* Based originally on the cpuset system, extracted by Paul Menage
* Copyright (C) 2006 Google, Inc
*
+ * Notifications support
+ * Copyright (C) 2009 Nokia Corporation
+ * Author: Kirill A. Shutemov
+ *
* Copyright notices from the original cpuset code:
* --------------------------------------------------
* Copyright (C) 2003 BULL SA.
*/
#include <linux/cgroup.h>
+#include <linux/ctype.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/sort.h>
#include <linux/kmod.h>
+#include <linux/module.h>
#include <linux/delayacct.h>
#include <linux/cgroupstats.h>
#include <linux/hash.h>
#include <linux/namei.h>
+#include <linux/smp_lock.h>
+#include <linux/pid_namespace.h>
+#include <linux/idr.h>
+#include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */
+#include <linux/eventfd.h>
+#include <linux/poll.h>
#include <asm/atomic.h>
static DEFINE_MUTEX(cgroup_mutex);
-/* Generate an array of cgroup subsystem pointers */
+/*
+ * Generate an array of cgroup subsystem pointers. At boot time, this is
+ * populated up to CGROUP_BUILTIN_SUBSYS_COUNT, and modular subsystems are
+ * registered after that. The mutable section of this array is protected by
+ * cgroup_mutex.
+ */
#define SUBSYS(_x) &_x ## _subsys,
-
-static struct cgroup_subsys *subsys[] = {
+static struct cgroup_subsys *subsys[CGROUP_SUBSYS_COUNT] = {
#include <linux/cgroup_subsys.h>
};
+#define MAX_CGROUP_ROOT_NAMELEN 64
+
/*
* A cgroupfs_root represents the root of a cgroup hierarchy,
* and may be associated with a superblock to form an active
*/
unsigned long subsys_bits;
+ /* Unique id for this hierarchy. */
+ int hierarchy_id;
+
/* The bitmask of subsystems currently attached to this hierarchy */
unsigned long actual_subsys_bits;
/* The path to use for release notifications. */
char release_agent_path[PATH_MAX];
-};
+ /* The name for this hierarchy - may be empty */
+ char name[MAX_CGROUP_ROOT_NAMELEN];
+};
/*
* The "rootnode" hierarchy is the "dummy hierarchy", reserved for the
*/
static struct cgroupfs_root rootnode;
+/*
+ * CSS ID -- ID per subsys's Cgroup Subsys State(CSS). used only when
+ * cgroup_subsys->use_id != 0.
+ */
+#define CSS_ID_MAX (65535)
+struct css_id {
+ /*
+ * The css to which this ID points. This pointer is set to valid value
+ * after cgroup is populated. If cgroup is removed, this will be NULL.
+ * This pointer is expected to be RCU-safe because destroy()
+ * is called after synchronize_rcu(). But for safe use, css_is_removed()
+ * css_tryget() should be used for avoiding race.
+ */
+ struct cgroup_subsys_state *css;
+ /*
+ * ID of this css.
+ */
+ unsigned short id;
+ /*
+ * Depth in hierarchy which this ID belongs to.
+ */
+ unsigned short depth;
+ /*
+ * ID is freed by RCU. (and lookup routine is RCU safe.)
+ */
+ struct rcu_head rcu_head;
+ /*
+ * Hierarchy of CSS ID belongs to.
+ */
+ unsigned short stack[0]; /* Array of Length (depth+1) */
+};
+
+/*
+ * cgroup_event represents events which userspace want to recieve.
+ */
+struct cgroup_event {
+ /*
+ * Cgroup which the event belongs to.
+ */
+ struct cgroup *cgrp;
+ /*
+ * Control file which the event associated.
+ */
+ struct cftype *cft;
+ /*
+ * eventfd to signal userspace about the event.
+ */
+ struct eventfd_ctx *eventfd;
+ /*
+ * Each of these stored in a list by the cgroup.
+ */
+ struct list_head list;
+ /*
+ * All fields below needed to unregister event when
+ * userspace closes eventfd.
+ */
+ poll_table pt;
+ wait_queue_head_t *wqh;
+ wait_queue_t wait;
+ struct work_struct remove;
+};
+
/* The list of hierarchy roots */
static LIST_HEAD(roots);
static int root_count;
+static DEFINE_IDA(hierarchy_ida);
+static int next_hierarchy_id;
+static DEFINE_SPINLOCK(hierarchy_id_lock);
+
/* dummytop is a shorthand for the dummy hierarchy's top cgroup */
#define dummytop (&rootnode.top_cgroup)
*/
static int need_forkexit_callback __read_mostly;
+#ifdef CONFIG_PROVE_LOCKING
+int cgroup_lock_is_held(void)
+{
+ return lockdep_is_held(&cgroup_mutex);
+}
+#else /* #ifdef CONFIG_PROVE_LOCKING */
+int cgroup_lock_is_held(void)
+{
+ return mutex_is_locked(&cgroup_mutex);
+}
+#endif /* #else #ifdef CONFIG_PROVE_LOCKING */
+
+EXPORT_SYMBOL_GPL(cgroup_lock_is_held);
+
/* convenient tests for these bits */
inline int cgroup_is_removed(const struct cgroup *cgrp)
{
* cgroup, anchored on cgroup->css_sets
*/
struct list_head cgrp_link_list;
+ struct cgroup *cgrp;
/*
* List running through cg_cgroup_links pointing at a
* single css_set object, anchored on css_set->cg_links
static struct css_set init_css_set;
static struct cg_cgroup_link init_css_set_link;
+static int cgroup_init_idr(struct cgroup_subsys *ss,
+ struct cgroup_subsys_state *css);
+
/* css_set_lock protects the list of css_set objects, and the
* chain of tasks off each css_set. Nests outside task->alloc_lock
* due to cgroup_iter_start() */
static DEFINE_RWLOCK(css_set_lock);
static int css_set_count;
-/* hash table for cgroup groups. This improves the performance to
- * find an existing css_set */
+/*
+ * hash table for cgroup groups. This improves the performance to find
+ * an existing css_set. This hash doesn't (currently) take into
+ * account cgroups in empty hierarchies.
+ */
#define CSS_SET_HASH_BITS 7
#define CSS_SET_TABLE_SIZE (1 << CSS_SET_HASH_BITS)
static struct hlist_head css_set_table[CSS_SET_TABLE_SIZE];
return &css_set_table[index];
}
+static void free_css_set_rcu(struct rcu_head *obj)
+{
+ struct css_set *cg = container_of(obj, struct css_set, rcu_head);
+ kfree(cg);
+}
+
/* We don't maintain the lists running through each css_set to its
* task until after the first call to cgroup_iter_start(). This
* reduces the fork()/exit() overhead for people who have cgroups
* compiled into their kernel but not actually in use */
static int use_task_css_set_links __read_mostly;
-/* 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)
+static void __put_css_set(struct css_set *cg, int taskexit)
{
struct cg_cgroup_link *link;
struct cg_cgroup_link *saved_link;
-
- hlist_del(&cg->hlist);
- css_set_count--;
-
- list_for_each_entry_safe(link, saved_link, &cg->cg_links,
- cg_link_list) {
- list_del(&link->cg_link_list);
- list_del(&link->cgrp_link_list);
- kfree(link);
- }
-}
-
-static void __put_css_set(struct css_set *cg, int taskexit)
-{
- int i;
/*
* Ensure that the refcount doesn't hit zero while any readers
* can see it. Similar to atomic_dec_and_lock(), but for an
write_unlock(&css_set_lock);
return;
}
- unlink_css_set(cg);
- write_unlock(&css_set_lock);
- rcu_read_lock();
- for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
- struct cgroup *cgrp = rcu_dereference(cg->subsys[i]->cgroup);
+ /* This css_set is dead. unlink it and release cgroup refcounts */
+ hlist_del(&cg->hlist);
+ css_set_count--;
+
+ list_for_each_entry_safe(link, saved_link, &cg->cg_links,
+ cg_link_list) {
+ struct cgroup *cgrp = link->cgrp;
+ list_del(&link->cg_link_list);
+ list_del(&link->cgrp_link_list);
if (atomic_dec_and_test(&cgrp->count) &&
notify_on_release(cgrp)) {
if (taskexit)
set_bit(CGRP_RELEASABLE, &cgrp->flags);
check_for_release(cgrp);
}
+
+ kfree(link);
}
- rcu_read_unlock();
- kfree(cg);
+
+ write_unlock(&css_set_lock);
+ call_rcu(&cg->rcu_head, free_css_set_rcu);
}
/*
__put_css_set(cg, 1);
}
+/*
+ * compare_css_sets - helper function for find_existing_css_set().
+ * @cg: candidate css_set being tested
+ * @old_cg: existing css_set for a task
+ * @new_cgrp: cgroup that's being entered by the task
+ * @template: desired set of css pointers in css_set (pre-calculated)
+ *
+ * Returns true if "cg" matches "old_cg" except for the hierarchy
+ * which "new_cgrp" belongs to, for which it should match "new_cgrp".
+ */
+static bool compare_css_sets(struct css_set *cg,
+ struct css_set *old_cg,
+ struct cgroup *new_cgrp,
+ struct cgroup_subsys_state *template[])
+{
+ struct list_head *l1, *l2;
+
+ if (memcmp(template, cg->subsys, sizeof(cg->subsys))) {
+ /* Not all subsystems matched */
+ return false;
+ }
+
+ /*
+ * Compare cgroup pointers in order to distinguish between
+ * different cgroups in heirarchies with no subsystems. We
+ * could get by with just this check alone (and skip the
+ * memcmp above) but on most setups the memcmp check will
+ * avoid the need for this more expensive check on almost all
+ * candidates.
+ */
+
+ l1 = &cg->cg_links;
+ l2 = &old_cg->cg_links;
+ while (1) {
+ struct cg_cgroup_link *cgl1, *cgl2;
+ struct cgroup *cg1, *cg2;
+
+ l1 = l1->next;
+ l2 = l2->next;
+ /* See if we reached the end - both lists are equal length. */
+ if (l1 == &cg->cg_links) {
+ BUG_ON(l2 != &old_cg->cg_links);
+ break;
+ } else {
+ BUG_ON(l2 == &old_cg->cg_links);
+ }
+ /* Locate the cgroups associated with these links. */
+ cgl1 = list_entry(l1, struct cg_cgroup_link, cg_link_list);
+ cgl2 = list_entry(l2, struct cg_cgroup_link, cg_link_list);
+ cg1 = cgl1->cgrp;
+ cg2 = cgl2->cgrp;
+ /* Hierarchies should be linked in the same order. */
+ BUG_ON(cg1->root != cg2->root);
+
+ /*
+ * If this hierarchy is the hierarchy of the cgroup
+ * that's changing, then we need to check that this
+ * css_set points to the new cgroup; if it's any other
+ * hierarchy, then this css_set should point to the
+ * same cgroup as the old css_set.
+ */
+ if (cg1->root == new_cgrp->root) {
+ if (cg1 != new_cgrp)
+ return false;
+ } else {
+ if (cg1 != cg2)
+ return false;
+ }
+ }
+ return true;
+}
+
/*
* find_existing_css_set() is a helper for
* find_css_set(), and checks to see whether an existing
struct hlist_node *node;
struct css_set *cg;
- /* Built the set of subsystem state objects that we want to
- * see in the new css_set */
+ /*
+ * Build the set of subsystem state objects that we want to see in the
+ * new css_set. while subsystems can change globally, the entries here
+ * won't change, so no need for locking.
+ */
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
if (root->subsys_bits & (1UL << i)) {
/* Subsystem is in this hierarchy. So we want
hhead = css_set_hash(template);
hlist_for_each_entry(cg, node, hhead, hlist) {
- if (!memcmp(template, cg->subsys, sizeof(cg->subsys))) {
- /* All subsystems matched */
- return cg;
- }
+ if (!compare_css_sets(cg, oldcg, cgrp, template))
+ continue;
+
+ /* This css_set matches what we need */
+ return cg;
}
/* No existing cgroup group matched */
link = list_first_entry(tmp_cg_links, struct cg_cgroup_link,
cgrp_link_list);
link->cg = cg;
+ link->cgrp = cgrp;
+ atomic_inc(&cgrp->count);
list_move(&link->cgrp_link_list, &cgrp->css_sets);
- list_add(&link->cg_link_list, &cg->cg_links);
+ /*
+ * Always add links to the tail of the list so that the list
+ * is sorted by order of hierarchy creation
+ */
+ list_add_tail(&link->cg_link_list, &cg->cg_links);
}
/*
{
struct css_set *res;
struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT];
- int i;
struct list_head tmp_cg_links;
struct hlist_head *hhead;
+ struct cg_cgroup_link *link;
/* First see if we already have a cgroup group that matches
* the desired set */
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)
- link_css_set(&tmp_cg_links, res, cgrp);
+ list_for_each_entry(link, &oldcg->cg_links, cg_link_list) {
+ struct cgroup *c = link->cgrp;
+ if (c->root == cgrp->root)
+ c = cgrp;
+ link_css_set(&tmp_cg_links, res, c);
}
- if (list_empty(&rootnode.subsys_list))
- link_css_set(&tmp_cg_links, res, dummytop);
BUG_ON(!list_empty(&tmp_cg_links));
return res;
}
+/*
+ * Return the cgroup for "task" from the given hierarchy. Must be
+ * called with cgroup_mutex held.
