From 51b8f812e5b327b343232685ea7969e02348d5dd Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 3 Aug 2021 08:31:05 -0700 Subject: [PATCH] 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: Eric Dumazet Cc: Justin Iurman Cc: Coco Li Signed-off-by: David S. Miller --- net/ipv6/exthdrs.c | 105 ++++++++++++++++++++------------------------- 1 file changed, 46 insertions(+), 59 deletions(-) diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c index d897faa4e9e6..3a871a09f962 100644 --- a/net/ipv6/exthdrs.c +++ b/net/ipv6/exthdrs.c @@ -55,19 +55,6 @@ #include -/* - * 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; + } + } 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; } } - if (curr->type < 0 && - !ip6_tlvopt_unknown(skb, off, disallow_unknowns)) - return false; - 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);