THIS_MODULE in its .c file.
Each subsystem may export the following methods. The only mandatory
-methods are create/destroy. Any others that are null are presumed to
+methods are css_alloc/free. Any others that are null are presumed to
be successful no-ops.
-struct cgroup_subsys_state *create(struct cgroup *cgrp)
+struct cgroup_subsys_state *css_alloc(struct cgroup *cgrp)
(cgroup_mutex held by caller)
-Called to create a subsystem state object for a cgroup. The
+Called to allocate a subsystem state object for a cgroup. The
subsystem should allocate its subsystem state object for the passed
cgroup, returning a pointer to the new object on success or a
-negative error code. On success, the subsystem pointer should point to
+ERR_PTR() value. On success, the subsystem pointer should point to
a structure of type cgroup_subsys_state (typically embedded in a
larger subsystem-specific object), which will be initialized by the
cgroup system. Note that this will be called at initialization to
it's the root of the hierarchy) and may be an appropriate place for
initialization code.
-void destroy(struct cgroup *cgrp)
+int css_online(struct cgroup *cgrp)
(cgroup_mutex held by caller)
-The cgroup system is about to destroy the passed cgroup; the subsystem
-should do any necessary cleanup and free its subsystem state
-object. By the time this method is called, the cgroup has already been
-unlinked from the file system and from the child list of its parent;
-cgroup->parent is still valid. (Note - can also be called for a
-newly-created cgroup if an error occurs after this subsystem's
-create() method has been called for the new cgroup).
-
-int pre_destroy(struct cgroup *cgrp);
-
-Called before checking the reference count on each subsystem. This may
-be useful for subsystems which have some extra references even if
-there are not tasks in the cgroup. If pre_destroy() returns error code,
-rmdir() will fail with it. From this behavior, pre_destroy() can be
-called multiple times against a cgroup.
+Called after @cgrp successfully completed all allocations and made
+visible to cgroup_for_each_child/descendant_*() iterators. The
+subsystem may choose to fail creation by returning -errno. This
+callback can be used to implement reliable state sharing and
+propagation along the hierarchy. See the comment on
+cgroup_for_each_descendant_pre() for details.
+
+void css_offline(struct cgroup *cgrp);
+
+This is the counterpart of css_online() and called iff css_online()
+has succeeded on @cgrp. This signifies the beginning of the end of
+@cgrp. @cgrp is being removed and the subsystem should start dropping
+all references it's holding on @cgrp. When all references are dropped,
+cgroup removal will proceed to the next step - css_free(). After this
+callback, @cgrp should be considered dead to the subsystem.
+
+void css_free(struct cgroup *cgrp)
+(cgroup_mutex held by caller)
+
+The cgroup system is about to free @cgrp; the subsystem should free
+its subsystem state object. By the time this method is called, @cgrp
+is completely unused; @cgrp->parent is still valid. (Note - can also
+be called for a newly-created cgroup if an error occurs after this
+subsystem's create() method has been called for the new cgroup).
int can_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
(cgroup_mutex held by caller)
};
/**
- * blkcg_pre_destroy - cgroup pre_destroy callback
+ * blkcg_css_offline - cgroup css_offline callback
* @cgroup: cgroup of interest
*
* This function is called when @cgroup is about to go away and responsible
*
* This is the blkcg counterpart of ioc_release_fn().
