is_removed(cont)));
- kfree(cont);
+ struct cgroup *cgrp = dentry->d_fsdata;
+ struct cgroup_subsys *ss;
+ BUG_ON(!(cgroup_is_removed(cgrp)));
+ /* It's possible for external users to be holding css
+ * reference counts on a cgroup; css_put() needs to
+ * be able to access the cgroup after decrementing
+ * the reference count in order to know if it needs to
+ * queue the cgroup to be handled by the release
+ * agent */
+ synchronize_rcu();
+
+ mutex_lock(&cgroup_mutex);
+ /*
+ * Release the subsystem state objects.
+ */
+ for_each_subsys(cgrp->root, ss) {
+ if (cgrp->subsys[ss->subsys_id])
+ ss->destroy(ss, cgrp);
+ }
+
+ cgrp->root->number_of_cgroups--;
+ mutex_unlock(&cgroup_mutex);
+
+ /* Drop the active superblock reference that we took when we
+ * created the cgroup */
+ deactivate_super(cgrp->root->sb);
+
+ kfree(cgrp);
}
iput(inode);
}
unsigned long final_bits)
{
unsigned long added_bits, removed_bits;
- struct cgroup *cont = &root->top_cgroup;
+ struct cgroup *cgrp = &root->top_cgroup;
int i;
removed_bits = root->actual_subsys_bits & ~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(&cont->children))
+ if (!list_empty(&cgrp->children))
return -EBUSY;
/* Process each subsystem */
unsigned long bit = 1UL << i;
if (bit & added_bits) {
/* We're binding this subsystem to this hierarchy */
- BUG_ON(cont->subsys[i]);
+ BUG_ON(cgrp->subsys[i]);
BUG_ON(!dummytop->subsys[i]);
BUG_ON(dummytop->subsys[i]->cgroup != dummytop);
- cont->subsys[i] = dummytop->subsys[i];
- cont->subsys[i]->cgroup = cont;
+ cgrp->subsys[i] = dummytop->subsys[i];
+ cgrp->subsys[i]->cgroup = cgrp;
list_add(&ss->sibling, &root->subsys_list);
rcu_assign_pointer(ss->root, root);
if (ss->bind)
- ss->bind(ss, cont);
+ ss->bind(ss, cgrp);
} else if (bit & removed_bits) {
/* We're removing this subsystem */
- BUG_ON(cont->subsys[i] != dummytop->subsys[i]);
- BUG_ON(cont->subsys[i]->cgroup != cont);
+ BUG_ON(cgrp->subsys[i] != dummytop->subsys[i]);
+ BUG_ON(cgrp->subsys[i]->cgroup != cgrp);
if (ss->bind)
ss->bind(ss, dummytop);
dummytop->subsys[i]->cgroup = dummytop;
- cont->subsys[i] = NULL;
+ cgrp->subsys[i] = NULL;
rcu_assign_pointer(subsys[i]->root, &rootnode);
list_del(&ss->sibling);
} else if (bit & final_bits) {
/* Subsystem state should already exist */
- BUG_ON(!cont->subsys[i]);
+ BUG_ON(!cgrp->subsys[i]);
} else {
/* Subsystem state shouldn't exist */
- BUG_ON(cont->subsys[i]);
+ BUG_ON(cgrp->subsys[i]);
}
}
root->subsys_bits = root->actual_subsys_bits = final_bits;
seq_printf(seq, ",%s", ss->name);
if (test_bit(ROOT_NOPREFIX, &root->flags))
seq_puts(seq, ",noprefix");
+ if (strlen(root->release_agent_path))
+ seq_printf(seq, ",release_agent=%s", root->release_agent_path);
mutex_unlock(&cgroup_mutex);
return 0;
}
struct cgroup_sb_opts {
unsigned long subsys_bits;
unsigned long flags;
+ char *release_agent;
};
/* Convert a hierarchy specifier into a bitmask of subsystems and
opts->subsys_bits = 0;
opts->flags = 0;
+ opts->release_agent = NULL;
while ((token = strsep(&o, ",")) != NULL) {
if (!*token)
opts->subsys_bits = (1 << CGROUP_SUBSYS_COUNT) - 1;
} else if (!strcmp(token, "noprefix")) {
set_bit(ROOT_NOPREFIX, &opts->flags);
+ } else if (!strncmp(token, "release_agent=", 14)) {
+ /* Specifying two release agents is forbidden */
+ if (opts->release_agent)
+ return -EINVAL;
+ opts->release_agent = kzalloc(PATH_MAX, GFP_KERNEL);
+ if (!opts->release_agent)
+ return -ENOMEM;
+ strncpy(opts->release_agent, token + 14, PATH_MAX - 1);
+ opts->release_agent[PATH_MAX - 1] = 0;
} else {
struct cgroup_subsys *ss;
int i;
{
int ret = 0;
struct cgroupfs_root *root = sb->s_fs_info;
- struct cgroup *cont = &root->top_cgroup;
+ struct cgroup *cgrp = &root->top_cgroup;
struct cgroup_sb_opts opts;
- mutex_lock(&cont->dentry->d_inode->i_mutex);
+ mutex_lock(&cgrp->dentry->d_inode->i_mutex);
mutex_lock(&cgroup_mutex);
/* See what subsystems are wanted */
/* (re)populate subsystem files */
if (!ret)
- cgroup_populate_dir(cont);
+ 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);
mutex_unlock(&cgroup_mutex);
- mutex_unlock(&cont->dentry->d_inode->i_mutex);
+ mutex_unlock(&cgrp->dentry->d_inode->i_mutex);
return ret;
}
static void init_cgroup_root(struct cgroupfs_root *root)
{
- struct cgroup *cont = &root->top_cgroup;
+ struct cgroup *cgrp = &root->top_cgroup;
INIT_LIST_HEAD(&root->subsys_list);
INIT_LIST_HEAD(&root->root_list);
root->number_of_cgroups = 1;
- cont->root = root;
- cont->top_cgroup = cont;
- INIT_LIST_HEAD(&cont->sibling);
- INIT_LIST_HEAD(&cont->children);
+ 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);
}
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);
/* First find the desired set of subsystems */
ret = parse_cgroupfs_options(data, &opts);
- if (ret)
+ if (ret) {
+ if (opts.release_agent)
+ kfree(opts.release_agent);
return ret;
+ }
root = kzalloc(sizeof(*root), GFP_KERNEL);
- if (!root)
+ if (!root) {
+ if (opts.release_agent)
+ kfree(opts.release_agent);
return -ENOMEM;
+ }
init_cgroup_root(root);
root->subsys_bits = opts.subsys_bits;
root->flags = opts.flags;
+ if (opts.release_agent) {
+ strcpy(root->release_agent_path, opts.release_agent);
+ kfree(opts.release_agent);
+ }
sb = sget(fs_type, cgroup_test_super, cgroup_set_super, root);
root = NULL;
} else {
/* New superblock */
- struct cgroup *cont = &root->top_cgroup;
+ struct cgroup *cgrp = &root->top_cgroup;
+ struct inode *inode;
BUG_ON(sb->s_root != NULL);
ret = cgroup_get_rootdir(sb);
if (ret)
goto drop_new_super;
+ inode = sb->s_root->d_inode;
+ mutex_lock(&inode->i_mutex);
mutex_lock(&cgroup_mutex);
+ /*
+ * We're accessing css_set_count without locking
+ * css_set_lock here, but that's OK - it can only be
+ * increased by someone holding cgroup_lock, and
+ * that's us. The worst that can happen is that we
+ * have some link structures left over
+ */
+ ret = allocate_cg_links(css_set_count, &tmp_cg_links);
+ if (ret) {
+ mutex_unlock(&cgroup_mutex);
+ mutex_unlock(&inode->i_mutex);
+ goto drop_new_super;
+ }
+
ret = rebind_subsystems(root, root->subsys_bits);
if (ret == -EBUSY) {
mutex_unlock(&cgroup_mutex);
+ mutex_unlock(&inode->i_mutex);
goto drop_new_super;
}
BUG_ON(ret);
list_add(&root->root_list, &roots);
+ root_count++;
sb->s_root->d_fsdata = &root->top_cgroup;
root->top_cgroup.dentry = sb->s_root;
- BUG_ON(!list_empty(&cont->sibling));
- BUG_ON(!list_empty(&cont->children));
+ /* Link the top cgroup in this hierarchy into all
+ * the css_set objects */
+ write_lock(&css_set_lock);
+ l = &init_css_set.list;
+ do {
+ 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);
+ 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(root->number_of_cgroups != 1);
- /*
- * I believe that it's safe to nest i_mutex inside
- * cgroup_mutex in this case, since no-one else can
