[Devel] Re: [PATCH 2/3] cgroups: add inactive subsystems to rootnode.root_list

[Paul Menage]

On Fri, Nov 28, 2008 at 2:02 AM, Li Zefan <lizf at cn.fujitsu.com> wrote:
> Though for an inactive hierarchy, we have subsys->root == &rootnode,
> but rootnode's root_list is always empty.

I think you mean "rootnode's subsys_list is always empty".

>
> The above code assumes rootnode.subsys_list links all inactive
> hierarchies.
>
> Signed-off-by: Li Zefan <lizf at cn.fujitsu.com>
> ---
>  kernel/cgroup.c |    5 +++--
>  1 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/cgroup.c b/kernel/cgroup.c
> index 33ba756..4e50e97 100644
> --- a/kernel/cgroup.c
> +++ b/kernel/cgroup.c
> @@ -716,7 +716,7 @@ static int rebind_subsystems(struct cgroupfs_root *root,
>                        BUG_ON(dummytop->subsys[i]->cgroup != dummytop);
>                        cgrp->subsys[i] = dummytop->subsys[i];
>                        cgrp->subsys[i]->cgroup = cgrp;
> -                       list_add(&ss->sibling, &root->subsys_list);
> +                       list_move(&ss->sibling, &root->subsys_list);
>                        rcu_assign_pointer(ss->root, root);
>                        if (ss->bind)
>                                ss->bind(ss, cgrp);
> @@ -730,7 +730,7 @@ static int rebind_subsystems(struct cgroupfs_root *root,
>                        dummytop->subsys[i]->cgroup = dummytop;
>                        cgrp->subsys[i] = NULL;
>                        rcu_assign_pointer(subsys[i]->root, &rootnode);
> -                       list_del(&ss->sibling);
> +                       list_move(&ss->sibling, &rootnode.subsys_list);
>                } else if (bit & final_bits) {
>                        /* Subsystem state should already exist */
>                        BUG_ON(!cgrp->subsys[i]);
> @@ -2522,6 +2522,7 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss)
>        printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name);
>
>        /* Create the top cgroup state for this subsystem */
> +       list_add(&ss->sibling, &rootnode.root_list);

This is wrong. cgroup_subsys.sibling is a member of the list of
subsystems attached to a given root, and rootnode.root_list is a
member of the list of hierarchies. Did you actually meant
&rootnode.subsys_list?

Paul
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