*/
-static void blkcg_pre_destroy(struct cgroup *cgroup)
+static void blkcg_css_offline(struct cgroup *cgroup)
{
struct blkcg *blkcg = cgroup_to_blkcg(cgroup);
spin_unlock_irq(&blkcg->lock);
}
-static void blkcg_destroy(struct cgroup *cgroup)
+static void blkcg_css_free(struct cgroup *cgroup)
{
struct blkcg *blkcg = cgroup_to_blkcg(cgroup);
kfree(blkcg);
}
-static struct cgroup_subsys_state *blkcg_create(struct cgroup *cgroup)
+static struct cgroup_subsys_state *blkcg_css_alloc(struct cgroup *cgroup)
{
static atomic64_t id_seq = ATOMIC64_INIT(0);
struct blkcg *blkcg;
struct cgroup_subsys blkio_subsys = {
.name = "blkio",
- .create = blkcg_create,
+ .css_alloc = blkcg_css_alloc,
+ .css_offline = blkcg_css_offline,
+ .css_free = blkcg_css_free,
.can_attach = blkcg_can_attach,
- .pre_destroy = blkcg_pre_destroy,
- .destroy = blkcg_destroy,
.subsys_id = blkio_subsys_id,
.base_cftypes = blkcg_files,
.module = THIS_MODULE,
/* bits in struct cgroup_subsys_state flags field */
enum {
CSS_ROOT = (1 << 0), /* this CSS is the root of the subsystem */
- CSS_ONLINE = (1 << 1), /* between ->post_create() and ->pre_destroy() */
+ CSS_ONLINE = (1 << 1), /* between ->css_online() and ->css_offline() */
};
/* Caller must verify that the css is not for root cgroup */
*/
struct cgroup_subsys {
- struct cgroup_subsys_state *(*create)(struct cgroup *cgrp);
- int (*post_create)(struct cgroup *cgrp);
- void (*pre_destroy)(struct cgroup *cgrp);
- void (*destroy)(struct cgroup *cgrp);
+ struct cgroup_subsys_state *(*css_alloc)(struct cgroup *cgrp);
+ int (*css_online)(struct cgroup *cgrp);
+ void (*css_offline)(struct cgroup *cgrp);
+ void (*css_free)(struct cgroup *cgrp);
+
int (*can_attach)(struct cgroup *cgrp, struct cgroup_taskset *tset);
void (*cancel_attach)(struct cgroup *cgrp, struct cgroup_taskset *tset);
void (*attach)(struct cgroup *cgrp, struct cgroup_taskset *tset);
* @cgroup: cgroup whose children to walk
*
* Walk @cgroup's children. Must be called under rcu_read_lock(). A child
- * cgroup which hasn't finished ->post_create() or already has finished
- * ->pre_destroy() may show up during traversal and it's each subsystem's
+ * cgroup which hasn't finished ->css_online() or already has finished
+ * ->css_offline() may show up during traversal and it's each subsystem's
* responsibility to verify that each @pos is alive.
*
- * If a subsystem synchronizes against the parent in its ->post_create()
- * and before starting iterating, a cgroup which finished ->post_create()
- * is guaranteed to be visible in the future iterations.
+ * If a subsystem synchronizes against the parent in its ->css_online() and
+ * before starting iterating, a cgroup which finished ->css_online() is
+ * guaranteed to be visible in the future iterations.
*/
#define cgroup_for_each_child(pos, cgroup) \
list_for_each_entry_rcu(pos, &(cgroup)->children, sibling)
* @cgroup: cgroup whose descendants to walk
*
* Walk @cgroup's descendants. Must be called under rcu_read_lock(). A
- * descendant cgroup which hasn't finished ->post_create() or already has
- * finished ->pre_destroy() may show up during traversal and it's each
+ * descendant cgroup which hasn't finished ->css_online() or already has
+ * finished ->css_offline() may show up during traversal and it's each
* subsystem's responsibility to verify that each @pos is alive.
*
- * If a subsystem synchronizes against the parent in its ->post_create()
- * and before starting iterating, and synchronizes against @pos on each
- * iteration, any descendant cgroup which finished ->post_create() is
+ * If a subsystem synchronizes against the parent in its ->css_online() and
+ * before starting iterating, and synchronizes against @pos on each
+ * iteration, any descendant cgroup which finished ->css_offline() is
* guaranteed to be visible in the future iterations.
*
* In other words, the following guarantees that a descendant can't escape
* state updates of its ancestors.
*
- * my_post_create(@cgrp)
+ * my_online(@cgrp)
* {
* Lock @cgrp->parent and @cgrp;
* Inherit state from @cgrp->parent;
* iteration should lock and unlock both @pos->parent and @pos.
