[PATCH 5/5] cgroup: separate out cgroup_attach_proc error handling code

[Mandeep Singh Baines <msb@chromium.org>]

Makes it easier to read the non-error path.

While at it, move the retval=0 assignment inside the !group_size
check. This way the comment describe this check is directly
above it(we also avoid an extra assignment not needed in the
normal path). Also return 0 directly instead of using retval.

Signed-off-by: Mandeep Singh Baines <msb@chromium.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: containers@lists.linux-foundation.org
Cc: cgroups@vger.kernel.org
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul Menage <paul@paulmenage.org>
---
 kernel/cgroup.c |   21 +++++++++++----------
 1 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 2ac9eee..9ce0872 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2067,9 +2067,10 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
 	read_unlock(&tasklist_lock);
 
 	/* methods shouldn't be called if no task is actually migrating */
-	retval = 0;
-	if (!group_size)
+	if (!group_size) {
+		retval = 0;
 		goto out_free_group_list;
+	}
 
 	/*
 	 * step 1: check that we can legitimately attach to the cgroup.
@@ -2126,20 +2127,20 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
 	 */
 	synchronize_rcu();
 	cgroup_wakeup_rmdir_waiter(cgrp);
-	retval = 0;
+	flex_array_free(group);
+	return 0;
+
 out_list_teardown:
 	for (i = 0; i < css_set_refs; i++) {
 		tc = flex_array_get(group, i);
 		put_css_set(tc->cg);
 	}
 out_cancel_attach:
-	if (retval) {
-		for_each_subsys(root, ss) {
-			if (ss == failed_ss)
-				break;
-			if (ss->cancel_attach)
-				ss->cancel_attach(ss, cgrp, &tset);
-		}
+	for_each_subsys(root, ss) {
+		if (ss == failed_ss)
+			break;
+		if (ss->cancel_attach)
+			ss->cancel_attach(ss, cgrp, &tset);
 	}
 out_free_group_list:
 	flex_array_free(group);
-- 
1.7.3.1