linux-kernel - Re: [PATCH 1/2 v3] net: add uevent socket member

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Message-ID: <20180319115941.GA7257@gmail.com>
Date:   Mon, 19 Mar 2018 12:59:42 +0100
From:   Christian Brauner <christian.brauner@...onical.com>
To:     Kirill Tkhai <ktkhai@...tuozzo.com>
Cc:     Christian Brauner <christian.brauner@...ntu.com>,
        ebiederm@...ssion.com, gregkh@...uxfoundation.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        serge@...lyn.com, avagin@...tuozzo.com
Subject: Re: [PATCH 1/2 v3] net: add uevent socket member

On Mon, Mar 19, 2018 at 02:53:09PM +0300, Kirill Tkhai wrote:
> Thanks for doing this. One small comment below.
> 
> On 17.03.2018 14:08, Christian Brauner wrote:
> > This commit adds struct uevent_sock to struct net. Since struct uevent_sock
> > records the position of the uevent socket in the uevent socket list we can
> > trivially remove it from the uevent socket list during cleanup. This speeds
> > up the old removal codepath.
> > Note, list_del() will hit __list_del_entry_valid() in its call chain which
> > will validate that the element is a member of the list. If it isn't it will
> > take care that the list is not modified.
> > 
> > Signed-off-by: Christian Brauner <christian.brauner@...ntu.com>
> > ---
> > Changelog v2->v3:
> > * patch added
> >   This patch was split out of the follow up patch
> >   Subject: [PATCH 2/2 v3] netns: send uevent messages
> > 
> > Changelog v1->v2:
> > * patch not present
> > 
> > Changelog v0->v1:
> > * patch not present
> > ---
> >  include/net/net_namespace.h |  4 +++-
> >  lib/kobject_uevent.c        | 19 +++++++++----------
> >  2 files changed, 12 insertions(+), 11 deletions(-)
> > 
> > diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
> > index f306b2aa15a4..abd7d91bffac 100644
> > --- a/include/net/net_namespace.h
> > +++ b/include/net/net_namespace.h
> > @@ -40,7 +40,7 @@ struct net_device;
> >  struct sock;
> >  struct ctl_table_header;
> >  struct net_generic;
> > -struct sock;
> > +struct uevent_sock;
> >  struct netns_ipvs;
> >  
> >  
> > @@ -79,6 +79,8 @@ struct net {
> >  	struct sock 		*rtnl;			/* rtnetlink socket */
> >  	struct sock		*genl_sock;
> >  
> > +	struct uevent_sock	*uevent_sock;		/* uevent socket */
> > +
> >  	struct list_head 	dev_base_head;
> >  	struct hlist_head 	*dev_name_head;
> >  	struct hlist_head	*dev_index_head;
> > diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c
> > index 9fe6ec8fda28..cbdc60542cab 100644
> > --- a/lib/kobject_uevent.c
> > +++ b/lib/kobject_uevent.c
> > @@ -32,11 +32,13 @@ u64 uevent_seqnum;
> >  #ifdef CONFIG_UEVENT_HELPER
> >  char uevent_helper[UEVENT_HELPER_PATH_LEN] = CONFIG_UEVENT_HELPER_PATH;
> >  #endif
> > -#ifdef CONFIG_NET
> > +
> >  struct uevent_sock {
> >  	struct list_head list;
> >  	struct sock *sk;
> >  };
> > +
> > +#ifdef CONFIG_NET
> >  static LIST_HEAD(uevent_sock_list);
> >  #endif
> >  
> > @@ -621,6 +623,9 @@ static int uevent_net_init(struct net *net)
> >  		kfree(ue_sk);
> >  		return -ENODEV;
> >  	}
> > +
> > +	net->uevent_sock = ue_sk;
> > +
> >  	mutex_lock(&uevent_sock_mutex);
> >  	list_add_tail(&ue_sk->list, &uevent_sock_list);
> >  	mutex_unlock(&uevent_sock_mutex);
> > @@ -629,22 +634,16 @@ static int uevent_net_init(struct net *net)
> >  
> >  static void uevent_net_exit(struct net *net)
> >  {
> > -	struct uevent_sock *ue_sk;
> > +	struct uevent_sock *ue_sk = net->uevent_sock;
> >  
> >  	mutex_lock(&uevent_sock_mutex);
> > -	list_for_each_entry(ue_sk, &uevent_sock_list, list) {
> > -		if (sock_net(ue_sk->sk) == net)
> > -			goto found;
> > -	}
> > -	mutex_unlock(&uevent_sock_mutex);
> > -	return;
> > -
> > -found:
> >  	list_del(&ue_sk->list);
> >  	mutex_unlock(&uevent_sock_mutex);
> >  
> >  	netlink_kernel_release(ue_sk->sk);
> >  	kfree(ue_sk);
> > +
> > +	return;
> 
> There is end of function. Doesn't return is excess here?

Yeah, I can remove it and resend it now.

Christian

> 
> >  }
> >  
> >  static struct pernet_operations uevent_net_ops = {
> > 
> 
> Kirill