# SPDX-License-Identifier: GPL-2.0
obj-y := cgroup.o rstat.o namespace.o cgroup-v1.o
-obj-$(CONFIG_CGROUP_FREEZER) += freezer.o
+obj-$(CONFIG_CGROUP_FREEZER) += legacy_freezer.o
obj-$(CONFIG_CGROUP_PIDS) += pids.o
obj-$(CONFIG_CGROUP_RDMA) += rdma.o
obj-$(CONFIG_CPUSETS) += cpuset.o
+++ /dev/null
-/*
- * 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>
-#include <linux/mutex.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;
-};
-
-static DEFINE_MUTEX(freezer_mutex);
-
-static inline struct freezer *css_freezer(struct cgroup_subsys_state *css)
-{
- return css ? container_of(css, struct freezer, css) : NULL;
-}
-
-static inline struct freezer *task_freezer(struct task_struct *task)
-{
- return css_freezer(task_css(task, freezer_cgrp_id));
-}
-
-static struct freezer *parent_freezer(struct freezer *freezer)
-{
- return css_freezer(freezer->css.parent);
-}
-
-bool cgroup_freezing(struct task_struct *task)
-{
- bool ret;
-
- rcu_read_lock();
- ret = task_freezer(task)->state & CGROUP_FREEZING;
- rcu_read_unlock();
-
- return ret;
-}
-
-static const char *freezer_state_strs(unsigned int state)
-{
- if (state & CGROUP_FROZEN)
- return "FROZEN";
- if (state & CGROUP_FREEZING)
- return "FREEZING";
- return "THAWED";
-};
-
-static struct cgroup_subsys_state *
-freezer_css_alloc(struct cgroup_subsys_state *parent_css)
-{
- struct freezer *freezer;
-
- freezer = kzalloc(sizeof(struct freezer), GFP_KERNEL);
- if (!freezer)
- return ERR_PTR(-ENOMEM);
-
- return &freezer->css;
-}
-
-/**
- * freezer_css_online - commit creation of a freezer css
- * @css: css being created
- *
- * We're committing to creation of @css. 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_subsys_state *css)
-{
- struct freezer *freezer = css_freezer(css);
- struct freezer *parent = parent_freezer(freezer);
-
- mutex_lock(&freezer_mutex);
-
- freezer->state |= CGROUP_FREEZER_ONLINE;
-
- if (parent && (parent->state & CGROUP_FREEZING)) {
- freezer->state |= CGROUP_FREEZING_PARENT | CGROUP_FROZEN;
- atomic_inc(&system_freezing_cnt);
- }
-
- mutex_unlock(&freezer_mutex);
- return 0;
-}
-
-/**
- * freezer_css_offline - initiate destruction of a freezer css
- * @css: css being destroyed
- *
- * @css is going away. Mark it dead and decrement system_freezing_count if
- * it was holding one.
- */
-static void freezer_css_offline(struct cgroup_subsys_state *css)
-{
- struct freezer *freezer = css_freezer(css);
-
- mutex_lock(&freezer_mutex);
-
- if (freezer->state & CGROUP_FREEZING)
- atomic_dec(&system_freezing_cnt);
-
- freezer->state = 0;
-
- mutex_unlock(&freezer_mutex);
-}
-
-static void freezer_css_free(struct cgroup_subsys_state *css)
-{
- kfree(css_freezer(css));
-}
-
-/*
- * 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_taskset *tset)
-{
- struct task_struct *task;
- struct cgroup_subsys_state *new_css;
-
- mutex_lock(&freezer_mutex);
-
- /*
- * Make the new tasks conform to the current state of @new_css.
- * 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_css 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_css, tset) {
- struct freezer *freezer = css_freezer(new_css);
-
- if (!(freezer->state & CGROUP_FREEZING)) {
- __thaw_task(task);
- } else {
- freeze_task(task);
- /* clear FROZEN and propagate upwards */
- while (freezer && (freezer->state & CGROUP_FROZEN)) {
- freezer->state &= ~CGROUP_FROZEN;
- freezer = parent_freezer(freezer);
- }
- }
- }
-
- mutex_unlock(&freezer_mutex);
-}
-
-/**
- * freezer_fork - cgroup post fork callback
- * @task: a task which has just been forked
- *
- * @task has just been created and should conform to the current state of
- * the cgroup_freezer it belongs to. This function may race against
- * freezer_attach(). Losing to freezer_attach() means that we don't have
- * to do anything as freezer_attach() will put @task into the appropriate
- * state.
