mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-23 01:10:04 +00:00
![Tom Rix](/assets/img/avatar_default.png)
for spdx, add a space before // replacements judgement to judgment transofrmed to transformed partitition to partition histrical to historical migratecd to migrated Signed-off-by: Tom Rix <trix@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org>
323 lines
7.8 KiB
C
323 lines
7.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
#include <linux/cgroup.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/sched/task.h>
|
|
#include <linux/sched/signal.h>
|
|
|
|
#include "cgroup-internal.h"
|
|
|
|
#include <trace/events/cgroup.h>
|
|
|
|
/*
|
|
* Propagate the cgroup frozen state upwards by the cgroup tree.
|
|
*/
|
|
static void cgroup_propagate_frozen(struct cgroup *cgrp, bool frozen)
|
|
{
|
|
int desc = 1;
|
|
|
|
/*
|
|
* If the new state is frozen, some freezing ancestor cgroups may change
|
|
* their state too, depending on if all their descendants are frozen.
|
|
*
|
|
* Otherwise, all ancestor cgroups are forced into the non-frozen state.
|
|
*/
|
|
while ((cgrp = cgroup_parent(cgrp))) {
|
|
if (frozen) {
|
|
cgrp->freezer.nr_frozen_descendants += desc;
|
|
if (!test_bit(CGRP_FROZEN, &cgrp->flags) &&
|
|
test_bit(CGRP_FREEZE, &cgrp->flags) &&
|
|
cgrp->freezer.nr_frozen_descendants ==
|
|
cgrp->nr_descendants) {
|
|
set_bit(CGRP_FROZEN, &cgrp->flags);
|
|
cgroup_file_notify(&cgrp->events_file);
|
|
TRACE_CGROUP_PATH(notify_frozen, cgrp, 1);
|
|
desc++;
|
|
}
|
|
} else {
|
|
cgrp->freezer.nr_frozen_descendants -= desc;
|
|
if (test_bit(CGRP_FROZEN, &cgrp->flags)) {
|
|
clear_bit(CGRP_FROZEN, &cgrp->flags);
|
|
cgroup_file_notify(&cgrp->events_file);
|
|
TRACE_CGROUP_PATH(notify_frozen, cgrp, 0);
|
|
desc++;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Revisit the cgroup frozen state.
|
|
* Checks if the cgroup is really frozen and perform all state transitions.
|
|
*/
|
|
void cgroup_update_frozen(struct cgroup *cgrp)
|
|
{
|
|
bool frozen;
|
|
|
|
lockdep_assert_held(&css_set_lock);
|
|
|
|
/*
|
|
* If the cgroup has to be frozen (CGRP_FREEZE bit set),
|
|
* and all tasks are frozen and/or stopped, let's consider
|
|
* the cgroup frozen. Otherwise it's not frozen.
|
|
*/
|
|
frozen = test_bit(CGRP_FREEZE, &cgrp->flags) &&
|
|
cgrp->freezer.nr_frozen_tasks == __cgroup_task_count(cgrp);
|
|
|
|
if (frozen) {
|
|
/* Already there? */
|
|
if (test_bit(CGRP_FROZEN, &cgrp->flags))
|
|
return;
|
|
|
|
set_bit(CGRP_FROZEN, &cgrp->flags);
|
|
} else {
|
|
/* Already there? */
|
|
if (!test_bit(CGRP_FROZEN, &cgrp->flags))
|
|
return;
|
|
|
|
clear_bit(CGRP_FROZEN, &cgrp->flags);
|
|
}
|
|
cgroup_file_notify(&cgrp->events_file);
|
|
TRACE_CGROUP_PATH(notify_frozen, cgrp, frozen);
|
|
|
|
/* Update the state of ancestor cgroups. */
|
|
cgroup_propagate_frozen(cgrp, frozen);
|
|
}
|
|
|
|
/*
|
|
* Increment cgroup's nr_frozen_tasks.
|
|
*/
|
|
static void cgroup_inc_frozen_cnt(struct cgroup *cgrp)
|
|
{
|
|
cgrp->freezer.nr_frozen_tasks++;
|
|
}
|
|
|
|
/*
|
|
* Decrement cgroup's nr_frozen_tasks.
