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-rw-r--r--kernel/cgroup_freezer.c43
1 files changed, 17 insertions, 26 deletions
diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
index 0b0e10545ef0..3d45503a21a2 100644
--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -213,41 +213,39 @@ out:
}
/*
- * caller must hold freezer->lock
+ * We change from FREEZING to FROZEN lazily if the cgroup was only
+ * partially frozen when we exitted write. Caller must hold freezer->lock.
+ *
+ * Task states and freezer state might disagree while tasks are being
+ * migrated into @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 cgroup *cgroup, struct freezer *freezer)
{
struct cgroup_iter it;
struct task_struct *task;
- unsigned int nfrozen = 0, ntotal = 0;
- enum freezer_state old_state = freezer->state;
+
+ if (freezer->state != CGROUP_FREEZING)
+ return;
cgroup_iter_start(cgroup, &it);
+
while ((task = cgroup_iter_next(cgroup, &it))) {
if (freezing(task)) {
- ntotal++;
/*
* 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) || task_is_stopped_or_traced(task) ||
- freezer_should_skip(task))
- nfrozen++;
+ if (!frozen(task) && !task_is_stopped_or_traced(task) &&
+ !freezer_should_skip(task))
+ goto notyet;
}
}
- if (old_state == CGROUP_THAWED) {
- BUG_ON(nfrozen > 0);
- } else if (old_state == CGROUP_FREEZING) {
- if (nfrozen == ntotal)
- freezer->state = CGROUP_FROZEN;
- } else { /* old_state == CGROUP_FROZEN */
- BUG_ON(nfrozen != ntotal);
- }
-
+ freezer->state = CGROUP_FROZEN;
+notyet:
cgroup_iter_end(cgroup, &it);
}
@@ -262,13 +260,8 @@ static int freezer_read(struct cgroup *cgroup, struct cftype *cft,
freezer = cgroup_freezer(cgroup);
spin_lock_irq(&freezer->lock);
+ update_if_frozen(cgroup, freezer);
state = freezer->state;
- if (state == CGROUP_FREEZING) {
- /* We change from FREEZING to FROZEN lazily if the cgroup was
- * only partially frozen when we exitted write. */
- update_if_frozen(cgroup, freezer);
- state = freezer->state;
- }
spin_unlock_irq(&freezer->lock);
cgroup_unlock();
@@ -306,8 +299,6 @@ static void freezer_change_state(struct cgroup *cgroup,
spin_lock_irq(&freezer->lock);
- update_if_frozen(cgroup, freezer);
-
switch (goal_state) {
case CGROUP_THAWED:
if (freezer->state != CGROUP_THAWED)