Commit 51b8f812 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

ipv6: exthdrs: get rid of indirect calls in ip6_parse_tlv() 



As presented last month in our "BIG TCP" talk at netdev 0x15,
we plan using IPv6 jumbograms.

One of the minor problem we talked about is the fact that
ip6_parse_tlv() is currently using tables to list known tlvs,
thus using potentially expensive indirect calls.

While we could mitigate this cost using macros from
indirect_call_wrapper.h, we also can get rid of the tables
and let the compiler emit optimized code.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Cc: Justin Iurman <justin.iurman@uliege.be>
Cc: Coco Li <lixiaoyan@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d8517985

net/ipv6/exthdrs.c

+46 −59
Original line number Diff line number Diff line
@@ -55,19 +55,6 @@ 


#include <linux/uaccess.h>



/*

 *	Parsing tlv encoded headers.

 *

 *	Parsing function "func" returns true, if parsing succeed

 *	and false, if it failed.

 *	It MUST NOT touch skb->h.

 */



struct tlvtype_proc {

	int	type;

	bool	(*func)(struct sk_buff *skb, int offset);

};



/*********************

  Generic functions

 *********************/
@@ -112,16 +99,23 @@ static bool ip6_tlvopt_unknown(struct sk_buff *skb, int optoff, 
	return false;

}



static bool ipv6_hop_ra(struct sk_buff *skb, int optoff);

static bool ipv6_hop_ioam(struct sk_buff *skb, int optoff);

static bool ipv6_hop_jumbo(struct sk_buff *skb, int optoff);

static bool ipv6_hop_calipso(struct sk_buff *skb, int optoff);

#if IS_ENABLED(CONFIG_IPV6_MIP6)

static bool ipv6_dest_hao(struct sk_buff *skb, int optoff);

#endif



/* Parse tlv encoded option header (hop-by-hop or destination) */



static bool ip6_parse_tlv(const struct tlvtype_proc *procs,

static bool ip6_parse_tlv(bool hopbyhop,

			  struct sk_buff *skb,

			  int max_count)

{

	int len = (skb_transport_header(skb)[1] + 1) << 3;

	const unsigned char *nh = skb_network_header(skb);

	int off = skb_network_header_len(skb);

	const struct tlvtype_proc *curr;

	bool disallow_unknowns = false;

	int tlv_count = 0;

	int padlen = 0;
@@ -176,20 +170,45 @@ static bool ip6_parse_tlv(const struct tlvtype_proc *procs, 
			if (tlv_count > max_count)

				goto bad;



			for (curr = procs; curr->type >= 0; curr++) {

				if (curr->type == nh[off]) {

					/* type specific length/alignment

					   checks will be performed in the

					   func(). */

					if (curr->func(skb, off) == false)

			if (hopbyhop) {

				switch (nh[off]) {

				case IPV6_TLV_ROUTERALERT:

					if (!ipv6_hop_ra(skb, off))

						return false;

					break;

				case IPV6_TLV_IOAM:

					if (!ipv6_hop_ioam(skb, off))

						return false;

					break;

				case IPV6_TLV_JUMBO:

					if (!ipv6_hop_jumbo(skb, off))

						return false;

					break;

				case IPV6_TLV_CALIPSO:

					if (!ipv6_hop_calipso(skb, off))

						return false;

					break;

				default:

					if (!ip6_tlvopt_unknown(skb, off,

								disallow_unknowns))

						return false;

					break;

				}

			}

			if (curr->type < 0 &&

			    !ip6_tlvopt_unknown(skb, off, disallow_unknowns))

			} else {

				switch (nh[off]) {

#if IS_ENABLED(CONFIG_IPV6_MIP6)

				case IPV6_TLV_HAO:

					if (!ipv6_dest_hao(skb, off))

						return false;



					break;

#endif

				default:

					if (!ip6_tlvopt_unknown(skb, off,

								disallow_unknowns))

						return false;

					break;

				}

			}

			padlen = 0;

		}

		off += optlen;
@@ -267,16 +286,6 @@ static bool ipv6_dest_hao(struct sk_buff *skb, int optoff) 
}

#endif



static const struct tlvtype_proc tlvprocdestopt_lst[] = {

#if IS_ENABLED(CONFIG_IPV6_MIP6)

	{

		.type	= IPV6_TLV_HAO,

		.func	= ipv6_dest_hao,

	},

#endif

	{-1,			NULL}

};



static int ipv6_destopt_rcv(struct sk_buff *skb)

{

	struct inet6_dev *idev = __in6_dev_get(skb->dev);
@@ -307,8 +316,7 @@ static int ipv6_destopt_rcv(struct sk_buff *skb) 
	dstbuf = opt->dst1;

#endif



	if (ip6_parse_tlv(tlvprocdestopt_lst, skb,

			  net->ipv6.sysctl.max_dst_opts_cnt)) {

	if (ip6_parse_tlv(false, skb, net->ipv6.sysctl.max_dst_opts_cnt)) {

		skb->transport_header += extlen;

		opt = IP6CB(skb);

#if IS_ENABLED(CONFIG_IPV6_MIP6)
@@ -1051,26 +1059,6 @@ static bool ipv6_hop_calipso(struct sk_buff *skb, int optoff) 
	return false;

}



static const struct tlvtype_proc tlvprochopopt_lst[] = {

	{

		.type	= IPV6_TLV_ROUTERALERT,

		.func	= ipv6_hop_ra,

	},

	{

		.type	= IPV6_TLV_IOAM,

		.func	= ipv6_hop_ioam,

	},

	{

		.type	= IPV6_TLV_JUMBO,

		.func	= ipv6_hop_jumbo,

	},

	{

		.type	= IPV6_TLV_CALIPSO,

		.func	= ipv6_hop_calipso,

	},

	{ -1, }

};



int ipv6_parse_hopopts(struct sk_buff *skb)

{

	struct inet6_skb_parm *opt = IP6CB(skb);
@@ -1096,8 +1084,7 @@ int ipv6_parse_hopopts(struct sk_buff *skb) 
		goto fail_and_free;



	opt->flags |= IP6SKB_HOPBYHOP;

	if (ip6_parse_tlv(tlvprochopopt_lst, skb,

			  net->ipv6.sysctl.max_hbh_opts_cnt)) {

	if (ip6_parse_tlv(true, skb, net->ipv6.sysctl.max_hbh_opts_cnt)) {

		skb->transport_header += extlen;

		opt = IP6CB(skb);

		opt->nhoff = sizeof(struct ipv6hdr);