+ */
+static struct cgroup *task_cgroup_from_root(struct task_struct *task,
+ struct cgroupfs_root *root)
+{
+ struct css_set *css;
+ struct cgroup *res = NULL;
+
+ BUG_ON(!mutex_is_locked(&cgroup_mutex));
+ read_lock(&css_set_lock);
+ /*
+ * No need to lock the task - since we hold cgroup_mutex the
+ * task can't change groups, so the only thing that can happen
+ * is that it exits and its css is set back to init_css_set.
+ */
+ css = task->cgroups;
+ if (css == &init_css_set) {
+ res = &root->top_cgroup;
+ } else {
+ struct cg_cgroup_link *link;
+ list_for_each_entry(link, &css->cg_links, cg_link_list) {
+ struct cgroup *c = link->cgrp;
+ if (c->root == root) {
+ res = c;
+ break;
+ }
+ }
+ }
+ read_unlock(&css_set_lock);
+ BUG_ON(!res);
+ return res;
+}
+
/*
* There is one global cgroup mutex. We also require taking
* task_lock() when dereferencing a task's cgroup subsys pointers.
{
mutex_lock(&cgroup_mutex);
}
+EXPORT_SYMBOL_GPL(cgroup_lock);
/**
* cgroup_unlock - release lock on cgroup changes
{
mutex_unlock(&cgroup_mutex);
}
+EXPORT_SYMBOL_GPL(cgroup_unlock);
/*
* A couple of forward declarations required, due to cyclic reference loop:
static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, int mode);
static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry);
static int cgroup_populate_dir(struct cgroup *cgrp);
-static struct inode_operations cgroup_dir_inode_operations;
-static struct file_operations proc_cgroupstats_operations;
+static const struct inode_operations cgroup_dir_inode_operations;
+static const struct file_operations proc_cgroupstats_operations;
static struct backing_dev_info cgroup_backing_dev_info = {
+ .name = "cgroup",
.capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
};
+static int alloc_css_id(struct cgroup_subsys *ss,
+ struct cgroup *parent, struct cgroup *child);
+
static struct inode *cgroup_new_inode(mode_t mode, struct super_block *sb)
{
struct inode *inode = new_inode(sb);
* Call subsys's pre_destroy handler.
* This is called before css refcnt check.
*/
-static void cgroup_call_pre_destroy(struct cgroup *cgrp)
+static int cgroup_call_pre_destroy(struct cgroup *cgrp)
{
struct cgroup_subsys *ss;
+ int ret = 0;
+
for_each_subsys(cgrp->root, ss)
- if (ss->pre_destroy)
- ss->pre_destroy(ss, cgrp);
- return;
+ if (ss->pre_destroy) {
+ ret = ss->pre_destroy(ss, cgrp);
+ if (ret)
+ break;
+ }
+
+ return ret;
}
static void free_cgroup_rcu(struct rcu_head *obj)
*/
deactivate_super(cgrp->root->sb);
+ /*
+ * if we're getting rid of the cgroup, refcount should ensure
+ * that there are no pidlists left.
+ */
+ BUG_ON(!list_empty(&cgrp->pidlists));
+
call_rcu(&cgrp->rcu_head, free_cgroup_rcu);
}
iput(inode);
remove_dir(dentry);
}
+/*
+ * A queue for waiters to do rmdir() cgroup. A tasks will sleep when
+ * cgroup->count == 0 && list_empty(&cgroup->children) && subsys has some
+ * reference to css->refcnt. In general, this refcnt is expected to goes down
+ * to zero, soon.
+ *
+ * CGRP_WAIT_ON_RMDIR flag is set under cgroup's inode->i_mutex;
+ */
+DECLARE_WAIT_QUEUE_HEAD(cgroup_rmdir_waitq);
+
+static void cgroup_wakeup_rmdir_waiter(struct cgroup *cgrp)
+{
+ if (unlikely(test_and_clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags)))
+ wake_up_all(&cgroup_rmdir_waitq);
+}
+
+void cgroup_exclude_rmdir(struct cgroup_subsys_state *css)
+{
+ css_get(css);
+}
+
+void cgroup_release_and_wakeup_rmdir(struct cgroup_subsys_state *css)
+{
+ cgroup_wakeup_rmdir_waiter(css->cgroup);
+ css_put(css);
+}
+
+/*
+ * Call with cgroup_mutex held. Drops reference counts on modules, including
+ * any duplicate ones that parse_cgroupfs_options took. If this function
+ * returns an error, no reference counts are touched.
+ */
static int rebind_subsystems(struct cgroupfs_root *root,
unsigned long final_bits)
{
struct cgroup *cgrp = &root->top_cgroup;
int i;
+ BUG_ON(!mutex_is_locked(&cgroup_mutex));
+
removed_bits = root->actual_subsys_bits & ~final_bits;
added_bits = final_bits & ~root->actual_subsys_bits;
/* Check that any added subsystems are currently free */
struct cgroup_subsys *ss = subsys[i];
if (!(bit & added_bits))
continue;
+ /*
+ * Nobody should tell us to do a subsys that doesn't exist:
+ * parse_cgroupfs_options should catch that case and refcounts
+ * ensure that subsystems won't disappear once selected.
+ */
+ BUG_ON(ss == NULL);
if (ss->root != &rootnode) {
/* Subsystem isn't free */
return -EBUSY;
unsigned long bit = 1UL << i;
if (bit & added_bits) {
/* We're binding this subsystem to this hierarchy */
+ BUG_ON(ss == NULL);
BUG_ON(cgrp->subsys[i]);
BUG_ON(!dummytop->subsys[i]);
BUG_ON(dummytop->subsys[i]->cgroup != dummytop);
if (ss->bind)
ss->bind(ss, cgrp);
mutex_unlock(&ss->hierarchy_mutex);
+ /* refcount was already taken, and we're keeping it */
} else if (bit & removed_bits) {
/* We're removing this subsystem */
+ BUG_ON(ss == NULL);
BUG_ON(cgrp->subsys[i] != dummytop->subsys[i]);
BUG_ON(cgrp->subsys[i]->cgroup != cgrp);
mutex_lock(&ss->hierarchy_mutex);
subsys[i]->root = &rootnode;
list_move(&ss->sibling, &rootnode.subsys_list);
mutex_unlock(&ss->hierarchy_mutex);
+ /* subsystem is now free - drop reference on module */
+ module_put(ss->module);
} else if (bit & final_bits) {
/* Subsystem state should already exist */
+ BUG_ON(ss == NULL);
BUG_ON(!cgrp->subsys[i]);
+ /*
+ * a refcount was taken, but we already had one, so
+ * drop the extra reference.
+ */
+ module_put(ss->module);
+#ifdef CONFIG_MODULE_UNLOAD
+ BUG_ON(ss->module && !module_refcount(ss->module));
+#endif
} else {
/* Subsystem state shouldn't exist */
BUG_ON(cgrp->subsys[i]);
seq_puts(seq, ",noprefix");
if (strlen(root->release_agent_path))
seq_printf(seq, ",release_agent=%s", root->release_agent_path);
+ if (strlen(root->name))
+ seq_printf(seq, ",name=%s", root->name);
mutex_unlock(&cgroup_mutex);
return 0;
}
unsigned long subsys_bits;
unsigned long flags;
char *release_agent;
+ char *name;
+ /* User explicitly requested empty subsystem */
+ bool none;
+
+ struct cgroupfs_root *new_root;
+
};
-/* Convert a hierarchy specifier into a bitmask of subsystems and
- * flags. */
-static int parse_cgroupfs_options(char *data,
- struct cgroup_sb_opts *opts)
+/*
+ * Convert a hierarchy specifier into a bitmask of subsystems and flags. Call
+ * with cgroup_mutex held to protect the subsys[] array. This function takes
+ * refcounts on subsystems to be used, unless it returns error, in which case
+ * no refcounts are taken.
+ */
+static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
{
char *token, *o = data ?: "all";
+ unsigned long mask = (unsigned long)-1;
+ int i;
+ bool module_pin_failed = false;
+
+ BUG_ON(!mutex_is_locked(&cgroup_mutex));
+
+#ifdef CONFIG_CPUSETS
+ mask = ~(1UL << cpuset_subsys_id);
+#endif
- opts->subsys_bits = 0;
- opts->flags = 0;
- opts->release_agent = NULL;
+ memset(opts, 0, sizeof(*opts));
while ((token = strsep(&o, ",")) != NULL) {
if (!*token)
return -EINVAL;
if (!strcmp(token, "all")) {
/* Add all non-disabled subsystems */
- int i;
opts->subsys_bits = 0;
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
struct cgroup_subsys *ss = subsys[i];
+ if (ss == NULL)
+ continue;
if (!ss->disabled)
opts->subsys_bits |= 1ul << i;
}
+ } else if (!strcmp(token, "none")) {
+ /* Explicitly have no subsystems */
+ opts->none = true;
} else if (!strcmp(token, "noprefix")) {
set_bit(ROOT_NOPREFIX, &opts->flags);
} else if (!strncmp(token, "release_agent=", 14)) {
/* Specifying two release agents is forbidden */
if (opts->release_agent)
return -EINVAL;
- opts->release_agent = kzalloc(PATH_MAX, GFP_KERNEL);
+ opts->release_agent =
+ kstrndup(token + 14, PATH_MAX - 1, 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 if (!strncmp(token, "name=", 5)) {
+ const char *name = token + 5;
+ /* Can't specify an empty name */
+ if (!strlen(name))
+ return -EINVAL;
+ /* Must match [\w.-]+ */
+ for (i = 0; i < strlen(name); i++) {
+ char c = name[i];
+ if (isalnum(c))
+ continue;
+ if ((c == '.') || (c == '-') || (c == '_'))
+ continue;
+ return -EINVAL;
+ }
+ /* Specifying two names is forbidden */
+ if (opts->name)
+ return -EINVAL;
+ opts->name = kstrndup(name,
+ MAX_CGROUP_ROOT_NAMELEN - 1,
+ GFP_KERNEL);
+ if (!opts->name)
+ return -ENOMEM;
} else {
struct cgroup_subsys *ss;
- int i;
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
ss = subsys[i];
+ if (ss == NULL)
+ continue;
if (!strcmp(token, ss->name)) {
if (!ss->disabled)
set_bit(i, &opts->subsys_bits);
}
}
- /* We can't have an empty hierarchy */
- if (!opts->subsys_bits)
+ /* Consistency checks */
+
+ /*
+ * Option noprefix was introduced just for backward compatibility
+ * with the old cpuset, so we allow noprefix only if mounting just
+ * the cpuset subsystem.
+ */
+ if (test_bit(ROOT_NOPREFIX, &opts->flags) &&
+ (opts->subsys_bits & mask))
+ return -EINVAL;
+
+
+ /* Can't specify "none" and some subsystems */
+ if (opts->subsys_bits && opts->none)
+ return -EINVAL;
+
+ /*
+ * We either have to specify by name or by subsystems. (So all
+ * empty hierarchies must have a name).
+ */
+ if (!opts->subsys_bits && !opts->name)
return -EINVAL;
+ /*
+ * Grab references on all the modules we'll need, so the subsystems
+ * don't dance around before rebind_subsystems attaches them. This may
+ * take duplicate reference counts on a subsystem that's already used,
+ * but rebind_subsystems handles this case.
+ */
+ for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) {
+ unsigned long bit = 1UL << i;
+
+ if (!(bit & opts->subsys_bits))
+ continue;
+ if (!try_module_get(subsys[i]->module)) {
+ module_pin_failed = true;
+ break;
+ }
+ }
+ if (module_pin_failed) {
+ /*
+ * oops, one of the modules was going away. this means that we
+ * raced with a module_delete call, and to the user this is
+ * essentially a "subsystem doesn't exist" case.
