On Tue, Jan 26, 2010 at 12:17 AM, Li Zefan <lizf@xxxxxxxxxxxxxx> wrote:
> Don't Call get_pid_ns() before we locate/alloc the ns.
>
> Signed-off-by: Li Zefan <lizf@xxxxxxxxxxxxxx>
Acked-by: Paul Menage <menage@xxxxxxxxxx>
> ---
> cgroup.c | 8 +++-----
> 1 file changed, 3 insertions(+), 5 deletions(-)
>
> --- a/kernel/cgroup.c.orig 2010-01-26 14:24:29.000000000 +0800
> +++ a/kernel/cgroup.c 2010-01-26 14:24:44.000000000 +0800
> @@ -2643,7 +2643,8 @@ static struct cgroup_pidlist *cgroup_pid
> {
> struct cgroup_pidlist *l;
> /* don't need task_nsproxy() if we're looking at ourself */
> - struct pid_namespace *ns = get_pid_ns(current->nsproxy->pid_ns);
> + struct pid_namespace *ns = current->nsproxy->pid_ns;
> +
> /*
> * We can't drop the pidlist_mutex before taking the l->mutex in case
> * the last ref-holder is trying to remove l from the list at the same
> @@ -2653,8 +2654,6 @@ static struct cgroup_pidlist *cgroup_pid
> mutex_lock(&cgrp->pidlist_mutex);
> list_for_each_entry(l, &cgrp->pidlists, links) {
> if (l->key.type == type && l->key.ns == ns) {
> - /* found a matching list - drop the extra refcount */
> - put_pid_ns(ns);
> /* make sure l doesn't vanish out from under us */
> down_write(&l->mutex);
> mutex_unlock(&cgrp->pidlist_mutex);
> @@ -2665,13 +2664,12 @@ static struct cgroup_pidlist *cgroup_pid
> l = kmalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL);
> if (!l) {
> mutex_unlock(&cgrp->pidlist_mutex);
> - put_pid_ns(ns);
> return l;
> }
> init_rwsem(&l->mutex);
> down_write(&l->mutex);
> l->key.type = type;
> - l->key.ns = ns;
> + l->key.ns = get_pid_ns(ns);
> l->use_count = 0; /* don't increment here */
> l->list = NULL;
> l->owner = cgrp;
>
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