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Commit b70cc5fd authored by Li Zefan's avatar Li Zefan Committed by Linus Torvalds
Browse files

cgroups: clean up cgroup_pidlist_find() a bit 



Don't call get_pid_ns() before we locate/alloc the ns.

Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Acked-by: default avatarPaul Menage <menage@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 67523c48

kernel/cgroup.c

+3 −5
Original line number Diff line number Diff line
@@ -2597,7 +2597,8 @@ static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp, 
{

	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
@@ -2607,8 +2608,6 @@ static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp, 
	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);
@@ -2619,13 +2618,12 @@ static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp, 
	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;