- * be accessing this directory yet. But we still need
- * to teach lockdep that this is the case - currently
- * a cgroupfs remount triggers a lockdep warning
- */
- mutex_lock(&cont->dentry->d_inode->i_mutex);
- cgroup_populate_dir(cont);
- mutex_unlock(&cont->dentry->d_inode->i_mutex);
+ cgroup_populate_dir(cgrp);
+ mutex_unlock(&inode->i_mutex);
mutex_unlock(&cgroup_mutex);
}
drop_new_super:
up_write(&sb->s_umount);
deactivate_super(sb);
+ free_cg_links(&tmp_cg_links);
return ret;
}
static void cgroup_kill_sb(struct super_block *sb) {
struct cgroupfs_root *root = sb->s_fs_info;
- struct cgroup *cont = &root->top_cgroup;
+ struct cgroup *cgrp = &root->top_cgroup;
int ret;
BUG_ON(!root);
BUG_ON(root->number_of_cgroups != 1);
- BUG_ON(!list_empty(&cont->children));
- BUG_ON(!list_empty(&cont->sibling));
+ BUG_ON(!list_empty(&cgrp->children));
+ BUG_ON(!list_empty(&cgrp->sibling));
mutex_lock(&cgroup_mutex);
/* Shouldn't be able to fail ... */
BUG_ON(ret);
- if (!list_empty(&root->root_list))
+ /*
+ * Release all the links from css_sets to this hierarchy's
+ * 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_del(&link->cg_link_list);
+ list_del(&link->cgrp_link_list);
+ kfree(link);
+ }
+ write_unlock(&css_set_lock);
+
+ if (!list_empty(&root->root_list)) {
list_del(&root->root_list);
+ root_count--;
+ }
mutex_unlock(&cgroup_mutex);
kfree(root);
.kill_sb = cgroup_kill_sb,
};
-static inline struct cgroup *__d_cont(struct dentry *dentry)
+static inline struct cgroup *__d_cgrp(struct dentry *dentry)
{
return dentry->d_fsdata;
}
return dentry->d_fsdata;
}
-/*
- * Called with cgroup_mutex held. Writes path of cgroup into buf.
+/**
+ * cgroup_path - generate the path of a cgroup
+ * @cgrp: the cgroup in question
+ * @buf: the buffer to write the path into
+ * @buflen: the length of the buffer
+ *
+ * Called with cgroup_mutex held. Writes path of cgroup into buf.
* Returns 0 on success, -errno on error.
*/
-int cgroup_path(const struct cgroup *cont, char *buf, int buflen)
+int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen)
{
char *start;
- if (cont == dummytop) {
+ if (cgrp == dummytop) {
/*
* Inactive subsystems have no dentry for their root
* cgroup
*--start = '\0';
for (;;) {
- int len = cont->dentry->d_name.len;
+ int len = cgrp->dentry->d_name.len;
if ((start -= len) < buf)
return -ENAMETOOLONG;
- memcpy(start, cont->dentry->d_name.name, len);
- cont = cont->parent;
- if (!cont)
+ memcpy(start, cgrp->dentry->d_name.name, len);
+ cgrp = cgrp->parent;
+ if (!cgrp)
break;
- if (!cont->parent)
+ if (!cgrp->parent)
continue;
if (--start < buf)
return -ENAMETOOLONG;
* its subsystem id.
*/
-static void get_first_subsys(const struct cgroup *cont,
+static void get_first_subsys(const struct cgroup *cgrp,
struct cgroup_subsys_state **css, int *subsys_id)
{
- const struct cgroupfs_root *root = cont->root;
+ const struct cgroupfs_root *root = cgrp->root;
const struct cgroup_subsys *test_ss;
BUG_ON(list_empty(&root->subsys_list));
test_ss = list_entry(root->subsys_list.next,
struct cgroup_subsys, sibling);
if (css) {
- *css = cont->subsys[test_ss->subsys_id];
+ *css = cgrp->subsys[test_ss->subsys_id];
BUG_ON(!*css);
}
if (subsys_id)
*subsys_id = test_ss->subsys_id;
}
-/*
- * Attach task 'tsk' to cgroup 'cont'
+/**
+ * cgroup_attach_task - attach task 'tsk' to cgroup 'cgrp'
+ * @cgrp: the cgroup the task is attaching to
+ * @tsk: the task to be attached
*
- * Call holding cgroup_mutex. May take task_lock of
- * the task 'pid' during call.
+ * Call holding cgroup_mutex. May take task_lock of
+ * the task 'tsk' during call.
*/
-static int attach_task(struct cgroup *cont, struct task_struct *tsk)
+int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
{
int retval = 0;
struct cgroup_subsys *ss;
- struct cgroup *oldcont;
- struct css_set *cg = &tsk->cgroups;
- struct cgroupfs_root *root = cont->root;
- int i;
+ struct cgroup *oldcgrp;
+ struct css_set *cg = tsk->cgroups;
+ struct css_set *newcg;
+ struct cgroupfs_root *root = cgrp->root;
int subsys_id;
- get_first_subsys(cont, NULL, &subsys_id);
+ get_first_subsys(cgrp, NULL, &subsys_id);
/* Nothing to do if the task is already in that cgroup */
- oldcont = task_cgroup(tsk, subsys_id);
- if (cont == oldcont)
+ oldcgrp = task_cgroup(tsk, subsys_id);
+ if (cgrp == oldcgrp)
return 0;
for_each_subsys(root, ss) {
if (ss->can_attach) {
- retval = ss->can_attach(ss, cont, tsk);
- if (retval) {
+ retval = ss->can_attach(ss, cgrp, tsk);
+ if (retval)
return retval;
- }
}
}
+ /*
+ * Locate or allocate a new css_set for this task,
+ * based on its final set of cgroups
+ */
+ newcg = find_css_set(cg, cgrp);
+ if (!newcg)
+ return -ENOMEM;
+
task_lock(tsk);
if (tsk->flags & PF_EXITING) {
task_unlock(tsk);
+ put_css_set(newcg);
return -ESRCH;
}
- /* Update the css_set pointers for the subsystems in this
- * hierarchy */
- for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
- if (root->subsys_bits & (1ull << i)) {
- /* Subsystem is in this hierarchy. So we want
- * the subsystem state from the new
- * cgroup. Transfer the refcount from the
- * old to the new */
- atomic_inc(&cont->count);
- atomic_dec(&cg->subsys[i]->cgroup->count);
- rcu_assign_pointer(cg->subsys[i], cont->subsys[i]);
- }
- }
+ rcu_assign_pointer(tsk->cgroups, newcg);
task_unlock(tsk);
- for_each_subsys(root, ss) {
- if (ss->attach) {
- ss->attach(ss, cont, oldcont, tsk);
- }
+ /* Update the css_set linked lists if we're using them */
+ write_lock(&css_set_lock);
+ if (!list_empty(&tsk->cg_list)) {
+ list_del(&tsk->cg_list);
+ list_add(&tsk->cg_list, &newcg->tasks);
}
+ write_unlock(&css_set_lock);
+ for_each_subsys(root, ss) {
+ if (ss->attach)
+ ss->attach(ss, cgrp, oldcgrp, tsk);
+ }
+ set_bit(CGRP_RELEASABLE, &oldcgrp->flags);
synchronize_rcu();
+ put_css_set(cg);
return 0;
}
/*
- * Attach task with pid 'pid' to cgroup 'cont'. Call with
+ * Attach task with pid 'pid' to cgroup 'cgrp'. Call with
* cgroup_mutex, may take task_lock of task
*/
-static int attach_task_by_pid(struct cgroup *cont, char *pidbuf)
+static int attach_task_by_pid(struct cgroup *cgrp, char *pidbuf)
{
pid_t pid;
struct task_struct *tsk;
if (pid) {
rcu_read_lock();
- tsk = find_task_by_pid(pid);
+ tsk = find_task_by_vpid(pid);
if (!tsk || tsk->flags & PF_EXITING) {
rcu_read_unlock();
return -ESRCH;
get_task_struct(tsk);
}
- ret = attach_task(cont, tsk);
+ ret = cgroup_attach_task(cgrp, tsk);
put_task_struct(tsk);
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 *cont, struct cftype *cft,
+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)
return -EINVAL;
/* Pass to subsystem */
- retval = cft->write_uint(cont, cft, val);
+ retval = cft->write_uint(cgrp, cft, val);
if (!retval)
retval = nbytes;
return retval;
}
-static ssize_t cgroup_common_file_write(struct cgroup *cont,