+ */
+ for (i--; i >= CGROUP_BUILTIN_SUBSYS_COUNT; i--) {
+ /* drop refcounts only on the ones we took */
+ unsigned long bit = 1UL << i;
+
+ if (!(bit & opts->subsys_bits))
+ continue;
+ module_put(subsys[i]->module);
+ }
+ return -ENOENT;
+ }
+
return 0;
}
+static void drop_parsed_module_refcounts(unsigned long subsys_bits)
+{
+ int i;
+ for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) {
+ unsigned long bit = 1UL << i;
+
+ if (!(bit & subsys_bits))
+ continue;
+ module_put(subsys[i]->module);
+ }
+}
+
static int cgroup_remount(struct super_block *sb, int *flags, char *data)
{
int ret = 0;
struct cgroup *cgrp = &root->top_cgroup;
struct cgroup_sb_opts opts;
+ lock_kernel();
mutex_lock(&cgrp->dentry->d_inode->i_mutex);
mutex_lock(&cgroup_mutex);
if (ret)
goto out_unlock;
- /* Don't allow flags to change at remount */
- if (opts.flags != root->flags) {
+ /* Don't allow flags or name to change at remount */
+ if (opts.flags != root->flags ||
+ (opts.name && strcmp(opts.name, root->name))) {
ret = -EINVAL;
+ drop_parsed_module_refcounts(opts.subsys_bits);
goto out_unlock;
}
ret = rebind_subsystems(root, opts.subsys_bits);
+ if (ret) {
+ drop_parsed_module_refcounts(opts.subsys_bits);
+ goto out_unlock;
+ }
/* (re)populate subsystem files */
- if (!ret)
- cgroup_populate_dir(cgrp);
+ cgroup_populate_dir(cgrp);
if (opts.release_agent)
strcpy(root->release_agent_path, opts.release_agent);
out_unlock:
- if (opts.release_agent)
- kfree(opts.release_agent);
+ kfree(opts.release_agent);
+ kfree(opts.name);
mutex_unlock(&cgroup_mutex);
mutex_unlock(&cgrp->dentry->d_inode->i_mutex);
+ unlock_kernel();
return ret;
}
-static struct super_operations cgroup_ops = {
+static const struct super_operations cgroup_ops = {
.statfs = simple_statfs,
.drop_inode = generic_delete_inode,
.show_options = cgroup_show_options,
INIT_LIST_HEAD(&cgrp->children);
INIT_LIST_HEAD(&cgrp->css_sets);
INIT_LIST_HEAD(&cgrp->release_list);
- init_rwsem(&cgrp->pids_mutex);
+ INIT_LIST_HEAD(&cgrp->pidlists);
+ mutex_init(&cgrp->pidlist_mutex);
+ INIT_LIST_HEAD(&cgrp->event_list);
+ spin_lock_init(&cgrp->event_list_lock);
}
+
static void init_cgroup_root(struct cgroupfs_root *root)
{
struct cgroup *cgrp = &root->top_cgroup;
init_cgroup_housekeeping(cgrp);
}
+static bool init_root_id(struct cgroupfs_root *root)
+{
+ int ret = 0;
+
+ do {
+ if (!ida_pre_get(&hierarchy_ida, GFP_KERNEL))
+ return false;
+ spin_lock(&hierarchy_id_lock);
+ /* Try to allocate the next unused ID */
+ ret = ida_get_new_above(&hierarchy_ida, next_hierarchy_id,
+ &root->hierarchy_id);
+ if (ret == -ENOSPC)
+ /* Try again starting from 0 */
+ ret = ida_get_new(&hierarchy_ida, &root->hierarchy_id);
+ if (!ret) {
+ next_hierarchy_id = root->hierarchy_id + 1;
+ } else if (ret != -EAGAIN) {
+ /* Can only get here if the 31-bit IDR is full ... */
+ BUG_ON(ret);
+ }
+ spin_unlock(&hierarchy_id_lock);
+ } while (ret);
+ return true;
+}
+
static int cgroup_test_super(struct super_block *sb, void *data)
{
- struct cgroupfs_root *new = data;
+ struct cgroup_sb_opts *opts = data;
struct cgroupfs_root *root = sb->s_fs_info;
- /* First check subsystems */
- if (new->subsys_bits != root->subsys_bits)
- return 0;
+ /* If we asked for a name then it must match */
+ if (opts->name && strcmp(opts->name, root->name))
+ return 0;
- /* Next check flags */
- if (new->flags != root->flags)
+ /*
+ * If we asked for subsystems (or explicitly for no
+ * subsystems) then they must match
+ */
+ if ((opts->subsys_bits || opts->none)
+ && (opts->subsys_bits != root->subsys_bits))
return 0;
return 1;
}
+static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts)
+{
+ struct cgroupfs_root *root;
+
+ if (!opts->subsys_bits && !opts->none)
+ return NULL;
+
+ root = kzalloc(sizeof(*root), GFP_KERNEL);
+ if (!root)
+ return ERR_PTR(-ENOMEM);
+
+ if (!init_root_id(root)) {
+ kfree(root);
+ return ERR_PTR(-ENOMEM);
+ }
+ init_cgroup_root(root);
+
+ root->subsys_bits = opts->subsys_bits;
+ root->flags = opts->flags;
+ if (opts->release_agent)
+ strcpy(root->release_agent_path, opts->release_agent);
+ if (opts->name)
+ strcpy(root->name, opts->name);
+ return root;
+}
+
+static void cgroup_drop_root(struct cgroupfs_root *root)
+{
+ if (!root)
+ return;
+
+ BUG_ON(!root->hierarchy_id);
+ spin_lock(&hierarchy_id_lock);
+ ida_remove(&hierarchy_ida, root->hierarchy_id);
+ spin_unlock(&hierarchy_id_lock);
+ kfree(root);
+}
+
static int cgroup_set_super(struct super_block *sb, void *data)
{
int ret;
- struct cgroupfs_root *root = data;
+ struct cgroup_sb_opts *opts = data;
+
+ /* If we don't have a new root, we can't set up a new sb */
+ if (!opts->new_root)
+ return -EINVAL;
+
+ BUG_ON(!opts->subsys_bits && !opts->none);
ret = set_anon_super(sb, NULL);
if (ret)
return ret;
- sb->s_fs_info = root;
- root->sb = sb;
+ sb->s_fs_info = opts->new_root;
+ opts->new_root->sb = sb;
sb->s_blocksize = PAGE_CACHE_SIZE;
sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
void *data, struct vfsmount *mnt)
{
struct cgroup_sb_opts opts;
+ struct cgroupfs_root *root;
int ret = 0;
struct super_block *sb;
- struct cgroupfs_root *root;
- struct list_head tmp_cg_links;
+ struct cgroupfs_root *new_root;
/* First find the desired set of subsystems */
+ mutex_lock(&cgroup_mutex);
ret = parse_cgroupfs_options(data, &opts);
- if (ret) {
- if (opts.release_agent)
- kfree(opts.release_agent);
- return ret;
- }
-
- root = kzalloc(sizeof(*root), GFP_KERNEL);
- if (!root) {
- if (opts.release_agent)
- kfree(opts.release_agent);
- return -ENOMEM;
- }
+ mutex_unlock(&cgroup_mutex);
+ if (ret)
+ goto out_err;
- 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);
+ /*
+ * Allocate a new cgroup root. We may not need it if we're
+ * reusing an existing hierarchy.
+ */
+ new_root = cgroup_root_from_opts(&opts);
+ if (IS_ERR(new_root)) {
+ ret = PTR_ERR(new_root);
+ goto drop_modules;
}
+ opts.new_root = new_root;
- sb = sget(fs_type, cgroup_test_super, cgroup_set_super, root);
-
+ /* Locate an existing or new sb for this hierarchy */
+ sb = sget(fs_type, cgroup_test_super, cgroup_set_super, &opts);
if (IS_ERR(sb)) {
- kfree(root);
- return PTR_ERR(sb);
+ ret = PTR_ERR(sb);
+ cgroup_drop_root(opts.new_root);
+ goto drop_modules;
}
- if (sb->s_fs_info != root) {
- /* Reusing an existing superblock */
- BUG_ON(sb->s_root == NULL);
- kfree(root);
- root = NULL;
- } else {
- /* New superblock */
+ root = sb->s_fs_info;
+ BUG_ON(!root);
+ if (root == opts.new_root) {
+ /* We used the new root structure, so this is a new hierarchy */
+ struct list_head tmp_cg_links;
struct cgroup *root_cgrp = &root->top_cgroup;
struct inode *inode;
+ struct cgroupfs_root *existing_root;
int i;
BUG_ON(sb->s_root != NULL);
mutex_lock(&inode->i_mutex);
mutex_lock(&cgroup_mutex);
+ if (strlen(root->name)) {
+ /* Check for name clashes with existing mounts */
+ for_each_active_root(existing_root) {
+ if (!strcmp(existing_root->name, root->name)) {
+ ret = -EBUSY;
+ mutex_unlock(&cgroup_mutex);
+ mutex_unlock(&inode->i_mutex);
+ goto drop_new_super;
+ }
+ }
+ }
+
/*
* We're accessing css_set_count without locking
* css_set_lock here, but that's OK - it can only be
if (ret == -EBUSY) {
mutex_unlock(&cgroup_mutex);
mutex_unlock(&inode->i_mutex);
- goto free_cg_links;
+ free_cg_links(&tmp_cg_links);
+ goto drop_new_super;
}
+ /*
+ * There must be no failure case after here, since rebinding
+ * takes care of subsystems' refcounts, which are explicitly
+ * dropped in the failure exit path.
+ */
/* EBUSY should be the only error here */
BUG_ON(ret);
BUG_ON(root->number_of_cgroups != 1);
cgroup_populate_dir(root_cgrp);
- mutex_unlock(&inode->i_mutex);
mutex_unlock(&cgroup_mutex);
+ mutex_unlock(&inode->i_mutex);
+ } else {
+ /*
+ * We re-used an existing hierarchy - the new root (if
+ * any) is not needed
+ */
+ cgroup_drop_root(opts.new_root);
+ /* no subsys rebinding, so refcounts don't change */
+ drop_parsed_module_refcounts(opts.subsys_bits);
}
- return simple_set_mnt(mnt, sb);
+ simple_set_mnt(mnt, sb);
+ kfree(opts.release_agent);
+ kfree(opts.name);
+ return 0;
- free_cg_links:
- free_cg_links(&tmp_cg_links);
drop_new_super:
- up_write(&sb->s_umount);
- deactivate_super(sb);
+ deactivate_locked_super(sb);
+ drop_modules:
+ drop_parsed_module_refcounts(opts.subsys_bits);
+ out_err:
+ kfree(opts.release_agent);
+ kfree(opts.name);
+
return ret;
}
}
write_unlock(&css_set_lock);
- list_del(&root->root_list);
- root_count--;
+ if (!list_empty(&root->root_list)) {
+ list_del(&root->root_list);
+ root_count--;
+ }
mutex_unlock(&cgroup_mutex);
- kfree(root);
kill_litter_super(sb);
+ cgroup_drop_root(root);
}
static struct file_system_type cgroup_fs_type = {
.kill_sb = cgroup_kill_sb,
};
+static struct kobject *cgroup_kobj;
+
static inline struct cgroup *__d_cgrp(struct dentry *dentry)
{
return dentry->d_fsdata;
int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen)
{
char *start;
- struct dentry *dentry = rcu_dereference(cgrp->dentry);
+ struct dentry *dentry = rcu_dereference_check(cgrp->dentry,
+ rcu_read_lock_held() ||
+ cgroup_lock_is_held());
if (!dentry || cgrp == dummytop) {
/*
*--start = '\0';
for (;;) {
int len = dentry->d_name.len;
+
if ((start -= len) < buf)
return -ENAMETOOLONG;
- memcpy(start, cgrp->dentry->d_name.name, len);
+ memcpy(start, dentry->d_name.name, len);
cgrp = cgrp->parent;
if (!cgrp)
break;
- dentry = rcu_dereference(cgrp->dentry);
+
+ dentry = rcu_dereference_check(cgrp->dentry,
+ rcu_read_lock_held() ||
+ cgroup_lock_is_held());
if (!cgrp->parent)
continue;
if (--start < buf)
memmove(buf, start, buf + buflen - start);
return 0;
}
-
-/*
- * Return the first subsystem attached to a cgroup's hierarchy, and
- * its subsystem id.
- */
-
-static void get_first_subsys(const struct cgroup *cgrp,
- struct cgroup_subsys_state **css, int *subsys_id)
-{
- 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 = cgrp->subsys[test_ss->subsys_id];
- BUG_ON(!*css);
- }
- if (subsys_id)
- *subsys_id = test_ss->subsys_id;
-}
+EXPORT_SYMBOL_GPL(cgroup_path);
/**
* cgroup_attach_task - attach task 'tsk' to cgroup 'cgrp'
int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
{
int retval = 0;
- struct cgroup_subsys *ss;
+ struct cgroup_subsys *ss, *failed_ss = NULL;
struct cgroup *oldcgrp;
struct css_set *cg;
struct css_set *newcg;
struct cgroupfs_root *root = cgrp->root;
- int subsys_id;
-
- get_first_subsys(cgrp, NULL, &subsys_id);
/* Nothing to do if the task is already in that cgroup */
- oldcgrp = task_cgroup(tsk, subsys_id);
+ oldcgrp = task_cgroup_from_root(tsk, root);
if (cgrp == oldcgrp)
return 0;
for_each_subsys(root, ss) {
if (ss->can_attach) {
- retval = ss->can_attach(ss, cgrp, tsk);
- if (retval)
- return retval;
+ retval = ss->can_attach(ss, cgrp, tsk, false);
+ if (retval) {
+ /*
+ * Remember on which subsystem the can_attach()
+ * failed, so that we only call cancel_attach()
+ * against the subsystems whose can_attach()
+ * succeeded. (See below)
+ */
+ failed_ss = ss;
+ goto out;
+ }
}
}
*/
newcg = find_css_set(cg, cgrp);
put_css_set(cg);
- if (!newcg)
- return -ENOMEM;
+ if (!newcg) {
+ retval = -ENOMEM;
+ goto out;
+ }
task_lock(tsk);
if (tsk->flags & PF_EXITING) {
task_unlock(tsk);
put_css_set(newcg);
- return -ESRCH;
+ retval = -ESRCH;
+ goto out;
}
rcu_assign_pointer(tsk->cgroups, newcg);
task_unlock(tsk);
for_each_subsys(root, ss) {
if (ss->attach)
- ss->attach(ss, cgrp, oldcgrp, tsk);
+ ss->attach(ss, cgrp, oldcgrp, tsk, false);
}
set_bit(CGRP_RELEASABLE, &oldcgrp->flags);
synchronize_rcu();
put_css_set(cg);
- return 0;
+
+ /*
+ * wake up rmdir() waiter. the rmdir should fail since the cgroup
+ * is no longer empty.