- */
-static void freezer_fork(struct task_struct *task)
-{
- struct freezer *freezer;
-
- /*
- * The root cgroup is non-freezable, so we can skip locking the
- * freezer. This is safe regardless of race with task migration.
- * If we didn't race or won, skipping is obviously the right thing
- * to do. If we lost and root is the new cgroup, noop is still the
- * right thing to do.
- */
- if (task_css_is_root(task, freezer_cgrp_id))
- return;
-
- mutex_lock(&freezer_mutex);
- rcu_read_lock();
-
- freezer = task_freezer(task);
- if (freezer->state & CGROUP_FREEZING)
- freeze_task(task);
-
- rcu_read_unlock();
- mutex_unlock(&freezer_mutex);
-}
-
-/**
- * update_if_frozen - update whether a cgroup finished freezing
- * @css: css 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 @css, so we can't verify task states against
- * @freezer state here. See freezer_attach() for details.
- */
-static void update_if_frozen(struct cgroup_subsys_state *css)
-{
- struct freezer *freezer = css_freezer(css);
- struct cgroup_subsys_state *pos;
- struct css_task_iter it;
- struct task_struct *task;
-
- lockdep_assert_held(&freezer_mutex);
-
- if (!(freezer->state & CGROUP_FREEZING) ||
- (freezer->state & CGROUP_FROZEN))
- return;
-
- /* are all (live) children frozen? */
- rcu_read_lock();
- css_for_each_child(pos, css) {
- struct freezer *child = css_freezer(pos);
-
- if ((child->state & CGROUP_FREEZER_ONLINE) &&
- !(child->state & CGROUP_FROZEN)) {
- rcu_read_unlock();
- return;
- }
- }
- rcu_read_unlock();
-
- /* are all tasks frozen? */
- css_task_iter_start(css, 0, &it);
-
- while ((task = css_task_iter_next(&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:
- css_task_iter_end(&it);
-}
-
-static int freezer_read(struct seq_file *m, void *v)
-{
- struct cgroup_subsys_state *css = seq_css(m), *pos;
-
- mutex_lock(&freezer_mutex);
- rcu_read_lock();
-
- /* update states bottom-up */
- css_for_each_descendant_post(pos, css) {
- if (!css_tryget_online(pos))
- continue;
- rcu_read_unlock();
-
- update_if_frozen(pos);
-
- rcu_read_lock();
- css_put(pos);
- }
-
- rcu_read_unlock();
- mutex_unlock(&freezer_mutex);
-
- seq_puts(m, freezer_state_strs(css_freezer(css)->state));
- seq_putc(m, '\n');
- return 0;
-}
-
-static void freeze_cgroup(struct freezer *freezer)
-{
- struct css_task_iter it;
- struct task_struct *task;
-
- css_task_iter_start(&freezer->css, 0, &it);
- while ((task = css_task_iter_next(&it)))
- freeze_task(task);
- css_task_iter_end(&it);
-}
-
-static void unfreeze_cgroup(struct freezer *freezer)
-{
- struct css_task_iter it;
- struct task_struct *task;
-
- css_task_iter_start(&freezer->css, 0, &it);
- while ((task = css_task_iter_next(&it)))
- __thaw_task(task);
- css_task_iter_end(&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_mutex);
-
- 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_subsys_state *pos;
-
- /*
- * Update all its descendants in pre-order traversal. Each
- * descendant will try to inherit its parent's FREEZING state as
- * CGROUP_FREEZING_PARENT.
