Re: [PATCH v2 3/9] socket: initial cgroup code.

[Glauber Costa]

On 09/07/2011 07:17 PM, Kirill A. Shutemov wrote:
> On Wed, Sep 07, 2011 at 01:23:13AM -0300, Glauber Costa wrote:
> > We aim to control the amount of kernel memory pinned at any
> > time by tcp sockets. To lay the foundations for this work,
> > this patch adds a pointer to the kmem_cgroup to the socket
> > structure.
> >
> > Signed-off-by: Glauber Costa<glommer@xxxxxxxxxxxxx>
> > CC: David S. Miller<davem@xxxxxxxxxxxxx>
> > CC: Hiroyouki Kamezawa<kamezawa.hiroyu@xxxxxxxxxxxxxx>
> > CC: Eric W. Biederman<ebiederm@xxxxxxxxxxxx>
> > ---
> >   include/linux/kmem_cgroup.h |   29 +++++++++++++++++++++++++++++
> >   include/net/sock.h          |    2 ++
> >   net/core/sock.c             |    5 ++---
> >   3 files changed, 33 insertions(+), 3 deletions(-)
> >
> > diff --git a/include/linux/kmem_cgroup.h b/include/linux/kmem_cgroup.h
> > index 0e4a74b..77076d8 100644
> > --- a/include/linux/kmem_cgroup.h
> > +++ b/include/linux/kmem_cgroup.h
> > @@ -49,5 +49,34 @@ static inline struct kmem_cgroup *kcg_from_task(struct task_struct *tsk)
> >   	return NULL;
> >   }
> >   #endif /* CONFIG_CGROUP_KMEM */
> > +
> > +#ifdef CONFIG_INET
>
> Will it break something if you define the helpers even if CONFIG_INET
> is not defined?
> It will be much cleaner. You can reuse ifdef CONFIG_CGROUP_KMEM in this
> case.

The helpers inside CONFIG_INET are needed for the network code, 
regardless of kmem cgroup is defined or not, not the other way around.

So I could remove CONFIG_INET, but I can't possibly move it inside
CONFIG_CGROUP_KMEM. So this buy us nothing.

> > +#include<net/sock.h>
> > +static inline void sock_update_kmem_cgrp(struct sock *sk)
> > +{
> > +#ifdef CONFIG_CGROUP_KMEM
> > +	sk->sk_cgrp = kcg_from_task(current);
> > +
> > +	/*
> > +	 * We don't need to protect against anything task-related, because
> > +	 * we are basically stuck with the sock pointer that won't change,
> > +	 * even if the task that originated the socket changes cgroups.
> > +	 *
> > +	 * What we do have to guarantee, is that the chain leading us to
> > +	 * the top level won't change under our noses. Incrementing the
> > +	 * reference count via cgroup_exclude_rmdir guarantees that.
> > +	 */
> > +	cgroup_exclude_rmdir(&sk->sk_cgrp->css);
> > +#endif
> > +}
> > +
> > +static inline void sock_release_kmem_cgrp(struct sock *sk)
> > +{
> > +#ifdef CONFIG_CGROUP_KMEM
> > +	cgroup_release_and_wakeup_rmdir(&sk->sk_cgrp->css);
> > +#endif
> > +}
> > +
> > +#endif /* CONFIG_INET */
> >   #endif /* _LINUX_KMEM_CGROUP_H */
>
> > @@ -2252,9 +2254,6 @@ void sk_common_release(struct sock *sk)
> >   }
> >   EXPORT_SYMBOL(sk_common_release);
> >
> > -static DEFINE_RWLOCK(proto_list_lock);
> > -static LIST_HEAD(proto_list);
> > -
>
> Wrong patch?
Yes, it is. Thanks for noticing.


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