+ */
+ cgroup_wakeup_rmdir_waiter(cgrp);
+out:
+ if (retval) {
+ for_each_subsys(root, ss) {
+ if (ss == failed_ss)
+ /*
+ * This subsystem was the one that failed the
+ * can_attach() check earlier, so we don't need
+ * to call cancel_attach() against it or any
+ * remaining subsystems.
+ */
+ break;
+ if (ss->cancel_attach)
+ ss->cancel_attach(ss, cgrp, tsk, false);
+ }
+ }
+ return retval;
+}
+
+/**
+ * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'
+ * @from: attach to all cgroups of a given task
+ * @tsk: the task to be attached
+ */
+int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
+{
+ struct cgroupfs_root *root;
+ struct cgroup *cur_cg;
+ int retval = 0;
+
+ cgroup_lock();
+ for_each_active_root(root) {
+ cur_cg = task_cgroup_from_root(from, root);
+ retval = cgroup_attach_task(cur_cg, tsk);
+ if (retval)
+ break;
+ }
+ cgroup_unlock();
+
+ return retval;
}
+EXPORT_SYMBOL_GPL(cgroup_attach_task_all);
/*
* Attach task with pid 'pid' to cgroup 'cgrp'. Call with cgroup_mutex
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_RELEASE_AGENT,
-};
-
/**
* cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive.
* @cgrp: the cgroup to be checked for liveness
}
return true;
}
+EXPORT_SYMBOL_GPL(cgroup_lock_live_group);
static int cgroup_release_agent_write(struct cgroup *cgrp, struct cftype *cft,
const char *buffer)
return -EFAULT;
buffer[nbytes] = 0; /* nul-terminate */
- strstrip(buffer);
if (cft->write_u64) {
- u64 val = simple_strtoull(buffer, &end, 0);
+ u64 val = simple_strtoull(strstrip(buffer), &end, 0);
if (*end)
return -EINVAL;
retval = cft->write_u64(cgrp, cft, val);
} else {
- s64 val = simple_strtoll(buffer, &end, 0);
+ s64 val = simple_strtoll(strstrip(buffer), &end, 0);
if (*end)
return -EINVAL;
retval = cft->write_s64(cgrp, cft, val);
}
buffer[nbytes] = 0; /* nul-terminate */
- strstrip(buffer);
- retval = cft->write_string(cgrp, cft, buffer);
+ retval = cft->write_string(cgrp, cft, strstrip(buffer));
if (!retval)
retval = nbytes;
out:
return single_release(inode, file);
}
-static struct file_operations cgroup_seqfile_operations = {
+static const struct file_operations cgroup_seqfile_operations = {
.read = seq_read,
.write = cgroup_file_write,
.llseek = seq_lseek,
return simple_rename(old_dir, old_dentry, new_dir, new_dentry);
}
-static struct file_operations cgroup_file_operations = {
+static const struct file_operations cgroup_file_operations = {
.read = cgroup_file_read,
.write = cgroup_file_write,
.llseek = generic_file_llseek,
.release = cgroup_file_release,
};
-static struct inode_operations cgroup_dir_inode_operations = {
+static const struct inode_operations cgroup_dir_inode_operations = {
.lookup = simple_lookup,
.mkdir = cgroup_mkdir,
.rmdir = cgroup_rmdir,
.rename = cgroup_rename,
};
-static int cgroup_create_file(struct dentry *dentry, int mode,
+/*
+ * Check if a file is a control file
+ */
+static inline struct cftype *__file_cft(struct file *file)
+{
+ if (file->f_dentry->d_inode->i_fop != &cgroup_file_operations)
+ return ERR_PTR(-EINVAL);
+ return __d_cft(file->f_dentry);
+}
+
+static int cgroup_create_file(struct dentry *dentry, mode_t mode,
struct super_block *sb)
{
- static struct dentry_operations cgroup_dops = {
+ static const struct dentry_operations cgroup_dops = {
.d_iput = cgroup_diput,
};
* @mode: mode to set on new directory.
*/
static int cgroup_create_dir(struct cgroup *cgrp, struct dentry *dentry,
- int mode)
+ mode_t mode)
{
struct dentry *parent;
int error = 0;
return error;
}
+/**
+ * cgroup_file_mode - deduce file mode of a control file
+ * @cft: the control file in question
+ *
+ * returns cft->mode if ->mode is not 0
+ * returns S_IRUGO|S_IWUSR if it has both a read and a write handler
+ * returns S_IRUGO if it has only a read handler
+ * returns S_IWUSR if it has only a write hander
+ */
+static mode_t cgroup_file_mode(const struct cftype *cft)
+{
+ mode_t mode = 0;
+
+ if (cft->mode)
+ return cft->mode;
+
+ if (cft->read || cft->read_u64 || cft->read_s64 ||
+ cft->read_map || cft->read_seq_string)
+ mode |= S_IRUGO;
+
+ if (cft->write || cft->write_u64 || cft->write_s64 ||
+ cft->write_string || cft->trigger)
+ mode |= S_IWUSR;
+
+ return mode;
+}
+
int cgroup_add_file(struct cgroup *cgrp,
struct cgroup_subsys *subsys,
const struct cftype *cft)
struct dentry *dir = cgrp->dentry;
struct dentry *dentry;
int error;
+ mode_t mode;
char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 };
if (subsys && !test_bit(ROOT_NOPREFIX, &cgrp->root->flags)) {
BUG_ON(!mutex_is_locked(&dir->d_inode->i_mutex));
dentry = lookup_one_len(name, dir, strlen(name));
if (!IS_ERR(dentry)) {
- error = cgroup_create_file(dentry, 0644 | S_IFREG,
+ mode = cgroup_file_mode(cft);
+ error = cgroup_create_file(dentry, mode | S_IFREG,
cgrp->root->sb);
if (!error)
dentry->d_fsdata = (void *)cft;
error = PTR_ERR(dentry);
return error;
}
+EXPORT_SYMBOL_GPL(cgroup_add_file);
int cgroup_add_files(struct cgroup *cgrp,
struct cgroup_subsys *subsys,
}
return 0;
}
+EXPORT_SYMBOL_GPL(cgroup_add_files);
/**
* cgroup_task_count - count the number of tasks in a cgroup.
* the start of a css_set
*/
static void cgroup_advance_iter(struct cgroup *cgrp,
- struct cgroup_iter *it)
+ struct cgroup_iter *it)
{
struct list_head *l = it->cg_link;
struct cg_cgroup_link *link;
}
/*
- * Stuff for reading the 'tasks' file.
+ * Stuff for reading the 'tasks'/'procs' files.
*
* Reading this file can return large amounts of data if a cgroup has
* *lots* of attached tasks. So it may need several calls to read(),
*/
/*
- * 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.
+ * The following two functions "fix" the issue where there are more pids
+ * than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
+ * TODO: replace with a kernel-wide solution to this problem
+ */
+#define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2))
+static void *pidlist_allocate(int count)
+{
+ if (PIDLIST_TOO_LARGE(count))
+ return vmalloc(count * sizeof(pid_t));
+ else
+ return kmalloc(count * sizeof(pid_t), GFP_KERNEL);
+}
+static void pidlist_free(void *p)
+{
+ if (is_vmalloc_addr(p))
+ vfree(p);
+ else
+ kfree(p);
+}
+static void *pidlist_resize(void *p, int newcount)
+{
+ void *newlist;
+ /* note: if new alloc fails, old p will still be valid either way */
+ if (is_vmalloc_addr(p)) {
+ newlist = vmalloc(newcount * sizeof(pid_t));
+ if (!newlist)
+ return NULL;
+ memcpy(newlist, p, newcount * sizeof(pid_t));
+ vfree(p);
+ } else {
+ newlist = krealloc(p, newcount * sizeof(pid_t), GFP_KERNEL);
+ }
+ return newlist;
+}
+
+/*
+ * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
+ * If the new stripped list is sufficiently smaller and there's enough memory
+ * to allocate a new buffer, will let go of the unneeded memory. Returns the
+ * number of unique elements.
+ */
+/* is the size difference enough that we should re-allocate the array? */
+#define PIDLIST_REALLOC_DIFFERENCE(old, new) ((old) - PAGE_SIZE >= (new))
+static int pidlist_uniq(pid_t **p, int length)
+{
+ int src, dest = 1;
+ pid_t *list = *p;
+ pid_t *newlist;
+
+ /*
+ * we presume the 0th element is unique, so i starts at 1. trivial
+ * edge cases first; no work needs to be done for either
+ */
+ if (length == 0 || length == 1)
+ return length;
+ /* src and dest walk down the list; dest counts unique elements */
+ for (src = 1; src < length; src++) {
+ /* find next unique element */
+ while (list[src] == list[src-1]) {
+ src++;
+ if (src == length)
+ goto after;
+ }
+ /* dest always points to where the next unique element goes */
+ list[dest] = list[src];
+ dest++;
+ }
+after:
+ /*
+ * if the length difference is large enough, we want to allocate a
+ * smaller buffer to save memory. if this fails due to out of memory,
+ * we'll just stay with what we've got.
+ */
+ if (PIDLIST_REALLOC_DIFFERENCE(length, dest)) {
+ newlist = pidlist_resize(list, dest);
+ if (newlist)
+ *p = newlist;
+ }
+ return dest;
+}
+
+static int cmppid(const void *a, const void *b)
+{
+ return *(pid_t *)a - *(pid_t *)b;
+}
+
+/*
+ * find the appropriate pidlist for our purpose (given procs vs tasks)
+ * returns with the lock on that pidlist already held, and takes care
+ * of the use count, or returns NULL with no locks held if we're out of
+ * memory.
+ */
+static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp,
+ enum cgroup_filetype type)
+{
+ struct cgroup_pidlist *l;
+ /* don't need task_nsproxy() if we're looking at ourself */
+ struct pid_namespace *ns = current->nsproxy->pid_ns;
+
+ /*
+ * We can't drop the pidlist_mutex before taking the l->mutex in case
+ * the last ref-holder is trying to remove l from the list at the same
+ * time. Holding the pidlist_mutex precludes somebody taking whichever
+ * list we find out from under us - compare release_pid_array().
+ */
+ mutex_lock(&cgrp->pidlist_mutex);
+ list_for_each_entry(l, &cgrp->pidlists, links) {
+ if (l->key.type == type && l->key.ns == ns) {
+ /* make sure l doesn't vanish out from under us */
+ down_write(&l->mutex);
+ mutex_unlock(&cgrp->pidlist_mutex);
+ return l;
+ }
+ }
+ /* entry not found; create a new one */
+ l = kmalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL);
+ if (!l) {
+ mutex_unlock(&cgrp->pidlist_mutex);
+ return l;
+ }
+ init_rwsem(&l->mutex);
+ down_write(&l->mutex);
+ l->key.type = type;
+ l->key.ns = get_pid_ns(ns);
+ l->use_count = 0; /* don't increment here */
+ l->list = NULL;
+ l->owner = cgrp;
+ list_add(&l->links, &cgrp->pidlists);
+ mutex_unlock(&cgrp->pidlist_mutex);
+ return l;
+}
+
+/*
+ * Load a cgroup's pidarray with either procs' tgids or tasks' pids
*/
-static int pid_array_load(pid_t *pidarray, int npids, struct cgroup *cgrp)
+static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
+ struct cgroup_pidlist **lp)
{
- int n = 0, pid;
+ pid_t *array;
+ int length;
+ int pid, n = 0; /* used for populating the array */
struct cgroup_iter it;
struct task_struct *tsk;
+ struct cgroup_pidlist *l;
+
+ /*
+ * If cgroup gets more users after we read count, we won't have
+ * enough space - tough. This race is indistinguishable to the
+ * caller from the case that the additional cgroup users didn't
+ * show up until sometime later on.
