Commit 86a3db56 authored Jan 24, 2013 by Li Zefan Committed by Tejun Heo Jan 24, 2013

cgroup: remove duplicate RCU free on struct cgroup



When destroying a cgroup, though in cgroup_diput() we've called
synchronize_rcu(), we then still have to free it via call_rcu().

The story is, long ago to fix a race between reading /proc/sched_debug
and freeing cgroup, the code was changed to utilize call_rcu(). See
commit a47295e6 ("cgroups: make
cgroup_path() RCU-safe")

As we've fixed cpu cgroup that cpu_cgroup_offline_css() is used
to unregister a task_group so there won't be concurrent access
to this task_group after synchronize_rcu() in diput(). Now we can
just kfree(cgrp).

Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

parent 2a73991b

kernel/cgroup.c

+1 −1

Original line number	Original line	Diff line number	Diff line
	@@ -892,7 +892,7 @@ static void cgroup_diput(struct dentry dentry, struct inode inode)
	simple_xattrs_free(&cgrp->xattrs);		simple_xattrs_free(&cgrp->xattrs);

	ida_simple_remove(&cgrp->root->cgroup_ida, cgrp->id);		ida_simple_remove(&cgrp->root->cgroup_ida, cgrp->id);
	kfree_rcu(cgrp, rcu_head);		kfree(cgrp);
	} else {		} else {
	struct cfent *cfe = __d_cfe(dentry);		struct cfent *cfe = __d_cfe(dentry);
	struct cgroup *cgrp = dentry->d_parent->d_fsdata;		struct cgroup *cgrp = dentry->d_parent->d_fsdata;