- */
- mutex_lock(&freezer_mutex);
- rcu_read_lock();
- css_for_each_descendant_pre(pos, &freezer->css) {
- struct freezer *pos_f = css_freezer(pos);
- struct freezer *parent = parent_freezer(pos_f);
-
- if (!css_tryget_online(pos))
- continue;
- rcu_read_unlock();
-
- if (pos_f == freezer)
- freezer_apply_state(pos_f, freeze,
- CGROUP_FREEZING_SELF);
- else
- freezer_apply_state(pos_f,
- parent->state & CGROUP_FREEZING,
- CGROUP_FREEZING_PARENT);
-
- rcu_read_lock();
- css_put(pos);
- }
- rcu_read_unlock();
- mutex_unlock(&freezer_mutex);
-}
-
-static ssize_t freezer_write(struct kernfs_open_file *of,
- char *buf, size_t nbytes, loff_t off)
-{
- bool freeze;
-
- buf = strstrip(buf);
-
- if (strcmp(buf, freezer_state_strs(0)) == 0)
- freeze = false;
- else if (strcmp(buf, freezer_state_strs(CGROUP_FROZEN)) == 0)
- freeze = true;
- else
- return -EINVAL;
-
- freezer_change_state(css_freezer(of_css(of)), freeze);
- return nbytes;
-}
-
-static u64 freezer_self_freezing_read(struct cgroup_subsys_state *css,
- struct cftype *cft)
-{
- struct freezer *freezer = css_freezer(css);
-
- return (bool)(freezer->state & CGROUP_FREEZING_SELF);
-}
-
-static u64 freezer_parent_freezing_read(struct cgroup_subsys_state *css,
- struct cftype *cft)
-{
- struct freezer *freezer = css_freezer(css);
-
- return (bool)(freezer->state & CGROUP_FREEZING_PARENT);
-}
-
-static struct cftype files[] = {
- {
- .name = "state",
- .flags = CFTYPE_NOT_ON_ROOT,
- .seq_show = freezer_read,
- .write = 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_cgrp_subsys = {
- .css_alloc = freezer_css_alloc,
- .css_online = freezer_css_online,
- .css_offline = freezer_css_offline,
- .css_free = freezer_css_free,
- .attach = freezer_attach,
- .fork = freezer_fork,
- .legacy_cftypes = files,
-};
--- /dev/null
+/*
+ * 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>
+#include <linux/mutex.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;
+};
+
+static DEFINE_MUTEX(freezer_mutex);
+
+static inline struct freezer *css_freezer(struct cgroup_subsys_state *css)
+{
+ return css ? container_of(css, struct freezer, css) : NULL;
+}
+
+static inline struct freezer *task_freezer(struct task_struct *task)
+{
+ return css_freezer(task_css(task, freezer_cgrp_id));
+}
+
+static struct freezer *parent_freezer(struct freezer *freezer)
+{
+ return css_freezer(freezer->css.parent);
+}
+
+bool cgroup_freezing(struct task_struct *task)
+{
+ bool ret;
+
+ rcu_read_lock();
+ ret = task_freezer(task)->state & CGROUP_FREEZING;
+ rcu_read_unlock();
+
+ return ret;
+}
+
+static const char *freezer_state_strs(unsigned int state)
+{
+ if (state & CGROUP_FROZEN)
+ return "FROZEN";
+ if (state & CGROUP_FREEZING)
+ return "FREEZING";
+ return "THAWED";
+};
+
+static struct cgroup_subsys_state *
+freezer_css_alloc(struct cgroup_subsys_state *parent_css)
+{
+ struct freezer *freezer;
+
+ freezer = kzalloc(sizeof(struct freezer), GFP_KERNEL);
+ if (!freezer)
+ return ERR_PTR(-ENOMEM);
+
+ return &freezer->css;
+}
+
+/**
+ * freezer_css_online - commit creation of a freezer css
+ * @css: css being created
+ *
+ * We're committing to creation of @css. 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_subsys_state *css)
+{
+ struct freezer *freezer = css_freezer(css);
+ struct freezer *parent = parent_freezer(freezer);
+
+ mutex_lock(&freezer_mutex);
+
+ freezer->state |= CGROUP_FREEZER_ONLINE;
+
+ if (parent && (parent->state & CGROUP_FREEZING)) {
+ freezer->state |= CGROUP_FREEZING_PARENT | CGROUP_FROZEN;
+ atomic_inc(&system_freezing_cnt);
+ }
+
+ mutex_unlock(&freezer_mutex);
+ return 0;
+}
+
+/**
+ * freezer_css_offline - initiate destruction of a freezer css
+ * @css: css being destroyed
+ *
+ * @css is going away. Mark it dead and decrement system_freezing_count if
+ * it was holding one.