*
* Alternatively, a subsystem may choose to use a single global lock to
- * synchronize ->post_create() and ->pre_destroy() against tree-walking
+ * synchronize ->css_online() and ->css_offline() against tree-walking
* operations.
*/
#define cgroup_for_each_descendant_pre(pos, cgroup) \
* Release the subsystem state objects.
*/
for_each_subsys(cgrp->root, ss)
- ss->destroy(cgrp);
+ ss->css_free(cgrp);
cgrp->root->number_of_cgroups--;
mutex_unlock(&cgroup_mutex);
lockdep_assert_held(&cgroup_mutex);
- if (ss->post_create)
- ret = ss->post_create(cgrp);
+ if (ss->css_online)
+ ret = ss->css_online(cgrp);
if (!ret)
cgrp->subsys[ss->subsys_id]->flags |= CSS_ONLINE;
return ret;
return;
/*
- * pre_destroy() should be called with cgroup_mutex unlocked. See
+ * css_offline() should be called with cgroup_mutex unlocked. See
* 3fa59dfbc3 ("cgroup: fix potential deadlock in pre_destroy") for
* details. This temporary unlocking should go away once
* cgroup_mutex is unexported from controllers.
*/
- if (ss->pre_destroy) {
+ if (ss->css_offline) {
mutex_unlock(&cgroup_mutex);
- ss->pre_destroy(cgrp);
+ ss->css_offline(cgrp);
mutex_lock(&cgroup_mutex);
}
for_each_subsys(root, ss) {
struct cgroup_subsys_state *css;
- css = ss->create(cgrp);
+ css = ss->css_alloc(cgrp);
if (IS_ERR(css)) {
err = PTR_ERR(css);
goto err_free_all;
if (err)
goto err_free_all;
}
- /* At error, ->destroy() callback has to free assigned ID. */
+ /* At error, ->css_free() callback has to free assigned ID. */
if (clone_children(parent) && ss->post_clone)
ss->post_clone(cgrp);
err_free_all:
for_each_subsys(root, ss) {
if (cgrp->subsys[ss->subsys_id])
- ss->destroy(cgrp);
+ ss->css_free(cgrp);
}
mutex_unlock(&cgroup_mutex);
/* Release the reference count that we took on the superblock */
/* Create the top cgroup state for this subsystem */
list_add(&ss->sibling, &rootnode.subsys_list);
ss->root = &rootnode;
- css = ss->create(dummytop);
+ css = ss->css_alloc(dummytop);
/* We don't handle early failures gracefully */
BUG_ON(IS_ERR(css));
init_cgroup_css(css, ss, dummytop);
/* check name and function validity */
if (ss->name == NULL || strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN ||
- ss->create == NULL || ss->destroy == NULL)
+ ss->css_alloc == NULL || ss->css_free == NULL)
return -EINVAL;
/*
subsys[ss->subsys_id] = ss;
/*
- * no ss->create seems to need anything important in the ss struct, so
- * this can happen first (i.e. before the rootnode attachment).
+ * no ss->css_alloc seems to need anything important in the ss
+ * struct, so this can happen first (i.e. before the rootnode
+ * attachment).
*/
- css = ss->create(dummytop);
+ css = ss->css_alloc(dummytop);
if (IS_ERR(css)) {
/* failure case - need to deassign the subsys[] slot. */
subsys[ss->subsys_id] = NULL;
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.
+ * remove subsystem's css from the dummytop and free it - need to
+ * free before marking as null because ss->css_free needs the
+ * cgrp->subsys pointer to find their state. note that this also
+ * takes care of freeing the css_id.
