Commit 4e985ada authored by Thomas Graf's avatar Thomas Graf Committed by David S. Miller
Browse files

rtnl: provide link dump consistency info 



This patch adds a change sequence counter to each net namespace
which is bumped whenever a netdevice is added or removed from
the list. If such a change occurred while a link dump took place,
the dump will have the NLM_F_DUMP_INTR flag set in the first
message which has been interrupted and in all subsequent messages
of the same dump.

Note that links may still be modified or renamed while a dump is
taking place but we can guarantee for userspace to receive a
complete list of links and not miss any.

Testing:
I have added 500 VLAN netdevices to make sure the dump is split
over multiple messages. Then while continuously dumping links in
one process I also continuously deleted and re-added a dummy
netdevice in another process. Multiple dumps per seconds have
had the NLM_F_DUMP_INTR flag set.

I guess we can wait for Johannes patch to hit net-next via the
wireless tree.  I just wanted to give this some testing right away.

Signed-off-by: default avatarThomas Graf <tgraf@infradead.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e77aeb71

include/net/net_namespace.h

+1 −0
Original line number Diff line number Diff line
@@ -65,6 +65,7 @@ struct net { 
	struct list_head 	dev_base_head;

	struct hlist_head 	*dev_name_head;

	struct hlist_head	*dev_index_head;

	unsigned int		dev_base_seq;	/* protected by rtnl_mutex */



	/* core fib_rules */

	struct list_head	rules_ops;

net/core/dev.c

+10 −0
Original line number Diff line number Diff line
@@ -199,6 +199,11 @@ static struct list_head ptype_all __read_mostly; /* Taps */ 
DEFINE_RWLOCK(dev_base_lock);

EXPORT_SYMBOL(dev_base_lock);



static inline void dev_base_seq_inc(struct net *net)

{

	while (++net->dev_base_seq == 0);

}



static inline struct hlist_head *dev_name_hash(struct net *net, const char *name)

{

	unsigned hash = full_name_hash(name, strnlen(name, IFNAMSIZ));
@@ -237,6 +242,9 @@ static int list_netdevice(struct net_device *dev) 
	hlist_add_head_rcu(&dev->index_hlist,

			   dev_index_hash(net, dev->ifindex));

	write_unlock_bh(&dev_base_lock);



	dev_base_seq_inc(net);



	return 0;

}
@@ -253,6 +261,8 @@ static void unlist_netdevice(struct net_device *dev) 
	hlist_del_rcu(&dev->name_hlist);

	hlist_del_rcu(&dev->index_hlist);

	write_unlock_bh(&dev_base_lock);



	dev_base_seq_inc(dev_net(dev));

}



/*

net/core/net_namespace.c

+1 −0
Original line number Diff line number Diff line
@@ -129,6 +129,7 @@ static __net_init int setup_net(struct net *net) 


	atomic_set(&net->count, 1);

	atomic_set(&net->passive, 1);

	net->dev_base_seq = 1;



#ifdef NETNS_REFCNT_DEBUG

	atomic_set(&net->use_count, 0);

net/core/rtnetlink.c

+4 −0
Original line number Diff line number Diff line
@@ -1032,6 +1032,8 @@ static int rtnl_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb) 
	s_idx = cb->args[1];



	rcu_read_lock();

	cb->seq = net->dev_base_seq;



	for (h = s_h; h < NETDEV_HASHENTRIES; h++, s_idx = 0) {

		idx = 0;

		head = &net->dev_index_head[h];
@@ -1043,6 +1045,8 @@ static int rtnl_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb) 
					     cb->nlh->nlmsg_seq, 0,

					     NLM_F_MULTI) <= 0)

				goto out;



			nl_dump_check_consistent(cb, nlmsg_hdr(skb));

cont:

			idx++;

		}

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