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Commit 0cc09020 authored by Florian Westphal's avatar Florian Westphal Committed by David S. Miller
Browse files

rtnetlink: small rtnl lock pushdown 



instead of rtnl lock/unload at the top level, push it down
to the called function.

This is just an intermediate step, next commit switches protection
of the rtnl_link ops table to rcu, in which case (for dumps) the
rtnl lock is acquired only by the netlink dumper infrastructure
(current lock/unlock/dump/lock/unlock rtnl sequence becomes
 rcu lock/rcu unlock/dump).

Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Reviewed-by: default avatarHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 019a3169

net/core/rtnetlink.c

+13 −6
Original line number Diff line number Diff line
@@ -4178,9 +4178,11 @@ static int rtnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, 
		rtnl_dumpit_func dumpit;

		u16 min_dump_alloc = 0;



		rtnl_lock();



		dumpit = rtnl_get_dumpit(family, type);

		if (dumpit == NULL)

			return -EOPNOTSUPP;

			goto err_unlock;



		refcount_inc(&rtnl_msg_handlers_ref[family]);
@@ -4196,23 +4198,28 @@ static int rtnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, 
			};

			err = netlink_dump_start(rtnl, skb, nlh, &c);

		}

		rtnl_lock();

		refcount_dec(&rtnl_msg_handlers_ref[family]);

		return err;

	}



	rtnl_lock();

	doit = rtnl_get_doit(family, type);

	if (doit == NULL)

		return -EOPNOTSUPP;

		goto err_unlock;



	err = doit(skb, nlh, extack);

	rtnl_unlock();



	return err;



	return doit(skb, nlh, extack);

err_unlock:

	rtnl_unlock();

	return -EOPNOTSUPP;

}



static void rtnetlink_rcv(struct sk_buff *skb)

{

	rtnl_lock();

	netlink_rcv_skb(skb, &rtnetlink_rcv_msg);

	rtnl_unlock();

}



static int rtnetlink_bind(struct net *net, int group)