+static ssize_t cgroup_common_file_write(struct cgroup *cgrp,
struct cftype *cft,
struct file *file,
const char __user *userbuf,
goto out1;
}
buffer[nbytes] = 0; /* nul-terminate */
+ strstrip(buffer); /* strip -just- trailing whitespace */
mutex_lock(&cgroup_mutex);
- if (cgroup_is_removed(cont)) {
+ /*
+ * 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(cont, buffer);
+ 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;
size_t nbytes, loff_t *ppos)
{
struct cftype *cft = __d_cft(file->f_dentry);
- struct cgroup *cont = __d_cont(file->f_dentry->d_parent);
+ struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);
- if (!cft)
+ if (!cft || cgroup_is_removed(cgrp))
return -ENODEV;
if (cft->write)
- return cft->write(cont, cft, file, buf, nbytes, ppos);
+ return cft->write(cgrp, cft, file, buf, nbytes, ppos);
if (cft->write_uint)
- return cgroup_write_uint(cont, cft, file, buf, nbytes, ppos);
+ return cgroup_write_uint(cgrp, cft, file, buf, nbytes, ppos);
return -EINVAL;
}
-static ssize_t cgroup_read_uint(struct cgroup *cont, struct cftype *cft,
+static ssize_t cgroup_read_uint(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(cont, cft);
+ u64 val = cft->read_uint(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)
+{
+ 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';
+
+ retval = simple_read_from_buffer(buf, nbytes, ppos, page, s - page);
+out:
+ free_page((unsigned long)page);
+ return retval;
+}
+
static ssize_t cgroup_file_read(struct file *file, char __user *buf,
size_t nbytes, loff_t *ppos)
{
struct cftype *cft = __d_cft(file->f_dentry);
- struct cgroup *cont = __d_cont(file->f_dentry->d_parent);
+ struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);
- if (!cft)
+ if (!cft || cgroup_is_removed(cgrp))
return -ENODEV;
if (cft->read)
- return cft->read(cont, cft, file, buf, nbytes, ppos);
+ return cft->read(cgrp, cft, file, buf, nbytes, ppos);
if (cft->read_uint)
- return cgroup_read_uint(cont, cft, file, buf, nbytes, ppos);
+ return cgroup_read_uint(cgrp, cft, file, buf, nbytes, ppos);
return -EINVAL;
}
/* start with the directory inode held, so that we can
* populate it without racing with another mkdir */
- mutex_lock(&inode->i_mutex);
+ mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD);
} else if (S_ISREG(mode)) {
inode->i_size = 0;
inode->i_fop = &cgroup_file_operations;
}
/*
- * cgroup_create_dir - create a directory for an object.
- * cont: the cgroup we create the directory for.
- * It must have a valid ->parent field
- * And we are going to fill its ->dentry field.
- * dentry: dentry of the new container
- * mode: mode to set on new directory.
+ * cgroup_create_dir - create a directory for an object.
+ * @cgrp: the cgroup we create the directory for. It must have a valid
+ * ->parent field. And we are going to fill its ->dentry field.
+ * @dentry: dentry of the new cgroup
+ * @mode: mode to set on new directory.
*/
-static int cgroup_create_dir(struct cgroup *cont, struct dentry *dentry,
+static int cgroup_create_dir(struct cgroup *cgrp, struct dentry *dentry,
int mode)
{
struct dentry *parent;
int error = 0;
- parent = cont->parent->dentry;
- error = cgroup_create_file(dentry, S_IFDIR | mode, cont->root->sb);
+ parent = cgrp->parent->dentry;
+ error = cgroup_create_file(dentry, S_IFDIR | mode, cgrp->root->sb);
if (!error) {
- dentry->d_fsdata = cont;
+ dentry->d_fsdata = cgrp;
inc_nlink(parent->d_inode);
- cont->dentry = dentry;
+ cgrp->dentry = dentry;
dget(dentry);
}
dput(dentry);
return error;
}
-int cgroup_add_file(struct cgroup *cont,
+int cgroup_add_file(struct cgroup *cgrp,
struct cgroup_subsys *subsys,
const struct cftype *cft)
{
- struct dentry *dir = cont->dentry;
+ struct dentry *dir = cgrp->dentry;
struct dentry *dentry;
int error;
char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 };
- if (subsys && !test_bit(ROOT_NOPREFIX, &cont->root->flags)) {
+ if (subsys && !test_bit(ROOT_NOPREFIX, &cgrp->root->flags)) {
strcpy(name, subsys->name);
strcat(name, ".");
}
dentry = lookup_one_len(name, dir, strlen(name));
if (!IS_ERR(dentry)) {
error = cgroup_create_file(dentry, 0644 | S_IFREG,
- cont->root->sb);
+ cgrp->root->sb);
if (!error)
dentry->d_fsdata = (void *)cft;
dput(dentry);
return error;
}
-int cgroup_add_files(struct cgroup *cont,
+int cgroup_add_files(struct cgroup *cgrp,
struct cgroup_subsys *subsys,
const struct cftype cft[],
int count)
{
int i, err;
for (i = 0; i < count; i++) {
- err = cgroup_add_file(cont, subsys, &cft[i]);
+ err = cgroup_add_file(cgrp, subsys, &cft[i]);
if (err)
return err;
}
return 0;
}
-/* Count the number of tasks in a cgroup. Could be made more
- * time-efficient but less space-efficient with more linked lists
- * running through each cgroup and the css_set structures that
- * referenced it. Must be called with tasklist_lock held for read or
- * write or in an rcu critical section.
+/**
+ * cgroup_task_count - count the number of tasks in a cgroup.
+ * @cgrp: the cgroup in question
+ *
+ * Return the number of tasks in the cgroup.
*/
-int __cgroup_task_count(const struct cgroup *cont)
+int cgroup_task_count(const struct cgroup *cgrp)
{
int count = 0;
- struct task_struct *g, *p;
- struct cgroup_subsys_state *css;
- int subsys_id;
-
- get_first_subsys(cont, &css, &subsys_id);
- do_each_thread(g, p) {
- if (task_subsys_state(p, subsys_id) == css)
- count ++;
- } while_each_thread(g, p);
+ struct list_head *l;
+
+ 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;
+ }
+ read_unlock(&css_set_lock);
return count;
}
/*
- * Stuff for reading the 'tasks' file.
- *
- * Reading this file can return large amounts of data if a cgroup has
- * *lots* of attached tasks. So it may need several calls to read(),
- * but we cannot guarantee that the information we produce is correct
- * unless we produce it entirely atomically.
- *
- * 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().
+ * Advance a list_head iterator. The iterator should be positioned at
+ * the start of a css_set
*/
-struct ctr_struct {
- char *buf;
- int bufsz;
-};
+static void cgroup_advance_iter(struct cgroup *cgrp,
+ struct cgroup_iter *it)
+{
+ struct list_head *l = it->cg_link;
+ struct cg_cgroup_link *link;
+ struct css_set *cg;
+
+ /* Advance to the next non-empty css_set */
+ do {
+ l = l->next;
+ if (l == &cgrp->css_sets) {
+ it->cg_link = NULL;
+ return;
+ }
+ link = list_entry(l, struct cg_cgroup_link, cgrp_link_list);
+ cg = link->cg;
+ } while (list_empty(&cg->tasks));
+ it->cg_link = l;
+ it->task = cg->tasks.next;
+}
/*
- * Load into 'pidarray' up to 'npids' of the tasks using cgroup
- * 'cont'. Return actual number of pids loaded. No need to
- * task_lock(p) when reading out p->cgroup, since we're in an RCU
- * read section, so the css_set can't go away, and is
- * immutable after creation.