|
|
*/
|
|
static void cgroup_dec_frozen_cnt(struct cgroup *cgrp)
|
|
{
|
|
cgrp->freezer.nr_frozen_tasks--;
|
|
WARN_ON_ONCE(cgrp->freezer.nr_frozen_tasks < 0);
|
|
}
|
|
|
|
/*
|
|
* Enter frozen/stopped state, if not yet there. Update cgroup's counters,
|
|
* and revisit the state of the cgroup, if necessary.
|
|
*/
|
|
void cgroup_enter_frozen(void)
|
|
{
|
|
struct cgroup *cgrp;
|
|
|
|
if (current->frozen)
|
|
return;
|
|
|
|
spin_lock_irq(&css_set_lock);
|
|
current->frozen = true;
|
|
cgrp = task_dfl_cgroup(current);
|
|
cgroup_inc_frozen_cnt(cgrp);
|
|
cgroup_update_frozen(cgrp);
|
|
spin_unlock_irq(&css_set_lock);
|
|
}
|
|
|
|
/*
|
|
* Conditionally leave frozen/stopped state. Update cgroup's counters,
|
|
* and revisit the state of the cgroup, if necessary.
|
|
*
|
|
* If always_leave is not set, and the cgroup is freezing,
|
|
* we're racing with the cgroup freezing. In this case, we don't
|
|
* drop the frozen counter to avoid a transient switch to
|
|
* the unfrozen state.
|
|
*/
|
|
void cgroup_leave_frozen(bool always_leave)
|
|
{
|
|
struct cgroup *cgrp;
|
|
|
|
spin_lock_irq(&css_set_lock);
|
|
cgrp = task_dfl_cgroup(current);
|
|
if (always_leave || !test_bit(CGRP_FREEZE, &cgrp->flags)) {
|
|
cgroup_dec_frozen_cnt(cgrp);
|
|
cgroup_update_frozen(cgrp);
|
|
WARN_ON_ONCE(!current->frozen);
|
|
current->frozen = false;
|
|
} else if (!(current->jobctl & JOBCTL_TRAP_FREEZE)) {
|
|
spin_lock(¤t->sighand->siglock);
|
|
current->jobctl |= JOBCTL_TRAP_FREEZE;
|
|
set_thread_flag(TIF_SIGPENDING);
|
|
spin_unlock(¤t->sighand->siglock);
|
|
}
|
|
spin_unlock_irq(&css_set_lock);
|
|
}
|
|
|
|
/*
|
|
* Freeze or unfreeze the task by setting or clearing the JOBCTL_TRAP_FREEZE
|
|
* jobctl bit.
|
|
*/
|
|
static void cgroup_freeze_task(struct task_struct *task, bool freeze)
|
|
{
|
|
unsigned long flags;
|
|
|
|
/* If the task is about to die, don't bother with freezing it. */
|
|
if (!lock_task_sighand(task, &flags))
|
|
return;
|
|
|
|
if (freeze) {
|
|
task->jobctl |= JOBCTL_TRAP_FREEZE;
|
|
signal_wake_up(task, false);
|
|
} else {
|
|
task->jobctl &= ~JOBCTL_TRAP_FREEZE;
|
|
wake_up_process(task);
|
|
}
|
|
|
|
unlock_task_sighand(task, &flags);
|
|
}
|
|
|
|
/*
|
|
* Freeze or unfreeze all tasks in the given cgroup.
|
|
*/
|
|
static void cgroup_do_freeze(struct cgroup *cgrp, bool freeze)
|
|
{
|
|
struct css_task_iter it;
|
|
struct task_struct *task;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
spin_lock_irq(&css_set_lock);
|
|
if (freeze)
|
|
set_bit(CGRP_FREEZE, &cgrp->flags);
|
|
else
|
|
clear_bit(CGRP_FREEZE, &cgrp->flags);
|
|
spin_unlock_irq(&css_set_lock);
|
|
|
|
if (freeze)
|
|
TRACE_CGROUP_PATH(freeze, cgrp);
|
|
else
|
|
TRACE_CGROUP_PATH(unfreeze, cgrp);
|
|
|
|
css_task_iter_start(&cgrp->self, 0, &it);
|
|
while ((task = css_task_iter_next(&it))) {
|
|
/*
|
|
* Ignore kernel threads here. Freezing cgroups containing
|
|
* kthreads isn't supported.
