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authorGrzegorz Nosek <root@localdomain.pl>2009-04-02 16:57:23 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-04-02 19:04:53 -0700
commit313e924c0852943e67335fad9d2608701f0dfe8e (patch)
treefa4c3f65a7ed6edea52ae78b012138ebab1420c3 /kernel/ns_cgroup.c
parentd20a390a0ee2bf2f692c539c6ce1c829e1080bb5 (diff)
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cgroups: relax ns_can_attach checks to allow attaching to grandchild cgroups
The ns_proxy cgroup allows moving processes to child cgroups only one level deep at a time. This commit relaxes this restriction and makes it possible to attach tasks directly to grandchild cgroups, e.g.: ($pid is in the root cgroup) echo $pid > /cgroup/CG1/CG2/tasks Previously this operation would fail with -EPERM and would have to be performed as two steps: echo $pid > /cgroup/CG1/tasks echo $pid > /cgroup/CG1/CG2/tasks Also, the target cgroup no longer needs to be empty to move a task there. Signed-off-by: Grzegorz Nosek <root@localdomain.pl> Acked-by: Serge Hallyn <serue@us.ibm.com> Reviewed-by: Li Zefan <lizf@cn.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>
Diffstat (limited to 'kernel/ns_cgroup.c')
-rw-r--r--kernel/ns_cgroup.c14
1 files changed, 4 insertions, 10 deletions
diff --git a/kernel/ns_cgroup.c b/kernel/ns_cgroup.c
index 78bc3fdac0d2..5aa854f9e5ae 100644
--- a/kernel/ns_cgroup.c
+++ b/kernel/ns_cgroup.c
@@ -34,7 +34,7 @@ int ns_cgroup_clone(struct task_struct *task, struct pid *pid)
/*
* Rules:
- * 1. you can only enter a cgroup which is a child of your current
+ * 1. you can only enter a cgroup which is a descendant of your current
* cgroup
* 2. you can only place another process into a cgroup if
* a. you have CAP_SYS_ADMIN
@@ -45,21 +45,15 @@ int ns_cgroup_clone(struct task_struct *task, struct pid *pid)
static int ns_can_attach(struct cgroup_subsys *ss,
struct cgroup *new_cgroup, struct task_struct *task)
{
- struct cgroup *orig;
-
if (current != task) {
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
- if (!cgroup_is_descendant(new_cgroup))
+ if (!cgroup_is_descendant(new_cgroup, current))
return -EPERM;
}
- if (atomic_read(&new_cgroup->count) != 0)
- return -EPERM;
-
- orig = task_cgroup(task, ns_subsys_id);
- if (orig && orig != new_cgroup->parent)
+ if (!cgroup_is_descendant(new_cgroup, task))
return -EPERM;
return 0;
@@ -77,7 +71,7 @@ static struct cgroup_subsys_state *ns_create(struct cgroup_subsys *ss,
if (!capable(CAP_SYS_ADMIN))
return ERR_PTR(-EPERM);
- if (!cgroup_is_descendant(cgroup))
+ if (!cgroup_is_descendant(cgroup, current))
return ERR_PTR(-EPERM);
ns_cgroup = kzalloc(sizeof(*ns_cgroup), GFP_KERNEL);