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Diffstat (limited to 'kernel/cgroup_freezer.c')
-rw-r--r--kernel/cgroup_freezer.c60
1 files changed, 27 insertions, 33 deletions
diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
index 2690830e7428..e76aa9fb3ef4 100644
--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -22,15 +22,14 @@
#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 = (1 << 1), /* this freezer is freezing */
+ CGROUP_FROZEN = (1 << 3), /* this and its descendants frozen */
};
struct freezer {
struct cgroup_subsys_state css;
- enum freezer_state state;
+ unsigned int state;
spinlock_t lock;
};
@@ -48,12 +47,10 @@ 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;
@@ -63,10 +60,13 @@ bool cgroup_freezing(struct task_struct *task)
* 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";
};
/*
@@ -91,7 +91,6 @@ static struct cgroup_subsys_state *freezer_create(struct cgroup *cgroup)
return ERR_PTR(-ENOMEM);
spin_lock_init(&freezer->lock);
- freezer->state = CGROUP_THAWED;
return &freezer->css;
}
@@ -99,7 +98,7 @@ static void freezer_destroy(struct cgroup *cgroup)
{
struct freezer *freezer = cgroup_freezer(cgroup);
- if (freezer->state != CGROUP_THAWED)
+ if (freezer->state & CGROUP_FREEZING)
atomic_dec(&system_freezing_cnt);
kfree(freezer);
}
@@ -129,15 +128,13 @@ static void freezer_attach(struct cgroup *new_cgrp, struct cgroup_taskset *tset)
* 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;
}
}
@@ -159,11 +156,7 @@ static void freezer_fork(struct task_struct *task)
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:
@@ -184,7 +177,8 @@ static void update_if_frozen(struct freezer *freezer)
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);
@@ -202,7 +196,7 @@ static void update_if_frozen(struct freezer *freezer)
}
}
- freezer->state = CGROUP_FROZEN;
+ freezer->state |= CGROUP_FROZEN;
notyet:
cgroup_iter_end(cgroup, &it);
}
@@ -211,14 +205,14 @@ static int freezer_read(struct cgroup *cgroup, struct cftype *cft,
struct seq_file *m)
{
struct freezer *freezer = cgroup_freezer(cgroup);
- enum freezer_state state;
+ unsigned int state;
spin_lock_irq(&freezer->lock);
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;
}
@@ -258,14 +252,14 @@ static void freezer_apply_state(struct freezer *freezer, bool freeze)
lockdep_assert_held(&freezer->lock);
if (freeze) {
- if (freezer->state == CGROUP_THAWED)
+ if (!(freezer->state & CGROUP_FREEZING))
atomic_inc(&system_freezing_cnt);
- freezer->state = CGROUP_FREEZING;
+ freezer->state |= CGROUP_FREEZING;
freeze_cgroup(freezer);
} else {
- if (freezer->state != CGROUP_THAWED)
+ if (freezer->state & CGROUP_FREEZING)
atomic_dec(&system_freezing_cnt);
- freezer->state = CGROUP_THAWED;
+ freezer->state &= ~(CGROUP_FREEZING | CGROUP_FROZEN);
unfreeze_cgroup(freezer);
}
}
@@ -290,9 +284,9 @@ static int freezer_write(struct cgroup *cgroup, struct cftype *cft,
{
bool freeze;
- if (strcmp(buffer, freezer_state_strs[CGROUP_THAWED]) == 0)
+ if (strcmp(buffer, freezer_state_strs(0)) == 0)
freeze = false;
- else if (strcmp(buffer, freezer_state_strs[CGROUP_FROZEN]) == 0)
+ else if (strcmp(buffer, freezer_state_strs(CGROUP_FROZEN)) == 0)
freeze = true;
else
return -EINVAL;