*/
- ss->destroy(dummytop);
+ ss->css_free(dummytop);
dummytop->subsys[ss->subsys_id] = NULL;
mutex_unlock(&cgroup_mutex);
BUG_ON(!ss->name);
BUG_ON(strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN);
- BUG_ON(!ss->create);
- BUG_ON(!ss->destroy);
+ BUG_ON(!ss->css_alloc);
+ BUG_ON(!ss->css_free);
if (ss->subsys_id != i) {
printk(KERN_ERR "cgroup: Subsys %s id == %d\n",
ss->name, ss->subsys_id);
}
#ifdef CONFIG_CGROUP_DEBUG
-static struct cgroup_subsys_state *debug_create(struct cgroup *cont)
+static struct cgroup_subsys_state *debug_css_alloc(struct cgroup *cont)
{
struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
return css;
}
-static void debug_destroy(struct cgroup *cont)
+static void debug_css_free(struct cgroup *cont)
{
kfree(cont->subsys[debug_subsys_id]);
}
struct cgroup_subsys debug_subsys = {
.name = "debug",
- .create = debug_create,
- .destroy = debug_destroy,
+ .css_alloc = debug_css_alloc,
+ .css_free = debug_css_free,
.subsys_id = debug_subsys_id,
.base_cftypes = debug_files,
};
struct cgroup_subsys freezer_subsys;
-static struct cgroup_subsys_state *freezer_create(struct cgroup *cgroup)
+static struct cgroup_subsys_state *freezer_css_alloc(struct cgroup *cgroup)
{
struct freezer *freezer;
}
/**
- * freezer_post_create - commit creation of a freezer cgroup
+ * freezer_css_online - commit creation of a freezer cgroup
* @cgroup: cgroup being created
*
* We're committing to creation of @cgroup. Mark it online and inherit
* parent's freezing state while holding both parent's and our
* freezer->lock.
*/
-static int freezer_post_create(struct cgroup *cgroup)
+static int freezer_css_online(struct cgroup *cgroup)
{
struct freezer *freezer = cgroup_freezer(cgroup);
struct freezer *parent = parent_freezer(freezer);
}
/**
- * freezer_pre_destroy - initiate destruction of @cgroup
+ * freezer_css_offline - initiate destruction of @cgroup
* @cgroup: cgroup being destroyed
*
* @cgroup is going away. Mark it dead and decrement system_freezing_count
* if it was holding one.
*/
-static void freezer_pre_destroy(struct cgroup *cgroup)
+static void freezer_css_offline(struct cgroup *cgroup)
{
struct freezer *freezer = cgroup_freezer(cgroup);
spin_unlock_irq(&freezer->lock);
}
-static void freezer_destroy(struct cgroup *cgroup)
+static void freezer_css_free(struct cgroup *cgroup)
{
kfree(cgroup_freezer(cgroup));
}
struct cgroup_subsys freezer_subsys = {
.name = "freezer",
- .create = freezer_create,
- .post_create = freezer_post_create,
- .pre_destroy = freezer_pre_destroy,
- .destroy = freezer_destroy,
+ .css_alloc = freezer_css_alloc,
+ .css_online = freezer_css_online,
+ .css_offline = freezer_css_offline,
+ .css_free = freezer_css_free,
.subsys_id = freezer_subsys_id,
.attach = freezer_attach,
.fork = freezer_fork,
}
/*
- * cpuset_create - create a cpuset
+ * cpuset_css_alloc - allocate a cpuset css
* cont: control group that the new cpuset will be part of
*/
-static struct cgroup_subsys_state *cpuset_create(struct cgroup *cont)
+static struct cgroup_subsys_state *cpuset_css_alloc(struct cgroup *cont)
{
struct cpuset *cs;
struct cpuset *parent;
* will call async_rebuild_sched_domains().
