From: Pavel Emelyanov <xemul@openvz.org>
Date: Thu, 20 Mar 2008 00:00:45 +0000 (-0700)
Subject: memcgroup: fix check for thread being a group leader in memcgroup
X-Git-Tag: v2.6.25-rc7~91
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=52ea27eb4cd5f250f33638029a134ff03c5e6bbb;p=linux-2.6

memcgroup: fix check for thread being a group leader in memcgroup

The check t->pid == t->pid is not the blessed way to check whether a task is a
group leader.

This is not about the code beautifulness only, but about pid namespaces fixes
- both the tgid and the pid fields on the task_struct are (slowly :( )
becoming deprecated.

Besides, the thread_group_leader() macro makes only one dereference :)

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 8b9f6cae93..9b648bd634 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1079,7 +1079,7 @@ static void mem_cgroup_move_task(struct cgroup_subsys *ss,
 	 * Only thread group leaders are allowed to migrate, the mm_struct is
 	 * in effect owned by the leader
 	 */
-	if (p->tgid != p->pid)
+	if (!thread_group_leader(p))
 		goto out;
 
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