+ */
+static void freezer_css_offline(struct cgroup_subsys_state *css)
+{
+ struct freezer *freezer = css_freezer(css);
+
+ mutex_lock(&freezer_mutex);
+
+ if (freezer->state & CGROUP_FREEZING)
+ atomic_dec(&system_freezing_cnt);
+
+ freezer->state = 0;
+
+ mutex_unlock(&freezer_mutex);
+}
+
+static void freezer_css_free(struct cgroup_subsys_state *css)
+{
+ kfree(css_freezer(css));
+}
+
+/*
+ * 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_taskset *tset)
+{
+ struct task_struct *task;
+ struct cgroup_subsys_state *new_css;
+
+ mutex_lock(&freezer_mutex);
+
+ /*
+ * Make the new tasks conform to the current state of @new_css.
+ * 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_css 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_css, tset) {
+ struct freezer *freezer = css_freezer(new_css);
+
+ if (!(freezer->state & CGROUP_FREEZING)) {
+ __thaw_task(task);
+ } else {
+ freeze_task(task);
+ /* clear FROZEN and propagate upwards */
+ while (freezer && (freezer->state & CGROUP_FROZEN)) {
+ freezer->state &= ~CGROUP_FROZEN;
+ freezer = parent_freezer(freezer);
+ }
+ }
+ }
+
+ mutex_unlock(&freezer_mutex);
+}
+
+/**
+ * freezer_fork - cgroup post fork callback
+ * @task: a task which has just been forked
+ *
+ * @task has just been created and should conform to the current state of
+ * the cgroup_freezer it belongs to. This function may race against
+ * freezer_attach(). Losing to freezer_attach() means that we don't have
+ * to do anything as freezer_attach() will put @task into the appropriate
+ * state.
+ */
+static void freezer_fork(struct task_struct *task)
+{
+ struct freezer *freezer;
+
+ /*
+ * The root cgroup is non-freezable, so we can skip locking the
+ * freezer. This is safe regardless of race with task migration.
+ * If we didn't race or won, skipping is obviously the right thing
+ * to do. If we lost and root is the new cgroup, noop is still the
+ * right thing to do.
+ */
+ if (task_css_is_root(task, freezer_cgrp_id))
+ return;
+
+ mutex_lock(&freezer_mutex);
+ rcu_read_lock();
+
+ freezer = task_freezer(task);
+ if (freezer->state & CGROUP_FREEZING)
+ freeze_task(task);
+
+ rcu_read_unlock();
+ mutex_unlock(&freezer_mutex);
+}
+
+/**
+ * update_if_frozen - update whether a cgroup finished freezing
+ * @css: css 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 @css, so we can't verify task states against
+ * @freezer state here. See freezer_attach() for details.
