X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=kernel%2Fcgroup_freezer.c;h=fb249e2bcada880a19105488c7fdde33e9483126;hb=0886751c5d8b19fcee2e65d34ae21c9111e652a9;hp=5e6d26b66e88200206a584f3daf7a1c287247651;hpb=00c2e63c31d0f431952ff2a671c5c6997dd4f8b2;p=safe%2Fjmp%2Flinux-2.6

diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
index 5e6d26b..fb249e2 100644
--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -184,9 +184,20 @@ static void freezer_fork(struct cgroup_subsys *ss, struct task_struct *task)
 {
 	struct freezer *freezer;
 
-	task_lock(task);
+	/*
+	 * No lock is needed, since the task isn't on tasklist yet,
+	 * so it can't be moved to another cgroup, which means the
+	 * freezer won't be removed and will be valid during this
+	 * function call.
+	 */
 	freezer = task_freezer(task);
-	task_unlock(task);
+
+	/*
+	 * The root cgroup is non-freezable, so we can skip the
+	 * following check.
+	 */
+	if (!freezer->css.cgroup->parent)
+		return;
 
 	spin_lock_irq(&freezer->lock);
 	BUG_ON(freezer->state == CGROUP_FROZEN);
@@ -296,27 +307,22 @@ static int freezer_change_state(struct cgroup *cgroup,
 	int retval = 0;
 
 	freezer = cgroup_freezer(cgroup);
+
 	spin_lock_irq(&freezer->lock);
+
 	update_freezer_state(cgroup, freezer);
 	if (goal_state == freezer->state)
 		goto out;
-	switch (freezer->state) {
+
+	switch (goal_state) {
 	case CGROUP_THAWED:
-		retval = try_to_freeze_cgroup(cgroup, freezer);
+		unfreeze_cgroup(cgroup, freezer);
 		break;
-	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 == THAWED, so unfreeze */
 	case CGROUP_FROZEN:
-		unfreeze_cgroup(cgroup, freezer);
+		retval = try_to_freeze_cgroup(cgroup, freezer);
 		break;
 	default:
-		break;
+		BUG();
 	}
 out:
 	spin_unlock_irq(&freezer->lock);
@@ -336,7 +342,7 @@ static int freezer_write(struct cgroup *cgroup,
 	else if (strcmp(buffer, freezer_state_strs[CGROUP_FROZEN]) == 0)
 		goal_state = CGROUP_FROZEN;
 	else
-		return -EIO;
+		return -EINVAL;
 
 	if (!cgroup_lock_live_group(cgroup))
 		return -ENODEV;
@@ -355,6 +361,8 @@ static struct cftype files[] = {
 
 static int freezer_populate(struct cgroup_subsys *ss, struct cgroup *cgroup)
 {
+	if (!cgroup->parent)
+		return 0;
 	return cgroup_add_files(cgroup, ss, files, ARRAY_SIZE(files));
 }