Commit 985ec6f5 authored by Justin Iurman's avatar Justin Iurman Committed by Paolo Abeni
Browse files

net: ipv6: rpl_iptunnel: mitigate 2-realloc issue 

This patch mitigates the two-reallocations issue with rpl_iptunnel by
providing the dst_entry (in the cache) to the first call to
skb_cow_head(). As a result, the very first iteration would still
trigger two reallocations (i.e., empty cache), while next iterations
would only trigger a single reallocation.

Performance tests before/after applying this patch, which clearly shows
there is no impact (it even shows improvement):
- before: https://ibb.co/nQJhqwc
- after: https://ibb.co/4ZvW6wV



Signed-off-by: default avatarJustin Iurman <justin.iurman@uliege.be>
Cc: Alexander Aring <aahringo@redhat.com>
Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parent 40475b63

net/ipv6/rpl_iptunnel.c

+25 −21
Original line number Diff line number Diff line
@@ -125,7 +125,8 @@ static void rpl_destroy_state(struct lwtunnel_state *lwt) 
}



static int rpl_do_srh_inline(struct sk_buff *skb, const struct rpl_lwt *rlwt,

			     const struct ipv6_rpl_sr_hdr *srh)

			     const struct ipv6_rpl_sr_hdr *srh,

			     struct dst_entry *cache_dst)

{

	struct ipv6_rpl_sr_hdr *isrh, *csrh;

	const struct ipv6hdr *oldhdr;
@@ -153,7 +154,7 @@ static int rpl_do_srh_inline(struct sk_buff *skb, const struct rpl_lwt *rlwt, 


	hdrlen = ((csrh->hdrlen + 1) << 3);



	err = skb_cow_head(skb, hdrlen + skb->mac_len);

	err = skb_cow_head(skb, hdrlen + dst_dev_overhead(cache_dst, skb));

	if (unlikely(err)) {

		kfree(buf);

		return err;
@@ -186,7 +187,8 @@ static int rpl_do_srh_inline(struct sk_buff *skb, const struct rpl_lwt *rlwt, 
	return 0;

}



static int rpl_do_srh(struct sk_buff *skb, const struct rpl_lwt *rlwt)

static int rpl_do_srh(struct sk_buff *skb, const struct rpl_lwt *rlwt,

		      struct dst_entry *cache_dst)

{

	struct dst_entry *dst = skb_dst(skb);

	struct rpl_iptunnel_encap *tinfo;
@@ -196,7 +198,7 @@ static int rpl_do_srh(struct sk_buff *skb, const struct rpl_lwt *rlwt) 


	tinfo = rpl_encap_lwtunnel(dst->lwtstate);



	return rpl_do_srh_inline(skb, rlwt, tinfo->srh);

	return rpl_do_srh_inline(skb, rlwt, tinfo->srh, cache_dst);

}



static int rpl_output(struct net *net, struct sock *sk, struct sk_buff *skb)
@@ -208,14 +210,14 @@ static int rpl_output(struct net *net, struct sock *sk, struct sk_buff *skb) 


	rlwt = rpl_lwt_lwtunnel(orig_dst->lwtstate);



	err = rpl_do_srh(skb, rlwt);

	if (unlikely(err))

		goto drop;



	local_bh_disable();

	dst = dst_cache_get(&rlwt->cache);

	local_bh_enable();



	err = rpl_do_srh(skb, rlwt, dst);

	if (unlikely(err))

		goto drop;



	if (unlikely(!dst)) {

		struct ipv6hdr *hdr = ipv6_hdr(skb);

		struct flowi6 fl6;
@@ -237,14 +239,14 @@ static int rpl_output(struct net *net, struct sock *sk, struct sk_buff *skb) 
		local_bh_disable();

		dst_cache_set_ip6(&rlwt->cache, dst, &fl6.saddr);

		local_bh_enable();

	}



	skb_dst_drop(skb);

	skb_dst_set(skb, dst);



		err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev));

		if (unlikely(err))

			goto drop;

	}



	skb_dst_drop(skb);

	skb_dst_set(skb, dst);



	return dst_output(net, sk, skb);
@@ -262,29 +264,31 @@ static int rpl_input(struct sk_buff *skb) 


	rlwt = rpl_lwt_lwtunnel(orig_dst->lwtstate);



	err = rpl_do_srh(skb, rlwt);

	if (unlikely(err))

		goto drop;



	local_bh_disable();

	dst = dst_cache_get(&rlwt->cache);

	local_bh_enable();



	err = rpl_do_srh(skb, rlwt, dst);

	if (unlikely(err))

		goto drop;



	if (!dst) {

		ip6_route_input(skb);

		dst = skb_dst(skb);

		if (!dst->error) {

			local_bh_disable();

			dst_cache_set_ip6(&rlwt->cache, dst,

					  &ipv6_hdr(skb)->saddr);

		}

	} else {

		skb_dst_drop(skb);

		skb_dst_set(skb, dst);

	}

			local_bh_enable();

		}



		err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev));

		if (unlikely(err))

			goto drop;

	} else {

		skb_dst_drop(skb);

		skb_dst_set(skb, dst);

	}



	return dst_input(skb);