+ */
+ length = cgroup_task_count(cgrp);
+ array = pidlist_allocate(length);
+ if (!array)
+ return -ENOMEM;
+ /* now, populate the array */
cgroup_iter_start(cgrp, &it);
while ((tsk = cgroup_iter_next(cgrp, &it))) {
- if (unlikely(n == npids))
+ if (unlikely(n == length))
break;
- pid = task_pid_vnr(tsk);
- if (pid > 0)
- pidarray[n++] = pid;
+ /* get tgid or pid for procs or tasks file respectively */
+ if (type == CGROUP_FILE_PROCS)
+ pid = task_tgid_vnr(tsk);
+ else
+ pid = task_pid_vnr(tsk);
+ if (pid > 0) /* make sure to only use valid results */
+ array[n++] = pid;
}
cgroup_iter_end(cgrp, &it);
- return n;
+ length = n;
+ /* now sort & (if procs) strip out duplicates */
+ sort(array, length, sizeof(pid_t), cmppid, NULL);
+ if (type == CGROUP_FILE_PROCS)
+ length = pidlist_uniq(&array, length);
+ l = cgroup_pidlist_find(cgrp, type);
+ if (!l) {
+ pidlist_free(array);
+ return -ENOMEM;
+ }
+ /* store array, freeing old if necessary - lock already held */
+ pidlist_free(l->list);
+ l->list = array;
+ l->length = length;
+ l->use_count++;
+ up_write(&l->mutex);
+ *lp = l;
+ return 0;
}
/**
return ret;
}
-static int cmppid(const void *a, const void *b)
-{
- return *(pid_t *)a - *(pid_t *)b;
-}
-
/*
- * seq_file methods for the "tasks" file. The seq_file position is the
+ * seq_file methods for the tasks/procs files. The seq_file position is the
* next pid to display; the seq_file iterator is a pointer to the pid
- * in the cgroup->tasks_pids array.
+ * in the cgroup->l->list array.
*/
-static void *cgroup_tasks_start(struct seq_file *s, loff_t *pos)
+static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos)
{
/*
* Initially we receive a position value that corresponds to
* after a seek to the start). Use a binary-search to find the
* next pid to display, if any
*/
- struct cgroup *cgrp = s->private;
+ struct cgroup_pidlist *l = s->private;
int index = 0, pid = *pos;
int *iter;
- down_read(&cgrp->pids_mutex);
+ down_read(&l->mutex);
if (pid) {
- int end = cgrp->pids_length;
+ int end = l->length;
while (index < end) {
int mid = (index + end) / 2;
- if (cgrp->tasks_pids[mid] == pid) {
+ if (l->list[mid] == pid) {
index = mid;
break;
- } else if (cgrp->tasks_pids[mid] <= pid)
+ } else if (l->list[mid] <= pid)
index = mid + 1;
else
end = mid;
}
}
/* If we're off the end of the array, we're done */
- if (index >= cgrp->pids_length)
+ if (index >= l->length)
return NULL;
/* Update the abstract position to be the actual pid that we found */
- iter = cgrp->tasks_pids + index;
+ iter = l->list + index;
*pos = *iter;
return iter;
}
-static void cgroup_tasks_stop(struct seq_file *s, void *v)
+static void cgroup_pidlist_stop(struct seq_file *s, void *v)
{
- struct cgroup *cgrp = s->private;
- up_read(&cgrp->pids_mutex);
+ struct cgroup_pidlist *l = s->private;
+ up_read(&l->mutex);
}
-static void *cgroup_tasks_next(struct seq_file *s, void *v, loff_t *pos)
+static void *cgroup_pidlist_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;
-
+ struct cgroup_pidlist *l = s->private;
+ pid_t *p = v;
+ pid_t *end = l->list + l->length;
/*
* Advance to the next pid in the array. If this goes off the
* end, we're done
}
}
-static int cgroup_tasks_show(struct seq_file *s, void *v)
+static int cgroup_pidlist_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,
+/*
+ * seq_operations functions for iterating on pidlists through seq_file -
+ * independent of whether it's tasks or procs
+ */
+static const struct seq_operations cgroup_pidlist_seq_operations = {
+ .start = cgroup_pidlist_start,
+ .stop = cgroup_pidlist_stop,
+ .next = cgroup_pidlist_next,
+ .show = cgroup_pidlist_show,
};
-static void release_cgroup_pid_array(struct cgroup *cgrp)
+static void cgroup_release_pid_array(struct cgroup_pidlist *l)
{
- 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;
+ /*
+ * the case where we're the last user of this particular pidlist will
+ * have us remove it from the cgroup's list, which entails taking the
+ * mutex. since in pidlist_find the pidlist->lock depends on cgroup->
+ * pidlist_mutex, we have to take pidlist_mutex first.
+ */
+ mutex_lock(&l->owner->pidlist_mutex);
+ down_write(&l->mutex);
+ BUG_ON(!l->use_count);
+ if (!--l->use_count) {
+ /* we're the last user if refcount is 0; remove and free */
+ list_del(&l->links);
+ mutex_unlock(&l->owner->pidlist_mutex);
+ pidlist_free(l->list);
+ put_pid_ns(l->key.ns);
+ up_write(&l->mutex);
+ kfree(l);
+ return;
}
- up_write(&cgrp->pids_mutex);
+ mutex_unlock(&l->owner->pidlist_mutex);
+ up_write(&l->mutex);
}
-static int cgroup_tasks_release(struct inode *inode, struct file *file)
+static int cgroup_pidlist_release(struct inode *inode, struct file *file)
{
- struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);
-
+ struct cgroup_pidlist *l;
if (!(file->f_mode & FMODE_READ))
return 0;
-
- release_cgroup_pid_array(cgrp);
+ /*
+ * the seq_file will only be initialized if the file was opened for
+ * reading; hence we check if it's not null only in that case.
+ */
+ l = ((struct seq_file *)file->private_data)->private;
+ cgroup_release_pid_array(l);
return seq_release(inode, file);
}
-static struct file_operations cgroup_tasks_operations = {
+static const struct file_operations cgroup_pidlist_operations = {
.read = seq_read,
.llseek = seq_lseek,
.write = cgroup_file_write,
- .release = cgroup_tasks_release,
+ .release = cgroup_pidlist_release,
};
/*
- * Handle an open on 'tasks' file. Prepare an array containing the
- * process id's of tasks currently attached to the cgroup being opened.
+ * The following functions handle opens on a file that displays a pidlist
+ * (tasks or procs). Prepare an array of the process/thread IDs of whoever's
+ * in the cgroup.
*/
-
-static int cgroup_tasks_open(struct inode *unused, struct file *file)
+/* helper function for the two below it */
+static int cgroup_pidlist_open(struct file *file, enum cgroup_filetype type)
{
struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);
- pid_t *pidarray;
- int npids;
+ struct cgroup_pidlist *l;
int retval;
/* Nothing to do for write-only files */
if (!(file->f_mode & FMODE_READ))
return 0;
- /*
- * If cgroup gets more users after we read count, we won't have
- * enough space - tough. This race is indistinguishable to the
- * caller from the case that the additional cgroup users didn't
- * show up until sometime later on.
- */
- npids = cgroup_task_count(cgrp);
- 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);
-
- /*
- * 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);
-
- file->f_op = &cgroup_tasks_operations;
+ /* have the array populated */
+ retval = pidlist_array_load(cgrp, type, &l);
+ if (retval)
+ return retval;
+ /* configure file information */
+ file->f_op = &cgroup_pidlist_operations;
- retval = seq_open(file, &cgroup_tasks_seq_operations);
+ retval = seq_open(file, &cgroup_pidlist_seq_operations);
if (retval) {
- release_cgroup_pid_array(cgrp);
+ cgroup_release_pid_array(l);
return retval;
}
- ((struct seq_file *)file->private_data)->private = cgrp;
+ ((struct seq_file *)file->private_data)->private = l;
return 0;
}
+static int cgroup_tasks_open(struct inode *unused, struct file *file)
+{
+ return cgroup_pidlist_open(file, CGROUP_FILE_TASKS);
+}
+static int cgroup_procs_open(struct inode *unused, struct file *file)
+{
+ return cgroup_pidlist_open(file, CGROUP_FILE_PROCS);
+}
static u64 cgroup_read_notify_on_release(struct cgroup *cgrp,
struct cftype *cft)
}
/*
- * for the common functions, 'private' gives the type of file
+ * Unregister event and free resources.
+ *
+ * Gets called from workqueue.
*/
-static struct cftype files[] = {
- {
- .name = "tasks",
- .open = cgroup_tasks_open,
- .write_u64 = cgroup_tasks_write,
- .release = cgroup_tasks_release,
- .private = FILE_TASKLIST,
- },
-
- {
- .name = "notify_on_release",
- .read_u64 = cgroup_read_notify_on_release,
- .write_u64 = cgroup_write_notify_on_release,
- .private = FILE_NOTIFY_ON_RELEASE,
- },
-};
-
-static struct cftype cft_release_agent = {
- .name = "release_agent",
- .read_seq_string = cgroup_release_agent_show,
- .write_string = cgroup_release_agent_write,
- .max_write_len = PATH_MAX,
- .private = FILE_RELEASE_AGENT,
-};
-
-static int cgroup_populate_dir(struct cgroup *cgrp)
+static void cgroup_event_remove(struct work_struct *work)
{
- int err;
- struct cgroup_subsys *ss;
-
- /* First clear out any existing files */
- cgroup_clear_directory(cgrp->dentry);
+ struct cgroup_event *event = container_of(work, struct cgroup_event,
+ remove);
+ struct cgroup *cgrp = event->cgrp;
- err = cgroup_add_files(cgrp, NULL, files, ARRAY_SIZE(files));
- if (err < 0)
- return err;
+ event->cft->unregister_event(cgrp, event->cft, event->eventfd);
- if (cgrp == cgrp->top_cgroup) {
- if ((err = cgroup_add_file(cgrp, NULL, &cft_release_agent)) < 0)
- return err;
- }
+ eventfd_ctx_put(event->eventfd);
+ kfree(event);
+ dput(cgrp->dentry);
+}
- for_each_subsys(cgrp->root, ss) {
- if (ss->populate && (err = ss->populate(ss, cgrp)) < 0)
- return err;
+/*
+ * Gets called on POLLHUP on eventfd when user closes it.
+ *
+ * Called with wqh->lock held and interrupts disabled.
+ */
+static int cgroup_event_wake(wait_queue_t *wait, unsigned mode,
+ int sync, void *key)
+{
+ struct cgroup_event *event = container_of(wait,
+ struct cgroup_event, wait);
+ struct cgroup *cgrp = event->cgrp;
+ unsigned long flags = (unsigned long)key;
+
+ if (flags & POLLHUP) {
+ __remove_wait_queue(event->wqh, &event->wait);
+ spin_lock(&cgrp->event_list_lock);
+ list_del(&event->list);
+ spin_unlock(&cgrp->event_list_lock);
+ /*
+ * We are in atomic context, but cgroup_event_remove() may
+ * sleep, so we have to call it in workqueue.
+ */
+ schedule_work(&event->remove);
}
return 0;
}
-static void init_cgroup_css(struct cgroup_subsys_state *css,
- struct cgroup_subsys *ss,
- struct cgroup *cgrp)
+static void cgroup_event_ptable_queue_proc(struct file *file,
+ wait_queue_head_t *wqh, poll_table *pt)
{
- css->cgroup = cgrp;
- atomic_set(&css->refcnt, 1);
- css->flags = 0;
- if (cgrp == dummytop)
- set_bit(CSS_ROOT, &css->flags);
- BUG_ON(cgrp->subsys[ss->subsys_id]);
- cgrp->subsys[ss->subsys_id] = css;
+ struct cgroup_event *event = container_of(pt,
+ struct cgroup_event, pt);
+
+ event->wqh = wqh;
+ add_wait_queue(wqh, &event->wait);
}
-static void cgroup_lock_hierarchy(struct cgroupfs_root *root)
+/*
+ * Parse input and register new cgroup event handler.
+ *
+ * Input must be in format '<event_fd> <control_fd> <args>'.
+ * Interpretation of args is defined by control file implementation.
