Re: [PATCH 09/10] cgroup: introduce struct cfent

[Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

On Tue, Mar 20, 2012 at 08:03:03PM +0400, Glauber Costa wrote:
> From 04604201411ab0a14fa1447072cd1b273d0774ed Mon Sep 17 00:00:00 2001
> From: Glauber Costa <glommer-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
> Date: Tue, 20 Mar 2012 18:12:55 +0400
> Subject: [PATCH] don't trigger warning when d_subdirs is not empty.
> 
> It is never empty at this point, because of the self references.
> a better test is to see if any of them gets d_inode set.
> 
> Signed-off-by: Glauber Costa <glommer-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
> Signed-off-by: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
> ---
>  kernel/cgroup.c |    8 +++++++-
>  1 files changed, 7 insertions(+), 1 deletions(-)
> 
> diff --git a/kernel/cgroup.c b/kernel/cgroup.c
> index cf7b298..b45a653 100644
> --- a/kernel/cgroup.c
> +++ b/kernel/cgroup.c
> @@ -947,10 +947,16 @@ static int cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
>  static void cgroup_clear_directory(struct dentry *dir)
>  {
>  	struct cgroup *cgrp = __d_cgrp(dir);
> +	struct list_head *child;
>  
>  	while (!list_empty(&cgrp->files))
>  		cgroup_rm_file(cgrp, NULL);
> -	WARN_ON_ONCE(!list_empty(&dir->d_subdirs));
> +
> +	list_for_each(child, &dir->d_subdirs) {
> +		struct dentry *d;
> +		d = list_entry(child, struct dentry, d_u.d_child);
> +		WARN_ON_ONCE(d->d_inode);
> +	}

This seems correct and I'll apply this but I still can't reproduce the
warning at will before the patch.  How do I a get negative dentry on
the d_subdirs when d_delete always returns 1?  Glauber, can you
trigger the warning at will?

Thanks.

-- 
tejun