+ */
+static void update_if_frozen(struct cgroup_subsys_state *css)
+{
+ struct freezer *freezer = css_freezer(css);
+ struct cgroup_subsys_state *pos;
+ struct css_task_iter it;
+ struct task_struct *task;
+
+ lockdep_assert_held(&freezer_mutex);
+
+ if (!(freezer->state & CGROUP_FREEZING) ||
+ (freezer->state & CGROUP_FROZEN))
+ return;
+
+ /* are all (live) children frozen? */
+ rcu_read_lock();
+ css_for_each_child(pos, css) {
+ struct freezer *child = css_freezer(pos);
+
+ if ((child->state & CGROUP_FREEZER_ONLINE) &&
+ !(child->state & CGROUP_FROZEN)) {
+ rcu_read_unlock();
+ return;
+ }
+ }
+ rcu_read_unlock();
+
+ /* are all tasks frozen? */
+ css_task_iter_start(css, 0, &it);
+
+ while ((task = css_task_iter_next(&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:
+ css_task_iter_end(&it);
+}
+
+static int freezer_read(struct seq_file *m, void *v)
+{
+ struct cgroup_subsys_state *css = seq_css(m), *pos;
+
+ mutex_lock(&freezer_mutex);
+ rcu_read_lock();
+
+ /* update states bottom-up */
+ css_for_each_descendant_post(pos, css) {
+ if (!css_tryget_online(pos))
+ continue;
+ rcu_read_unlock();
+
+ update_if_frozen(pos);
+
+ rcu_read_lock();
+ css_put(pos);
+ }
+
+ rcu_read_unlock();
+ mutex_unlock(&freezer_mutex);
+
+ seq_puts(m, freezer_state_strs(css_freezer(css)->state));
+ seq_putc(m, '\n');
+ return 0;
+}
+
+static void freeze_cgroup(struct freezer *freezer)
+{
+ struct css_task_iter it;
+ struct task_struct *task;
+
+ css_task_iter_start(&freezer->css, 0, &it);
+ while ((task = css_task_iter_next(&it)))
+ freeze_task(task);
+ css_task_iter_end(&it);
+}
+
+static void unfreeze_cgroup(struct freezer *freezer)
+{
+ struct css_task_iter it;
+ struct task_struct *task;
+
+ css_task_iter_start(&freezer->css, 0, &it);
+ while ((task = css_task_iter_next(&it)))
+ __thaw_task(task);
+ css_task_iter_end(&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_mutex);
+
+ 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_subsys_state *pos;
+
+ /*
+ * Update all its descendants in pre-order traversal. Each
+ * descendant will try to inherit its parent's FREEZING state as
+ * CGROUP_FREEZING_PARENT.
+ */
+ mutex_lock(&freezer_mutex);
+ rcu_read_lock();
+ css_for_each_descendant_pre(pos, &freezer->css) {
+ struct freezer *pos_f = css_freezer(pos);
+ struct freezer *parent = parent_freezer(pos_f);
+
+ if (!css_tryget_online(pos))
+ continue;
+ rcu_read_unlock();
+
+ if (pos_f == freezer)
+ freezer_apply_state(pos_f, freeze,
+ CGROUP_FREEZING_SELF);
+ else
+ freezer_apply_state(pos_f,
+ parent->state & CGROUP_FREEZING,
+ CGROUP_FREEZING_PARENT);
+
+ rcu_read_lock();
+ css_put(pos);
+ }
+ rcu_read_unlock();
+ mutex_unlock(&freezer_mutex);
+}
+
+static ssize_t freezer_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ bool freeze;
+
+ buf = strstrip(buf);
+
+ if (strcmp(buf, freezer_state_strs(0)) == 0)
+ freeze = false;
+ else if (strcmp(buf, freezer_state_strs(CGROUP_FROZEN)) == 0)
+ freeze = true;
+ else
+ return -EINVAL;
+
+ freezer_change_state(css_freezer(of_css(of)), freeze);
+ return nbytes;
+}
+
+static u64 freezer_self_freezing_read(struct cgroup_subsys_state *css,
+ struct cftype *cft)
+{
+ struct freezer *freezer = css_freezer(css);
+
+ return (bool)(freezer->state & CGROUP_FREEZING_SELF);
+}
+
+static u64 freezer_parent_freezing_read(struct cgroup_subsys_state *css,
+ struct cftype *cft)
+{
+ struct freezer *freezer = css_freezer(css);
+
+ return (bool)(freezer->state & CGROUP_FREEZING_PARENT);
+}
+
+static struct cftype files[] = {
+ {
+ .name = "state",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .seq_show = freezer_read,
+ .write = 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_cgrp_subsys = {
+ .css_alloc = freezer_css_alloc,
+ .css_online = freezer_css_online,
+ .css_offline = freezer_css_offline,
+ .css_free = freezer_css_free,
+ .attach = freezer_attach,
+ .fork = freezer_fork,
+ .legacy_cftypes = files,
+};
projects / linux-2.6-microblaze.git / commitdiff