+ */
+static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft,
+ const char *buffer)
{
- /* We need to take each hierarchy_mutex in a consistent order */
- int i;
+ struct cgroup_event *event = NULL;
+ unsigned int efd, cfd;
+ struct file *efile = NULL;
+ struct file *cfile = NULL;
+ char *endp;
+ int ret;
- 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);
- }
+ efd = simple_strtoul(buffer, &endp, 10);
+ if (*endp != ' ')
+ return -EINVAL;
+ buffer = endp + 1;
+
+ cfd = simple_strtoul(buffer, &endp, 10);
+ if ((*endp != ' ') && (*endp != '\0'))
+ return -EINVAL;
+ buffer = endp + 1;
+
+ event = kzalloc(sizeof(*event), GFP_KERNEL);
+ if (!event)
+ return -ENOMEM;
+ event->cgrp = cgrp;
+ INIT_LIST_HEAD(&event->list);
+ init_poll_funcptr(&event->pt, cgroup_event_ptable_queue_proc);
+ init_waitqueue_func_entry(&event->wait, cgroup_event_wake);
+ INIT_WORK(&event->remove, cgroup_event_remove);
+
+ efile = eventfd_fget(efd);
+ if (IS_ERR(efile)) {
+ ret = PTR_ERR(efile);
+ goto fail;
+ }
+
+ event->eventfd = eventfd_ctx_fileget(efile);
+ if (IS_ERR(event->eventfd)) {
+ ret = PTR_ERR(event->eventfd);
+ goto fail;
+ }
+
+ cfile = fget(cfd);
+ if (!cfile) {
+ ret = -EBADF;
+ goto fail;
+ }
+
+ /* the process need read permission on control file */
+ ret = file_permission(cfile, MAY_READ);
+ if (ret < 0)
+ goto fail;
+
+ event->cft = __file_cft(cfile);
+ if (IS_ERR(event->cft)) {
+ ret = PTR_ERR(event->cft);
+ goto fail;
+ }
+
+ if (!event->cft->register_event || !event->cft->unregister_event) {
+ ret = -EINVAL;
+ goto fail;
+ }
+
+ ret = event->cft->register_event(cgrp, event->cft,
+ event->eventfd, buffer);
+ if (ret)
+ goto fail;
+
+ if (efile->f_op->poll(efile, &event->pt) & POLLHUP) {
+ event->cft->unregister_event(cgrp, event->cft, event->eventfd);
+ ret = 0;
+ goto fail;
+ }
+
+ /*
+ * Events should be removed after rmdir of cgroup directory, but before
+ * destroying subsystem state objects. Let's take reference to cgroup
+ * directory dentry to do that.
+ */
+ dget(cgrp->dentry);
+
+ spin_lock(&cgrp->event_list_lock);
+ list_add(&event->list, &cgrp->event_list);
+ spin_unlock(&cgrp->event_list_lock);
+
+ fput(cfile);
+ fput(efile);
+
+ return 0;
+
+fail:
+ if (cfile)
+ fput(cfile);
+
+ if (event && event->eventfd && !IS_ERR(event->eventfd))
+ eventfd_ctx_put(event->eventfd);
+
+ if (!IS_ERR_OR_NULL(efile))
+ fput(efile);
+
+ kfree(event);
+
+ return ret;
+}
+
+/*
+ * for the common functions, 'private' gives the type of file
+ */
+/* for hysterical raisins, we can't put this on the older files */
+#define CGROUP_FILE_GENERIC_PREFIX "cgroup."
+static struct cftype files[] = {
+ {
+ .name = "tasks",
+ .open = cgroup_tasks_open,
+ .write_u64 = cgroup_tasks_write,
+ .release = cgroup_pidlist_release,
+ .mode = S_IRUGO | S_IWUSR,
+ },
+ {
+ .name = CGROUP_FILE_GENERIC_PREFIX "procs",
+ .open = cgroup_procs_open,
+ /* .write_u64 = cgroup_procs_write, TODO */
+ .release = cgroup_pidlist_release,
+ .mode = S_IRUGO,
+ },
+ {
+ .name = "notify_on_release",
+ .read_u64 = cgroup_read_notify_on_release,
+ .write_u64 = cgroup_write_notify_on_release,
+ },
+ {
+ .name = CGROUP_FILE_GENERIC_PREFIX "event_control",
+ .write_string = cgroup_write_event_control,
+ .mode = S_IWUGO,
+ },
+};
+
+static struct cftype cft_release_agent = {
+ .name = "release_agent",
+ .read_seq_string = cgroup_release_agent_show,
+ .write_string = cgroup_release_agent_write,
+ .max_write_len = PATH_MAX,
+};
+
+static int cgroup_populate_dir(struct cgroup *cgrp)
+{
+ int err;
+ struct cgroup_subsys *ss;
+
+ /* First clear out any existing files */
+ cgroup_clear_directory(cgrp->dentry);
+
+ err = cgroup_add_files(cgrp, NULL, files, ARRAY_SIZE(files));
+ if (err < 0)
+ return err;
+
+ if (cgrp == cgrp->top_cgroup) {
+ if ((err = cgroup_add_file(cgrp, NULL, &cft_release_agent)) < 0)
+ return err;
+ }
+
+ for_each_subsys(cgrp->root, ss) {
+ if (ss->populate && (err = ss->populate(ss, cgrp)) < 0)
+ return err;
+ }
+ /* This cgroup is ready now */
+ for_each_subsys(cgrp->root, ss) {
+ struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];
+ /*
+ * Update id->css pointer and make this css visible from
+ * CSS ID functions. This pointer will be dereferened
+ * from RCU-read-side without locks.
+ */
+ if (css->id)
+ rcu_assign_pointer(css->id->css, css);
+ }
+
+ return 0;
+}
+
+static void init_cgroup_css(struct cgroup_subsys_state *css,
+ struct cgroup_subsys *ss,
+ struct cgroup *cgrp)
+{
+ css->cgroup = cgrp;
+ atomic_set(&css->refcnt, 1);
+ css->flags = 0;
+ css->id = NULL;
+ if (cgrp == dummytop)
+ set_bit(CSS_ROOT, &css->flags);
+ BUG_ON(cgrp->subsys[ss->subsys_id]);
+ cgrp->subsys[ss->subsys_id] = css;
+}
+
+static void cgroup_lock_hierarchy(struct cgroupfs_root *root)
+{
+ /* We need to take each hierarchy_mutex in a consistent order */
+ int i;
+
+ /*
+ * No worry about a race with rebind_subsystems that might mess up the
+ * locking order, since both parties are under cgroup_mutex.
+ */
+ for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
+ struct cgroup_subsys *ss = subsys[i];
+ if (ss == NULL)
+ continue;
+ if (ss->root == root)
+ mutex_lock(&ss->hierarchy_mutex);
+ }
}
static void cgroup_unlock_hierarchy(struct cgroupfs_root *root)
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
struct cgroup_subsys *ss = subsys[i];
+ if (ss == NULL)
+ continue;
if (ss->root == root)
mutex_unlock(&ss->hierarchy_mutex);
}
* Must be called with the mutex on the parent inode held
*/
static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
- int mode)
+ mode_t mode)
{
struct cgroup *cgrp;
struct cgroupfs_root *root = parent->root;
for_each_subsys(root, ss) {
struct cgroup_subsys_state *css = ss->create(ss, cgrp);
+
if (IS_ERR(css)) {
err = PTR_ERR(css);
goto err_destroy;
}
init_cgroup_css(css, ss, cgrp);
+ if (ss->use_id) {
+ err = alloc_css_id(ss, parent, cgrp);
+ if (err)
+ goto err_destroy;
+ }
+ /* At error, ->destroy() callback has to free assigned ID. */
}
cgroup_lock_hierarchy(root);
* synchronization other than RCU, and the subsystem linked
* list isn't RCU-safe */
int i;
+ /*
+ * We won't need to lock the subsys array, because the subsystems
+ * we're concerned about aren't going anywhere since our cgroup root
+ * has a reference on them.
+ */
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)
+ /* Skip subsystems not present or not in this hierarchy */
+ if (ss == NULL || ss->root != cgrp->root)
continue;
css = cgrp->subsys[ss->subsys_id];
/* When called from check_for_release() it's possible
for_each_subsys(cgrp->root, ss) {
struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];
int refcnt;
- do {
+ while (1) {
/* We can only remove a CSS with a refcnt==1 */
refcnt = atomic_read(&css->refcnt);
if (refcnt > 1) {
* css_tryget() to spin until we set the
* CSS_REMOVED bits or abort
*/
- } while (atomic_cmpxchg(&css->refcnt, refcnt, 0) != refcnt);
+ if (atomic_cmpxchg(&css->refcnt, refcnt, 0) == refcnt)
+ break;
+ cpu_relax();
+ }
}
done:
for_each_subsys(cgrp->root, ss) {
struct cgroup *cgrp = dentry->d_fsdata;
struct dentry *d;
struct cgroup *parent;
+ DEFINE_WAIT(wait);
+ struct cgroup_event *event, *tmp;
+ int ret;
/* the vfs holds both inode->i_mutex already */
-
+again:
mutex_lock(&cgroup_mutex);
if (atomic_read(&cgrp->count) != 0) {
mutex_unlock(&cgroup_mutex);
}
mutex_unlock(&cgroup_mutex);
+ /*
+ * In general, subsystem has no css->refcnt after pre_destroy(). But
+ * in racy cases, subsystem may have to get css->refcnt after
+ * pre_destroy() and it makes rmdir return with -EBUSY. This sometimes
+ * make rmdir return -EBUSY too often. To avoid that, we use waitqueue
+ * for cgroup's rmdir. CGRP_WAIT_ON_RMDIR is for synchronizing rmdir
+ * and subsystem's reference count handling. Please see css_get/put
+ * and css_tryget() and cgroup_wakeup_rmdir_waiter() implementation.
+ */
+ set_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags);
+
/*
* Call pre_destroy handlers of subsys. Notify subsystems
* that rmdir() request comes.
*/
- cgroup_call_pre_destroy(cgrp);
+ ret = cgroup_call_pre_destroy(cgrp);
+ if (ret) {
+ clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags);
+ return ret;
+ }
mutex_lock(&cgroup_mutex);
parent = cgrp->parent;
-
- if (atomic_read(&cgrp->count)
- || !list_empty(&cgrp->children)
- || !cgroup_clear_css_refs(cgrp)) {
+ if (atomic_read(&cgrp->count) || !list_empty(&cgrp->children)) {
+ clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags);
mutex_unlock(&cgroup_mutex);
return -EBUSY;
}
+ prepare_to_wait(&cgroup_rmdir_waitq, &wait, TASK_INTERRUPTIBLE);
+ if (!cgroup_clear_css_refs(cgrp)) {
+ mutex_unlock(&cgroup_mutex);
+ /*
+ * Because someone may call cgroup_wakeup_rmdir_waiter() before
+ * prepare_to_wait(), we need to check this flag.
+ */
+ if (test_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags))
+ schedule();
+ finish_wait(&cgroup_rmdir_waitq, &wait);
+ clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags);
+ if (signal_pending(current))
+ return -EINTR;
+ goto again;
+ }
+ /* NO css_tryget() can success after here. */
+ finish_wait(&cgroup_rmdir_waitq, &wait);
+ clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags);
spin_lock(&release_list_lock);
set_bit(CGRP_REMOVED, &cgrp->flags);
set_bit(CGRP_RELEASABLE, &parent->flags);
check_for_release(parent);
+ /*
+ * Unregister events and notify userspace.
+ * Notify userspace about cgroup removing only after rmdir of cgroup
+ * directory to avoid race between userspace and kernelspace
+ */
+ spin_lock(&cgrp->event_list_lock);
+ list_for_each_entry_safe(event, tmp, &cgrp->event_list, list) {
+ list_del(&event->list);
+ remove_wait_queue(event->wqh, &event->wait);
+ eventfd_signal(event->eventfd, 1);
+ schedule_work(&event->remove);
+ }
+ spin_unlock(&cgrp->event_list_lock);
+
mutex_unlock(&cgroup_mutex);
return 0;
}
BUG_ON(!list_empty(&init_task.tasks));
mutex_init(&ss->hierarchy_mutex);
+ lockdep_set_class(&ss->hierarchy_mutex, &ss->subsys_key);
ss->active = 1;
+
+ /* this function shouldn't be used with modular subsystems, since they
+ * need to register a subsys_id, among other things */
+ BUG_ON(ss->module);
}
+/**
+ * cgroup_load_subsys: load and register a modular subsystem at runtime
+ * @ss: the subsystem to load
+ *
+ * This function should be called in a modular subsystem's initcall. If the
+ * subsystem is built as a module, it will be assigned a new subsys_id and set
+ * up for use. If the subsystem is built-in anyway, work is delegated to the
+ * simpler cgroup_init_subsys.
+ */
+int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
+{
+ int i;
+ struct cgroup_subsys_state *css;
+
+ /* check name and function validity */
+ if (ss->name == NULL || strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN ||
+ ss->create == NULL || ss->destroy == NULL)
+ return -EINVAL;
+
+ /*
+ * we don't support callbacks in modular subsystems. this check is
+ * before the ss->module check for consistency; a subsystem that could
+ * be a module should still have no callbacks even if the user isn't
+ * compiling it as one.
+ */
+ if (ss->fork || ss->exit)
+ return -EINVAL;
+
+ /*
+ * an optionally modular subsystem is built-in: we want to do nothing,
+ * since cgroup_init_subsys will have already taken care of it.
+ */
+ if (ss->module == NULL) {
+ /* a few sanity checks */
+ BUG_ON(ss->subsys_id >= CGROUP_BUILTIN_SUBSYS_COUNT);
+ BUG_ON(subsys[ss->subsys_id] != ss);
+ return 0;
+ }
+
+ /*
+ * need to register a subsys id before anything else - for example,
+ * init_cgroup_css needs it.
