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

[Li Zefan <lizf-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>]

Paul Menage wrote:
> On Fri, Nov 28, 2008 at 2:02 AM, Li Zefan <lizf-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org> 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".
> 

Yes, I mean subsys_list not root_list.

>> The above code assumes rootnode.subsys_list links all inactive
>> hierarchies.
>>
>> Signed-off-by: Li Zefan <lizf-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
>> ---
>>  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?
> 

I thought I corrected all the s/root_list/subsys_list/ in patch v2. :(

If this patch makes sense, I'll fix it, otherwise we'll going to ask Andrew to drop it from -mm.