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Commit c5501eb3 authored by Florian Westphal's avatar Florian Westphal Committed by David S. Miller
Browse files

net: ipv4: avoid repeated calls to ip_skb_dst_mtu helper 



ip_skb_dst_mtu is small inline helper, but its called in several places.

before: 17061      44       0   17105    42d1 net/ipv4/ip_output.o
after:  16805      44       0   16849    41d1 net/ipv4/ip_output.o

Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Acked-by: default avatarHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 8c0ce770

net/ipv4/ip_output.c

+12 −7
Original line number Diff line number Diff line
@@ -84,6 +84,7 @@ int sysctl_ip_default_ttl __read_mostly = IPDEFTTL; 
EXPORT_SYMBOL(sysctl_ip_default_ttl);



static int ip_fragment(struct sock *sk, struct sk_buff *skb,

		       unsigned int mtu,

		       int (*output)(struct sock *, struct sk_buff *));



/* Generate a checksum for an outgoing IP datagram. */
@@ -219,7 +220,8 @@ static inline int ip_finish_output2(struct sock *sk, struct sk_buff *skb) 
	return -EINVAL;

}



static int ip_finish_output_gso(struct sock *sk, struct sk_buff *skb)

static int ip_finish_output_gso(struct sock *sk, struct sk_buff *skb,

				unsigned int mtu)

{

	netdev_features_t features;

	struct sk_buff *segs;
@@ -227,7 +229,7 @@ static int ip_finish_output_gso(struct sock *sk, struct sk_buff *skb) 


	/* common case: locally created skb or seglen is <= mtu */

	if (((IPCB(skb)->flags & IPSKB_FORWARDED) == 0) ||

	      skb_gso_network_seglen(skb) <= ip_skb_dst_mtu(skb))

	      skb_gso_network_seglen(skb) <= mtu)

		return ip_finish_output2(sk, skb);



	/* Slowpath -  GSO segment length is exceeding the dst MTU.
@@ -251,7 +253,7 @@ static int ip_finish_output_gso(struct sock *sk, struct sk_buff *skb) 
		int err;



		segs->next = NULL;

		err = ip_fragment(sk, segs, ip_finish_output2);

		err = ip_fragment(sk, segs, mtu, ip_finish_output2);



		if (err && ret == 0)

			ret = err;
@@ -263,6 +265,8 @@ static int ip_finish_output_gso(struct sock *sk, struct sk_buff *skb) 


static int ip_finish_output(struct sock *sk, struct sk_buff *skb)

{

	unsigned int mtu;



#if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)

	/* Policy lookup after SNAT yielded a new policy */

	if (skb_dst(skb)->xfrm) {
@@ -270,11 +274,12 @@ static int ip_finish_output(struct sock *sk, struct sk_buff *skb) 
		return dst_output_sk(sk, skb);

	}

#endif

	mtu = ip_skb_dst_mtu(skb);

	if (skb_is_gso(skb))

		return ip_finish_output_gso(sk, skb);

		return ip_finish_output_gso(sk, skb, mtu);



	if (skb->len > ip_skb_dst_mtu(skb))

		return ip_fragment(sk, skb, ip_finish_output2);

	if (skb->len > mtu)

		return ip_fragment(sk, skb, mtu, ip_finish_output2);



	return ip_finish_output2(sk, skb);

}
@@ -482,10 +487,10 @@ static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from) 
}



static int ip_fragment(struct sock *sk, struct sk_buff *skb,

		       unsigned int mtu,

		       int (*output)(struct sock *, struct sk_buff *))

{

	struct iphdr *iph = ip_hdr(skb);

	unsigned int mtu = ip_skb_dst_mtu(skb);



	if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->ignore_df) ||

		     (IPCB(skb)->frag_max_size &&