mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-05 23:06:41 +07:00
92fb97487a
Rename cgroup_subsys css lifetime related callbacks to better describe what their roles are. Also, update documentation. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
489 lines
13 KiB
C
489 lines
13 KiB
C
/*
|
|
* cgroup_freezer.c - control group freezer subsystem
|
|
*
|
|
* Copyright IBM Corporation, 2007
|
|
*
|
|
* Author : Cedric Le Goater <clg@fr.ibm.com>
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify it
|
|
* under the terms of version 2.1 of the GNU Lesser General Public License
|
|
* as published by the Free Software Foundation.
|
|
*
|
|
* This program is distributed in the hope that it would be useful, but
|
|
* WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
|
|
*/
|
|
|
|
#include <linux/export.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/cgroup.h>
|
|
#include <linux/fs.h>
|
|
#include <linux/uaccess.h>
|
|
#include <linux/freezer.h>
|
|
#include <linux/seq_file.h>
|
|
|
|
/*
|
|
* A cgroup is freezing if any FREEZING flags are set. FREEZING_SELF is
|
|
* set if "FROZEN" is written to freezer.state cgroupfs file, and cleared
|
|
* for "THAWED". FREEZING_PARENT is set if the parent freezer is FREEZING
|
|
* for whatever reason. IOW, a cgroup has FREEZING_PARENT set if one of
|
|
* its ancestors has FREEZING_SELF set.
|
|
*/
|
|
enum freezer_state_flags {
|
|
CGROUP_FREEZER_ONLINE = (1 << 0), /* freezer is fully online */
|
|
CGROUP_FREEZING_SELF = (1 << 1), /* this freezer is freezing */
|
|
CGROUP_FREEZING_PARENT = (1 << 2), /* the parent freezer is freezing */
|
|
CGROUP_FROZEN = (1 << 3), /* this and its descendants frozen */
|
|
|
|
/* mask for all FREEZING flags */
|
|
CGROUP_FREEZING = CGROUP_FREEZING_SELF | CGROUP_FREEZING_PARENT,
|
|
};
|
|
|
|
struct freezer {
|
|
struct cgroup_subsys_state css;
|
|
unsigned int state;
|
|
spinlock_t lock;
|
|
};
|
|
|
|
static inline struct freezer *cgroup_freezer(struct cgroup *cgroup)
|
|
{
|
|
return container_of(cgroup_subsys_state(cgroup, freezer_subsys_id),
|
|
struct freezer, css);
|
|
}
|
|
|
|
static inline struct freezer *task_freezer(struct task_struct *task)
|
|
{
|
|
return container_of(task_subsys_state(task, freezer_subsys_id),
|
|
struct freezer, css);
|
|
}
|
|
|
|
static struct freezer *parent_freezer(struct freezer *freezer)
|
|
{
|
|
struct cgroup *pcg = freezer->css.cgroup->parent;
|
|
|
|
if (pcg)
|
|
return cgroup_freezer(pcg);
|
|
return NULL;
|
|
}
|
|
|
|
bool cgroup_freezing(struct task_struct *task)
|
|
{
|
|
bool ret;
|
|
|
|
rcu_read_lock();
|
|
ret = task_freezer(task)->state & CGROUP_FREEZING;
|
|
rcu_read_unlock();
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* cgroups_write_string() limits the size of freezer state strings to
|
|
* CGROUP_LOCAL_BUFFER_SIZE
|
|
*/
|
|
static const char *freezer_state_strs(unsigned int state)
|
|
{
|
|
if (state & CGROUP_FROZEN)
|
|
return "FROZEN";
|
|
if (state & CGROUP_FREEZING)
|
|
return "FREEZING";
|
|
return "THAWED";
|
|
};
|
|
|
|
struct cgroup_subsys freezer_subsys;
|
|
|
|
static struct cgroup_subsys_state *freezer_css_alloc(struct cgroup *cgroup)
|
|
{
|
|
struct freezer *freezer;
|
|
|
|
freezer = kzalloc(sizeof(struct freezer), GFP_KERNEL);
|
|
if (!freezer)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
spin_lock_init(&freezer->lock);
|
|
return &freezer->css;
|
|
}
|
|
|
|
/**
|
|
* 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_css_online(struct cgroup *cgroup)
|
|
{
|
|
struct freezer *freezer = cgroup_freezer(cgroup);
|
|
struct freezer *parent = parent_freezer(freezer);
|
|
|
|
/*
|
|
* The following double locking and freezing state inheritance
|
|
* guarantee that @cgroup can never escape ancestors' freezing
|
|
* states. See cgroup_for_each_descendant_pre() for details.
