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Menglong Dong says: ==================== net: ip: add skb drop reasons to ip ingress In the series "net: use kfree_skb_reason() for ip/udp packet receive", skb drop reasons are added to the basic ingress path of IPv4. And in the series "net: use kfree_skb_reason() for ip/neighbour", the egress paths of IPv4 and IPv6 are handled. Related links: https://lore.kernel.org/netdev/20220205074739.543606-1-imagedong@tencent.com/ https://lore.kernel.org/netdev/20220226041831.2058437-1-imagedong@tencent.com/ Seems we still have a lot work to do with IP layer, including IPv6 basic ingress path, IPv4/IPv6 forwarding, IPv6 exthdrs, fragment and defrag, etc. In this series, skb drop reasons are added to the basic ingress path of IPv6 protocol and IPv4/IPv6 packet forwarding. Following functions, which are used for IPv6 packet receiving are handled: ip6_pkt_drop() ip6_rcv_core() ip6_protocol_deliver_rcu() And following functions that used for IPv6 TLV parse are handled: ip6_parse_tlv() ipv6_hop_ra() ipv6_hop_ioam() ipv6_hop_jumbo() ipv6_hop_calipso() ipv6_dest_hao() Besides, ip_forward() and ip6_forward(), which are used for IPv4/IPv6 forwarding, are also handled. And following new drop reasons are added: /* host unreachable, corresponding to IPSTATS_MIB_INADDRERRORS */ SKB_DROP_REASON_IP_INADDRERRORS /* network unreachable, corresponding to IPSTATS_MIB_INADDRERRORS */ SKB_DROP_REASON_IP_INNOROUTES /* packet size is too big, corresponding to * IPSTATS_MIB_INTOOBIGERRORS */ SKB_DROP_REASON_PKT_TOO_BIG In order to simply the definition and assignment for 'enum skb_drop_reason', some helper functions are introduced in the 1th patch. I'm not such if this is necessary, but it makes the code simpler. For example, we can replace the code: if (reason == SKB_DROP_REASON_NOT_SPECIFIED) reason = SKB_DROP_REASON_IP_INHDR; with: SKB_DR_OR(reason, IP_INHDR); In the 6th patch, the statistics for skb in ipv6_hop_jum() is removed, as I think it is redundant. 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. ====================================================================== Here is a basic test for IPv6 forwarding packet drop that monitored by 'dropwatch' tool: drop at: ip6_forward+0x81a/0xb70 (0xffffffff86c73f8a) origin: software input port ifindex: 7 timestamp: Wed Apr 13 11:51:06 2022 130010176 nsec protocol: 0x86dd length: 94 original length: 94 drop reason: IP_INADDRERRORS The origin cause of this case is that IPv6 doesn't allow to forward the packet with LOCAL-LINK saddr, and results the 'IP_INADDRERRORS' drop reason. ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
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