+ * To reduce the fork() overhead for systems that are not actually
+ * using their cgroups capability, we don't maintain the lists running
+ * through each css_set to its tasks until we see the list actually
+ * used - in other words after the first call to cgroup_iter_start().
+ *
+ * The tasklist_lock is not held here, as do_each_thread() and
+ * while_each_thread() are protected by RCU.
*/
-static int pid_array_load(pid_t *pidarray, int npids, struct cgroup *cont)
+void cgroup_enable_task_cg_lists(void)
{
- int n = 0;
- struct task_struct *g, *p;
- struct cgroup_subsys_state *css;
- int subsys_id;
-
- get_first_subsys(cont, &css, &subsys_id);
- rcu_read_lock();
+ struct task_struct *p, *g;
+ write_lock(&css_set_lock);
+ use_task_css_set_links = 1;
do_each_thread(g, p) {
- if (task_subsys_state(p, subsys_id) == css) {
- pidarray[n++] = pid_nr(task_pid(p));
- if (unlikely(n == npids))
- goto array_full;
- }
+ task_lock(p);
+ if (list_empty(&p->cg_list))
+ list_add(&p->cg_list, &p->cgroups->tasks);
+ task_unlock(p);
} while_each_thread(g, p);
-
-array_full:
- rcu_read_unlock();
- return n;
+ write_unlock(&css_set_lock);
}
-static int cmppid(const void *a, const void *b)
+void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it)
{
- return *(pid_t *)a - *(pid_t *)b;
+ /*
+ * The first time anyone tries to iterate across a cgroup,
+ * we need to enable the list linking each css_set to its
+ * tasks, and fix up all existing tasks.
+ */
+ if (!use_task_css_set_links)
+ cgroup_enable_task_cg_lists();
+
+ read_lock(&css_set_lock);
+ it->cg_link = &cgrp->css_sets;
+ cgroup_advance_iter(cgrp, it);
}
-/*
- * Convert array 'a' of 'npids' pid_t's to a string of newline separated
+struct task_struct *cgroup_iter_next(struct cgroup *cgrp,
+ struct cgroup_iter *it)
+{
+ struct task_struct *res;
+ struct list_head *l = it->task;
+
+ /* If the iterator cg is NULL, we have no tasks */
+ if (!it->cg_link)
+ return NULL;
+ res = list_entry(l, struct task_struct, cg_list);
+ /* Advance iterator to find next entry */
+ l = l->next;
+ if (l == &res->cgroups->tasks) {
+ /* We reached the end of this task list - move on to
+ * the next cg_cgroup_link */
+ cgroup_advance_iter(cgrp, it);
+ } else {
+ it->task = l;
+ }
+ return res;
+}
+
+void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it)
+{
+ read_unlock(&css_set_lock);
+}
+
+static inline int started_after_time(struct task_struct *t1,
+ struct timespec *time,
+ struct task_struct *t2)
+{
+ int start_diff = timespec_compare(&t1->start_time, time);
+ if (start_diff > 0) {
+ return 1;
+ } else if (start_diff < 0) {
+ return 0;
+ } else {
+ /*
+ * Arbitrarily, if two processes started at the same
+ * time, we'll say that the lower pointer value
+ * started first. Note that t2 may have exited by now
+ * so this may not be a valid pointer any longer, but
+ * that's fine - it still serves to distinguish
+ * between two tasks started (effectively) simultaneously.
+ */
+ return t1 > t2;
+ }
+}
+
+/*
+ * This function is a callback from heap_insert() and is used to order
+ * the heap.
+ * In this case we order the heap in descending task start time.
+ */
+static inline int started_after(void *p1, void *p2)
+{
+ struct task_struct *t1 = p1;
+ struct task_struct *t2 = p2;
+ return started_after_time(t1, &t2->start_time, t2);
+}
+
+/**
+ * cgroup_scan_tasks - iterate though all the tasks in a cgroup
+ * @scan: struct cgroup_scanner containing arguments for the scan
+ *
+ * Arguments include pointers to callback functions test_task() and
+ * process_task().
+ * Iterate through all the tasks in a cgroup, calling test_task() for each,
+ * and if it returns true, call process_task() for it also.
+ * The test_task pointer may be NULL, meaning always true (select all tasks).
+ * Effectively duplicates cgroup_iter_{start,next,end}()
+ * but does not lock css_set_lock for the call to process_task().
+ * The struct cgroup_scanner may be embedded in any structure of the caller's
+ * creation.
+ * It is guaranteed that process_task() will act on every task that
+ * is a member of the cgroup for the duration of this call. This
+ * function may or may not call process_task() for tasks that exit
+ * or move to a different cgroup during the call, or are forked or
+ * move into the cgroup during the call.
+ *
+ * Note that test_task() may be called with locks held, and may in some
+ * situations be called multiple times for the same task, so it should
+ * be cheap.
+ * If the heap pointer in the struct cgroup_scanner is non-NULL, a heap has been
+ * pre-allocated and will be used for heap operations (and its "gt" member will
+ * be overwritten), else a temporary heap will be used (allocation of which
+ * may cause this function to fail).
+ */
+int cgroup_scan_tasks(struct cgroup_scanner *scan)
+{
+ int retval, i;
+ struct cgroup_iter it;
+ struct task_struct *p, *dropped;
+ /* Never dereference latest_task, since it's not refcounted */
+ struct task_struct *latest_task = NULL;
+ struct ptr_heap tmp_heap;
+ struct ptr_heap *heap;
+ struct timespec latest_time = { 0, 0 };
+
+ if (scan->heap) {
+ /* The caller supplied our heap and pre-allocated its memory */
+ heap = scan->heap;
+ heap->gt = &started_after;
+ } else {
+ /* We need to allocate our own heap memory */
+ heap = &tmp_heap;
+ retval = heap_init(heap, PAGE_SIZE, GFP_KERNEL, &started_after);
+ if (retval)
+ /* cannot allocate the heap */
+ return retval;
+ }
+
+ again:
+ /*
+ * Scan tasks in the cgroup, using the scanner's "test_task" callback
+ * to determine which are of interest, and using the scanner's
+ * "process_task" callback to process any of them that need an update.
+ * Since we don't want to hold any locks during the task updates,
+ * gather tasks to be processed in a heap structure.
+ * The heap is sorted by descending task start time.
+ * If the statically-sized heap fills up, we overflow tasks that
+ * started later, and in future iterations only consider tasks that
+ * started after the latest task in the previous pass. This
+ * guarantees forward progress and that we don't miss any tasks.
+ */
+ heap->size = 0;
+ cgroup_iter_start(scan->cg, &it);
+ while ((p = cgroup_iter_next(scan->cg, &it))) {
+ /*
+ * Only affect tasks that qualify per the caller's callback,
+ * if he provided one
+ */
+ if (scan->test_task && !scan->test_task(p, scan))
+ continue;
+ /*
+ * Only process tasks that started after the last task
+ * we processed
+ */
+ if (!started_after_time(p, &latest_time, latest_task))
+ continue;
+ dropped = heap_insert(heap, p);
+ if (dropped == NULL) {
+ /*
+ * The new task was inserted; the heap wasn't
+ * previously full
+ */
+ get_task_struct(p);
+ } else if (dropped != p) {
+ /*
+ * The new task was inserted, and pushed out a
+ * different task
+ */
+ get_task_struct(p);
+ put_task_struct(dropped);
+ }
+ /*
+ * Else the new task was newer than anything already in
+ * the heap and wasn't inserted
+ */
+ }
+ cgroup_iter_end(scan->cg, &it);
+
+ if (heap->size) {
+ for (i = 0; i < heap->size; i++) {
+ struct task_struct *p = heap->ptrs[i];
+ if (i == 0) {
+ latest_time = p->start_time;
+ latest_task = p;
+ }
+ /* Process the task per the caller's callback */
+ scan->process_task(p, scan);
+ put_task_struct(p);
+ }
+ /*
+ * If we had to process any tasks at all, scan again
+ * in case some of them were in the middle of forking
+ * children that didn't get processed.
