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Commit 5ada5527 authored by David S. Miller's avatar David S. Miller
Browse files

ipv4: Simplify output route creation call sequence. 



There's a lot of redundancy and unnecessary stack frames
in the output route creation path.

1) Make __mkroute_output() return error pointers.

2) Eliminate ip_mkroute_output() entirely, made possible by #1.

3) Call __mkroute_output() directly and handling the returning error
   pointers in ip_route_output_slow().

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent cf0bdefd

net/ipv4/route.c

+23 −35
Original line number Diff line number Diff line
@@ -2323,33 +2323,32 @@ int ip_route_input_common(struct sk_buff *skb, __be32 daddr, __be32 saddr, 
EXPORT_SYMBOL(ip_route_input_common);



/* called with rcu_read_lock() */

static int __mkroute_output(struct rtable **result,

			    struct fib_result *res,

static struct rtable *__mkroute_output(struct fib_result *res,

				       const struct flowi *fl,

				       const struct flowi *oldflp,

				       struct net_device *dev_out,

			    unsigned flags)

				       unsigned int flags)

{

	struct rtable *rth;

	struct in_device *in_dev;

	u32 tos = RT_FL_TOS(oldflp);

	struct in_device *in_dev;

	struct rtable *rth;



	if (ipv4_is_loopback(fl->fl4_src) && !(dev_out->flags & IFF_LOOPBACK))

		return -EINVAL;

		return ERR_PTR(-EINVAL);



	if (ipv4_is_lbcast(fl->fl4_dst))

		res->type = RTN_BROADCAST;

	else if (ipv4_is_multicast(fl->fl4_dst))

		res->type = RTN_MULTICAST;

	else if (ipv4_is_zeronet(fl->fl4_dst))

		return -EINVAL;

		return ERR_PTR(-EINVAL);



	if (dev_out->flags & IFF_LOOPBACK)

		flags |= RTCF_LOCAL;



	in_dev = __in_dev_get_rcu(dev_out);

	if (!in_dev)

		return -EINVAL;

		return ERR_PTR(-EINVAL);



	if (res->type == RTN_BROADCAST) {

		flags |= RTCF_BROADCAST | RTCF_LOCAL;
@@ -2370,7 +2369,7 @@ static int __mkroute_output(struct rtable **result, 


	rth = dst_alloc(&ipv4_dst_ops);

	if (!rth)

		return -ENOBUFS;

		return ERR_PTR(-ENOBUFS);



	atomic_set(&rth->dst.__refcnt, 1);

	rth->dst.flags= DST_HOST;
@@ -2425,28 +2424,7 @@ static int __mkroute_output(struct rtable **result, 
	rt_set_nexthop(rth, res, 0);



	rth->rt_flags = flags;

	*result = rth;

	return 0;

}



/* called with rcu_read_lock() */

static int ip_mkroute_output(struct rtable **rp,

			     struct fib_result *res,

			     const struct flowi *fl,

			     const struct flowi *oldflp,

			     struct net_device *dev_out,

			     unsigned flags)

{

	struct rtable *rth = NULL;

	int err = __mkroute_output(&rth, res, fl, oldflp, dev_out, flags);

	unsigned hash;

	if (err == 0) {

		hash = rt_hash(oldflp->fl4_dst, oldflp->fl4_src, oldflp->oif,

			       rt_genid(dev_net(dev_out)));

		err = rt_intern_hash(hash, rth, rp, NULL, oldflp->oif);

	}



	return err;

	return rth;

}



/*
@@ -2469,6 +2447,7 @@ static int ip_route_output_slow(struct net *net, struct rtable **rp, 
	struct fib_result res;

	unsigned int flags = 0;

	struct net_device *dev_out = NULL;

	struct rtable *rth;

	int err;
@@ -2627,7 +2606,16 @@ static int ip_route_output_slow(struct net *net, struct rtable **rp, 




make_route:

	err = ip_mkroute_output(rp, &res, &fl, oldflp, dev_out, flags);

	rth = __mkroute_output(&res, &fl, oldflp, dev_out, flags);

	if (IS_ERR(rth))

		err = PTR_ERR(rth);

	else {

		unsigned int hash;



		hash = rt_hash(oldflp->fl4_dst, oldflp->fl4_src, oldflp->oif,

			       rt_genid(dev_net(dev_out)));

		err = rt_intern_hash(hash, rth, rp, NULL, oldflp->oif);

	}



out:	return err;

}