|
|
*/
|
|
if (parent)
|
|
spin_lock_irq(&parent->lock);
|
|
spin_lock_nested(&freezer->lock, SINGLE_DEPTH_NESTING);
|
|
|
|
freezer->state |= CGROUP_FREEZER_ONLINE;
|
|
|
|
if (parent && (parent->state & CGROUP_FREEZING)) {
|
|
freezer->state |= CGROUP_FREEZING_PARENT | CGROUP_FROZEN;
|
|
atomic_inc(&system_freezing_cnt);
|
|
}
|
|
|
|
spin_unlock(&freezer->lock);
|
|
if (parent)
|
|
spin_unlock_irq(&parent->lock);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* 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_css_offline(struct cgroup *cgroup)
|
|
{
|
|
struct freezer *freezer = cgroup_freezer(cgroup);
|
|
|
|
spin_lock_irq(&freezer->lock);
|
|
|
|
if (freezer->state & CGROUP_FREEZING)
|
|
atomic_dec(&system_freezing_cnt);
|
|
|
|
freezer->state = 0;
|
|
|
|
spin_unlock_irq(&freezer->lock);
|
|
}
|
|
|
|
static void freezer_css_free(struct cgroup *cgroup)
|
|
{
|
|
kfree(cgroup_freezer(cgroup));
|
|
}
|
|
|
|
/*
|
|
* Tasks can be migrated into a different freezer anytime regardless of its
|
|
* current state. freezer_attach() is responsible for making new tasks
|
|
* conform to the current state.
|
|
*
|
|
* Freezer state changes and task migration are synchronized via
|
|
* @freezer->lock. freezer_attach() makes the new tasks conform to the
|
|
* current state and all following state changes can see the new tasks.
|
|
*/
|
|
static void freezer_attach(struct cgroup *new_cgrp, struct cgroup_taskset *tset)
|
|
{
|
|
struct freezer *freezer = cgroup_freezer(new_cgrp);
|
|
struct task_struct *task;
|
|
bool clear_frozen = false;
|
|
|
|
spin_lock_irq(&freezer->lock);
|
|
|
|
/*
|
|
* Make the new tasks conform to the current state of @new_cgrp.
|
|
* For simplicity, when migrating any task to a FROZEN cgroup, we
|
|
* revert it to FREEZING and let update_if_frozen() determine the
|
|
* correct state later.
|
|
*
|
|
* Tasks in @tset are on @new_cgrp but may not conform to its
|
|
* current state before executing the following - !frozen tasks may
|
|
* be visible in a FROZEN cgroup and frozen tasks in a THAWED one.
|
|
*/
|
|
cgroup_taskset_for_each(task, new_cgrp, tset) {
|
|
if (!(freezer->state & CGROUP_FREEZING)) {
|
|
__thaw_task(task);
|
|
} else {
|
|
freeze_task(task);
|
|
freezer->state &= ~CGROUP_FROZEN;
|
|
clear_frozen = true;
|
|
}
|
|
}
|
|
|
|
spin_unlock_irq(&freezer->lock);
|
|
|
|
/*
|
|
* Propagate FROZEN clearing upwards. We may race with
|
|
* update_if_frozen(), but as long as both work bottom-up, either
|
|
* update_if_frozen() sees child's FROZEN cleared or we clear the
|
|
* parent's FROZEN later. No parent w/ !FROZEN children can be
|
|
* left FROZEN.
|
|
*/
|
|
while (clear_frozen && (freezer = parent_freezer(freezer))) {
|
|
spin_lock_irq(&freezer->lock);
|
|
freezer->state &= ~CGROUP_FROZEN;
|
|
clear_frozen = freezer->state & CGROUP_FREEZING;
|
|
spin_unlock_irq(&freezer->lock);
|
|
}
|
|
}
|
|
|
|
static void freezer_fork(struct task_struct *task)
|
|
{
|
|
struct freezer *freezer;
|
|
|
|
rcu_read_lock();
|
|
freezer = task_freezer(task);
|
|
|
|
/*
|
|
* The root cgroup is non-freezable, so we can skip the
|
|
* following check.
|
|
*/
|
|
if (!freezer->css.cgroup->parent)
|
|
goto out;
|
|
|
|
spin_lock_irq(&freezer->lock);
|
|
if (freezer->state & CGROUP_FREEZING)
|
|
freeze_task(task);
|
|
spin_unlock_irq(&freezer->lock);
|
|
out:
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
/**
|
|
* update_if_frozen - update whether a cgroup finished freezing
|
|
* @cgroup: cgroup of interest
|
|
*
|
|
* Once FREEZING is initiated, transition to FROZEN is lazily updated by
|
|
* calling this function. If the current state is FREEZING but not FROZEN,
|
|
* this function checks whether all tasks of this cgroup and the descendant
|
|
* cgroups finished freezing and, if so, sets FROZEN.