+ * Not the most efficient way to do it, but it avoids
+ * having to take callback_mutex in the fork path
+ */
+ goto again;
+ }
+ if (heap == &tmp_heap)
+ heap_free(&tmp_heap);
+ return 0;
+}
+
+/*
+ * Stuff for reading the 'tasks' file.
+ *
+ * Reading this file can return large amounts of data if a cgroup has
+ * *lots* of attached tasks. So it may need several calls to read(),
+ * but we cannot guarantee that the information we produce is correct
+ * unless we produce it entirely atomically.
+ *
+ * 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
+ * 'cgrp'. Return actual number of pids loaded. No need to
+ * task_lock(p) when reading out p->cgroup, since we're in an RCU
+ * read section, so the css_set can't go away, and is
+ * immutable after creation.
+ */
+static int pid_array_load(pid_t *pidarray, int npids, struct cgroup *cgrp)
+{
+ int n = 0;
+ 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);
+ }
+ cgroup_iter_end(cgrp, &it);
+ return n;
+}
+
+/**
+ * cgroupstats_build - build and fill cgroupstats
+ * @stats: cgroupstats to fill information into
+ * @dentry: A dentry entry belonging to the cgroup for which stats have
+ * been requested.
+ *
+ * Build and fill cgroupstats so that taskstats can export it to user
+ * space.
+ */
+int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
+{
+ int ret = -EINVAL;
+ struct cgroup *cgrp;
+ struct cgroup_iter it;
+ struct task_struct *tsk;
+ /*
+ * Validate dentry by checking the superblock operations
+ */
+ if (dentry->d_sb->s_op != &cgroup_ops)
+ goto err;
+
+ ret = 0;
+ cgrp = dentry->d_fsdata;
+ rcu_read_lock();
+
+ cgroup_iter_start(cgrp, &it);
+ while ((tsk = cgroup_iter_next(cgrp, &it))) {
+ switch (tsk->state) {
+ case TASK_RUNNING:
+ stats->nr_running++;
+ break;
+ case TASK_INTERRUPTIBLE:
+ stats->nr_sleeping++;
+ break;
+ case TASK_UNINTERRUPTIBLE:
+ stats->nr_uninterruptible++;
+ break;
+ case TASK_STOPPED:
+ stats->nr_stopped++;
+ break;
+ default:
+ if (delayacct_is_task_waiting_on_io(tsk))
+ stats->nr_io_wait++;
+ break;
+ }
+ }
+ cgroup_iter_end(cgrp, &it);
+
+ rcu_read_unlock();
+err:
+ return ret;
+}
+
+static int cmppid(const void *a, const void *b)
+{
+ 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.
*/
*/
static int cgroup_tasks_open(struct inode *unused, struct file *file)
{
- struct cgroup *cont = __d_cont(file->f_dentry->d_parent);
+ struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);
struct ctr_struct *ctr;
pid_t *pidarray;
int npids;
* caller from the case that the additional cgroup users didn't
* show up until sometime later on.
*/
- npids = cgroup_task_count(cont);
+ 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, cont);
+ 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 */
return -ENOMEM;
}
-static ssize_t cgroup_tasks_read(struct cgroup *cont,
+static ssize_t cgroup_tasks_read(struct cgroup *cgrp,
struct cftype *cft,
struct file *file, char __user *buf,
size_t nbytes, loff_t *ppos)
return 0;
}
+static u64 cgroup_read_notify_on_release(struct cgroup *cgrp,
+ struct cftype *cft)
+{
+ return notify_on_release(cgrp);
+}
+
+static u64 cgroup_read_releasable(struct cgroup *cgrp, struct cftype *cft)
+{
+ return test_bit(CGRP_RELEASABLE, &cgrp->flags);
+}
+
/*
* for the common functions, 'private' gives the type of file
*/
-static struct cftype cft_tasks = {
- .name = "tasks",
- .open = cgroup_tasks_open,
- .read = cgroup_tasks_read,
+static struct cftype files[] = {
+ {
+ .name = "tasks",
+ .open = cgroup_tasks_open,
+ .read = cgroup_tasks_read,
+ .write = cgroup_common_file_write,
+ .release = cgroup_tasks_release,
+ .private = FILE_TASKLIST,
+ },
+
+ {
+ .name = "notify_on_release",
+ .read_uint = cgroup_read_notify_on_release,
+ .write = cgroup_common_file_write,
+ .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,
- .release = cgroup_tasks_release,
- .private = FILE_TASKLIST,
+ .private = FILE_RELEASE_AGENT,
};
-static int cgroup_populate_dir(struct cgroup *cont)
+static int cgroup_populate_dir(struct cgroup *cgrp)
{
int err;
struct cgroup_subsys *ss;
/* First clear out any existing files */
- cgroup_clear_directory(cont->dentry);
+ cgroup_clear_directory(cgrp->dentry);
- err = cgroup_add_file(cont, NULL, &cft_tasks);
+ err = cgroup_add_files(cgrp, NULL, files, ARRAY_SIZE(files));
if (err < 0)
return err;
- for_each_subsys(cont->root, ss) {
- if (ss->populate && (err = ss->populate(ss, cont)) < 0)
+ if (cgrp == cgrp->top_cgroup) {
+ if ((err = cgroup_add_file(cgrp, NULL, &cft_release_agent)) < 0)
+ return err;
+ }
+
+ for_each_subsys(cgrp->root, ss) {
+ if (ss->populate && (err = ss->populate(ss, cgrp)) < 0)
return err;
}
static void init_cgroup_css(struct cgroup_subsys_state *css,
struct cgroup_subsys *ss,
- struct cgroup *cont)
+ struct cgroup *cgrp)
{
- css->cgroup = cont;
+ css->cgroup = cgrp;
atomic_set(&css->refcnt, 0);
css->flags = 0;
- if (cont == dummytop)
+ if (cgrp == dummytop)
set_bit(CSS_ROOT, &css->flags);
- BUG_ON(cont->subsys[ss->subsys_id]);
- cont->subsys[ss->subsys_id] = css;
+ BUG_ON(cgrp->subsys[ss->subsys_id]);
+ cgrp->subsys[ss->subsys_id] = css;
}
/*
- * cgroup_create - create a cgroup
- * parent: cgroup that will be parent of the new cgroup.
- * name: name of the new cgroup. Will be strcpy'ed.