+ */
+ mutex_lock(&cgroup_mutex);
+ /* find the first empty slot in the array */
+ for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) {
+ if (subsys[i] == NULL)
+ break;
+ }
+ if (i == CGROUP_SUBSYS_COUNT) {
+ /* maximum number of subsystems already registered! */
+ mutex_unlock(&cgroup_mutex);
+ return -EBUSY;
+ }
+ /* assign ourselves the subsys_id */
+ ss->subsys_id = i;
+ subsys[i] = ss;
+
+ /*
+ * no ss->create seems to need anything important in the ss struct, so
+ * this can happen first (i.e. before the rootnode attachment).
+ */
+ css = ss->create(ss, dummytop);
+ if (IS_ERR(css)) {
+ /* failure case - need to deassign the subsys[] slot. */
+ subsys[i] = NULL;
+ mutex_unlock(&cgroup_mutex);
+ return PTR_ERR(css);
+ }
+
+ list_add(&ss->sibling, &rootnode.subsys_list);
+ ss->root = &rootnode;
+
+ /* our new subsystem will be attached to the dummy hierarchy. */
+ init_cgroup_css(css, ss, dummytop);
+ /* init_idr must be after init_cgroup_css because it sets css->id. */
+ if (ss->use_id) {
+ int ret = cgroup_init_idr(ss, css);
+ if (ret) {
+ dummytop->subsys[ss->subsys_id] = NULL;
+ ss->destroy(ss, dummytop);
+ subsys[i] = NULL;
+ mutex_unlock(&cgroup_mutex);
+ return ret;
+ }
+ }
+
+ /*
+ * Now we need to entangle the css into the existing css_sets. unlike
+ * in cgroup_init_subsys, there are now multiple css_sets, so each one
+ * will need a new pointer to it; done by iterating the css_set_table.
+ * furthermore, modifying the existing css_sets will corrupt the hash
+ * table state, so each changed css_set will need its hash recomputed.
+ * this is all done under the css_set_lock.
+ */
+ write_lock(&css_set_lock);
+ for (i = 0; i < CSS_SET_TABLE_SIZE; i++) {
+ struct css_set *cg;
+ struct hlist_node *node, *tmp;
+ struct hlist_head *bucket = &css_set_table[i], *new_bucket;
+
+ hlist_for_each_entry_safe(cg, node, tmp, bucket, hlist) {
+ /* skip entries that we already rehashed */
+ if (cg->subsys[ss->subsys_id])
+ continue;
+ /* remove existing entry */
+ hlist_del(&cg->hlist);
+ /* set new value */
+ cg->subsys[ss->subsys_id] = css;
+ /* recompute hash and restore entry */
+ new_bucket = css_set_hash(cg->subsys);
+ hlist_add_head(&cg->hlist, new_bucket);
+ }
+ }
+ write_unlock(&css_set_lock);
+
+ mutex_init(&ss->hierarchy_mutex);
+ lockdep_set_class(&ss->hierarchy_mutex, &ss->subsys_key);
+ ss->active = 1;
+
+ /* success! */
+ mutex_unlock(&cgroup_mutex);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(cgroup_load_subsys);
+
+/**
+ * cgroup_unload_subsys: unload a modular subsystem
+ * @ss: the subsystem to unload
+ *
+ * This function should be called in a modular subsystem's exitcall. When this
+ * function is invoked, the refcount on the subsystem's module will be 0, so
+ * the subsystem will not be attached to any hierarchy.
+ */
+void cgroup_unload_subsys(struct cgroup_subsys *ss)
+{
+ struct cg_cgroup_link *link;
+ struct hlist_head *hhead;
+
+ BUG_ON(ss->module == NULL);
+
+ /*
+ * we shouldn't be called if the subsystem is in use, and the use of
+ * try_module_get in parse_cgroupfs_options should ensure that it
+ * doesn't start being used while we're killing it off.
+ */
+ BUG_ON(ss->root != &rootnode);
+
+ mutex_lock(&cgroup_mutex);
+ /* deassign the subsys_id */
+ BUG_ON(ss->subsys_id < CGROUP_BUILTIN_SUBSYS_COUNT);
+ subsys[ss->subsys_id] = NULL;
+
+ /* remove subsystem from rootnode's list of subsystems */
+ list_del(&ss->sibling);
+
+ /*
+ * disentangle the css from all css_sets attached to the dummytop. as
+ * in loading, we need to pay our respects to the hashtable gods.
+ */
+ write_lock(&css_set_lock);
+ list_for_each_entry(link, &dummytop->css_sets, cgrp_link_list) {
+ struct css_set *cg = link->cg;
+
+ hlist_del(&cg->hlist);
+ BUG_ON(!cg->subsys[ss->subsys_id]);
+ cg->subsys[ss->subsys_id] = NULL;
+ hhead = css_set_hash(cg->subsys);
+ hlist_add_head(&cg->hlist, hhead);
+ }
+ write_unlock(&css_set_lock);
+
+ /*
+ * remove subsystem's css from the dummytop and free it - need to free
+ * before marking as null because ss->destroy needs the cgrp->subsys
+ * pointer to find their state. note that this also takes care of
+ * freeing the css_id.
+ */
+ ss->destroy(ss, dummytop);
+ dummytop->subsys[ss->subsys_id] = NULL;
+
+ mutex_unlock(&cgroup_mutex);
+}
+EXPORT_SYMBOL_GPL(cgroup_unload_subsys);
+
/**
* cgroup_init_early - cgroup initialization at system boot
*
init_task.cgroups = &init_css_set;
init_css_set_link.cg = &init_css_set;
+ init_css_set_link.cgrp = dummytop;
list_add(&init_css_set_link.cgrp_link_list,
&rootnode.top_cgroup.css_sets);
list_add(&init_css_set_link.cg_link_list,
for (i = 0; i < CSS_SET_TABLE_SIZE; i++)
INIT_HLIST_HEAD(&css_set_table[i]);
- for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
+ /* at bootup time, we don't worry about modular subsystems */
+ for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
struct cgroup_subsys *ss = subsys[i];
BUG_ON(!ss->name);
if (err)
return err;
- for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
+ /* at bootup time, we don't worry about modular subsystems */
+ for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
struct cgroup_subsys *ss = subsys[i];
if (!ss->early_init)
cgroup_init_subsys(ss);
+ if (ss->use_id)
+ cgroup_init_idr(ss, init_css_set.subsys[ss->subsys_id]);
}
/* Add init_css_set to the hash table */
hhead = css_set_hash(init_css_set.subsys);
hlist_add_head(&init_css_set.hlist, hhead);
+ BUG_ON(!init_root_id(&rootnode));
+
+ cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj);
+ if (!cgroup_kobj) {
+ err = -ENOMEM;
+ goto out;
+ }
err = register_filesystem(&cgroup_fs_type);
- if (err < 0)
+ if (err < 0) {
+ kobject_put(cgroup_kobj);
goto out;
+ }
proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations);
for_each_active_root(root) {
struct cgroup_subsys *ss;
struct cgroup *cgrp;
- int subsys_id;
int count = 0;
- seq_printf(m, "%lu:", root->subsys_bits);
+ seq_printf(m, "%d:", root->hierarchy_id);
for_each_subsys(root, ss)
seq_printf(m, "%s%s", count++ ? "," : "", ss->name);
+ if (strlen(root->name))
+ seq_printf(m, "%sname=%s", count ? "," : "",
+ root->name);
seq_putc(m, ':');
- get_first_subsys(&root->top_cgroup, NULL, &subsys_id);
- cgrp = task_cgroup(tsk, subsys_id);
+ cgrp = task_cgroup_from_root(tsk, root);
retval = cgroup_path(cgrp, buf, PAGE_SIZE);
if (retval < 0)
goto out_unlock;
return single_open(file, proc_cgroup_show, pid);
}
-struct file_operations proc_cgroup_operations = {
+const struct file_operations proc_cgroup_operations = {
.open = cgroup_open,
.read = seq_read,
.llseek = seq_lseek,
int i;
seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
+ /*
+ * ideally we don't want subsystems moving around while we do this.
+ * cgroup_mutex is also necessary to guarantee an atomic snapshot of
+ * subsys/hierarchy state.
+ */
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\t%d\n",
- ss->name, ss->root->subsys_bits,
+ if (ss == NULL)
+ continue;
+ seq_printf(m, "%s\t%d\t%d\t%d\n",
+ ss->name, ss->root->hierarchy_id,
ss->root->number_of_cgroups, !ss->disabled);
}
mutex_unlock(&cgroup_mutex);
return single_open(file, proc_cgroupstats_show, NULL);
}
-static struct file_operations proc_cgroupstats_operations = {
+static const struct file_operations proc_cgroupstats_operations = {
.open = cgroupstats_open,
.read = seq_read,
.llseek = seq_lseek,
{
if (need_forkexit_callback) {
int i;
- for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
+ /*
+ * forkexit callbacks are only supported for builtin
+ * subsystems, and the builtin section of the subsys array is
+ * immutable, so we don't need to lock the subsys array here.
+ */
+ for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
struct cgroup_subsys *ss = subsys[i];
if (ss->fork)
ss->fork(ss, child);
struct css_set *cg;
if (run_callbacks && need_forkexit_callback) {
- for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
+ /*
+ * modular subsystems can't use callbacks, so no need to lock
+ * the subsys array
+ */
+ for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
struct cgroup_subsys *ss = subsys[i];
if (ss->exit)
ss->exit(ss, tsk);
mutex_unlock(&cgroup_mutex);
return 0;
}
- task_lock(tsk);
- cg = tsk->cgroups;
- parent = task_cgroup(tsk, subsys->subsys_id);
/* Pin the hierarchy */
- if (!atomic_inc_not_zero(&parent->root->sb->s_active)) {
+ if (!atomic_inc_not_zero(&root->sb->s_active)) {
/* We race with the final deactivate_super() */
mutex_unlock(&cgroup_mutex);
return 0;
}
/* Keep the cgroup alive */
+ task_lock(tsk);
+ parent = task_cgroup(tsk, subsys->subsys_id);
+ cg = tsk->cgroups;
get_css_set(cg);
task_unlock(tsk);
+
mutex_unlock(&cgroup_mutex);
/* Now do the VFS work to create a cgroup */
mutex_unlock(&inode->i_mutex);
put_css_set(cg);
- deactivate_super(parent->root->sb);
+ deactivate_super(root->sb);
/* The cgroup is still accessible in the VFS, but
* we're not going to try to rmdir() it at this
* point. */
mutex_lock(&cgroup_mutex);
put_css_set(cg);
mutex_unlock(&cgroup_mutex);
- deactivate_super(parent->root->sb);
+ deactivate_super(root->sb);
return ret;
}
/**
- * cgroup_is_descendant - see if @cgrp is a descendant of current task's cgrp
+ * cgroup_is_descendant - see if @cgrp is a descendant of @task's cgrp
* @cgrp: the cgroup in question
+ * @task: the task in question
*
- * See if @cgrp is a descendant of the current task's cgroup in
- * the appropriate hierarchy.
+ * See if @cgrp is a descendant of @task's cgroup in the appropriate
+ * hierarchy.
*
* If we are sending in dummytop, then presumably we are creating
* the top cgroup in the subsystem.
*
* Called only by the ns (nsproxy) cgroup.
*/
-int cgroup_is_descendant(const struct cgroup *cgrp)
+int cgroup_is_descendant(const struct cgroup *cgrp, struct task_struct *task)
{
int ret;
struct cgroup *target;
- int subsys_id;
if (cgrp == dummytop)
return 1;
- get_first_subsys(cgrp, NULL, &subsys_id);
- target = task_cgroup(current, subsys_id);
+ target = task_cgroup_from_root(task, cgrp->root);
while (cgrp != target && cgrp!= cgrp->top_cgroup)
cgrp = cgrp->parent;
ret = (cgrp == target);
}
}
-void __css_put(struct cgroup_subsys_state *css)
+/* Caller must verify that the css is not for root cgroup */
+void __css_put(struct cgroup_subsys_state *css, int count)
{
struct cgroup *cgrp = css->cgroup;
+ int val;
rcu_read_lock();
- if ((atomic_dec_return(&css->refcnt) == 1) &&
- notify_on_release(cgrp)) {
- set_bit(CGRP_RELEASABLE, &cgrp->flags);
- check_for_release(cgrp);
+ val = atomic_sub_return(count, &css->refcnt);
+ if (val == 1) {
+ if (notify_on_release(cgrp)) {
+ set_bit(CGRP_RELEASABLE, &cgrp->flags);
+ check_for_release(cgrp);
+ }
+ cgroup_wakeup_rmdir_waiter(cgrp);
}
rcu_read_unlock();
+ WARN_ON_ONCE(val < 1);
}
+EXPORT_SYMBOL_GPL(__css_put);
/*
* Notify userspace when a cgroup is released, by running the
while ((token = strsep(&str, ",")) != NULL) {
if (!*token)
continue;
-
- for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
+ /*
+ * cgroup_disable, being at boot time, can't know about module
+ * subsystems, so we don't worry about them.