|
|
*
|
|
* The caller is responsible for grabbing RCU read lock and calling
|
|
* update_if_frozen() on all descendants prior to invoking this function.
|
|
*
|
|
* Task states and freezer state might disagree while tasks are being
|
|
* migrated into or out of @cgroup, so we can't verify task states against
|
|
* @freezer state here. See freezer_attach() for details.
|
|
*/
|
|
static void update_if_frozen(struct cgroup *cgroup)
|
|
{
|
|
struct freezer *freezer = cgroup_freezer(cgroup);
|
|
struct cgroup *pos;
|
|
struct cgroup_iter it;
|
|
struct task_struct *task;
|
|
|
|
WARN_ON_ONCE(!rcu_read_lock_held());
|
|
|
|
spin_lock_irq(&freezer->lock);
|
|
|
|
if (!(freezer->state & CGROUP_FREEZING) ||
|
|
(freezer->state & CGROUP_FROZEN))
|
|
goto out_unlock;
|
|
|
|
/* are all (live) children frozen? */
|
|
cgroup_for_each_child(pos, cgroup) {
|
|
struct freezer *child = cgroup_freezer(pos);
|
|
|
|
if ((child->state & CGROUP_FREEZER_ONLINE) &&
|
|
!(child->state & CGROUP_FROZEN))
|
|
goto out_unlock;
|
|
}
|
|
|
|
/* are all tasks frozen? */
|
|
cgroup_iter_start(cgroup, &it);
|
|
|
|
while ((task = cgroup_iter_next(cgroup, &it))) {
|
|
if (freezing(task)) {
|
|
/*
|
|
* freezer_should_skip() indicates that the task
|
|
* should be skipped when determining freezing
|
|
* completion. Consider it frozen in addition to
|
|
* the usual frozen condition.
|
|
*/
|
|
if (!frozen(task) && !freezer_should_skip(task))
|
|
goto out_iter_end;
|
|
}
|
|
}
|
|
|
|
freezer->state |= CGROUP_FROZEN;
|
|
out_iter_end:
|
|
cgroup_iter_end(cgroup, &it);
|
|
out_unlock:
|
|
spin_unlock_irq(&freezer->lock);
|
|
}
|
|
|
|
static int freezer_read(struct cgroup *cgroup, struct cftype *cft,
|
|
struct seq_file *m)
|
|
{
|
|
struct cgroup *pos;
|
|
|
|
rcu_read_lock();
|
|
|
|
/* update states bottom-up */
|
|
cgroup_for_each_descendant_post(pos, cgroup)
|
|
update_if_frozen(pos);
|
|
update_if_frozen(cgroup);
|
|
|
|
rcu_read_unlock();
|
|
|
|
seq_puts(m, freezer_state_strs(cgroup_freezer(cgroup)->state));
|
|
seq_putc(m, '\n');
|
|
return 0;
|
|
}
|
|
|
|
static void freeze_cgroup(struct freezer *freezer)
|
|
{
|
|
struct cgroup *cgroup = freezer->css.cgroup;
|
|
struct cgroup_iter it;
|
|
struct task_struct *task;
|
|
|
|
cgroup_iter_start(cgroup, &it);
|
|
while ((task = cgroup_iter_next(cgroup, &it)))
|
|
freeze_task(task);
|
|
cgroup_iter_end(cgroup, &it);
|
|
}
|
|
|
|
static void unfreeze_cgroup(struct freezer *freezer)
|
|
{
|
|
struct cgroup *cgroup = freezer->css.cgroup;
|
|
struct cgroup_iter it;
|
|
struct task_struct *task;
|
|
|
|
cgroup_iter_start(cgroup, &it);
|
|
while ((task = cgroup_iter_next(cgroup, &it)))
|
|
__thaw_task(task);
|
|
cgroup_iter_end(cgroup, &it);
|
|
}
|
|
|
|
/**
|
|
* freezer_apply_state - apply state change to a single cgroup_freezer
|
|
* @freezer: freezer to apply state change to
|
|
* @freeze: whether to freeze or unfreeze
|
|
* @state: CGROUP_FREEZING_* flag to set or clear
|
|
*
|
|
* Set or clear @state on @cgroup according to @freeze, and perform
|
|
* freezing or thawing as necessary.