- * mode: mode to set on new inode
+ * cgroup_create - create a cgroup
+ * @parent: cgroup that will be parent of the new cgroup
+ * @dentry: dentry of the new cgroup
+ * @mode: mode to set on new inode
*
- * Must be called with the mutex on the parent inode held
+ * Must be called with the mutex on the parent inode held
*/
-
static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
int mode)
{
- struct cgroup *cont;
+ struct cgroup *cgrp;
struct cgroupfs_root *root = parent->root;
int err = 0;
struct cgroup_subsys *ss;
struct super_block *sb = root->sb;
- cont = kzalloc(sizeof(*cont), GFP_KERNEL);
- if (!cont)
+ cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL);
+ if (!cgrp)
return -ENOMEM;
/* Grab a reference on the superblock so the hierarchy doesn't
mutex_lock(&cgroup_mutex);
- cont->flags = 0;
- INIT_LIST_HEAD(&cont->sibling);
- INIT_LIST_HEAD(&cont->children);
+ cgrp->flags = 0;
+ INIT_LIST_HEAD(&cgrp->sibling);
+ INIT_LIST_HEAD(&cgrp->children);
+ INIT_LIST_HEAD(&cgrp->css_sets);
+ INIT_LIST_HEAD(&cgrp->release_list);
- cont->parent = parent;
- cont->root = parent->root;
- cont->top_cgroup = parent->top_cgroup;
+ cgrp->parent = parent;
+ cgrp->root = parent->root;
+ cgrp->top_cgroup = parent->top_cgroup;
for_each_subsys(root, ss) {
- struct cgroup_subsys_state *css = ss->create(ss, cont);
+ struct cgroup_subsys_state *css = ss->create(ss, cgrp);
if (IS_ERR(css)) {
err = PTR_ERR(css);
goto err_destroy;
}
- init_cgroup_css(css, ss, cont);
+ init_cgroup_css(css, ss, cgrp);
}
- list_add(&cont->sibling, &cont->parent->children);
+ list_add(&cgrp->sibling, &cgrp->parent->children);
root->number_of_cgroups++;
- err = cgroup_create_dir(cont, dentry, mode);
+ err = cgroup_create_dir(cgrp, dentry, mode);
if (err < 0)
goto err_remove;
/* The cgroup directory was pre-locked for us */
- BUG_ON(!mutex_is_locked(&cont->dentry->d_inode->i_mutex));
+ BUG_ON(!mutex_is_locked(&cgrp->dentry->d_inode->i_mutex));
- err = cgroup_populate_dir(cont);
+ err = cgroup_populate_dir(cgrp);
/* If err < 0, we have a half-filled directory - oh well ;) */
mutex_unlock(&cgroup_mutex);
- mutex_unlock(&cont->dentry->d_inode->i_mutex);
+ mutex_unlock(&cgrp->dentry->d_inode->i_mutex);
return 0;
err_remove:
- list_del(&cont->sibling);
+ list_del(&cgrp->sibling);
root->number_of_cgroups--;
err_destroy:
for_each_subsys(root, ss) {
- if (cont->subsys[ss->subsys_id])
- ss->destroy(ss, cont);
+ if (cgrp->subsys[ss->subsys_id])
+ ss->destroy(ss, cgrp);
}
mutex_unlock(&cgroup_mutex);
/* Release the reference count that we took on the superblock */
deactivate_super(sb);
- kfree(cont);
+ kfree(cgrp);
return err;
}
return cgroup_create(c_parent, dentry, mode | S_IFDIR);
}
+static inline 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
+ * be no outstanding references, so the subsystem is safe to
+ * destroy. We scan across all subsystems rather than using
+ * the per-hierarchy linked list of mounted subsystems since
+ * we can be called via check_for_release() with no
+ * synchronization other than RCU, and the subsystem linked
+ * list isn't RCU-safe */
+ int i;
+ for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
+ struct cgroup_subsys *ss = subsys[i];
+ struct cgroup_subsys_state *css;
+ /* Skip subsystems not in this hierarchy */
+ if (ss->root != cgrp->root)
+ continue;
+ css = cgrp->subsys[ss->subsys_id];
+ /* When called from check_for_release() it's possible
+ * that by this point the cgroup has been removed
+ * and the css deleted. But a false-positive doesn't
+ * matter, since it can only happen if the cgroup
+ * has been deleted and hence no longer needs the
+ * release agent to be called anyway. */
+ if (css && atomic_read(&css->refcnt))
+ return 1;
+ }
+ return 0;
+}
+
static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry)
{
- struct cgroup *cont = dentry->d_fsdata;
+ struct cgroup *cgrp = dentry->d_fsdata;
struct dentry *d;
struct cgroup *parent;
- struct cgroup_subsys *ss;
struct super_block *sb;
struct cgroupfs_root *root;
- int css_busy = 0;
/* the vfs holds both inode->i_mutex already */
mutex_lock(&cgroup_mutex);
- if (atomic_read(&cont->count) != 0) {
+ if (atomic_read(&cgrp->count) != 0) {
mutex_unlock(&cgroup_mutex);
return -EBUSY;
}
- if (!list_empty(&cont->children)) {
+ if (!list_empty(&cgrp->children)) {
mutex_unlock(&cgroup_mutex);
return -EBUSY;
}
- parent = cont->parent;
- root = cont->root;
+ parent = cgrp->parent;
+ root = cgrp->root;
sb = root->sb;
- /* 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
- * be no outstanding references, so the subsystem is safe to
- * destroy */
- for_each_subsys(root, ss) {
- struct cgroup_subsys_state *css;
- css = cont->subsys[ss->subsys_id];
- if (atomic_read(&css->refcnt)) {
- css_busy = 1;
- break;
- }
- }
- if (css_busy) {
+ /*
+ * Call pre_destroy handlers of subsys. Notify subsystems
+ * that rmdir() request comes.
+ */
+ cgroup_call_pre_destroy(cgrp);
+
+ if (cgroup_has_css_refs(cgrp)) {
mutex_unlock(&cgroup_mutex);
return -EBUSY;
}
- for_each_subsys(root, ss) {
- if (cont->subsys[ss->subsys_id])
- ss->destroy(ss, cont);
- }
-
- set_bit(CONT_REMOVED, &cont->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 */
- list_del(&cont->sibling);
- spin_lock(&cont->dentry->d_lock);
- d = dget(cont->dentry);
- cont->dentry = NULL;
+ list_del(&cgrp->sibling);
+ spin_lock(&cgrp->dentry->d_lock);
+ d = dget(cgrp->dentry);
+ cgrp->dentry = NULL;
spin_unlock(&d->d_lock);
cgroup_d_remove_dir(d);
dput(d);
- root->number_of_cgroups--;
+
+ set_bit(CGRP_RELEASABLE, &parent->flags);
+ check_for_release(parent);
mutex_unlock(&cgroup_mutex);
- /* Drop the active superblock reference that we took when we
- * created the cgroup */
- deactivate_super(sb);
return 0;
}
static void cgroup_init_subsys(struct cgroup_subsys *ss)
{
- struct task_struct *g, *p;
struct cgroup_subsys_state *css;
- printk(KERN_ERR "Initializing cgroup subsys %s\n", ss->name);
+ struct list_head *l;
+
+ printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name);
/* Create the top cgroup state for this subsystem */
ss->root = &rootnode;
BUG_ON(IS_ERR(css));
init_cgroup_css(css, ss, dummytop);
- /* Update all tasks to contain a subsys pointer to this state
- * - since the subsystem is newly registered, all tasks are in
- * the subsystem's top cgroup. */
+ /* Update all cgroup groups 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);
- init_task.cgroups.subsys[ss->subsys_id] = css;
- if (ss->fork)
- ss->fork(ss, &init_task);
-
- do_each_thread(g, p) {
- printk(KERN_INFO "Setting task %p css to %p (%d)\n", css, p, p->pid);
- p->cgroups.subsys[ss->subsys_id] = css;
- if (ss->fork)
+ read_lock(&tasklist_lock);
+ do_each_thread(g, p) {
ss->fork(ss, p);
- } while_each_thread(g, p);
- read_unlock(&tasklist_lock);
+ } while_each_thread(g, p);
+ read_unlock(&tasklist_lock);
+ }
need_forkexit_callback |= ss->fork || ss->exit;
}
/**
- * cgroup_init_early - initialize cgroups at system boot, and
- * initialize any subsystems that request early init.
+ * cgroup_init_early - cgroup initialization at system boot
+ *
+ * Initialize cgroups at system boot, and initialize any
+ * subsystems that request early init.
*/
int __init cgroup_init_early(void)
{
int i;
+ kref_init(&init_css_set.ref);
+ kref_get(&init_css_set.ref);
+ INIT_LIST_HEAD(&init_css_set.list);
+ INIT_LIST_HEAD(&init_css_set.cg_links);
+ INIT_LIST_HEAD(&init_css_set.tasks);
+ css_set_count = 1;
init_cgroup_root(&rootnode);
list_add(&rootnode.root_list, &roots);
+ root_count = 1;
+ init_task.cgroups = &init_css_set;
+
+ init_css_set_link.cg = &init_css_set;
+ list_add(&init_css_set_link.cgrp_link_list,
+ &rootnode.top_cgroup.css_sets);
+ list_add(&init_css_set_link.cg_link_list,
+ &init_css_set.cg_links);
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
struct cgroup_subsys *ss = subsys[i];
BUG_ON(!ss->create);
BUG_ON(!ss->destroy);
if (ss->subsys_id != i) {
- printk(KERN_ERR "Subsys %s id == %d\n",
+ printk(KERN_ERR "cgroup: Subsys %s id == %d\n",
ss->name, ss->subsys_id);
BUG();
}
}
/**
- * cgroup_init - register cgroup filesystem and /proc file, and
- * initialize any subsystems that didn't request early init.
