#include <linux/freezer.h>
#include <linux/seq_file.h>
-enum freezer_state {
- CGROUP_THAWED = 0,
- CGROUP_FREEZING,
- CGROUP_FROZEN,
+enum freezer_state_flags {
+ 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;
- enum freezer_state state;
- spinlock_t lock; /* protects _writes_ to state */
+ struct cgroup_subsys_state css;
+ unsigned int state;
+ spinlock_t lock;
};
-static inline struct freezer *cgroup_freezer(
- struct cgroup *cgroup)
+static inline struct freezer *cgroup_freezer(struct cgroup *cgroup)
{
- return container_of(
- cgroup_subsys_state(cgroup, freezer_subsys_id),
- struct freezer, css);
+ return container_of(cgroup_subsys_state(cgroup, freezer_subsys_id),
+ struct freezer, css);
}
static inline struct freezer *task_freezer(struct task_struct *task)
bool cgroup_freezing(struct task_struct *task)
{
- enum freezer_state state;
bool ret;
rcu_read_lock();
- state = task_freezer(task)->state;
- ret = state == CGROUP_FREEZING || state == CGROUP_FROZEN;
+ 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[] = {
- "THAWED",
- "FREEZING",
- "FROZEN",
+static const char *freezer_state_strs(unsigned int state)
+{
+ if (state & CGROUP_FROZEN)
+ return "FROZEN";
+ if (state & CGROUP_FREEZING)
+ return "FREEZING";
+ return "THAWED";
};
/*
return ERR_PTR(-ENOMEM);
spin_lock_init(&freezer->lock);
- freezer->state = CGROUP_THAWED;
return &freezer->css;
}
{
struct freezer *freezer = cgroup_freezer(cgroup);
- if (freezer->state != CGROUP_THAWED)
+ if (freezer->state & CGROUP_FREEZING)
atomic_dec(&system_freezing_cnt);
kfree(freezer);
}
* 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.
- * This means that, to determine whether to freeze, one should test
- * whether the state equals THAWED.
*/
cgroup_taskset_for_each(task, new_cgrp, tset) {
- if (freezer->state == CGROUP_THAWED) {
+ if (!(freezer->state & CGROUP_FREEZING)) {
__thaw_task(task);
} else {
freeze_task(task);
- freezer->state = CGROUP_FREEZING;
+ freezer->state &= ~CGROUP_FROZEN;
}
}
goto out;
spin_lock_irq(&freezer->lock);
- /*
- * @task might have been just migrated into a FROZEN cgroup. Test
- * equality with THAWED. Read the comment in freezer_attach().
- */
- if (freezer->state != CGROUP_THAWED)
+ if (freezer->state & CGROUP_FREEZING)
freeze_task(task);
spin_unlock_irq(&freezer->lock);
out:
* 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)
+static void update_if_frozen(struct freezer *freezer)
{
+ struct cgroup *cgroup = freezer->css.cgroup;
struct cgroup_iter it;
struct task_struct *task;
- if (freezer->state != CGROUP_FREEZING)
+ if (!(freezer->state & CGROUP_FREEZING) ||
+ (freezer->state & CGROUP_FROZEN))
return;
cgroup_iter_start(cgroup, &it);
* completion. Consider it frozen in addition to
* the usual frozen condition.
*/
- if (!frozen(task) && !task_is_stopped_or_traced(task) &&
- !freezer_should_skip(task))
+ if (!frozen(task) && !freezer_should_skip(task))
goto notyet;
}
}
- freezer->state = CGROUP_FROZEN;
+ freezer->state |= CGROUP_FROZEN;
notyet:
cgroup_iter_end(cgroup, &it);
}
static int freezer_read(struct cgroup *cgroup, struct cftype *cft,
struct seq_file *m)
{
- struct freezer *freezer;
- enum freezer_state state;
+ struct freezer *freezer = cgroup_freezer(cgroup);
+ unsigned int state;
- freezer = cgroup_freezer(cgroup);
spin_lock_irq(&freezer->lock);
- update_if_frozen(cgroup, freezer);
+ update_if_frozen(freezer);
state = freezer->state;
spin_unlock_irq(&freezer->lock);
- seq_puts(m, freezer_state_strs[state]);
+ seq_puts(m, freezer_state_strs(state));
seq_putc(m, '\n');
return 0;
}
-static void freeze_cgroup(struct cgroup *cgroup, struct freezer *freezer)
+static void freeze_cgroup(struct freezer *freezer)
{
+ struct cgroup *cgroup = freezer->css.cgroup;
struct cgroup_iter it;
struct task_struct *task;
cgroup_iter_end(cgroup, &it);
}
-static void unfreeze_cgroup(struct cgroup *cgroup, struct freezer *freezer)
+static void unfreeze_cgroup(struct freezer *freezer)
{
+ struct cgroup *cgroup = freezer->css.cgroup;
struct cgroup_iter it;
struct task_struct *task;
cgroup_iter_end(cgroup, &it);
}
-static void freezer_change_state(struct cgroup *cgroup,
- enum freezer_state goal_state)
+/**
+ * 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)
{
- struct freezer *freezer = cgroup_freezer(cgroup);
-
/* also synchronizes against task migration, see freezer_attach() */
- spin_lock_irq(&freezer->lock);
+ lockdep_assert_held(&freezer->lock);
- switch (goal_state) {
- case CGROUP_THAWED:
- if (freezer->state != CGROUP_THAWED)
- atomic_dec(&system_freezing_cnt);
- freezer->state = CGROUP_THAWED;
- unfreeze_cgroup(cgroup, freezer);
- break;
- case CGROUP_FROZEN:
- if (freezer->state == CGROUP_THAWED)
+ if (freeze) {
+ if (!(freezer->state & CGROUP_FREEZING))
atomic_inc(&system_freezing_cnt);
- freezer->state = CGROUP_FREEZING;
- freeze_cgroup(cgroup, freezer);
- break;
- default:
- BUG();
+ 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 @cgroup according to @freeze.
+ */
+static void freezer_change_state(struct freezer *freezer, bool freeze)
+{
+ /* update @freezer */
+ spin_lock_irq(&freezer->lock);
+ freezer_apply_state(freezer, freeze, CGROUP_FREEZING_SELF);
spin_unlock_irq(&freezer->lock);
}
-static int freezer_write(struct cgroup *cgroup,
- struct cftype *cft,
+static int freezer_write(struct cgroup *cgroup, struct cftype *cft,
const char *buffer)
{
- enum freezer_state goal_state;
+ bool freeze;
- if (strcmp(buffer, freezer_state_strs[CGROUP_THAWED]) == 0)
- goal_state = CGROUP_THAWED;
- else if (strcmp(buffer, freezer_state_strs[CGROUP_FROZEN]) == 0)
- goal_state = CGROUP_FROZEN;
+ 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, goal_state);
+ 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",
.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 */
};
projects / deliverable / linux.git / blobdiff