*/
-static void cpuset_destroy(struct cgroup *cont)
+static void cpuset_css_free(struct cgroup *cont)
{
struct cpuset *cs = cgroup_cs(cont);
struct cgroup_subsys cpuset_subsys = {
.name = "cpuset",
- .create = cpuset_create,
- .destroy = cpuset_destroy,
+ .css_alloc = cpuset_css_alloc,
+ .css_free = cpuset_css_free,
.can_attach = cpuset_can_attach,
.attach = cpuset_attach,
.post_clone = cpuset_post_clone,
device_initcall(perf_event_sysfs_init);
#ifdef CONFIG_CGROUP_PERF
-static struct cgroup_subsys_state *perf_cgroup_create(struct cgroup *cont)
+static struct cgroup_subsys_state *perf_cgroup_css_alloc(struct cgroup *cont)
{
struct perf_cgroup *jc;
return &jc->css;
}
-static void perf_cgroup_destroy(struct cgroup *cont)
+static void perf_cgroup_css_free(struct cgroup *cont)
{
struct perf_cgroup *jc;
jc = container_of(cgroup_subsys_state(cont, perf_subsys_id),
struct cgroup_subsys perf_subsys = {
.name = "perf_event",
.subsys_id = perf_subsys_id,
- .create = perf_cgroup_create,
- .destroy = perf_cgroup_destroy,
+ .css_alloc = perf_cgroup_css_alloc,
+ .css_free = perf_cgroup_css_free,
.exit = perf_cgroup_exit,
.attach = perf_cgroup_attach,
struct task_group, css);
}
-static struct cgroup_subsys_state *cpu_cgroup_create(struct cgroup *cgrp)
+static struct cgroup_subsys_state *cpu_cgroup_css_alloc(struct cgroup *cgrp)
{
struct task_group *tg, *parent;
return &tg->css;
}
-static void cpu_cgroup_destroy(struct cgroup *cgrp)
+static void cpu_cgroup_css_free(struct cgroup *cgrp)
{
struct task_group *tg = cgroup_tg(cgrp);
struct cgroup_subsys cpu_cgroup_subsys = {
.name = "cpu",
- .create = cpu_cgroup_create,
- .destroy = cpu_cgroup_destroy,
+ .css_alloc = cpu_cgroup_css_alloc,
+ .css_free = cpu_cgroup_css_free,
.can_attach = cpu_cgroup_can_attach,
.attach = cpu_cgroup_attach,
.exit = cpu_cgroup_exit,
struct cpuacct root_cpuacct;
/* create a new cpu accounting group */
-static struct cgroup_subsys_state *cpuacct_create(struct cgroup *cgrp)
+static struct cgroup_subsys_state *cpuacct_css_alloc(struct cgroup *cgrp)
{
struct cpuacct *ca;
}
/* destroy an existing cpu accounting group */
-static void cpuacct_destroy(struct cgroup *cgrp)
+static void cpuacct_css_free(struct cgroup *cgrp)
{
struct cpuacct *ca = cgroup_ca(cgrp);
struct cgroup_subsys cpuacct_subsys = {
.name = "cpuacct",
- .create = cpuacct_create,
- .destroy = cpuacct_destroy,
+ .css_alloc = cpuacct_css_alloc,
+ .css_free = cpuacct_css_free,
.subsys_id = cpuacct_subsys_id,
.base_cftypes = files,
};
return false;
}
-static struct cgroup_subsys_state *hugetlb_cgroup_create(struct cgroup *cgroup)
+static struct cgroup_subsys_state *hugetlb_cgroup_css_alloc(struct cgroup *cgroup)
{
int idx;
struct cgroup *parent_cgroup;
return &h_cgroup->css;
}
-static void hugetlb_cgroup_destroy(struct cgroup *cgroup)
+static void hugetlb_cgroup_css_free(struct cgroup *cgroup)
{
struct hugetlb_cgroup *h_cgroup;
* Force the hugetlb cgroup to empty the hugetlb resources by moving them to
* the parent cgroup.