+ * cgroup_init - cgroup initialization
+ *
+ * Register cgroup filesystem and /proc file, and initialize
+ * any subsystems that didn't request early init.
*/
int __init cgroup_init(void)
{
int err;
int i;
+ struct proc_dir_entry *entry;
+
+ err = bdi_init(&cgroup_backing_dev_info);
+ if (err)
+ return err;
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
struct cgroup_subsys *ss = subsys[i];
if (err < 0)
goto out;
+ entry = create_proc_entry("cgroups", 0, NULL);
+ if (entry)
+ entry->proc_fops = &proc_cgroupstats_operations;
+
out:
+ if (err)
+ bdi_destroy(&cgroup_backing_dev_info);
+
return err;
}
+
+/*
+ * proc_cgroup_show()
+ * - Print task's cgroup paths into seq_file, one line for each hierarchy
+ * - Used for /proc/<pid>/cgroup.
+ * - No need to task_lock(tsk) on this tsk->cgroup reference, as it
+ * doesn't really matter if tsk->cgroup changes after we read it,
+ * and we take cgroup_mutex, keeping cgroup_attach_task() from changing it
+ * anyway. No need to check that tsk->cgroup != NULL, thanks to
+ * the_top_cgroup_hack in cgroup_exit(), which sets an exiting tasks
+ * cgroup to top_cgroup.
+ */
+
+/* TODO: Use a proper seq_file iterator */
+static int proc_cgroup_show(struct seq_file *m, void *v)
+{
+ struct pid *pid;
+ struct task_struct *tsk;
+ char *buf;
+ int retval;
+ struct cgroupfs_root *root;
+
+ retval = -ENOMEM;
+ buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
+ if (!buf)
+ goto out;
+
+ retval = -ESRCH;
+ pid = m->private;
+ tsk = get_pid_task(pid, PIDTYPE_PID);
+ if (!tsk)
+ goto out_free;
+
+ retval = 0;
+
+ mutex_lock(&cgroup_mutex);
+
+ for_each_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;
+ for_each_subsys(root, ss)
+ seq_printf(m, "%s%s", count++ ? "," : "", ss->name);
+ seq_putc(m, ':');
+ get_first_subsys(&root->top_cgroup, NULL, &subsys_id);
+ cgrp = task_cgroup(tsk, subsys_id);
+ retval = cgroup_path(cgrp, buf, PAGE_SIZE);
+ if (retval < 0)
+ goto out_unlock;
+ seq_puts(m, buf);
+ seq_putc(m, '\n');
+ }
+
+out_unlock:
+ mutex_unlock(&cgroup_mutex);
+ put_task_struct(tsk);
+out_free:
+ kfree(buf);
+out:
+ return retval;
+}
+
+static int cgroup_open(struct inode *inode, struct file *file)
+{
+ struct pid *pid = PROC_I(inode)->pid;
+ return single_open(file, proc_cgroup_show, pid);
+}
+
+struct file_operations proc_cgroup_operations = {
+ .open = cgroup_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+/* Display information about each subsystem and each hierarchy */
+static int proc_cgroupstats_show(struct seq_file *m, void *v)
+{
+ int i;
+
+ seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\n");
+ mutex_lock(&cgroup_mutex);
+ for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
+ struct cgroup_subsys *ss = subsys[i];
+ seq_printf(m, "%s\t%lu\t%d\n",
+ ss->name, ss->root->subsys_bits,
+ ss->root->number_of_cgroups);
+ }
+ mutex_unlock(&cgroup_mutex);
+ return 0;
+}
+
+static int cgroupstats_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, proc_cgroupstats_show, 0);
+}
+
+static struct file_operations proc_cgroupstats_operations = {
+ .open = cgroupstats_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+/**
+ * cgroup_fork - attach newly forked task to its parents cgroup.
+ * @child: pointer to task_struct of forking parent process.
+ *
+ * Description: A task inherits its parent's cgroup at fork().
+ *
+ * A pointer to the shared css_set was automatically copied in
+ * fork.c by dup_task_struct(). However, we ignore that copy, since
+ * it was not made under the protection of RCU or cgroup_mutex, so
+ * might no longer be a valid cgroup pointer. cgroup_attach_task() might
+ * have already changed current->cgroups, allowing the previously
+ * referenced cgroup group to be removed and freed.
+ *
+ * At the point that cgroup_fork() is called, 'current' is the parent
+ * task, and the passed argument 'child' points to the child task.
+ */
+void cgroup_fork(struct task_struct *child)
+{
+ task_lock(current);
+ child->cgroups = current->cgroups;
+ get_css_set(child->cgroups);
+ task_unlock(current);
+ INIT_LIST_HEAD(&child->cg_list);
+}
+
+/**
+ * cgroup_fork_callbacks - run fork callbacks
+ * @child: the new task
+ *
+ * Called on a new task very soon before adding it to the
+ * tasklist. No need to take any locks since no-one can
+ * be operating on this task.
+ */
+void cgroup_fork_callbacks(struct task_struct *child)
+{
+ if (need_forkexit_callback) {
+ int i;
+ for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
+ struct cgroup_subsys *ss = subsys[i];
+ if (ss->fork)
+ ss->fork(ss, child);
+ }
+ }
+}
+
+/**
+ * cgroup_post_fork - called on a new task after adding it to the task list
+ * @child: the task in question
+ *
+ * Adds the task to the list running through its css_set if necessary.
+ * Has to be after the task is visible on the task list in case we race
+ * with the first call to cgroup_iter_start() - to guarantee that the
+ * new task ends up on its list.
+ */
+void cgroup_post_fork(struct task_struct *child)
+{
+ if (use_task_css_set_links) {
+ write_lock(&css_set_lock);
+ if (list_empty(&child->cg_list))
+ list_add(&child->cg_list, &child->cgroups->tasks);
+ write_unlock(&css_set_lock);
+ }
+}
+/**
+ * cgroup_exit - detach cgroup from exiting task
+ * @tsk: pointer to task_struct of exiting process
+ * @run_callback: run exit callbacks?
+ *
+ * Description: Detach cgroup from @tsk and release it.
+ *
+ * Note that cgroups marked notify_on_release force every task in
+ * them to take the global cgroup_mutex mutex when exiting.
+ * This could impact scaling on very large systems. Be reluctant to
+ * use notify_on_release cgroups where very high task exit scaling
+ * is required on large systems.
+ *
+ * the_top_cgroup_hack:
+ *
+ * Set the exiting tasks cgroup to the root cgroup (top_cgroup).
+ *
+ * We call cgroup_exit() while the task is still competent to
+ * handle notify_on_release(), then leave the task attached to the
+ * root cgroup in each hierarchy for the remainder of its exit.
+ *
+ * To do this properly, we would increment the reference count on
+ * top_cgroup, and near the very end of the kernel/exit.c do_exit()
+ * code we would add a second cgroup function call, to drop that
+ * reference. This would just create an unnecessary hot spot on
+ * the top_cgroup reference count, to no avail.
+ *
+ * Normally, holding a reference to a cgroup without bumping its
+ * count is unsafe. The cgroup could go away, or someone could
+ * attach us to a different cgroup, decrementing the count on
+ * the first cgroup that we never incremented. But in this case,
+ * top_cgroup isn't going away, and either task has PF_EXITING set,
+ * which wards off any cgroup_attach_task() attempts, or task is a failed
+ * fork, never visible to cgroup_attach_task.
+ */
+void cgroup_exit(struct task_struct *tsk, int run_callbacks)
+{
+ int i;
+ struct css_set *cg;
+
+ if (run_callbacks && need_forkexit_callback) {
+ for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
+ struct cgroup_subsys *ss = subsys[i];
+ if (ss->exit)
+ ss->exit(ss, tsk);
+ }
+ }
+
+ /*
+ * Unlink from the css_set task list if necessary.
