net: ipv6: remove redundant statistics in ipv6_hop_jumbo()

There are two call chains for ipv6_hop_jumbo(). The first one is:

ipv6_destopt_rcv() -> ip6_parse_tlv() -> ipv6_hop_jumbo()

On this call chain, the drop statistics will be done in
ipv6_destopt_rcv() with 'IPSTATS_MIB_INHDRERRORS' if ipv6_hop_jumbo()
returns false.

The second call chain is:

ip6_rcv_core() -> ipv6_parse_hopopts() -> ip6_parse_tlv()

And the drop statistics will also be done in ip6_rcv_core() with
'IPSTATS_MIB_INHDRERRORS' if ipv6_hop_jumbo() returns false.

Therefore, the statistics in ipv6_hop_jumbo() is redundant, which
means the drop is counted twice. The statistics in ipv6_hop_jumbo()
is almost the same as the outside, except the
'IPSTATS_MIB_INTRUNCATEDPKTS', which seems that we have to ignore it.

Signed-off-by: Menglong Dong <imagedong@tencent.com>
Reviewed-by: Jiang Biao <benbjiang@tencent.com>
Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c
index a2094aa1cb32d63577ab7299336b7014677cde4d..403f8ba76b9fbeb05ef13c44e8b019e3031895e7 100644 (file)
--- a/net/ipv6/exthdrs.c
+++ b/net/ipv6/exthdrs.c
@@ -994,33 +994,26 @@ drop:
 static bool ipv6_hop_jumbo(struct sk_buff *skb, int optoff)
 {
        const unsigned char *nh = skb_network_header(skb);
-       struct inet6_dev *idev = __in6_dev_get_safely(skb->dev);
-       struct net *net = ipv6_skb_net(skb);
        u32 pkt_len;
 
        if (nh[optoff + 1] != 4 || (optoff & 3) != 2) {
                net_dbg_ratelimited("ipv6_hop_jumbo: wrong jumbo opt length/alignment %d\n",
                                    nh[optoff+1]);
-               __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
                goto drop;
        }
 
        pkt_len = ntohl(*(__be32 *)(nh + optoff + 2));
        if (pkt_len <= IPV6_MAXPLEN) {
-               __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
                icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff+2);
                return false;
        }
        if (ipv6_hdr(skb)->payload_len) {
-               __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
                icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff);
                return false;
        }
 
-       if (pkt_len > skb->len - sizeof(struct ipv6hdr)) {
-               __IP6_INC_STATS(net, idev, IPSTATS_MIB_INTRUNCATEDPKTS);
+       if (pkt_len > skb->len - sizeof(struct ipv6hdr))
                goto drop;
-       }
 
        if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
                goto drop;