#include <linux/seq_file.h>
enum freezer_state {
- STATE_RUNNING = 0,
- STATE_FREEZING,
- STATE_FROZEN,
+ CGROUP_THAWED = 0,
+ CGROUP_FREEZING,
+ CGROUP_FROZEN,
};
struct freezer {
state = freezer->state;
task_unlock(task);
- return state == STATE_FROZEN;
+ return state == CGROUP_FROZEN;
}
/*
* CGROUP_LOCAL_BUFFER_SIZE
*/
static const char *freezer_state_strs[] = {
- "RUNNING",
+ "THAWED",
"FREEZING",
"FROZEN",
};
* Transitions are caused by userspace writes to the freezer.state file.
* The values in parenthesis are state labels. The rest are edge labels.
*
- * (RUNNING) --FROZEN--> (FREEZING) --FROZEN--> (FROZEN)
- * ^ ^ | |
- * | \_______RUNNING_______/ |
- * \_____________________________RUNNING___________/
+ * (THAWED) --FROZEN--> (FREEZING) --FROZEN--> (FROZEN)
+ * ^ ^ | |
+ * | \_______THAWED_______/ |
+ * \__________________________THAWED____________/
*/
struct cgroup_subsys freezer_subsys;
return ERR_PTR(-ENOMEM);
spin_lock_init(&freezer->lock);
- freezer->state = STATE_RUNNING;
+ freezer->state = CGROUP_THAWED;
return &freezer->css;
}
kfree(cgroup_freezer(cgroup));
}
+/* Task is frozen or will freeze immediately when next it gets woken */
+static bool is_task_frozen_enough(struct task_struct *task)
+{
+ return frozen(task) ||
+ (task_is_stopped_or_traced(task) && freezing(task));
+}
+/*
+ * The call to cgroup_lock() in the freezer.state write method prevents
+ * a write to that file racing against an attach, and hence the
+ * can_attach() result will remain valid until the attach completes.
+ */
static int freezer_can_attach(struct cgroup_subsys *ss,
struct cgroup *new_cgroup,
struct task_struct *task)
{
struct freezer *freezer;
- int retval = 0;
+ int retval;
+
+ /* Anything frozen can't move or be moved to/from */
+
+ if (is_task_frozen_enough(task))
+ return -EBUSY;
- /*
- * The call to cgroup_lock() in the freezer.state write method prevents
- * a write to that file racing against an attach, and hence the
- * can_attach() result will remain valid until the attach completes.
- */
freezer = cgroup_freezer(new_cgroup);
- if (freezer->state == STATE_FROZEN)
+ if (freezer->state == CGROUP_FROZEN)
+ return -EBUSY;
+
+ retval = 0;
+ task_lock(task);
+ freezer = task_freezer(task);
+ if (freezer->state == CGROUP_FROZEN)
retval = -EBUSY;
+ task_unlock(task);
return retval;
}
freezer = task_freezer(task);
task_unlock(task);
- BUG_ON(freezer->state == STATE_FROZEN);
+ BUG_ON(freezer->state == CGROUP_FROZEN);
spin_lock_irq(&freezer->lock);
- /* Locking avoids race with FREEZING -> RUNNING transitions. */
- if (freezer->state == STATE_FREEZING)
+ /* Locking avoids race with FREEZING -> THAWED transitions. */
+ if (freezer->state == CGROUP_FREEZING)
freeze_task(task, true);
spin_unlock_irq(&freezer->lock);
}
/*
* caller must hold freezer->lock
*/
-static void check_if_frozen(struct cgroup *cgroup,
- struct freezer *freezer)
+static void update_freezer_state(struct cgroup *cgroup,
+ struct freezer *freezer)
{
struct cgroup_iter it;
struct task_struct *task;
cgroup_iter_start(cgroup, &it);
while ((task = cgroup_iter_next(cgroup, &it))) {
ntotal++;
- /*
- * Task is frozen or will freeze immediately when next it gets
- * woken
- */
- if (frozen(task) ||
- (task_is_stopped_or_traced(task) && freezing(task)))
+ if (is_task_frozen_enough(task))
nfrozen++;
}
* tasks.
*/
if (nfrozen == ntotal)
- freezer->state = STATE_FROZEN;
+ freezer->state = CGROUP_FROZEN;
+ else if (nfrozen > 0)
+ freezer->state = CGROUP_FREEZING;
+ else
+ freezer->state = CGROUP_THAWED;
cgroup_iter_end(cgroup, &it);
}
freezer = cgroup_freezer(cgroup);
spin_lock_irq(&freezer->lock);
state = freezer->state;
- if (state == STATE_FREEZING) {
+ if (state == CGROUP_FREEZING) {
/* We change from FREEZING to FROZEN lazily if the cgroup was
* only partially frozen when we exitted write. */
- check_if_frozen(cgroup, freezer);
+ update_freezer_state(cgroup, freezer);
state = freezer->state;
}
spin_unlock_irq(&freezer->lock);
struct task_struct *task;
unsigned int num_cant_freeze_now = 0;
- freezer->state = STATE_FREEZING;
+ freezer->state = CGROUP_FREEZING;
cgroup_iter_start(cgroup, &it);
while ((task = cgroup_iter_next(cgroup, &it))) {
if (!freeze_task(task, true))
continue;
- if (task_is_stopped_or_traced(task) && freezing(task))
- /*
- * The freeze flag is set so these tasks will
- * immediately go into the fridge upon waking.
- */
+ if (is_task_frozen_enough(task))
continue;
if (!freezing(task) && !freezer_should_skip(task))
num_cant_freeze_now++;
wake_up_process(task);
}
cgroup_iter_end(cgroup, &it);
- freezer->state = STATE_RUNNING;
+ freezer->state = CGROUP_THAWED;
return 0;
}
freezer = cgroup_freezer(cgroup);
spin_lock_irq(&freezer->lock);
- check_if_frozen(cgroup, freezer); /* may update freezer->state */
+ update_freezer_state(cgroup, freezer);
if (goal_state == freezer->state)
goto out;
switch (freezer->state) {
- case STATE_RUNNING:
+ case CGROUP_THAWED:
retval = try_to_freeze_cgroup(cgroup, freezer);
break;
- case STATE_FREEZING:
- if (goal_state == STATE_FROZEN) {
+ case CGROUP_FREEZING:
+ if (goal_state == CGROUP_FROZEN) {
/* Userspace is retrying after
* "/bin/echo FROZEN > freezer.state" returned -EBUSY */
retval = try_to_freeze_cgroup(cgroup, freezer);
break;
}
- /* state == FREEZING and goal_state == RUNNING, so unfreeze */
- case STATE_FROZEN:
+ /* state == FREEZING and goal_state == THAWED, so unfreeze */
+ case CGROUP_FROZEN:
retval = unfreeze_cgroup(cgroup, freezer);
break;
default:
int retval;
enum freezer_state goal_state;
- if (strcmp(buffer, freezer_state_strs[STATE_RUNNING]) == 0)
- goal_state = STATE_RUNNING;
- else if (strcmp(buffer, freezer_state_strs[STATE_FROZEN]) == 0)
- goal_state = STATE_FROZEN;
+ 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;
else
return -EIO;
projects / linux-2.6-omap-h63xx.git / blobdiff