+ * Optimistically check cg_list before taking
+ * css_set_lock
+ */
+ if (!list_empty(&tsk->cg_list)) {
+ write_lock(&css_set_lock);
+ if (!list_empty(&tsk->cg_list))
+ list_del(&tsk->cg_list);
+ write_unlock(&css_set_lock);
+ }
+
+ /* Reassign the task to the init_css_set. */
+ task_lock(tsk);
+ cg = tsk->cgroups;
+ tsk->cgroups = &init_css_set;
+ task_unlock(tsk);
+ if (cg)
+ put_css_set_taskexit(cg);
+}
+
+/**
+ * cgroup_clone - clone the cgroup the given subsystem is attached to
+ * @tsk: the task to be moved
+ * @subsys: the given subsystem
+ *
+ * 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)
+{
+ struct dentry *dentry;
+ int ret = 0;
+ char nodename[MAX_CGROUP_TYPE_NAMELEN];
+ struct cgroup *parent, *child;
+ struct inode *inode;
+ struct css_set *cg;
+ struct cgroupfs_root *root;
+ struct cgroup_subsys *ss;
+
+ /* We shouldn't be called by an unregistered subsystem */
+ BUG_ON(!subsys->active);
+
+ /* First figure out what hierarchy and cgroup we're dealing
+ * with, and pin them so we can drop cgroup_mutex */
+ mutex_lock(&cgroup_mutex);
+ again:
+ root = subsys->root;
+ if (root == &rootnode) {
+ 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);
+
+ /* Keep the cgroup alive */
+ get_css_set(cg);
+ mutex_unlock(&cgroup_mutex);
+
+ /* Now do the VFS work to create a cgroup */
+ inode = parent->dentry->d_inode;
+
+ /* Hold the parent directory mutex across this operation to
+ * stop anyone else deleting the new cgroup */
+ mutex_lock(&inode->i_mutex);
+ dentry = lookup_one_len(nodename, parent->dentry, strlen(nodename));
+ if (IS_ERR(dentry)) {
+ printk(KERN_INFO
+ "cgroup: Couldn't allocate dentry for %s: %ld\n", nodename,
+ PTR_ERR(dentry));
+ ret = PTR_ERR(dentry);
+ goto out_release;
+ }
+
+ /* Create the cgroup directory, which also creates the cgroup */
+ ret = vfs_mkdir(inode, dentry, S_IFDIR | 0755);
+ child = __d_cgrp(dentry);
+ dput(dentry);
+ if (ret) {
+ printk(KERN_INFO
+ "Failed to create cgroup %s: %d\n", nodename,
+ 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_lock(&cgroup_mutex);
+ if ((root != subsys->root) ||
+ (parent != task_cgroup(tsk, subsys->subsys_id))) {
+ /* Aargh, we raced ... */
+ mutex_unlock(&inode->i_mutex);
+ put_css_set(cg);
+
+ deactivate_super(parent->root->sb);
+ /* The cgroup is still accessible in the VFS, but
+ * we're not going to try to rmdir() it at this
+ * point. */
+ printk(KERN_INFO
+ "Race in cgroup_clone() - leaking cgroup %s\n",
+ nodename);
+ goto again;
+ }
+
+ /* do any required auto-setup */
+ for_each_subsys(root, ss) {
+ if (ss->post_clone)
+ ss->post_clone(ss, child);
+ }
+
+ /* All seems fine. Finish by moving the task into the new cgroup */
+ ret = cgroup_attach_task(child, tsk);
+ mutex_unlock(&cgroup_mutex);
+
+ out_release:
+ mutex_unlock(&inode->i_mutex);
+
+ mutex_lock(&cgroup_mutex);
+ put_css_set(cg);
+ mutex_unlock(&cgroup_mutex);
+ deactivate_super(parent->root->sb);
+ return ret;
+}
+
+/**
+ * cgroup_is_descendant - see if @cgrp is a descendant of current task's cgrp
+ * @cgrp: the cgroup in question
+ *
+ * See if @cgrp is a descendant of the current 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 ret;
+ struct cgroup *target;
+ int subsys_id;
+
+ if (cgrp == dummytop)
+ return 1;
+
+ get_first_subsys(cgrp, NULL, &subsys_id);
+ target = task_cgroup(current, subsys_id);
+ while (cgrp != target && cgrp!= cgrp->top_cgroup)
+ cgrp = cgrp->parent;
+ ret = (cgrp == target);
+ return ret;
+}
+
+static void check_for_release(struct cgroup *cgrp)
+{
+ /* All of these checks rely on RCU to keep the cgroup
+ * structure alive */
+ if (cgroup_is_releasable(cgrp) && !atomic_read(&cgrp->count)
+ && list_empty(&cgrp->children) && !cgroup_has_css_refs(cgrp)) {
+ /* Control Group is currently removeable. If it's not
+ * already queued for a userspace notification, queue
+ * it now */
+ int need_schedule_work = 0;
+ spin_lock(&release_list_lock);
+ if (!cgroup_is_removed(cgrp) &&
+ list_empty(&cgrp->release_list)) {
+ list_add(&cgrp->release_list, &release_list);
+ need_schedule_work = 1;
+ }
+ spin_unlock(&release_list_lock);
+ if (need_schedule_work)
+ schedule_work(&release_agent_work);
+ }
+}
+
+void __css_put(struct cgroup_subsys_state *css)
+{
+ struct cgroup *cgrp = css->cgroup;
+ rcu_read_lock();
+ if (atomic_dec_and_test(&css->refcnt) && notify_on_release(cgrp)) {
+ set_bit(CGRP_RELEASABLE, &cgrp->flags);
+ check_for_release(cgrp);
+ }
+ rcu_read_unlock();
+}
+
+/*
+ * Notify userspace when a cgroup is released, by running the
+ * configured release agent with the name of the cgroup (path
+ * relative to the root of cgroup file system) as the argument.
+ *
+ * Most likely, this user command will try to rmdir this cgroup.
+ *
+ * This races with the possibility that some other task will be
+ * attached to this cgroup before it is removed, or that some other
+ * user task will 'mkdir' a child cgroup of this cgroup. That's ok.
+ * The presumed 'rmdir' will fail quietly if this cgroup is no longer
+ * unused, and this cgroup will be reprieved from its death sentence,
+ * to continue to serve a useful existence. Next time it's released,
+ * we will get notified again, if it still has 'notify_on_release' set.
+ *
+ * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
+ * means only wait until the task is successfully execve()'d. The
+ * separate release agent task is forked by call_usermodehelper(),
+ * then control in this thread returns here, without waiting for the
+ * release agent task. We don't bother to wait because the caller of
+ * this routine has no use for the exit status of the release agent
+ * task, so no sense holding our caller up for that.
+ */
+static void cgroup_release_agent(struct work_struct *work)
+{
+ BUG_ON(work != &release_agent_work);
+ mutex_lock(&cgroup_mutex);
+ spin_lock(&release_list_lock);
+ while (!list_empty(&release_list)) {
+ char *argv[3], *envp[3];
+ int i;
+ char *pathbuf;
+ 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;
+ }
+
+ i = 0;
+ argv[i++] = cgrp->root->release_agent_path;
+ argv[i++] = (char *)pathbuf;
+ argv[i] = NULL;
+
+ i = 0;
+ /* minimal command environment */
+ envp[i++] = "HOME=/";
+ envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
+ envp[i] = NULL;
+
+ /* Drop the lock while we invoke the usermode helper,
+ * since the exec could involve hitting disk and hence
+ * be a slow process */
+ mutex_unlock(&cgroup_mutex);
+ call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
+ kfree(pathbuf);
+ mutex_lock(&cgroup_mutex);
+ spin_lock(&release_list_lock);
+ }
+ spin_unlock(&release_list_lock);
+ mutex_unlock(&cgroup_mutex);
+}
git.samba.org / sfrench / cifs-2.6.git / blobdiff