|
|
*/
|
|
if (task->flags & PF_KTHREAD)
|
|
continue;
|
|
cgroup_freeze_task(task, freeze);
|
|
}
|
|
css_task_iter_end(&it);
|
|
|
|
/*
|
|
* Cgroup state should be revisited here to cover empty leaf cgroups
|
|
* and cgroups which descendants are already in the desired state.
|
|
*/
|
|
spin_lock_irq(&css_set_lock);
|
|
if (cgrp->nr_descendants == cgrp->freezer.nr_frozen_descendants)
|
|
cgroup_update_frozen(cgrp);
|
|
spin_unlock_irq(&css_set_lock);
|
|
}
|
|
|
|
/*
|
|
* Adjust the task state (freeze or unfreeze) and revisit the state of
|
|
* source and destination cgroups.
|
|
*/
|
|
void cgroup_freezer_migrate_task(struct task_struct *task,
|
|
struct cgroup *src, struct cgroup *dst)
|
|
{
|
|
lockdep_assert_held(&css_set_lock);
|
|
|
|
/*
|
|
* Kernel threads are not supposed to be frozen at all.
|
|
*/
|
|
if (task->flags & PF_KTHREAD)
|
|
return;
|
|
|
|
/*
|
|
* It's not necessary to do changes if both of the src and dst cgroups
|
|
* are not freezing and task is not frozen.
|
|
*/
|
|
if (!test_bit(CGRP_FREEZE, &src->flags) &&
|
|
!test_bit(CGRP_FREEZE, &dst->flags) &&
|
|
!task->frozen)
|
|
return;
|
|
|
|
/*
|
|
* Adjust counters of freezing and frozen tasks.
|
|
* Note, that if the task is frozen, but the destination cgroup is not
|
|
* frozen, we bump both counters to keep them balanced.
|
|
*/
|
|
if (task->frozen) {
|
|
cgroup_inc_frozen_cnt(dst);
|
|
cgroup_dec_frozen_cnt(src);
|
|
}
|
|
cgroup_update_frozen(dst);
|
|
cgroup_update_frozen(src);
|
|
|
|
/*
|
|
* Force the task to the desired state.
|
|
*/
|
|
cgroup_freeze_task(task, test_bit(CGRP_FREEZE, &dst->flags));
|
|
}
|
|
|
|
void cgroup_freeze(struct cgroup *cgrp, bool freeze)
|
|
{
|
|
struct cgroup_subsys_state *css;
|
|
struct cgroup *dsct;
|
|
bool applied = false;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
/*
|
|
* Nothing changed? Just exit.
|
|
*/
|
|
if (cgrp->freezer.freeze == freeze)
|
|
return;
|
|
|
|
cgrp->freezer.freeze = freeze;
|
|
|
|
/*
|
|
* Propagate changes downwards the cgroup tree.
|
|
*/
|
|
css_for_each_descendant_pre(css, &cgrp->self) {
|
|
dsct = css->cgroup;
|
|
|
|
if (cgroup_is_dead(dsct))
|
|
continue;
|
|
|
|
if (freeze) {
|
|
dsct->freezer.e_freeze++;
|
|
/*
|
|
* Already frozen because of ancestor's settings?
|
|
*/
|
|
if (dsct->freezer.e_freeze > 1)
|
|
continue;
|
|
} else {
|
|
dsct->freezer.e_freeze--;
|
|
/*
|
|
* Still frozen because of ancestor's settings?
|
|
*/
|
|
if (dsct->freezer.e_freeze > 0)
|
|
continue;
|
|
|
|
WARN_ON_ONCE(dsct->freezer.e_freeze < 0);
|
|
}
|
|
|
|
/*
|
|
* Do change actual state: freeze or unfreeze.
|
|
*/
|
|
cgroup_do_freeze(dsct, freeze);
|
|
applied = true;
|
|
}
|
|
|
|
/*
|
|
* Even if the actual state hasn't changed, let's notify a user.
|
|
* The state can be enforced by an ancestor cgroup: the cgroup
|
|
* can already be in the desired state or it can be locked in the
|
|
* opposite state, so that the transition will never happen.
|
|
* In both cases it's better to notify a user, that there is
|
|
* nothing to wait for.
|
|
*/
|
|
if (!applied) {
|
|
TRACE_CGROUP_PATH(notify_frozen, cgrp,
|
|
test_bit(CGRP_FROZEN, &cgrp->flags));
|
|
cgroup_file_notify(&cgrp->events_file);
|
|
}
|
|
}
|