+ */
+ for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
struct cgroup_subsys *ss = subsys[i];
if (!strcmp(token, ss->name)) {
return 1;
}
__setup("cgroup_disable=", cgroup_disable);
+
+/*
+ * Functons for CSS ID.
+ */
+
+/*
+ *To get ID other than 0, this should be called when !cgroup_is_removed().
+ */
+unsigned short css_id(struct cgroup_subsys_state *css)
+{
+ struct css_id *cssid;
+
+ /*
+ * This css_id() can return correct value when somone has refcnt
+ * on this or this is under rcu_read_lock(). Once css->id is allocated,
+ * it's unchanged until freed.
+ */
+ cssid = rcu_dereference_check(css->id,
+ rcu_read_lock_held() || atomic_read(&css->refcnt));
+
+ if (cssid)
+ return cssid->id;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(css_id);
+
+unsigned short css_depth(struct cgroup_subsys_state *css)
+{
+ struct css_id *cssid;
+
+ cssid = rcu_dereference_check(css->id,
+ rcu_read_lock_held() || atomic_read(&css->refcnt));
+
+ if (cssid)
+ return cssid->depth;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(css_depth);
+
+/**
+ * css_is_ancestor - test "root" css is an ancestor of "child"
+ * @child: the css to be tested.
+ * @root: the css supporsed to be an ancestor of the child.
+ *
+ * Returns true if "root" is an ancestor of "child" in its hierarchy. Because
+ * this function reads css->id, this use rcu_dereference() and rcu_read_lock().
+ * But, considering usual usage, the csses should be valid objects after test.
+ * Assuming that the caller will do some action to the child if this returns
+ * returns true, the caller must take "child";s reference count.
+ * If "child" is valid object and this returns true, "root" is valid, too.
+ */
+
+bool css_is_ancestor(struct cgroup_subsys_state *child,
+ const struct cgroup_subsys_state *root)
+{
+ struct css_id *child_id;
+ struct css_id *root_id;
+ bool ret = true;
+
+ rcu_read_lock();
+ child_id = rcu_dereference(child->id);
+ root_id = rcu_dereference(root->id);
+ if (!child_id
+ || !root_id
+ || (child_id->depth < root_id->depth)
+ || (child_id->stack[root_id->depth] != root_id->id))
+ ret = false;
+ rcu_read_unlock();
+ return ret;
+}
+
+static void __free_css_id_cb(struct rcu_head *head)
+{
+ struct css_id *id;
+
+ id = container_of(head, struct css_id, rcu_head);
+ kfree(id);
+}
+
+void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css)
+{
+ struct css_id *id = css->id;
+ /* When this is called before css_id initialization, id can be NULL */
+ if (!id)
+ return;
+
+ BUG_ON(!ss->use_id);
+
+ rcu_assign_pointer(id->css, NULL);
+ rcu_assign_pointer(css->id, NULL);
+ spin_lock(&ss->id_lock);
+ idr_remove(&ss->idr, id->id);
+ spin_unlock(&ss->id_lock);
+ call_rcu(&id->rcu_head, __free_css_id_cb);
+}
+EXPORT_SYMBOL_GPL(free_css_id);
+
+/*
+ * This is called by init or create(). Then, calls to this function are
+ * always serialized (By cgroup_mutex() at create()).
+ */
+
+static struct css_id *get_new_cssid(struct cgroup_subsys *ss, int depth)
+{
+ struct css_id *newid;
+ int myid, error, size;
+
+ BUG_ON(!ss->use_id);
+
+ size = sizeof(*newid) + sizeof(unsigned short) * (depth + 1);
+ newid = kzalloc(size, GFP_KERNEL);
+ if (!newid)
+ return ERR_PTR(-ENOMEM);
+ /* get id */
+ if (unlikely(!idr_pre_get(&ss->idr, GFP_KERNEL))) {
+ error = -ENOMEM;
+ goto err_out;
+ }
+ spin_lock(&ss->id_lock);
+ /* Don't use 0. allocates an ID of 1-65535 */
+ error = idr_get_new_above(&ss->idr, newid, 1, &myid);
+ spin_unlock(&ss->id_lock);
+
+ /* Returns error when there are no free spaces for new ID.*/
+ if (error) {
+ error = -ENOSPC;
+ goto err_out;
+ }
+ if (myid > CSS_ID_MAX)
+ goto remove_idr;
+
+ newid->id = myid;
+ newid->depth = depth;
+ return newid;
+remove_idr:
+ error = -ENOSPC;
+ spin_lock(&ss->id_lock);
+ idr_remove(&ss->idr, myid);
+ spin_unlock(&ss->id_lock);
+err_out:
+ kfree(newid);
+ return ERR_PTR(error);
+
+}
+
+static int __init_or_module cgroup_init_idr(struct cgroup_subsys *ss,
+ struct cgroup_subsys_state *rootcss)
+{
+ struct css_id *newid;
+
+ spin_lock_init(&ss->id_lock);
+ idr_init(&ss->idr);
+
+ newid = get_new_cssid(ss, 0);
+ if (IS_ERR(newid))
+ return PTR_ERR(newid);
+
+ newid->stack[0] = newid->id;
+ newid->css = rootcss;
+ rootcss->id = newid;
+ return 0;
+}
+
+static int alloc_css_id(struct cgroup_subsys *ss, struct cgroup *parent,
+ struct cgroup *child)
+{
+ int subsys_id, i, depth = 0;
+ struct cgroup_subsys_state *parent_css, *child_css;
+ struct css_id *child_id, *parent_id;
+
+ subsys_id = ss->subsys_id;
+ parent_css = parent->subsys[subsys_id];
+ child_css = child->subsys[subsys_id];
+ parent_id = parent_css->id;
+ depth = parent_id->depth + 1;
+
+ child_id = get_new_cssid(ss, depth);
+ if (IS_ERR(child_id))
+ return PTR_ERR(child_id);
+
+ for (i = 0; i < depth; i++)
+ child_id->stack[i] = parent_id->stack[i];
+ child_id->stack[depth] = child_id->id;
+ /*
+ * child_id->css pointer will be set after this cgroup is available
+ * see cgroup_populate_dir()
+ */
+ rcu_assign_pointer(child_css->id, child_id);
+
+ return 0;
+}
+
+/**
+ * css_lookup - lookup css by id
+ * @ss: cgroup subsys to be looked into.
+ * @id: the id
+ *
+ * Returns pointer to cgroup_subsys_state if there is valid one with id.
+ * NULL if not. Should be called under rcu_read_lock()
+ */
+struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id)
+{
+ struct css_id *cssid = NULL;
+
+ BUG_ON(!ss->use_id);
+ cssid = idr_find(&ss->idr, id);
+
+ if (unlikely(!cssid))
+ return NULL;
+
+ return rcu_dereference(cssid->css);
+}
+EXPORT_SYMBOL_GPL(css_lookup);
+
+/**
+ * css_get_next - lookup next cgroup under specified hierarchy.
+ * @ss: pointer to subsystem
+ * @id: current position of iteration.
+ * @root: pointer to css. search tree under this.
+ * @foundid: position of found object.
+ *
+ * Search next css under the specified hierarchy of rootid. Calling under
+ * rcu_read_lock() is necessary. Returns NULL if it reaches the end.
+ */
+struct cgroup_subsys_state *
+css_get_next(struct cgroup_subsys *ss, int id,
+ struct cgroup_subsys_state *root, int *foundid)
+{
+ struct cgroup_subsys_state *ret = NULL;
+ struct css_id *tmp;
+ int tmpid;
+ int rootid = css_id(root);
+ int depth = css_depth(root);
+
+ if (!rootid)
+ return NULL;
+
+ BUG_ON(!ss->use_id);
+ /* fill start point for scan */
+ tmpid = id;
+ while (1) {
+ /*
+ * scan next entry from bitmap(tree), tmpid is updated after
+ * idr_get_next().
+ */
+ spin_lock(&ss->id_lock);
+ tmp = idr_get_next(&ss->idr, &tmpid);
+ spin_unlock(&ss->id_lock);
+
+ if (!tmp)
+ break;
+ if (tmp->depth >= depth && tmp->stack[depth] == rootid) {
+ ret = rcu_dereference(tmp->css);
+ if (ret) {
+ *foundid = tmpid;
+ break;
+ }
+ }
+ /* continue to scan from next id */
+ tmpid = tmpid + 1;
+ }
+ return ret;
+}
+
+#ifdef CONFIG_CGROUP_DEBUG
+static struct cgroup_subsys_state *debug_create(struct cgroup_subsys *ss,
+ struct cgroup *cont)
+{
+ struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
+
+ if (!css)
+ return ERR_PTR(-ENOMEM);
+
+ return css;
+}
+
+static void debug_destroy(struct cgroup_subsys *ss, struct cgroup *cont)
+{
+ kfree(cont->subsys[debug_subsys_id]);
+}
+
+static u64 cgroup_refcount_read(struct cgroup *cont, struct cftype *cft)
+{
+ return atomic_read(&cont->count);
+}
+
+static u64 debug_taskcount_read(struct cgroup *cont, struct cftype *cft)
+{
+ return cgroup_task_count(cont);
+}
+
+static u64 current_css_set_read(struct cgroup *cont, struct cftype *cft)
+{
+ return (u64)(unsigned long)current->cgroups;
+}
+
+static u64 current_css_set_refcount_read(struct cgroup *cont,
+ struct cftype *cft)
+{
+ u64 count;
+
+ rcu_read_lock();
+ count = atomic_read(¤t->cgroups->refcount);
+ rcu_read_unlock();
+ return count;
+}
+
+static int current_css_set_cg_links_read(struct cgroup *cont,
+ struct cftype *cft,
+ struct seq_file *seq)
+{
+ struct cg_cgroup_link *link;
+ struct css_set *cg;
+
+ read_lock(&css_set_lock);
+ rcu_read_lock();
+ cg = rcu_dereference(current->cgroups);
+ list_for_each_entry(link, &cg->cg_links, cg_link_list) {
+ struct cgroup *c = link->cgrp;
+ const char *name;
+
+ if (c->dentry)
+ name = c->dentry->d_name.name;
+ else
+ name = "?";
+ seq_printf(seq, "Root %d group %s\n",
+ c->root->hierarchy_id, name);
+ }
+ rcu_read_unlock();
+ read_unlock(&css_set_lock);
+ return 0;
+}
+
+#define MAX_TASKS_SHOWN_PER_CSS 25
+static int cgroup_css_links_read(struct cgroup *cont,
+ struct cftype *cft,
+ struct seq_file *seq)
+{
+ struct cg_cgroup_link *link;
+
+ read_lock(&css_set_lock);
+ list_for_each_entry(link, &cont->css_sets, cgrp_link_list) {
+ struct css_set *cg = link->cg;
+ struct task_struct *task;
+ int count = 0;
+ seq_printf(seq, "css_set %p\n", cg);
+ list_for_each_entry(task, &cg->tasks, cg_list) {
+ if (count++ > MAX_TASKS_SHOWN_PER_CSS) {
+ seq_puts(seq, " ...\n");
+ break;
+ } else {
+ seq_printf(seq, " task %d\n",
+ task_pid_vnr(task));
+ }
+ }
+ }
+ read_unlock(&css_set_lock);
+ return 0;
+}
+
+static u64 releasable_read(struct cgroup *cgrp, struct cftype *cft)
+{
+ return test_bit(CGRP_RELEASABLE, &cgrp->flags);
+}
+
+static struct cftype debug_files[] = {
+ {
+ .name = "cgroup_refcount",
+ .read_u64 = cgroup_refcount_read,
+ },
+ {
+ .name = "taskcount",
+ .read_u64 = debug_taskcount_read,
+ },
+
+ {
+ .name = "current_css_set",
+ .read_u64 = current_css_set_read,
+ },
+
+ {
+ .name = "current_css_set_refcount",
+ .read_u64 = current_css_set_refcount_read,
+ },
+
+ {
+ .name = "current_css_set_cg_links",
+ .read_seq_string = current_css_set_cg_links_read,
+ },
+
+ {
+ .name = "cgroup_css_links",
+ .read_seq_string = cgroup_css_links_read,
+ },
+
+ {
+ .name = "releasable",
+ .read_u64 = releasable_read,
+ },
+};
+
+static int debug_populate(struct cgroup_subsys *ss, struct cgroup *cont)
+{
+ return cgroup_add_files(cont, ss, debug_files,
+ ARRAY_SIZE(debug_files));
+}
+
+struct cgroup_subsys debug_subsys = {
+ .name = "debug",
+ .create = debug_create,
+ .destroy = debug_destroy,
+ .populate = debug_populate,
+ .subsys_id = debug_subsys_id,
+};
+#endif /* CONFIG_CGROUP_DEBUG */
Code Review / linux-2.6.git / blobdiff