|
|
*/
|
|
static void freezer_apply_state(struct freezer *freezer, bool freeze,
|
|
unsigned int state)
|
|
{
|
|
/* also synchronizes against task migration, see freezer_attach() */
|
|
lockdep_assert_held(&freezer->lock);
|
|
|
|
if (!(freezer->state & CGROUP_FREEZER_ONLINE))
|
|
return;
|
|
|
|
if (freeze) {
|
|
if (!(freezer->state & CGROUP_FREEZING))
|
|
atomic_inc(&system_freezing_cnt);
|
|
freezer->state |= state;
|
|
freeze_cgroup(freezer);
|
|
} else {
|
|
bool was_freezing = freezer->state & CGROUP_FREEZING;
|
|
|
|
freezer->state &= ~state;
|
|
|
|
if (!(freezer->state & CGROUP_FREEZING)) {
|
|
if (was_freezing)
|
|
atomic_dec(&system_freezing_cnt);
|
|
freezer->state &= ~CGROUP_FROZEN;
|
|
unfreeze_cgroup(freezer);
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* freezer_change_state - change the freezing state of a cgroup_freezer
|
|
* @freezer: freezer of interest
|
|
* @freeze: whether to freeze or thaw
|
|
*
|
|
* Freeze or thaw @freezer according to @freeze. The operations are
|
|
* recursive - all descendants of @freezer will be affected.
|
|
*/
|
|
static void freezer_change_state(struct freezer *freezer, bool freeze)
|
|
{
|
|
struct cgroup *pos;
|
|
|
|
/* update @freezer */
|
|
spin_lock_irq(&freezer->lock);
|
|
freezer_apply_state(freezer, freeze, CGROUP_FREEZING_SELF);
|
|
spin_unlock_irq(&freezer->lock);
|
|
|
|
/*
|
|
* Update all its descendants in pre-order traversal. Each
|
|
* descendant will try to inherit its parent's FREEZING state as
|
|
* CGROUP_FREEZING_PARENT.
|
|
*/
|
|
rcu_read_lock();
|
|
cgroup_for_each_descendant_pre(pos, freezer->css.cgroup) {
|
|
struct freezer *pos_f = cgroup_freezer(pos);
|
|
struct freezer *parent = parent_freezer(pos_f);
|
|
|
|
/*
|
|
* Our update to @parent->state is already visible which is
|
|
* all we need. No need to lock @parent. For more info on
|
|
* synchronization, see freezer_post_create().
|
|
*/
|
|
spin_lock_irq(&pos_f->lock);
|
|
freezer_apply_state(pos_f, parent->state & CGROUP_FREEZING,
|
|
CGROUP_FREEZING_PARENT);
|
|
spin_unlock_irq(&pos_f->lock);
|
|
}
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
static int freezer_write(struct cgroup *cgroup, struct cftype *cft,
|
|
const char *buffer)
|
|
{
|
|
bool freeze;
|
|
|
|
if (strcmp(buffer, freezer_state_strs(0)) == 0)
|
|
freeze = false;
|
|
else if (strcmp(buffer, freezer_state_strs(CGROUP_FROZEN)) == 0)
|
|
freeze = true;
|
|
else
|
|
return -EINVAL;
|
|
|
|
freezer_change_state(cgroup_freezer(cgroup), freeze);
|
|
return 0;
|
|
}
|
|
|
|
static u64 freezer_self_freezing_read(struct cgroup *cgroup, struct cftype *cft)
|
|
{
|
|
struct freezer *freezer = cgroup_freezer(cgroup);
|
|
|
|
return (bool)(freezer->state & CGROUP_FREEZING_SELF);
|
|
}
|
|
|
|
static u64 freezer_parent_freezing_read(struct cgroup *cgroup, struct cftype *cft)
|
|
{
|
|
struct freezer *freezer = cgroup_freezer(cgroup);
|
|
|
|
return (bool)(freezer->state & CGROUP_FREEZING_PARENT);
|
|
}
|
|
|
|
static struct cftype files[] = {
|
|
{
|
|
.name = "state",
|
|
.flags = CFTYPE_NOT_ON_ROOT,
|
|
.read_seq_string = freezer_read,
|
|
.write_string = freezer_write,
|
|
},
|
|
{
|
|
.name = "self_freezing",
|
|
.flags = CFTYPE_NOT_ON_ROOT,
|
|
.read_u64 = freezer_self_freezing_read,
|
|
},
|
|
{
|
|
.name = "parent_freezing",
|
|
.flags = CFTYPE_NOT_ON_ROOT,
|
|
.read_u64 = freezer_parent_freezing_read,
|
|
},
|
|
{ } /* terminate */
|
|
};
|
|
|
|
struct cgroup_subsys freezer_subsys = {
|
|
.name = "freezer",
|
|
.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,
|
|
.base_cftypes = files,
|
|
};
|