diff options
| -rw-r--r-- | kernel/cgroup_freezer.c | 60 |
1 files changed, 27 insertions, 33 deletions
diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c index 2690830e742..e76aa9fb3ef 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; |