*/
-static void hugetlb_cgroup_pre_destroy(struct cgroup *cgroup)
+static void hugetlb_cgroup_css_offline(struct cgroup *cgroup)
{
struct hstate *h;
struct page *page;
struct cgroup_subsys hugetlb_subsys = {
.name = "hugetlb",
- .create = hugetlb_cgroup_create,
- .pre_destroy = hugetlb_cgroup_pre_destroy,
- .destroy = hugetlb_cgroup_destroy,
- .subsys_id = hugetlb_subsys_id,
+ .css_alloc = hugetlb_cgroup_css_alloc,
+ .css_offline = hugetlb_cgroup_css_offline,
+ .css_free = hugetlb_cgroup_css_free,
+ .subsys_id = hugetlb_subsys_id,
};
}
static struct cgroup_subsys_state * __ref
-mem_cgroup_create(struct cgroup *cont)
+mem_cgroup_css_alloc(struct cgroup *cont)
{
struct mem_cgroup *memcg, *parent;
long error = -ENOMEM;
return ERR_PTR(error);
}
-static void mem_cgroup_pre_destroy(struct cgroup *cont)
+static void mem_cgroup_css_offline(struct cgroup *cont)
{
struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
mem_cgroup_reparent_charges(memcg);
}
-static void mem_cgroup_destroy(struct cgroup *cont)
+static void mem_cgroup_css_free(struct cgroup *cont)
{
struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
struct cgroup_subsys mem_cgroup_subsys = {
.name = "memory",
.subsys_id = mem_cgroup_subsys_id,
- .create = mem_cgroup_create,
- .pre_destroy = mem_cgroup_pre_destroy,
- .destroy = mem_cgroup_destroy,
+ .css_alloc = mem_cgroup_css_alloc,
+ .css_offline = mem_cgroup_css_offline,
+ .css_free = mem_cgroup_css_free,
.can_attach = mem_cgroup_can_attach,
.cancel_attach = mem_cgroup_cancel_attach,
.attach = mem_cgroup_move_task,
return ret;
}
-static struct cgroup_subsys_state *cgrp_create(struct cgroup *cgrp)
+static struct cgroup_subsys_state *cgrp_css_alloc(struct cgroup *cgrp)
{
struct cgroup_netprio_state *cs;
int ret = -EINVAL;
return ERR_PTR(ret);
}
-static void cgrp_destroy(struct cgroup *cgrp)
+static void cgrp_css_free(struct cgroup *cgrp)
{
struct cgroup_netprio_state *cs;
struct net_device *dev;
struct cgroup_subsys net_prio_subsys = {
.name = "net_prio",
- .create = cgrp_create,
- .destroy = cgrp_destroy,
+ .css_alloc = cgrp_css_alloc,
+ .css_free = cgrp_css_free,
.attach = net_prio_attach,
.subsys_id = net_prio_subsys_id,
.base_cftypes = ss_files,
struct cgroup_cls_state, css);
}
-static struct cgroup_subsys_state *cgrp_create(struct cgroup *cgrp)
+static struct cgroup_subsys_state *cgrp_css_alloc(struct cgroup *cgrp)
{
struct cgroup_cls_state *cs;
return &cs->css;
}
-static void cgrp_destroy(struct cgroup *cgrp)
+static void cgrp_css_free(struct cgroup *cgrp)
{
kfree(cgrp_cls_state(cgrp));
}
struct cgroup_subsys net_cls_subsys = {
.name = "net_cls",
- .create = cgrp_create,
- .destroy = cgrp_destroy,
+ .css_alloc = cgrp_css_alloc,
+ .css_free = cgrp_css_free,
.subsys_id = net_cls_subsys_id,
.base_cftypes = ss_files,
.module = THIS_MODULE,
/*
* called from kernel/cgroup.c with cgroup_lock() held.
*/
-static struct cgroup_subsys_state *devcgroup_create(struct cgroup *cgroup)
+static struct cgroup_subsys_state *devcgroup_css_alloc(struct cgroup *cgroup)
{
struct dev_cgroup *dev_cgroup, *parent_dev_cgroup;
struct cgroup *parent_cgroup;
return &dev_cgroup->css;
}
-static void devcgroup_destroy(struct cgroup *cgroup)
+static void devcgroup_css_free(struct cgroup *cgroup)
{
struct dev_cgroup *dev_cgroup;
struct cgroup_subsys devices_subsys = {
.name = "devices",
.can_attach = devcgroup_can_attach,
- .create = devcgroup_create,
- .destroy = devcgroup_destroy,
+ .css_alloc = devcgroup_css_alloc,
+ .css_free = devcgroup_css_free,
.subsys_id = devices_subsys_id,
.base_cftypes = dev_cgroup_files,
projects / platform / kernel / linux-rpi.git / commitdiff